CC SR 20201219 01 - PB Landslide EIR Scoping
PUBLIC HEARING
Date: December 19, 2020
Subject:
Consideration and possible action to receive public comments on environmental issues to be
addressed in the Environmental Impact Report (EIR) for the Portuguese Bend Landslide Mitigation
Project.
Recommendation:
(1) Open the public hearing and receive public comments regarding environmental issues to be
addressed in the Environmental Impact Report (EIR) as stated in the Initial Study for the
Portuguese Bend Landslide Mitigation Project.
1. Report of Notice Given: Deputy City Clerk
2. Declare Public Hearing Open: Mayor Alegria
3. Request for Staff Report: Mayor Alegria
4. Staff Report & Recommendation: Ron Dragoo, Public Works Principal Civil Engineer
5. Council Questions of Staff (factual and without bias):
6. Testimony from members of the public:
The normal time limit for each speaker is three (3) minutes. The Presiding Officer may grant additional time to a representative speaking
for an entire group. The Mayor also may adjust the time limit for individual speakers depending upon the number of speakers who
intend to speak.
7. Declare Hearing Closed/or Continue the Public Hearing to a later date: Mayor Alegria
8. Council Deliberation:
The Council may ask staff to address questions raised by the testimony, or to clarify matters. Staff and/or Council may also answer
questions posed by speakers during their testimony. The Council will then debate and/or make motions on the matter.
9. Council Action:
The Council may: vote on the item; offer amendments or substitute motions to decide the matter; reopen the hearing for additional
testimony; continue the matter to a later date for a decision.
CITY COUNCIL MEETING DATE: 12/19/2020
AGENDA REPORT AGENDA HEADING: Public Hearing
AGENDA TITLE:
Consideration and possible action to receive public comments on environmental issues
to be addressed in the Environmental Impact Report (EIR) for the Portuguese Bend
Landslide Mitigation Project.
RECOMMENDED COUNCIL ACTION:
(1) Open the public hearing and receive public comments regarding environmental
issues to be addressed in the Environmental Impact Report (EIR) as stated in the
Initial Study for the Portuguese Bend Landslide Mitigation Project.
FISCAL IMPACT: None at this time
Amount Budgeted: N/A
Additional Appropriation: N/A
Account Number(s): N/A
ORIGINATED BY: Nasser Razepoor, PE, Associate Engineer
Ron Dragoo, PE, Principal Engineer
REVIEWED BY: Ramzi Awwad, PE, Deputy Director of Public Works
APPROVED BY: Ara Mihranian, AICP, City Manager
ATTACHED SUPPORTING DOCUMENTS:
A. Initial Study for Portuguese Bend Landslide Mitigation Project (page A–1)
B. December 17, 2019 City Council Staff Report accepting the design of the
Portuguese Bend Landslide Mitigation Project (page B-1)
C. December 18, 2018 Staff Report approving PSA for design (page C-1)
D. Project Design and Geotechnical Evaluation Report (page D-1)
E. IMAC Subcommittee Report (page E-1)
F. Public Comments (page F-1)
BACKGROUND:
On January 16, 2018, after a series of public workshops where input from residents was
received regarding ideas on minimizing land movement and on the anticipated effects
repairs would have on that movement, Staff presented City Council with a draft copy of
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a Feasibility Study addressing extensive work to stabilize the Portuguese Bend
Landslide complex. City Council received and filed the Updated Feasibility Study on
August 7, 2018.
On December 18, 2018, City Council approved the award of a new professional
services agreement for design services associated with the Portuguese Bend Landslide
Mitigation (PBLM) Project (Attachment C).
On December 17, 2019, following several meetings with staff, including meetings with
the Palos Verdes Peninsula Land Conservancy (PVPLC) and others, staff presented to
the City Council the proposed design drawings, hydrologic analysis, and geotechnical
analysis associated with the PBLM Project (Attachments B and D). After considering
public testimony, City Council accepted the proposed plan.
The proposed plan involves a series of recommended mitigation measures which follow
a phased approach to construction. Construction is likely to be implemented in stages,
which may occur separately. The anticipated construction phasing is ordered as follows:
(i) Surface Fracture Infilling: fill existing fissures ranging in width from a few feet
to 15 feet with flowable fill material to eliminate storm runoff from easily
becoming part of the groundwater;
(ii) Surface Water Improvements: install engineered swales, a flow reduction
area, a new pipe, and rehabilitate existing pipes and channels to convey
storm runoff and prevent it from easily becoming part of the groundwater; and
(iii) Groundwater Mitigation Improvements: install hydraugers to alleviate artesian
water pressure underground in the landslide area.
On December 17, 2019, City Council also authorized Staff to proceed with preparing the
project-required environmental documents pursuant to the California Environmental
Quality Act (CEQA). The environmental documents are intended to study and provide
information on the potential impacts the proposed project may have on the surrounding
environment and provide mitigation measures to reduce the potential impacts to a less
than significant level.
On May 19, 2020, the City Council approved the award of a professional services
agreement to Chambers Group, Inc. (consultant) to prepare the project-required
environmental documents. The scope of environmental assessment included
preparation of an Initial Study (IS) to determine whether a Mitigated Negative
Declaration (MND) or an Environmental Impact Report (EIR) would be appropriate for
the proposed project (Attachment A). An MND is prepared when the IS shows no
substantial evidence that a project may have a significant effect on the environment.
Should the results of the IS and technical reports identify that significant impacts may
occur that cannot be mitigated to a less than significant level or that other factors may
warrant a higher level of CEQA documentation, an EIR report will be prepared.
The IS has been prepared by the consultant, and it has been determined that the
project would require the preparation of an EIR. On November 12, 2020 A Notice of
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Preparation (NOP) announcing that a Draft Environmental Impact Report (DEIR) will be
prepared for the proposed project was released to the public for a comment or “scoping”
period (concluding on January 15, 2021, at 4:30pm).
The City Council is being asked to conduct a public hearing to receive verbal comments
on the environmental issues and topics to be addressed in the preparation of the project
EIR.
DISCUSSION:
The purpose of the NOP/IS is to provide public agencies and the general public an
opportunity to comment on what should be evaluated in the forthcoming DEIR.
Notification of the NOP/IS and information on how to view these documents was mailed
out to property owners within 500 feet of the project site, interested persons, posted on
the City’s Website, and is available for viewing at City Hall and Hesse Park. It was also
transmitted via list-serve on November 16, 2020. To access the Initial Study on the
City’s Website or other information regarding the proposed project, click on:
http://www.rpvca.gov/1031/Portuguese-Bend-Landslide. Due to the COVID 19
pandemic, viewing these documents at public libraries is not possible.
According to the Initial Study, the following environmental topics have the potential to be
significant as described in the Project’s Initial Study:
• Aesthetics
• Air Quality
• Biological Resources
• Cultural Resources
• Energy
• Geology/Soils
• Greenhouse Gas Emissions
• Hazards and Hazardous Materials
• Hydrology and Water Quality
• Land Use/Planning
• Noise
• Recreation
• Transportation
• Tribal Cultural Resources
• Utilities/Service Systems
• Wildfire
According to CEQA, the public comment period for the NOP/IS shall be at least 30 -days
during which time the City may elect to conduct a scoping meeting. The City has opted
to conduct a scoping meeting to provide the public with an opportunity to submit ve rbal
comments, in addition to the typical written comments, on environmental issues
associated with the proposed project (the comment period exceeds 60 days).
Comments should be focused on what environmental issues should be analyzed in the
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forthcoming DEIR document. The minutes from the scoping meeting and written
comments received during the NOP/IS comment period will be forwarded to the City’s
EIR consultant. The EIR consultant, working with City Staff, will then ensure that
germane environmental issues identified by the public are addressed in the forthcoming
DEIR. Comments made in support of the project or in opposition to the project are not
responded to as these comments should be considered by the decision makers at the
time the public meetings are held on the merits of the project. The DEIR is expected to
be completed and available to the public in June 2021.
The role of City Council at the scoping meeting will be simply to provide the forum for
the public to provide verbal comments on the NOP/IS.
This special Scoping Meeting will be held on December 19, 2020, at 12:30 PM, at
Hesse Park, McTaggart Hall, 29301 Hawthorne Boulevard, Rancho Palos Verdes, CA
90275. The meeting will be a Hybrid (in-person or virtual), via teleconference using the
Zoom platform. Additional information regarding this meeting is provided on the City’s
Website at www.rpvca.gov.
Staff envisions the scoping meeting to involve a brief presentation by staff and the EIR
consultant describing the project and EIR process followed by the opening of the public
hearing to hear comments from the public. At the conclusion of the public comments, City
Council will have an opportunity to offer their own verbal comments regarding the NOP/IS,
or provide written comments by the January 15, 2021 deadline .
Infrastructure Management Advisory Committee (IMAC)
At the Council’s pleasure, the IMAC is requesting a 15- to 20-minute time slot to present
their view of the proposed project. IMAC suggests that the efficiency and survivability of
the hydraugers is critical to the success of the project; and should therefore be the first
phase (Attachment E). IMAC also recommends considering an alternate location for an
existing pipe that would convey water from the flow reduction area across Palos Verdes
Drive South. Council may direct staff to include these elements as alternative in the EIR .
ADDITIONAL INFORMATION:
Public Notice
Pursuant to the State and City’s CEQA guidelines, On Thursday, November 12, 2020, the
NOP/IS was published in the Peninsula News. Following this, information on how to view
the NOP/IS was mailed to property owners within a 500-foot radius of the subject property,
interested parties and to list-serve subscribers. As previously noted, the public comment
period will end on Friday, January 15, 2021.
Public Comments
To date, the City has received 14 comment letters. Comments have been received from
the California Department of Transportation, the Native American Heritage Commission,
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and from residents. In general, comments from residents have primarily voiced concern
over the preservation and construction of trails (Attachment F).
Comment Letters or email submitted after the transmittal of this staff report and received
by the morning of December 19 meeting will be provided to the City Council at the
meeting. As previously reported, all comments received during the comment period will
be provided to the City’s environmental consultant for consideration in the preparation of
the project’s Draft EIR.
Estimated Project Timeline
The following is a tentative project schedule for the completion of the project EIR,
including the anticipated dates for the various public hearings on the project applications
and EIR (please note that the meeting dates are tentative and may change. A Ci ty
notice will announce the actual dates):
December 19, 2020 City Council Scoping Meeting
June 10, 2021 Release of the Draft EIR
August 16, 2021 City Council Hearing to receive comments on the Draft EIR
November 9, 2021 City Council Hearing and certification of Final EIR
City of Rolling Hills Sewer Project Study Update
The project plan approved by the City Council at its December 17, 2019 meeting
recommended that the upslope homes in the City of Rolling Hills consider the
installation of a sewer system to replace the septic systems currently serving homes in
the Flying Triangle area whose effluent groundwater could impact the Portuguese Bend
Landslide. A draft conceptual report has been prepared and staff is currently working
with Rolling Hills on the feasibility of a sewer collection/transmission system.
CONCLUSION:
Staff recommends opening the public hearing and receiving public comments regarding
environmental issues to be addressed in the Environmental Impact Report (EIR) for the
Portuguese Bend Landslide Mitigation Project.
ALTERNATIVES:
In addition to the Staff recommendations, the following action is available for the City
Council’s consideration:
1. Take other action as deemed appropriate by the City Council.
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PORTUGESE BEND LANDSLIDE MITIGATION
PROJECT
RANCHO PALOS VERDES, CALIFORNIA
Prepared for:
CITY OF RANCHO PALOS VERDES
30940 Hawthorne Boulevard
Rancho Palos Verdes, California 90275
Prepared by:
CHAMBERS GROUP, INC.
5 Hutton Centre Drive, Suite 750
Santa Ana, California 92707
(949) 261-5414
November 2020
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TABLE OF CONTENTS
Page
SECTION 1.0 – PROJECT DESCRIPTION AND ENVIRONMENTAL SETTING ................................................. 5
1.1 PROJECT BACKGROUND AND PURPOSE.................................................................................... 5
1.2 PROJECT LOCATION AND SITE CHARACTERISTICS ..................................................................... 5
1.2.1 General Plan Designation/Zoning ................................................................................. 5
1.2.2 Surrounding Land Uses ................................................................................................ 5
1.3 PROJECT DESCRIPTION ........................................................................................................... 11
1.4 PROJECT CONSTRUCTION ...................................................................................................... 11
1.4.1 Construction Phase I -Surface Fracture Infilling .......................................................... 11
1.4.2 Construction Phase II – Surface Water Improvements................................................ 11
1.4.3 Construction Phase III – Groundwater Mitigation Drains (Hydraugers) ....................... 12
1.5 REQUIRED PERMITS AND APPROVALS .................................................................................... 15
1.5.1 Lead Agency Approval ............................................................................................... 15
1.5.2 Reviewing Agencies ................................................................................................... 15
SECTION 2.0 – ENVIRONMENTAL DETERMINATION .............................................................................. 16
2.1 ENVIRONMENTAL FACTORS POTENTIALLY AFFECTED: ............................................................ 16
2.2 DETERMINATION ................................................................................................................... 16
SECTION 3.0 – EVALUATION OF ENVIRONMENTAL IMPACTS .................................................................. 1
SECTION 4.0 – CHECKLIST OF ENVIRONMENTAL ISSUES.......................................................................... 3
4.1 AESTHETICS ............................................................................................................................. 3
Impact Analysis ........................................................................................................................ 3
4.2 AGRICULTURE & FORESTRY RESOURCES................................................................................... 4
Impact Analysis ........................................................................................................................ 5
4.3 AIR QUALITY ............................................................................................................................ 6
Impact Analysis ........................................................................................................................ 6
4.4 BIOLOGICAL RESOURCES .......................................................................................................... 7
Impact Analysis ........................................................................................................................ 8
4.5 CULTURAL RESOURCES ............................................................................................................ 9
Impact Analysis ........................................................................................................................ 9
4.6 ENERGY ................................................................................................................................. 10
Impact Analysis ...................................................................................................................... 10
4.7 GEOLOGY AND SOILS ............................................................................................................. 11
Impact Analysis ...................................................................................................................... 11
4.8 GREENHOUSE GAS EMISSIONS ............................................................................................... 13
Impact Analysis ...................................................................................................................... 13
4.9 HAZARDS AND HAZARDOUS MATERIALS ................................................................................ 14
Impact Analysis ...................................................................................................................... 14
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4.10 HYDROLOGY AND WATER QUALITY ........................................................................................ 16
Impact Analysis ...................................................................................................................... 17
4.11 LAND USE AND PLANNING ..................................................................................................... 19
Impact Analysis ...................................................................................................................... 19
4.12 MINERAL RESOURCES ............................................................................................................ 19
Impact Analysis ...................................................................................................................... 19
4.13 NOISE .................................................................................................................................... 20
Impact Analysis ...................................................................................................................... 20
4.14 POPULATION AND HOUSING .................................................................................................. 21
Impact Analysis ...................................................................................................................... 21
4.15 PUBLIC SERVICES ................................................................................................................... 22
Impact Analysis ...................................................................................................................... 22
4.16 RECREATION .......................................................................................................................... 23
Impact Analysis ...................................................................................................................... 23
4.17 TRANSPORTATION ................................................................................................................. 24
Impact Analysis ...................................................................................................................... 24
4.18 TRIBAL CULTURAL RESOURCES ............................................................................................... 25
Impact Analysis ...................................................................................................................... 25
4.19 UTILITIES AND SERVICE SYSTEMS ........................................................................................... 26
Impact Analysis ...................................................................................................................... 27
4.20 WILDFIRE ............................................................................................................................... 28
Impact Analysis ...................................................................................................................... 29
4.21 MANDATORY FINDINGS OF SIGNIFICANCE ............................................................................. 30
Impact Analysis ...................................................................................................................... 30
SECTION 5.0 – REFERENCES ................................................................................................................... 32
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LIST OF FIGURES
Page
Figure 1: Project Site Location ................................................................................................................. 6
Figure 2: Palos Verdes Peninsula Land Conservancy Areas ....................................................................... 7
Figure 3: Land Use Designation ................................................................................................................ 8
Figure 4: Zoning ....................................................................................................................................... 9
Figure 5: Coastal Specific Plan ................................................................................................................ 10
Figure 6: Staging Areas .......................................................................................................................... 13
Figure 7: Hydrauger Locations ............................................................................................................... 14
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SECTION 1.0 – PROJECT DESCRIPTION AND ENVIRONMENTAL SETTING
1.1 PROJECT BACKGROUND AND PURPOSE
The Portuguese Bend Landslide began moving in 1956, and continued land movement has resulted in
significant infrastructure damage to homes, utilities, and roadways. The City of Rancho Palos Verdes (City)
and its citizens are seeking to control the landslide to preserve infrastructures, open lands, preserve
natural vegetation and recreational features of the Palos Verdes Nature Preserve, reduce soil erosion
loses, and reduce health and safety concerns related to the integrity of the surrounding road system,
sewer system and other infrastructure (proposed Project).
1.2 PROJECT LOCATION AND SITE CHARACTERISTICS
The Portuguese Bend Landslide Complex (PBLC) is located along the south section of the Palos Verdes
Peninsula within the City (Project Site). The terminus of the active landslide complex, and generally the
southwest boundary of the PBLC is the Pacific Ocean as seen in Figure 1, Project Site Location. The PBLC
area is approximately 285 acres, however the area of land which contributes to the landslide instability is
much larger, and approximately 750 acres. The Project Site also includes approximately 96 acres of
preserve land associated with the Palos Verdes Peninsula Land Conservancy, Portuguese Bend and
Abalone Cove conservancy areas as shown in Figure 2, Palos Verdes Peninsula Land Conservancy Areas.
Several residences exist on the northwestern side of the Project Site while a series of trail networks are
located on the eastern side of the Project Site and south of Palos Verdes Drive South. Vegetation consist
of mostly native coastal vegetation. Due to the land sliding, surface fractures exist throughout the site. As
previously mentioned, the Pacific Ocean is located south of the Project Site which contains several coastal
bluffs.
Two parks exist within the Project Site boundaries; the Abalone Cove Shoreline Park which features two
beach areas (Abalone Cove and Sacred Cove) and Founders Park which is approximately 5.5 acres located
within the northern portion of the site.
1.2.1 General Plan Designation/Zoning
The General Plan Land Use Element designates the site as agricultural/socio-cultural and
agricultural/residential (≤1 dwelling unit per acre) (General Plan Land Use Map 1975) as shown in Figure
3, Land Use Designation. The Project Site is zoned as open space – hazard (oh) (City of Rancho Palos
Verdes 2012) as shown in Figure 4, Zoning. Additionally, a portion of the Project Site is located within the
Coastal Specific Plan Area designated as mostly hazard area and partially as agricultural area (City of
Rancho Palos Verdes 1978) as shown in Figure 5, Coastal Specific Plan. Portions of the Project Site are
also located in the City’s OC-3 Urban Appearance Overlay Control District.
1.2.2 Surrounding Land Uses
Surrounding the Project Site are residential uses to the east and west. Directly north of the Project Site is
more of the Portuguese Bend Preserve followed by additional residential uses. The Pacific Ocean is located
to the south of the Project Site.
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SanBernardino
Kern
SanLuisObispo
Ventura
Santa Barbara
RiversideOrange
Los Angeles
San Diego
1:24,000 1:5,000,000
Figure 1
Portuguese Bend Landslide Mitigation
Project Site Location
Name: 21243 PLAN Fig 1 Project Site Location.Mxd
Print Date: 10/21/2020, Author: pcarlos
Project Site Location
0 600 1,200300
Feet
´
")
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Figure 2
Portuguese Bend Landslide Mitigation
Palos Verdes Peinsula Conservancy Areas
Name: 21243 PLAN Fig 2 Palos Verdes Peninsula Land Conservancy Areas.Mxd
Print Date: 10/26/2020, Author: pcarlos
Project Site Location
Conservancy Areas
0 2,000 4,0001,000
Feet
´
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R 1-2/OH
OSP
R 1-2
OH
R <= 1
RP
RP
RP
OHR 1-2
R 1-2
OSP
OSP
OSPR <= 1
R <= 1
R 1-2
R -2-4
OH
Figure 3
Portuguese Bend Landslide Mitigation
Land Use Designation
Name: 21243 PLAN Fig 3 Land Use Designation.Mxd
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0 500 1,000250
Feet
´
Project Site Location
Land Use Designation
Open Space Hazard
Open Space Preservation
Recreational Passive
Residential 1-2 DU/Acre
Residential 1-2/Open Space
Residential 2-4 DU/Acre
Residential <= 1 DU/Acre
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OH
OH
OH
OH
OH
OH
OH
OHOR
OR
RS-1
RS-1
RS-1
RS-1
RS-1 RS-1
RS-1
RS-1
RS-2
RS-2
RS-2
RS-4
RS-1
Figure 4
Portuguese Bend Landslide Mitigation
Zoning
Name: 21243 PLAN Fig 4 Zoning.Mxd
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0 500 1,000250
Feet
´
Project Site LocationZoning
Open Space - Hazard
Open Space - Recreational
Residential Single - Lot > 1 Acre
Residential Single - Lot > 20;000 Square Feet A-9
Figure 5Portuguese Bend Landslide Mitigation Coastal Specific Plan
Name: 21243 PLAN Fig 5 Coastal Specific Plan.Mx d Print Date: 10/21/2020, Author: pcarlos
0 500 1,000250
Feet
´Coastal Specific Plan
Natural
Control Districts
Hazard Areas Residential - ≤ 1 d.u./acres
Parkland
Project Site Location
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1.3 PROJECT DESCRIPTION
The Portuguese Bend Landslide Mitigation Project (Project) would control the existing landslide area. The
proposed Project involves a series of recommended mitigation measures which follow a phased-approach
to construction and installation. The construction is likely to be implemented in stages, which may occur
separately. The anticipated construction phasing as follows: (i) surface fracture infilling; (ii) surface water
improvements; and (iii) groundwater mitigation improvements. Periodic field observation should be
performed during construction under the supervision of the appropriate California registered Engineer.
Post-construction items are anticipated to include long-term maintenance, landslide monitoring, and
possible future construction phases.
1.4 PROJECT CONSTRUCTION
The construction of the Project would last up to approximately 14 months for Phase I and Phase II. The
time required for Phase III will rely on the outcome of these two phases. Construction would occur
between the hours of Monday through Friday 7:00 a.m. and 6:00 p.m. and Saturday 9:00 am and 5:00 pm
with the exception of Sundays and federal holidays in accordance with City noise standards.
Two separate staging areas will be utilized for construction equipment as shown in Figure 6, Staging Areas.
Construction activities would be expected to include site preparation, fencing, mowing, grading, drilling,
etc. Site preparation would involve access paths, working platforms, staging areas, and other temporary
site features as needed to perform the construction. These items would be established in the field during
the construction mobilization. Site preparation and construction of the Project would be in accordance
with all federal, state, and City zoning codes and requirements. Noise-generating construction activities
would be limited to the construction hours noted above. All stationary equipment and machines with the
potential to generate a significant increase in noise or vibration levels would be located away from noise
receptors to the extent practicable. The contractor would conduct construction activities in such a manner
that the maximum noise levels at the affected buildings would not exceed established noise levels.
1.4.1 Construction Phase I -Surface Fracture Infilling
Surface fracture infilling will be performed during the first phase of construction. These existing fractures
are a few feet wide and some are as deep as 15 feet. The fractures intercept stormwater runoff where
this water discharges into the ground. The identified fractures should be infilled with a controlled low
strength flowable/pumpable fly ash-based slurry conforming to the Standard Specification Section 201-6,
Controlled low strength material and the associated mix design. This is intended to eliminate storm runoff
from easily becoming part of the groundwater and is an important component in efforts to minimize
landslide-related ground movement.
After the initial fracture infilling event, the City will perform period ic observation to identify fractures
which may open in the future due to ongoing landslide movement. Fractures identified during periodic
observation should be infilled as part of post-construction maintenance.
1.4.2 Construction Phase II – Surface Water Improvements
Surface water improvements will be installed, which include the following:
▪ Engineered swales;
▪ Flow reduction area (approximately 8 acres);
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▪ Installation of new 36-inch-diameter pipe below Burma Road using trenchless techniques;
▪ Removal and disposal of existing 36-inch-diameter plastic pipe south of Palos Verdes Drive South
and replacement with thick-walled fusion-welded plastic pipe;
▪ Refurbishment (i.e., cleanout, lining with smooth polymeric material, and structural retrofit if
needed) of existing 60-inch-diameter pipe below Palos Verdes Drive South.
1.4.3 Construction Phase III – Groundwater Mitigation Drains (Hydraugers)
Hydraugers will be constructed below grade and designed to alleviate artesian water pressure
underground in the landslide area. These will be installed horizontally, beneath the active movement zone
of the landslide. Approximate locations of the hydraugers are shown in Figure 7, Hydrauger Locations.
The groundwater mitigation program is planned to be implemented in three sub-phases. The sub-phases
generally consist of: (i) preparatory work and instrumentation; (ii) installation of up-gradient drains using
horizontal drilling; and (iii) installation of down-gradient drains using directional drilling. The pace and
sequence of construction within each sub-phase is likely to require adjustment based on field
observations.
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Primary Staging Area
Secondary Staging Area
Figure 6
Portuguese Bend Landslide Mitigation
Staging Areas
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Project Site Location
Staging Areas
0 500 1,000250
Feet
´
A-13
A2
A3
A4
A1
A6A5
Figure 7
Portuguese Bend Landslide Mitigation
Hydrauger Locations
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Project Site Location
Hydrauger Locations
Directional/Gravity Flow
Directional/Pump Assisted Flow
Horizontal/Gravity Flow 0 500 1,000250
Feet
´
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1.5 REQUIRED PERMITS AND APPROVALS
As required by the CEQA Guidelines, this section provides, to the extent the information is known, a list of
the agencies that are expected to use this Initial Study (IS) in their decision making and a list of permits
and other approvals required to implement the project. The project will obtain or comply with the
following permits:
▪ Clean Water Act Section 404 Permit
▪ Clean Water Act Section 401 Water Quality Certification
▪ California Department of Fish and Game Code Section 1602 (Streambed Alteration Notification)
▪ Construction General Permit Order 2009-0009-DWQ
▪ Potential local or county permits, as applicable
1.5.1 Lead Agency Approval
The Environmental Analysis or Environmental Impact Report must be certified by the City Council (Council)
as to its adequacy in complying with the requirements of the California Environmental Quality Act (CEQA)
before taking any action on the proposed Project. The Council will consider the information contained in
the EIR in making a decision to approve or deny the proposed Project. The analysis in the EIR is intended
to provide environmental review for the whole of the proposed Project, including the project planning,
site clearance, site excavation, and installation of project improvements in accordance with CEQA
requirements.
The lead agency for the proposed Project would be the City of Rancho Palos Verdes.
1.5.2 Reviewing Agencies
Reviewing Agencies include those agencies that do not have discretionary powers but that may review
the Environmental Analysis or EIR for adequacy and accuracy. Potential Reviewing Agencies include the
following:
State Agencies
▪ California Coastal Commission
▪ California Department of Fish and Wildlife
▪ United States Army Corps of Engineers
▪ California Department of Water Resources
Regional Agencies
▪ Palos Verdes Peninsula Land Conservancy
▪ Portuguese Bend Sewer District
▪ Abalone Cove Landslide Abatement District
▪ Los Angeles County Fire Department
▪ Los Angeles County Sheriff’s Department
▪ South Coast Air Quality Management District
▪ Los Angeles County Flood Control District
▪ Sanitation District of Los Angeles County
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SECTION 2.0 – ENVIRONMENTAL DETERMINATION
2.1 ENVIRONMENTAL FACTORS POTENTIALLY AFFECTED:
The environmental factors checked below would potentially be affected by this project, involving at least
one impact that is a “Potentially Significant Impact," as indicated by the checklists on the following pages.
For each of the potentially affected factors, mitigation measures are recommended that would reduce the
impacts to less than significant levels.
Aesthetics Agriculture and Forestry Resources Air Quality
Biological Resources Cultural Resources Energy
Geology /Soils Greenhouse Gas Emissions Hazards & Hazardous Materials
Hydrology /Water Quality Land Use / Planning Mineral Resources
Noise Population / Housing Public Services
Recreation Transportation Tribal Cultural Resources
Utilities /Service Systems Wildfire Mandatory Findings of Significance
2.2 DETERMINATION
On the basis of this initial evaluation:
1. I find that the project could not have a significant effect on the environment, and a
NEGATIVE DECLARATION will be prepared.
2. I find that although the proposed project could have a significant effect on the
environment, there will not be a significant effect in this case because revisions in the
project have been made by or agreed to by the project proponent. A MITIGATED
NEGATIVE DECLARATION will be prepared.
3. I find the proposed project may have a significant effect on the environment, and an
ENVIRONMENTAL IMPACT REPORT is required.
4. I find that the proposed project may have a “potentially significant impact” or
“potentially significant unless mitigated impact” on the environment, but at least one
effect (1) has been adequately analyzed in an earlier document pursuant to applicable
legal standards, and (2) has been addressed by mitigation measures based on the earlier
analysis as described on attached sheets. An ENVIRONMENTAL IMPACT REPORT is
required, but it must analyze only the effects that remain to be addressed.
5. I find that although the proposed project could have a significant effect on the
environment, because all potentially significant effects (a) have been analyzed
adequately in an earlier EIR or Negative Declaration pursuant to applicable standards,
and (b) have been avoided or mitigated pursuant to that earlier EIR or Negative
Declaration, including revisions or mitigation measures that are imposed upon the
proposed project, nothing further is required.
Signature Date
Name Title
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SECTION 3.0 – EVALUATION OF ENVIRONMENTAL IMPACTS
1. A brief explanation is required for all answers except “No Impact” answers that are adequately
supported by the information sources a lead agency cites. A “No Impact” answer is adequately
supported if the referenced information sources show that the impact simply does not apply to
projects like the one involved (e.g., the project falls outside a fault rupture zone). A “No Impact”
answer should be explained where it is based on project-specific factors as well as general standards
(e.g., the project will not expose sensitive receptors to pollutants, based on a project-specific
screening analysis).
2. All answers must take account of the whole action involved, including offsite as well as onsite,
cumulative as well as project-level, indirect as well as direct, and construction as well as operational
impacts.
3. Once the lead agency has determined that a particular physical impact may occur, then the checklist
answers must indicate whether the impact is potentially significant, less than significant with
mitigation, or less than significant. “Potentially Significant Impact” is appropriate if substantial
evidence exists that an effect may be significant. If one or more “Potentially Significant Impact” entries
are marked when the determination is made, an EIR is required.
4. “Negative Declaration: Less Than Significant With Mitigation Incorporated” applies where the
incorporation of mitigation measures has reduced an effect from “Potentially Significant Impact” to a
“Less Than Significant Impact.” The lead agency must describe the mitigation measures and briefly
explain how they reduce the effect to a less than significant level (mitigation measures from earlier
analyses may be cross-referenced).
5. Earlier analyses may be used where, pursuant to the tiering, program EIR, or other CEQA process, an
effect has been adequately analyzed in an earlier EIR or negative declaration. Section 15063(c)(3)(D).
In this case, a brief discussion should identify the following:
a. Earlier Analysis Used. Identify and state where they are available for review.
b. Impacts Adequately Addressed. Identify which effects from the above checklist were within the
scope of and adequately analyzed in an earlier document pursuant to applicable legal standards,
and state whether such effects were addressed by mitigation measures based on the earlier
analysis.
c. Mitigation Measures. For effects that are “Less than Significant with Mitigation Measures
Incorporated,” describe the mitigation measures which were incorporated or refined from the
earlier document and the extent to which they address site-specific conditions for the project.
6. Lead agencies are encouraged to incorporate into the checklist references to information sources for
potential impacts (e.g., general plans, zoning ordinances). Reference to a previously prepared or
outside document should, where appropriate, include a reference to the page or pages where the
statement is substantiated.
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7. Supporting Information Sources: A source list should be attached, and other sources used or
individuals contacted should be cited in the discussion.
8. The explanation of each issue should identify:
a. the significance criteria or threshold, if any, used to evaluate each question; and
b. the mitigation measure identified, if any, to reduce the impact to less than significant.
*Note: Instructions may be omitted from final document.
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SECTION 4.0 – CHECKLIST OF ENVIRONMENTAL ISSUES
4.1 AESTHETICS
1.
AESTHETICS.
Except as provided in Public Resources Code
Section 21099, would the project:
Potentially
Significant
Impact
Less than
Significant
With
Mitigation
Incorporated
Less Than
Significant
Impact
No
Impact
(a) Have a substantial adverse effect on a scenic vista?
(b) Substantially damage scenic resources, including, but
not limited to, trees, rock outcroppings, and historic
buildings within a state scenic highway?
(c) In non-urbanized areas, substantially degrade the
existing visual character or quality of public views of
the site and its surroundings? (Public views are those
that are experienced from publicly accessible
vantage point). If the project is in an urbanized area,
would the project conflict with applicable zoning and
other regulations governing scenic quality?
(d) Create a new source of substantial light or glare
which would adversely affect day or nighttime views
in the area?
Impact Analysis
a) Would the project have a substantial adverse effect on a scenic vista?
Potentially Significant Impact. The Project Site is located partially within the Coastal Zone with views
of the Pacific Ocean in an area containing scenic and visual qualities. The proposed Project would
close some existing fissures on the site and may have the potential to impact a scenic vista. A detailed
analysis of the potential impacts on visual resources, including those to scenic vistas, will be included
in the EIR.
b) Would the project substantially damage scenic resources, including, but not limited to, trees, rock
outcroppings, and historic buildings within a state scenic highway?
No Impact. The Project Site does not contain scenic trees, rock outcroppings, historic buildings or
other known scenic resources. Further, the nearest scenic highway is located over 13 miles northeast
of the Project Site (Caltrans 2020) For these reasons, there would be no impact in this regard and no
further discussion is required.
c) Would the project, in non-urbanized areas, substantially degrade the existing visual character or
quality of public views of the site and its surroundings? (Public views are those that are experienced
from publicly accessible vantage point). If the project is in an urbanized area, would the project conflict
with applicable zoning and other regulations governing scenic quality?
Less than Significant Impact. The Project is largely undeveloped land within an urbanized area. The
repair of the Rancho Palos Verdes Landslide Complex would further prevent the hillside from eroding
into the ocean which would long term improve the aesthetic of the area. Construction of the Project
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would temporarily impact the scenic quality of the site due to construction equipment as discussed
in (a) above; however, the project is considered necessary for erosion mitigation. Therefore, there
would be no conflict with applicable zoning or other regulations governing scenic quality. Impacts
would be less than significant, and no further discussion is required.
d) Create a new source of substantial light or glare which would adversely affect day or nigh ttime views
in the area?
Less than Significant Impact. Construction of the proposed Project would be required to adhere to
Rancho Palos Verdes Municipal Code (RPVMC) §17.56.020 which allows construction from 7:00 AM
to 6:00 PM Monday through Friday and 9:00 AM to 5:00 PM on Saturdays therefore lighting would
not be required during construction. Construction the proposed Project would require construction
equipment which may result in temporary glare impacts. However, these glare impacts would be
temporary and would cease upon completion of the Project.
Operation of the proposed Project would not construct any structures or buildings that would result
in permanent increases to lighting or glare. Impacts would be less than significant and no further
discussion is required.
4.2 AGRICULTURE & FORESTRY RESOURCES
2.
AGRICULTURE & FOREST RESOURCES.
(In determining whether impacts to agricultural
resources are significant environmental effects,
lead agencies may refer to the California
Agricultural Land Evaluation and Site Assessment
Model (1997) prepared by the California
Department of Conservation as an optional model
to use in assessing impacts on agriculture and
farmland. In determining whether impacts to
forest resources, including timberland, are
significant environmental effects, lead agencies
may refer to information compiled by the
California Department of Forestry and Fire
Protection regarding the state’s inventory of forest
land, including the Forest and Range Assessment
Project and the Forest Legacy Assessment project;
and forest carbon measurement methodology
provided in Forest Protocols adopted by the
California Air Resources Board. Would the project:
Potentially
Significant
Impact
Less than
Significant
With
Mitigation
Incorporated
Less Than
Significant
Impact
No
Impact
(a) Convert Prime Farmland, Unique Farmland, or
Farmland of Statewide Importance (Farmland), as
shown on the maps prepared pursuant to the
Farmland Mapping and Monitoring Program of the
California Resources Agency, to non-agricultural
use?
(b) Conflict with existing zoning for agricultural use, or a
Williamson Act contract?
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(c) Conflict with existing zoning for, or cause rezoning of,
forest land (as defined in Public Resources Code
section 12220(g)), timberland (as defined by Public
Resources Code section 4526), or timberland zoned
Timberland Production (as defined by Government
Code section 51104(g))?
(d) Result in the loss of forest land or conversion of
forest land to non-forest use?
(e) Involve other changes in the existing environment
which, due to their location or nature, could result in
conversion of Farmland, to non-agricultural use or
the conversion of forest land to non-forest use?
Impact Analysis
a) Would the project convert Prime Farmland, Unique Farmland, or Farmland of Statewide Importance
(Farmland), as shown on the maps prepared pursuant to the Farmland Mapping and Monitoring
Program of the California Resources Agency, to non -agricultural use?
No Impact. The General Plan notes that the Portuguese Bend slide area is the first major agricultural
area (City of Rancho Palos Verdes 1975). The General Plan Land Use Element designates the site as
agricultural/socio-cultural and agricultural/residential (≤1 dwelling unit per acre) (City of Rancho Palos
Verdes 1975). The Project Site is zoned as open space – hazard (oh) (City of Rancho Palos Verdes 2012)
and is not currently used for agricultural uses. The Project Site is listed as an area which falls outside
of the Natural Resources Conservation Service (NRCS) soils survey area, not mapped by the Farmland
Mapping and Monitoring Program (FMMP) (DOC 2016). This site is not identified as Prime Farmland,
Unique Farmland, or Farmland of Statewide Importance. Therefore, there would be no impacts to
important farmland and no further discussion is required.
b) Would the project conflict with existing zoning for agricultural use, or a Williamson Act contract?
No Impact. As previously mentioned, the Project Site is zoned as oh and is not under a Williamson Act
Contract (DOC 2019). No impact to land zoned for agricultural use or subject to a Williamson Act
Contract would occur and no further discussion is required.
c) Would the project conflict with existing zoning for, or cause rezoning of, forest land (as defined in
Public Resources Code section 12220(g)), timberland (as defined by Public Resources Code section
4526), or timberland zoned Timberland Production (as defined by Government Code section
51104(g))?
No Impact. The Project Site is zoned as oh. No impact to land zoned as forestland, timberland, or
Timberland Production land would occur and no further discussion is required.
d) Would the project result in the loss of forest land or conversion of forest land to non-forest use?
No Impact. The Project Site is not forest land, therefore no impact to forest land would occur and no
further discussion is required.
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e) Would the project involve other changes in the existing environment which, due to their location or
nature, could result in conversion of Farmland, to non -agricultural use or the conversion of forest land
to non-forest use?
No Impact. Agricultural uses and forest land are not located in the immediate vicinity or on the Project
Site. The Project Site is surrounded by residential uses to the east and west, and open space uses to
the north. No impact would occur and no further discussion is required.
4.3 AIR QUALITY
3.
AIR QUALITY.
Where available, the significance criteria
established by the applicable air quality
management district or air pollution control
district may be relied upon to make the following
determinations. Would the project:
Potentially
Significant
Impact
Less than
Significant
With
Mitigation
Incorporated
Less Than
Significant
Impact
No
Impact
(a) Conflict with or obstruct implementation of the
applicable air quality plan?
(b) Result in a cumulatively considerable net increase of
any criteria pollutant for which the project region is
non-attainment under an applicable federal or state
ambient air quality standard?
(c) Expose sensitive receptors to substantial pollutant
concentrations?
(d) Result in other emissions (such as those leading to
odors) adversely affecting a substantial number of
people?
Impact Analysis
a) Would the project conflict with or obstruct implementation of the applicable air quality plan?
Potentially Significant Impact. The South Coast Air Quality Management District (SCAQMD)
monitors air quality within the South Coast Air Basin, which includes the portion of Los Angeles
County containing the Project Site. The proposed Project would control the Rancho Palos Verdes
Landslide Complex to prevent further sliding in the area. It is not anticipated that a substantial
number of new vehicle trips would be created. Thus, long-term air quality impacts during the
operational phase are not anticipated. An air quality and greenhouse gases technical report will
be prepared for the proposed Project to determine whether short-term construction emissions
would exceed the emissions budgeted for the Project Site in the applicable air quality
management plan. Further analysis is required and will be included in the EIR.
b) Would the project result in a cumulatively considerable net increase of any criteria pollutant for
which the project region is non-attainment under an applicable federal or state ambient air quality
standard?
Potentially Significant Impact. The SCAQMD recommends that a project’s potential contribution
to cumulative impacts should be assessed utilizing the same significance criteria as those for
project specific impacts. The air quality technical report prepared for the proposed Project will
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evaluate the potential for cumulative air quality impacts. Further analysis is required and will be
included in the EIR.
c) Would the project expose sensitive receptors to substantial pollutant concentrations ?
Potentially Significant Impact. The SCAQMD indicates that sensitive receptors include residences,
schools, playgrounds, child care centers, athletic facilities, long -term health care facilities,
rehabilitation centers, convalescent centers, and retirement homes. Operation of the proposed
Project would not be anticipated to generate substantial new sources of pollutant concentrations.
The air quality technical report prepared for the proposed Project will evaluate the potential for
individual receptors to be exposed to unhealthful pollutant concentrations during construction.
Further analysis is required and will be included in the EIR.
d) Would the project result in other emissions (such as those leading to odors ) adversely affecting a
substantial number of people?
Potentially Significant Impact. Construction activities may result in short-term fugitive dust or
other potential emissions. Further evaluation of the significance of this impact is required and will
be included in the EIR.
4.4 BIOLOGICAL RESOURCES
4. BIOLOGICAL RESOURCES.
Would the project:
Potentially
Significant
Impact
Less than
Significant
With
Mitigation
Incorporated
Less Than
Significant
Impact
No
Impact
(a) Have a substantial adverse effect, either directly or
through habitat modifications, on any species
identified as a candidate, sensitive, or special status
species in local or regional plans, policies, or
regulations, or by the California Department of Fish
and Game or U.S. Fish and Wildlife Service?
(b) Have a substantial adverse effect on any riparian
habitat or other sensitive natural community
identified in local or regional plans, policies,
regulations or by the California Department of Fish
and Wildlife or U.S. Fish and Wildlife Service?
(c) Have a substantial adverse effect on state or
federally protected wetlands (including, but not
limited to, marsh, vernal pool, coastal, etc.) through
direct removal, filling, hydrological interruption, or
other means?
(d) Interfere substantially with the movement of any
native resident or migratory fish or wildlife species or
with established native resident or migratory wildlife
corridors, or impede the use of native wildlife
nursery sites?
(e) Conflict with any local policies or ordinances
protecting biological resources, such as a tree
preservation policy or ordinance?
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4. BIOLOGICAL RESOURCES.
Would the project:
Potentially
Significant
Impact
Less than
Significant
With
Mitigation
Incorporated
Less Than
Significant
Impact
No
Impact
(f) Conflict with the provisions of an adopted Habitat
Conservation Plan, Natural Community Conservation
Plan, or other approved local, regional, or state
habitat conservation plan?
Impact Analysis
a) Would the project have a substantial adverse effect, either directly or through habitat modification,
on any species identified as candidate, sensitive or special status species in local or regional plans,
policies or regulations, or by the California Department of Fish and Game or U.S. Fish and Wildlife
Service?
Potentially Significant Impact. The proposed Project area is undisturbed open space. There is a
potential for the site to contain habitat that is potentially suitable for sensitive and/or special status
plant and wildlife species. However, a natural community conservation plan (NCCP)/habitat
conservation plan (HCP) was prepared to maximize benefits to wildlife and vegetation communities
and provide for the comprehensive management and conservation of various listed and/or sensitive
species. The Rancho Palos Verdes NCCP and HCP that was adopted in 2019. Project conformance with
the NCCP will be required, and mitigation measures will be incorporated. A biological resources
technical report will be prepared to evaluate potential impacts to sensitive and/or special status
species. Further analysis is required and will be included in the EIR.
b) Would the project have a substantial adverse effect on any riparian habitat or other sensitive natural
community identified in local or regional plans, policies or regulations, or by the California Department
of Fish and Wildlife or U.S. Fish and Wildlife Service?
Potentially Significant Impact. According to the U.S. Fish and Wildlife (USFWS) National Wetlands
Inventory there are two dry rivers that run through the Project Site classified as Riverine habitat
(USFWS 2020). The biological resources technical report prepared for the proposed Project will
identify any potential impacts on riparian habitat. Further analysis is required and will be included in
the EIR.
c) Would the project have a substantial adverse effect on state or federally protected wetlands (including
but not limited to marsh, vernal pool, coastal, etc.) through direct removal, filling, hydrological
interruption, or other means?
Potentially Significant Impact. As previously mentioned, there are two USFWS riverine designated
streams on the Project Site. Additionally, runoff from the Project Site travels directly into the Pacific
Ocean identified as USFWS as estuarine and marine wetland. The biological resources technical report
prepared for the proposed Project will identify any potential impacts to wetlands. Further analysis is
required and will be included in the EIR.
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d) Would the project Interfere substantially with the movement of any native resident or migratory fish
or wildlife species or with established native resident or migratory wildlife corridors, or impede the use
of native wildlife nursery sites?
Potentially Significant Impact. As previously mentioned, the Project Site may contain habitat suitable
to support a sensitive natural community and wildlife corridors. The biological resources technical
report prepared for the proposed Project will evaluate potential impacts to sensitive habitat and
wildlife corridors. While the Project does not propose development of structures that would impeded
wildlife movement or migration, further analysis is warranted.
e) Would the project conflict with any local policies or ordinances protecting biological resources, such
as a tree preservation policy or ordinance?
Potentially Significant Impact. The biological resources technical report prepared for the proposed
Project will identify protected biological resources on the Project Site (if any), as well as potential
impacts to policies or ordinances protecting such resources. Further analysis is required and will be
included in the EIR.
f) Would the project conflict with the provisions of an adopted Habitat Conservation Plan, Natural
Conservancy Conservation Plan, or other approved local, regional, or state habitat conservation plan?
Potentially Significant Impact. The City’s General Plan designates portions of the Project Site as
wildlife habitat area for preservation (City of Rancho Palos Verdes 1975). The biological resources
technical report prepared for the proposed Project will assess the any potential impacts to such
conservation and habitat plans. Further analysis is required and will be included in the EIR.
4.5 CULTURAL RESOURCES
5. CULTURAL RESOURCES.
Would the project:
Potentially
Significant
Impact
Less than
Significant
With
Mitigation
Incorporated
Less Than
Significant
Impact
No
Impact
(a) Cause a substantial adverse change in the
significance of a historical resource pursuant to
§15064.5?
(b) Cause a substantial adverse change in the
significance of an archaeological resource pursuant
to §15064.5?
(c) Disturb any human remains, including those interred
outside of formal cemeteries?
Impact Analysis
a) Would the project cause a substantial adverse change in the significance of a historical resource
pursuant to §15064.5?
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Potentially Significant Impact. A detailed cultural resources technical report will be prepared for the
proposed Project, which will identify any significant historical resources in the Project area, and will
assess any potential impacts to such resources. Further analysis is required and will be included in the
EIR.
b) Would the project cause a substantial adverse change in the significance of an archaeological resource
pursuant to §15064.5?
Potentially Significant Impact. The cultural resources technical report prepared for the proposed
Project will identify any archaeological resources in the Project area, and will assess potential impacts
to such resources. Further analysis is required and will be included in the EIR.
c) Would the project disturb any human remains, including those interred outside of formal cemeteries?
Potentially Significant Impact. No known burial sites are located within the Project Site, however, the
cultural resources technical report will assess potential impacts related to disturbance of unknown
human remains. Further analysis is required and will be included in the EIR.
4.6 ENERGY
6. ENERGY
Would the project:
Potentially
Significant
Impact
Less than
Significant
With
Mitigation
Incorporated
Less Than
Significant
Impact
No
Impact
(a) Result in potentially significant environmental
impact due to wasteful, inefficient, or unnecessary
consumption of energy resources, during project
construction or operation?
(b) Conflict with or obstruct a state or local plan
for renewable energy or energy efficiency?
Impact Analysis
a) Would the project result in potentially significant environmental impact due to wasteful, inefficient, or
unnecessary consumption of energy resources, during project construction or operation ?
Potentially Significant Impact. The proposed Project would control the Rancho Palos Verdes Landslide
Complex to prevent further sliding in the area. Energy for the project would only be required during
construction and would not require additional capacity on a local or regional scale. An energy
technical report will be prepared for the proposed Project to determine whether short-term
construction emissions would result in wasteful, inefficient, or unnecessary consumption of energy
resources. Further analysis is required and will be included in the EIR.
b) Would the project Conflict with or obstruct a state or local plan for renewable energy or energy
efficiency?
Potentially Significant Impact. It is not expected that the proposed Project would conflict or obstruct
the goals and policies of the City’s Emissions Reduction Action Plan. However, the energy technical
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report would address consistency with applicable plans. Further analysis is required and will be
included in the EIR.
4.7 GEOLOGY AND SOILS
7. GEOLOGY AND SOILS.
Would the project:
Potentially
Significant
Impact
Less than
Significant
With
Mitigation
Incorporated
Less Than
Significant
Impact
No
Impact
(a) Directly or indirectly cause potential substantial
adverse effects, including the risk of loss, injury, or
death involving:
i) Rupture of a known earthquake fault, as
delineated on the most recent Alquist-Priolo
Earthquake Fault Zoning Map issued by the State
Geologist for the area or based on other
substantial evidence of a known fault? Refer to
Division of Mines and Geology Special
Publication 42.
ii) Strong seismic ground shaking?
iii) Seismic-related ground failure, including
liquefaction?
iv) Landslides?
(b) Result in substantial soil erosion or the loss of
topsoil?
(c) Be located on a geologic unit or soil that is unstable,
or that would become unstable as a result of the
project, and potentially result in on- or off-site
landslide, lateral spreading, subsidence, liquefaction
or collapse?
(d) Be located on expansive soil, as defined in Table 18-
1-B of the Uniform Building Code (1994), creating
substantial direct or indirect risks to life or property?
(e) Have soils incapable of adequately supporting the
use of septic tanks or alternative waste water
disposal systems where sewers are not available for
the disposal of waste water?
(f) Directly or indirectly destroy a unique
paleontological resource or site or unique geological
feature?
Impact Analysis
a) i) Would the project directly or indirectly cause potential substantial adverse effects, including the
risk of loss, injury, or death involving rupture of a known earthquake fault, as delineated on the most
recent Alquist-Priolo Earthquake Fault Zoning Map issued by the State Geologist for the area or based
on other substantial evidence of a known fault? Refer to Division of Mines and Geology Special
Publication 42.
No Impact. The nearest fault is the Cabrillo Fault located over one mile north of the Project Site (USGS
2020). The Cabrillo Fault is not designated as an Alquist-Priolo Fault and therefore no impacts would
occur. No further analysis is required.
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ii)Would the project directly or indirectly cause potential substantial adverse effects, including the risk
of loss, injury, or death involving strong seismic ground shaking?
No Impact. As previously mentioned, the nearest fault is the Cabrillo Fault located over one mile away
from the Project Site. The proposed Project would not construct any buildings or structures and
therefore would not risk loss, injury, or death from strong seismic ground shaking. No impacts would
occur and no further analysis is required.
iii)Would the project directly or indirectly cause potential substantial adverse effects, including the risk
of loss, injury, or death involving seismic-related ground failure, including liquefaction?
No Impact. According to the Department of Conservation, no portion of the Project Site is l ocated
within a liquefaction zone (DOC 2020). Additionally, the proposed Project would not construct any
buildings or structures and therefore would not risk loss, injury, or death from strong seismic ground
shaking. No impacts would occur and no further analysis is required.
iv)Would the project directly or indirectly cause potential substantial adverse effects, including the risk
of loss, injury, or death involving landslides?
Potentially Significant Impact. The Project Site is located in the PBLC which is an active landslide area.
The proposed Project would control the current landslide to prevent further issues. Further analysis
of land sliding potential is required and will be provided in the EIR.
b) Would the project result in substantial soil erosion or the loss of topsoil?
Potentially Significant Impact. Construction activities would result in ground surface disruption that
could result in the potential for erosion to occur. A geotechnical report will be prepared for the
proposed Project that will include an analysis of potential erosion. Further analysis is required and will
be provided in the EIR.
c) Would the project be located on a geologic unit or soil that is unstable, or that would become unstable
as a result of the project, and potentially result in on - or off-site landslide, lateral spreading,
subsidence, liquefaction or collapse?
Potentially Significant Impact. Construction activities would result in ground surface disruption that
could result in the potential for the soil to become unstable. A geotechnical report will be prepared
for the proposed Project that will include an analysis of the soil stability. Further analysis is required
and will be provided in the EIR.
d) Would the project be located on expansive soil, as defined in Table 18-1-B of the Uniform Building Code
(1994), creating substantial direct or indirect risks to life or property?
Potentially Significant Impact. The geotechnical investigation report prepared for the proposed
Project will address soil conditions in the Project vicinity with respect to expansion potential. Further
analysis is required and will be provided in the EIR.
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e) Would the project have soils incapable of adequately supporting the use of septic tank s or alternative
waste water disposal systems where sewers are not available for the disposal of waste water?
No Impact. The proposed Project would not include the construction of any structures or buildings
that would result in additional wastewater generation. Septic tanks are not proposed and therefore
no impacts would occur. No further analysis is required.
f) Would the project directly or indirectly destroy a unique paleontological resource or site or unique
geological feature?
Less than Significant Impact. A detailed cultural paleontological resources technical report is being
prepared for the proposed Project. The field results indicate that Monterey formations and
Quaternary Terrace deposits are located withing the project area and have yielded fossil recoveries.
Observations from a recent field survey indicate that these formations have been impacted by the
landslide and have little possibility to have significant cultural resources. As such, less than significant
impacts would occur. No further analysis is required.
4.8 GREENHOUSE GAS EMISSIONS
8. GREENHOUSE GAS EMISSIONS.
Would the project:
Potentially
Significant
Impact
Less than
Significant
With
Mitigation
Incorporated
Less Than
Significant
Impact
No
Impact
(a) Generate greenhouse gas emissions, either directly
or indirectly, that may have a significant impact on
the environment?
(b) Conflict with an applicable plan, policy, or regulation
adopted for the purpose of reducing the emissions of
greenhouse gases?
Impact Analysis
a) Would the project generate greenhouse gas emissions, either directly or indirectly, that may have a
significant impact on the environment?
Potentially Significant Impact. As the proposed Project is intended to control the landslide, it is not
anticipated that a substantial net increase in greenhouse gas emissions would be generated during
operation. However, construction of the proposed Project would generate greenhouse gas emissions.
Construction-related emissions would be generated from off-road construction equipment and on-
road vehicle exhaust. A greenhouse gases technical report will be prepared for the proposed Project
to determine if any potentially significant impacts related to greenhouse gas emissions would occur.
A detailed analysis of this issue will be included in the EIR. Further analysis is required and will be
included in the EIR.
b) Would the project conflict with an applicable plan, policy, or regulation adopted for the purpose of
reducing the emissions of greenhouse gases?
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Potentially Significant Impact. As discussed in Section 4.8a above, the proposed Project would
generate greenhouse gas emissions during construction. In addition to analyzing impacts related to
such emissions, the EIR will also include a detailed analysis of the Project’s compliance with applicable
plans policies, and regulations adopted for the purposes of reducing greenhouse gas emissions.
Further analysis is required and will be included in the EIR.
4.9 HAZARDS AND HAZARDOUS MATERIALS
9. HAZARDS AND HAZARDOUS MATERIALS.
Would the project:
Potentially
Significant
Impact
Less than
Significant
With
Mitigation
Incorporated
Less Than
Significant
Impact
No
Impact
(a) Create a significant hazard to the public or the
environment through the routine transport, use, or
disposal of hazardous materials?
(b) Create a significant hazard to the public or the
environment through reasonably foreseeable upset
and accident conditions involving the release of
hazardous materials into the environment?
(c) Emit hazardous emissions or handle hazardous or
acutely hazardous materials, substances, or waste
within one-quarter mile of an existing or proposed
school?
(d) Be located on a site which is included on a list of
hazardous materials sites compiled pursuant to
Government Code Section 65962.5 and, as a result,
would it create a significant hazard to the public or
the environment?
(e) For a project located within an airport land use plan
or, where such a plan has not been adopted, within
2 miles of a public airport or public use airport, would
the project result in a safety hazard or excessive
noise for people residing or working in the project
area?
(f) Impair implementation of or physically interfere with
an adopted emergency response plan or emergency
evacuation plan?
(g) Expose people or structures, either directly or
indirectly, to a significant risk of loss, injury, or death
involving wildland fires?
Impact Analysis
a) Would the project create a significant hazard to the public or the environment through the routine
transport, use, or disposal of hazardous materials?
Less than Significant Impact. Construction of the proposed Project would use hazardous materials
typical of construction (i.e., fuel for construction equipment, materials for road construction).
However, the transport, use, and disposal of construction-related hazardous materials would comply
with applicable laws and regulations for such activities, such as the Hazardous Materials
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Transportation Act, Resource Conservation and Recovery Act, the California Hazardous Material
Management Act, and the California Code of Regulations, Title 22. Operation of the proposed Project
would not require the routine transport, use, or disposal of hazardous materials. Therefore, impacts
related to the routine transport, use, or disposal of hazardous materials would be less than significant,
and no further analysis is required.
b) Would the project create a significant hazard to the public or th e environment through reasonably
foreseeable upset and accident conditions involving the release of hazardous materials into the
environment?
Less than Significant Impact. Construction activities for the proposed Project would involve the
limited transport, storage, use, or disposal of hazardous materials, such as fuel for construction
equipment and materials for road construction. These types of materials, however, are not acutely
hazardous, and all storage, handling, and disposal of these materials would comply with existing
regulations. Compliance with regulations would ensure a less than significant impact related to
creating a significant hazard to the public through reasonably foreseeable upset or accident conditions
involving the release of hazardous materials into the environment with regard to construction of the
proposed Project. No further analysis is required.
c) Would the project emit hazardous emissions or handle hazardous or acutely hazardous materials,
substances, or waste within one-quarter mile of an existing or proposed school?
No Impact. The nearest school is Chadwick School located at 26800 South Academy Drive, which is
over 1.8 miles north of the Project Site. There are no schools with in a one-quarter mile radius and
therefore no impacts would occur.
d) Would the project be located on a site which is included on a list of hazardous materials sites compiled
pursuant to Government Code Section 65962.5 and, as a result, would it create a significant hazard to
the public or the environment?
Less than Significant Impact. A review of Geotracker (SWRCB 2020) and Envirostor (Department of
Toxic Substances 2020) was completed. The review of the databases determined that there is one
closed case of a Leaking Underground Storage Tank (LUST) Cleanup Site located within the Project Site
boundaries on the northern portion of the site. However, this case was cleaned up and closed as of
December 3, 1996. Construction activities would occur approximately 300 feet northeast of this clean
up location and this site would not be disturbed. There are no other hazardous materials sites on the
Project Site or within a one quarter mile radius. Impacts would be less than significant, and no further
analysis is required.
e) For a project located within an airport land use plan or, where such a plan has not been adopted,
within 2 miles of a public airport or public use airport, would the project result in a safety hazard or
excessive noise for people residing or working in the project area?
No Impact. The nearest airport to the Project Site is over 3.5 miles north. The Torrance Municipal
Airport – Zamperini Field serves as a general aviation airport, but is mostly home to private aircraft.
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The Project Site is not within 2 miles of airport or within an airport land use plan. No impacts would
occur and no further analysis is required.
f) Would the project impair implementation of or physically interfere with an adopted emergency
response plan or emergency evacuation plan?
Potentially Significant Impact. Palos Verdes Drive is designated by the General Plan as a disaster route
(City of Rancho Palos Verdes 1975). As previously mentioned, there is a potential that portions of
Palos Verdes Drive may be affected temporarily during construction. For this reason, further analysis
is required and will be included in the EIR.
g) Would the project expose people or structures, either directly or indirectly, to a significant risk of loss,
injury or death involving wildland fires?
Potentially Significant Impact. The proposed Project would control the existing Rancho Palos Verdes
Landslide Complex area and would not construct any buildings or structures. However, construction
would occur within an area designated as a Local Responsibility Area (LRA) Very High Fire Hazard Zone
(VHFHSZ) (CalFire 2011). Further analysis is required and will be included in the EIR.
4.10 HYDROLOGY AND WATER QUALITY
10. HYDROLOGY AND WATER QUALITY.
Would the project:
Potentially
Significant
Impact
Less than
Significant
With
Mitigation
Incorporated
Less Than
Significant
Impact
No
Impact
(a) Violate any water quality standards or waste
discharge requirements or otherwise substantially
degrade surface or ground water quality?
(b) Substantially decrease groundwater supplies or
interfere substantially with groundwater recharge
such that the project may impede sustainable
groundwater management of the basin?
(c) Substantially alter the existing drainage pattern of
the site or area, including through the alteration of
the course of a stream or river or through the
addition of impervious surfaces, in a manner which
would:
i) Result in substantial erosion or siltation on- or off-
site;
ii) Substantially increase the rate or amount of
surface runoff in a manner which would result in
flood on- or off-site;
iii) Create or contribute runoff water which would
exceed the capacity of existing or planned
stormwater drainage systems or provide substantial
additional sources of polluted runoff; or
iv) Impede or redirect flood flows?
(d) In flood hazard, tsunami, or seiche zones, risk release
of pollutants due to project inundation?
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10. HYDROLOGY AND WATER QUALITY.
Would the project:
Potentially
Significant
Impact
Less than
Significant
With
Mitigation
Incorporated
Less Than
Significant
Impact
No
Impact
(e) Conflict with or obstruct implementation of a water
quality control plan or sustainable groundwater
management plan?
Impact Analysis
a) Would the project violate any water quality standards or waste discharge requirements, or otherwise
substantially degrade surface or ground water quality?
Potentially Significant Impact. Construction activities have the potential to degrade water quality
through the exposure of surface runoff to exposed soils, dust, and other debris, as well as from runoff
from construction equipment. As the proposed Project would control the roadway to prevent further
sliding in the area, it is not anticipated that a substantial net increase in runoff would be generated at
the Project Site during operation. A hydrology and water quality analysis will be prepared for the
proposed Project to assess potential impacts to water quality. Further analysis is required and will be
included in the EIR.
b) Would the project substantially decrease groundwater supplies or interfere substantially with
groundwater recharge such that the project may impede sustainable groundwater management of
the basin?
Potentially Significant Impact. The Project Site is underlain by the West Basin operated by the West
Basin Municipal District. The Project would change the existing stormwater drainage which may alter
how the groundwater basin is recharged. The hydrology and water quality analysis prepared for the
proposed Project will assess potential impacts to groundwater supply and recharge. Further analysis
is required and will be included in the EIR.
c) Would the project substantially alter the existing drainage pattern of the site or area, including
through the alteration of the course of a stream or river or through the addition of impervious surfaces,
in a manner which would:
i) result in substantial erosion or siltation on - or off-site;
Potentially Significant Impact. No streams or rivers cross the Project Site. However,
implementation of the proposed Project may have the potential to alter drainage patterns. The
hydrology and water quality analysis prepared for the proposed Project will evaluate potential
impacts to the alteration of drainage patterns. Further analysis is required and will be included in
the EIR.
ii) substantially increase the rate or amount of surface runoff in a manner which would result in
flooding on- or off-site;
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Potentially Significant Impact. As discussed in Section 4.10 c.i. above, the hydrology and water
quality analysis prepared for the proposed Project will evaluate potential impacts to the alteration
of drainage patterns. Further analysis is required and will be included in the EIR.
iii) create or contribute runoff water which would exceed the capacity of existing or planned
stormwater drainage systems or provide substantial additional sources or polluted runoff; or
Potentially Significant Impact. The proposed Project may have the potential to change runoff
volumes. The hydrology and water quality analysis prepared for the proposed Project will evaluate
potential impacts to the storm drain system due to changes in runoff volumes. Further analysis is
required and will be included in the EIR.
iv) impede or redirect flood flows?
Potentially Significant Impact. As discussed in Section 4.10 c.i. above, the hydrology and water
quality analysis prepared for the proposed Project will evaluate potential impacts to the alteration
of drainage patterns. Further analysis is required and will be included in the EIR.
d) Would the project in flood hazard, tsunami, or seiche zones, risk release of pollutants due to project
inundation?
Less than Significant Impact. The Project Site is not located in proximity to a closed body of water
(e.g., lake or reservoir) or storage tank and would not be subject to hazards associated with inundation
from a seiche and would not risk release of pollutants. However, the Project Site is located on a bluff
above the Pacific Ocean coastline. A small portion of the Project Site is located within a tsunami
inundation hazard area mapped by the California Geological Survey (DOC 2020). However, the
landslide mitigation Project does not involve the construction of any structures that could be affected
by a tsunami. nor does the project involve the long-term use or storage of hazardous materials that
would result in a release of pollutants due to inundation. Conditions under the proposed project
would be similar to the existing conditions and would not increase the potential of site inundation.
For these reasons, impacts would be less than significant and no further discussion is required.
e) Would the project conflict with or obstruct implementation of a water quality control plan or
sustainable groundwater management plan?
Potentially Significant Impact. As previously mentioned, the Project would change the existing
stormwater drainage which may alter how the groundwater basin is recharged. The hydrology and
water quality analysis prepared for the proposed Project will assess potential impacts to groundwater
supply and recharge. Further analysis is required and will be included in the EIR.
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4.11 LAND USE AND PLANNING
11. LAND USE/PLANNING
Would the project:
Potentially
Significant
Impact
Less than
Significant
With
Mitigation
Incorporated
Less Than
Significant
Impact
No
Impact
(a) Physically divide an established community?
(b) Cause a significant environmental impact due to a
conflict with any land use plan, policy, or regulation
adopted for the purpose of avoiding or mitigating an
environmental effect?
Impact Analysis
a) Would the project physically divide an established community?
No Impact. The proposed Project would control the existing Rancho Palos Verdes Landslide Complex
area and would not construct any buildings or structures. The Project would not physically divide an
established community. No impacts would occur and no further analysis is required.
b) Would the project cause a significant environmental impact due to a conflict with any land use plan,
policy, or regulation adopted for the purpose of avoiding or mitigating an environmental effect?
Potentially Significant Impact. The General Plan Land Use Element designated the site as
agricultural/socio-cultural and agricultural/residential (≤1 dwelling unit per acre) (General Plan Land
Use Map 1975). The Project Site is zoned as open space – hazard (oh) (City of Rancho Palos Verdes
2012). Additionally, a portion of the site is located within Coastal Zone. Further analysis of the
Project’s consistency with applicable plans, policies and regulations is required and will be included in
the EIR.
4.12 MINERAL RESOURCES
12. MINERAL RESOURCES
Would the project:
Potentially
Significant
Impact
Less than
Significant
With
Mitigation
Incorporated
Less Than
Significant
Impact
No
Impact
(a) Result in the loss of availability of a known mineral
resource that would be of value to the region and the
residents of the state?
(b) Result in the loss of availability of a locally-important
mineral resource recovery site delineated on a local
general plan, specific plan or other land use plan?
Impact Analysis
a) Would the project result in the loss of availability of a known mineral resource that would be of value
to the region and the residents of the state?
No Impact. The General Plan does not specifically designate the Project Site as an area with known
mineral resources (City of Rancho Palos Verdes 1975). Additionally, the Department of Conservation
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notes that there are no active mines operations, no land designated with soils known to contain
mineral resources, and no land classified as MRZ-2 within the entire City of Rancho Palos Verdes
(California Geological Survey 2010). There are no active or abandoned wells within or near the Project
Site (DOC 2020). Therefore, no impact to the loss of a known mineral resource would occur and no
further discussion is required.
b) Would the project result in the loss of availability of a locally-important mineral resource recovery site
delineated on a local general plan, specific plan or other land use plan?
No Impact. As noted in response 4.12a above, the Project Site does not contain any mineral resources
and therefore no impacts would occur and no further discussion is required.
4.13 NOISE
13. NOISE
Would the project result in:
Potentially
Significant
Impact
Less than
Significant
With
Mitigation
Incorporated
Less Than
Significant
Impact
No
Impact
(a) Generation of a substantial temporary or permanent
increase in ambient noise levels in the vicinity of the
project in excess of standards established in the local
general plan or noise ordinance, or applicable
standards of other agencies?
(b) Generation of excessive groundborne vibration or
groundborne noise levels?
(c) For a project located within the vicinity of a private
airstrip or an airport land use plan or, where such a
plan has not been adopted, within two miles of a
public airport or public use airport, would the project
expose people residing or working in the project area
to excessive noise levels?
Impact Analysis
a) Would the project result in generation of a substantial temporary or permanent increase in ambient
noise levels in the vicinity of the project in excess of standards established in the local general plan or
noise ordinance, or applicable standards of other agencies?
Potentially Significant Impact. The proposed Project may generate increased noise levels during
construction activities. A technical noise analysis will be prepared for the proposed Project that will
assess the potential for short and long-term increases in noise levels and any associated impacts.
Further analysis is required and will be included in the EIR.
b) Would the project result in generation of excessive groundborne vibration or groundborne noise
levels?
Potentially Significant Impact. Construction activities associated with the proposed Project may
generate ground-borne vibration from use of heavy equipment. The technical noise analysis prepared
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for the proposed Project will evaluate the potential for groundborne noise and vibration, as well as
any associated impacts. Further analysis is required and will be included in the EIR.
c) For a project located within the vicinity of a private airstrip or an airport land use plan or, where such
a plan has not been adopted, within two miles of a public airport or public us airport, would the project
expose people residing or working in the project area to excessive noise levels?
No Impact. The nearest airport to the Project Site is over 3.5 miles north. The Torrance Municipal
Airport – Zamperini Field serves as a general aviation airport, but is mostly home to private aircraft.
The Project Site is not within 2 miles of airport or within an airport land use plan. No impacts would
occur and no further analysis is required.
4.14 POPULATION AND HOUSING
14. POPULATION AND HOUSING.
Would the project:
Potentially
Significant
Impact
Less than
Significant
With
Mitigation
Incorporated
Less Than
Significant
Impact
No
Impact
(a) Induce substantial unplanned population growth in
an area, either directly (for example, by proposing
new homes and businesses) or indirectly (for
example, through extension of roads or other
infrastructure)?
(b) Displace substantial numbers of existing people or
housing, necessitating the construction of
replacement housing elsewhere?
Impact Analysis
a) Would the project induce substantial unplanned population growth in an area, either directly (for
example, by proposing new homes and businesses) or indirectly (for example, through ext ension of
roads or other infrastructure)?
No Impact. The proposed Project would control the existing Rancho Palos Verdes Landslide Complex
area. Construction would require employees that would likely come from the existing employment
population. The proposed Project would not directly or indirectly induce population growth. No
impact would occur and no further discussion is required.
b) Would the project displace substantial numbers of existing people or housing, necessitating the
construction of replacement housing elsewhere?
No Impact. The Project Site contains several single family residences however, the proposed Project
involves controlling the existing slopes and would not demolish or displace any of these houses. No
impacts would occur and no further analysis is required.
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4.15 PUBLIC SERVICES
15. PUBLIC SERVICES.
Potentially
Significant
Impact
Less than
Significant
With
Mitigation
Incorporated
Less Than
Significant
Impact
No
Impact
(a) Would the project result in substantial adverse
physical impacts associated with the provision of
new or physically altered governmental facilities,
need for new or physically altered governmental
facilities, the construction of which could cause
significant environmental impacts, in order to
maintain acceptable service ratios, response times or
other performance objectives for any of the public
services:
i) Fire Protection?
ii) Police Protection?
iii) Schools?
iv) Parks?
v) Other public facilities?
Impact Analysis
a) Would the project result in substantial adverse physical impacts associated with the provision of new
or physically altered governmental facilities, need for new or physically altered governmental facilities,
the construction of which could cause significant environmental impacts, in order to maintain
acceptable service ratios, response times or other performance objectives for fire protection?
Less than Significant Impact. The proposed Project would not result in an increase in population, and
thus, would not generate a need for new or altered fire protection facilities. The proposed Project
would be constructed in accordance with all applicable fire codes set forth by the State Fire Marshall
and Los Angeles Fire Department. Therefore, the proposed Project would not be considered a fire
hazard and would not exceed the capacity of the Los Angeles Fire Department to serve the site or
other areas with existing fire protection services. The nearest local fire responders, Station 53 located
at 6124 Palos Verdes Drive South, would be notified as appropriate, of traffic control plans during
construction so as to coordinate emergency response routing during construction work. The impact
would be less than significant and no further discussion is required.
b) Would the project result in substantial adverse physical impacts associated with the provision of new
or physically altered governmental facilities, need for new or physically altered governmental facilities,
the construction of which could cause significant environmental impacts, in order to maintain
acceptable service ratios, response times or other performance objectives for police protection?
Less than Significant Impact. The proposed Project would not require additional police protection
beyond what is currently provided. The nearest local police station, Palos Verdes Estates Police
Department located at 340 Palos Verdes Drive West, would be notified as appropriate, of traffic
control plans during construction so as to coordinate emergency response routing during construction
work. The impact would be less than significant and no further discussion is required.
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c) Would the project result in substantial adverse physical impacts associated with the provision of new
or physically altered governmental facilities, need for new or physically altered governmental facilities,
the construction of which could cause significant environmental impacts, in order to mainta in
acceptable service ratios, response times or other performance objectives for schools?
No Impact. The proposed Project would not induce employment or population growth, either directly
or indirectly, and would therefore not increase the demand for schools in the area. No impact would
occur and no further discussion is required.
d) Would the project result in substantial adverse physical impacts associated with the provision of new
or physically altered governmental facilities, need for new or physically altered governmental facilities,
the construction of which could cause significant environmental impacts, in order to maintain
acceptable service ratios, response times or other performance objectives for parks?
No Impact. The proposed Project would not generate residents that would increase the demand for
park facilities. No impact would occur and no further discussion is required.
e) Would the project result in substantial adverse physical impacts associated with the provision of new
or physically altered governmental facilities, need for new or physically altered governmental facilities,
the construction of which could cause significant environmental impacts, in order to maintain
acceptable service ratios, response times or other performance objectives for other public facilities?
No Impact. The proposed Project would not generate residents that would increase the demand for
other public facilities. No impact would occur and no further discussion is required.
4.16 RECREATION
16. RECREATION.
Would the project:
Potentially
Significant
Impact
Less than
Significant
With
Mitigation
Incorporated
Less Than
Significant
Impact
No
Impact
(a) Would the project increase the use of existing
neighborhood and regional parks or other
recreational facilities such that substantial physical
deterioration of the facility would occur or be
accelerated?
(b) Does the project include recreational facilities or
require the construction or expansion of recreational
facilities which might have an adverse physical effect
on the environment?
Impact Analysis
a) Would the project increase the use of existing neighborhood and regional parks or other recreational
facilities such that substantial physical deterioration of the facility would occur or be accelerated?
Potentially Significant Impact. The proposed Project would not result in an increase in population
that would increase the use of existing recreational facilities. However, the Project Site contains a
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series of trail networks that may require closure during construction. Further analysis is required and
will be included in the EIR.
b) Does the project include recreational facilities or require the construction or expansion of recreational
facilities which might have an adverse physical effect on the environment?
No Impact. As mentioned in Section 4.16d above, the proposed Project would not generate residents
that would increase the demand for park facilities. The proposed Project does not include the
construction of any additional recreational facilities. No impact would occur and no further discussion
is required.
4.17 TRANSPORTATION
17. TRANSPORTATION.
Would the project:
Potentially
Significant
Impact
Less than
Significant
With
Mitigation
Incorporated
Less Than
Significant
Impact
No
Impact
(a) Conflict with a program, plan, ordinance or policy
addressing the circulation system, including transit,
roadways, bicycle and pedestrian facilities?
(b) Conflict or be inconsistent with CEQA Guidelines
section 15064.3, subdivision (b)?
(c) Substantially increase hazards due to a geometric
design feature (e. g., sharp curves or dangerous
intersections) or incompatible uses (e.g., farm
equipment)?
(d) Result in inadequate emergency access?
Impact Analysis
a) Would the project conflict with a program, plan, ordinance or policy addressing the circulation system,
including transit, roadways, bicycle and pedestrian facilities?
Potentially Significant Impact. The proposed Project is intended to control the Rancho Palos Verdes
Landslide Complex, and is not anticipated to create a substantial amount of new vehicle trips during
operation. Traffic may be affected temporarily due to construction activities, including the potential
closing of portions of Palos Verdes Drive. Additionally, the Project Site contains a number of trail
networks that may need to be closed temporarily during construction. A traffic study will be prepared
for the proposed Project, including an analysis of construction traffic impacts. Further analysis is
required and will be included in the EIR.
b) Would the project Conflict or be inconsistent with CEQA Guidelines section 15064.3, subdivision (b)?
Potentially Significant Impact. CEQA Guidelines Section 15064.3(c) creates a process to change the
way that transportation impacts are analyzed under the California Environmental Quality Act (CEQA).
Specifically, SB 743 requires the Governor’s Office of Planning and Research (OPR) to amend the CEQA
Guidelines to provide an alternative to LOS for evaluating transportation impacts. Vehicle Miles
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Travelled (VMT) is a key measure of effectiveness with regard to various initiatives intended to reduce
emissions, including Green House Gas (GHG) emissions. The traffic study will address any potential
impacts to VMT. Further analysis is required and will be included in the EIR.
c) Would the project substantially increase hazards due to a geometric design feature (e.g., sharp curves
or dangerous intersections) or incompatible uses (e.g. farm equipment)?
Potentially Significant Impact. The proposed Project would control the Rancho Palos Verdes Landslide
Complex and would not alter the existing roadway long term. However, with the potential for roadway
closures along portions of Palos Verdes Drive, may result in a temporary increase to hazards. The
traffic study will address any potential hazards. Further analysis is required and will be included in the
EIR.
d) Would the project result in inadequate emergency access?
Potentially Significant Impact. Palos Verdes Drive is designated by the General Plan as a disaster route
(City of Rancho Palos Verdes 1975). As previously mentioned, there is a potential that portions of
Palos Verdes Drive may be affected temporarily during construction. For this reason, further analysis
is required and will be included in the EIR.
4.18 TRIBAL CULTURAL RESOURCES
18.
TRIBAL CULTURAL RESOURCES.
Would the project cause a substantial adverse
change in the significance of a tribal cultural
resource, defined in Public Resources Code section
21074 as either a site, feature, place, cultural
landscape that is geographically defined in terms
of the size and scope of the landscape, sacred
place, or object with cultural value to a California
Native American tribe, and that is:
Potentially
Significant
Impact
Less than
Significant
With
Mitigation
Incorporated
Less Than
Significant
Impact
No
Impact
(a) Listed or eligible for listing in the California Register
of Historical Resources, or in a local register of
historical resources as defined in Public Resources
Code section 5020.1(k), or
(b) A resource determined by the lead agency, in its
discretion and supported by substantial evidence, to
be significant pursuant to criteria set forth in
subdivision (c) of Public Resources Code Section
5024.1. In applying the criteria set forth in
subdivision (c) of Public Resources Code Section
5024.1, the lead agency shall consider the
significance of the resource to a California Native
American tribe.
Impact Analysis
a) Would the project cause a substantial adverse change in the significance of a tribal cultural resource,
defined in Public Resources Code section 21074 as either a site, feature, place, cultural landscape that
is geographically defined in terms of the size and scope of the landscape, sacred place, or object with
cultural value to a California Native American tribe, and that is Listed or eligible for listing in th e
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California Register of Historical Resources, or in a local register of historical resources as defined in
Public Resources Code section 5020.1(k)?
Potentially Significant Impact. As noted in Section 4.5a above, a detailed cultural resources technical
report will be prepared for the proposed Project, which will identify any significant historical resources
in the Project area, and will assess any potential impacts to such resources. Further analysis is required
and will be included in the EIR.
b) Would the project cause a substantial adverse change in the significance of a tribal cultural resource,
defined in Public Resources Code section 21074 as either a site, feature, place, cultural landscape that
is geographically defined in terms of the size and scope of the landscape, sacred place, or object with
cultural value to a California Native American tribe, and that is a resource determined by the lead
agency, in its discretion and supported by substantial evidence, to be significant pursuant to criteria
set forth in subdivision (c) of Public Resources Code Section 5024.1. In applying the criteria set forth in
subdivision (c) of Public Resources Code Section 5024.1, the lead agency shall consider the significance
of the resource to a California Native American tribe?
Potentially Significant Impact. Public Resources Code Section 21080.3.1 establishes a formal process
for Lead Agencies to consult with California Native American Tribes to identify potentially significant
impacts to Tribal Cultural Resources, as defined in Public Resources Code Section 21074. Letters were
sent to each representative of seven tribes Native American groups and individuals who may have
knowledge of cultural resources in the Project area on August 6, 2020. The Project Applicant is
required to comply with existing regulations, including California Public Resources Code Section
21083.2, that specifies a protocol if archaeological resources are discovered during excavation,
grading, or construction activities. As the Project would construct on a mostly undisturbed site,
impacts to buried Tribal Cultural Resources could be potentially significant. Further analysis is
required.
4.19 UTILITIES AND SERVICE SYSTEMS
19. UTILITIES/SERVICE SYSTEMS.
Would the project:
Potentially
Significant
Impact
Less than
Significant
With
Mitigation
Incorporated
Less Than
Significant
Impact
No
Impact
(a) Require or result in the relocation or construction of
new or expanded water, wastewater treatment or
storm water drainage, electric power, natural gas, or
telecommunications facilities, the construction or
relocation of which could cause significant
environmental effects?
(b) Have sufficient water supplies available to serve the
project and reasonably foreseeable future
development during normal, dry and multiple dry
years?
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19. UTILITIES/SERVICE SYSTEMS.
Would the project:
Potentially
Significant
Impact
Less than
Significant
With
Mitigation
Incorporated
Less Than
Significant
Impact
No
Impact
(c) Result in a determination by the wastewater
treatment provider which serves or may serve the
project that it has adequate capacity to serve the
project’s projected demand in addition to the
provider’s existing commitments?
(d) Generate solid waste in excess of State or local
standards, or in excess of the capacity of local
infrastructure, or otherwise impair the attainment of
solid waste reduction goals?
(e) Comply with federal, state, and local management
and reduction statutes and regulations related to
solid wastes?
Impact Analysis
a) Would the project require or result in the relocation or construction of new or expanded water,
wastewater treatment or stormwater drainage, electric power, natural gas, or telecommunication s
facilities, the construction or expansion of which could cause significant environmental effects?
Potentially Significant Impact. The proposed Project would not develop any buildings or structures
or result in an increase in population that would require additional water, wastewater, electrical,
natural gas or telecommunications facilities. The proposed Project would require small amounts of
water, which may result in wastewater for construction activities. However, these activities would be
temporary.
The proposed Project involves controlling an existing landslide by utilizing several different methods.
One of these methods involves diverting stormwater under the slope so that the water would not
cause further erosion. Impacts related to stormwater drainage require further analysis and will be
included in the EIR.
b) Would the project have sufficient water supplies available to serve the project and reasonably
foreseeable future development during normal dry and multiple dry years?
Less than Significant Impact. The proposed Project would require small amounts of water for
construction activities. Operation of the Project would not develop any buildings or structures or
result in an increase in population that would increase water demand. The proposed Project would
not use additional water that would exceed existing capacity. Impacts would be considered less than
significant and no fur ther discussion is required.
c) Would the project result in a determination by the wastewater treatment provider which serves or
may serve the project that it has adequate capacity to serve the project’s projected demand in addition
to the provider’s existing commitments?
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Less than Significant Impact. The proposed Project may generate small amounts of wastewater
during construction activities. Operation of the Project would not develop any buildings or structures
or result in an increase in population that would increase wastewater generation. The proposed
Project would not generate wastewater that would exceed existing capacity. Impacts would be
considered less than significant and no further discussion is required.
d) Generate solid waste in excess of State or local standards, or in excess of the capacity of local
infrastructure, or otherwise impair the attainment of solid waste reduction goals?
Less than Significant Impact. Construction activities associated with the Project may generate solid
wastes requiring disposal at area landfills. Waste generated during Project construction would be
limited to vegetation debris. Waste generation would be temporary during construction and would
not reduce available capacities at existing landfills. Operation of the Project would not result in an
increase to solid waste. The impact would be less than significant, and no further discussion is
required.
e) Would the project comply with federal, state, and local management and reduction statutes and
regulations related to solid waste?
Less than Significant Impact. The proposed Project would be constructed following all applicable laws,
regulations, ordinances, and formally adopted City standards regarding solid waste disposal.
Operation of the Project would not result in an increase to solid waste. The impact would be less than
significant, and no further discussion is required.
4.20 WILDFIRE
20.
WILDFIRE.
If located in or near state responsibility areas or
lands classified as very high fire hazard severity
zones, would the project:
Potentially
Significant
Impact
Less than
Significant
With
Mitigation
Incorporated
Less Than
Significant
Impact
No
Impact
(a) Substantially impair an adopted emergency response
plan or emergency evacuation plan?
(b) Due to slope, prevailing winds, and other factors,
exacerbate wildfire risks, and thereby expose project
occupants to, pollutant concentrations from a
wildfire or the uncontrolled spread of a wildfire?
(c) Require the installation or maintenance of
associated infrastructure (such as roads, fuel breaks,
emergency water sources, power lines or other
utilities) that may exacerbate fire risk or that may
result in temporary or ongoing impacts to the
environment?
(d) Expose people or structures to significant risks,
including downslope or downstream flooding or
landslides, as a result of runoff, post-fire slope
instability, or drainage changes?
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Impact Analysis
a) Would the project impair an adopted emergency response plan or emergency evacuation plan?
Potentially Significant Impact. Palos Verdes Drive is designated by the General Plan as a disaster route
(City of Rancho Palos Verdes 1975). As previously mentioned, the Project Site is designated as a Local
Responsibility Area (LRA) Very High Fire Hazard Zone (VHFHSZ). For this reason, further evaluation of
potential impacts from fire events is needed to determine the significance of any potential impacts
and will be included in the EIR.
b) Would the project, due to slope, prevailing winds, and other factors, exacerbate wildfire risks, and
thereby expose project occupants to, pollutant concentrations from a wildfire or the uncontrolled
spread of a wildfire?
Potentially Significant Impact. The Project Site is surrounded by ridgelines and slopes, which may
have the potential to contribute to exacerbating wildfire risks. Further evaluation of potential impacts
from fire events is needed to determine the significance of any potential impacts and will be included
in the EIR
c) Would the project require the installation or maintenance of associated infrastructure (such as roads,
fuel breaks, emergency water sources, power lines, or other utilities) that may exacerbate fire risk or
that may result in temporary or ongoing impacts to the environment?
Less than Significant Impact. The Project involves the control of a failing landslide area. The Project
would not require the installation of infrastructure that might exacerbate fire risk. Impacts would be
less than significant and no further discussion is required.
d) Would the project expose people or structures to significant risks, including downslope or downstream
flooding or landslides, as a result of runoff, post-fire slope instability or drainage changes?
Potentially Significant Impact. As previously mentioned, landslide areas have been mapped along the
borders of the Project Site. Additionally, the Project Site is located within a Very High Fire Hazard
Severity Zone. Potential impacts due to fire related flooding impacts requires further evaluation to
determine the significance of any potential impacts and will be included in the EIR.
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4.21 MANDATORY FINDINGS OF SIGNIFICANCE
21. MANDATORY FINDINGS OF SIGNIFICANCE.
Potentially
Significant
Impact
Less than
Significant
With
Mitigation
Incorporated
Less Than
Significant
Impact
No
Impact
(a) Does the project have the potential to substantially
degrade the quality of the environment,
substantially reduce the habitat of a fish or wildlife
species, cause a fish or wildlife population to drop
below self-sustaining levels, threaten to eliminate a
plant or animal community, substantially reduce the
number or restrict the range of a rare or endangered
plant or animal or eliminate important examples of
the major periods of California history or prehistory?
(b) Does the project have impacts that are individually
limited, but cumulatively considerable?
(“Cumulatively considerable” means that the
incremental effects of a project are considerable
when viewed in connection with the effects of past
projects, the effects of other current projects, and
the effects of probable future projects?)
(c) Does the project have environmental effects which
will cause substantial adverse effects on human
beings, either directly or indirectly?
Impact Analysis
a) Does the project have the potential to substantially degrade the quality of the environment,
substantially reduce the habitat of a fish or wildlife species, cause a fish or wildlife population to drop
below self-sustaining levels, threaten to eliminate a plant or animal community, substantially reduce
the number or restrict the range of a rare or endangered plant or animal or eliminate important
examples of the major periods of California history or prehistory?
Potentially Significant Impact. As mentioned above, the Project would further review biological and
cultural resources in the EIR. The Project may have a potentially significant effect and further
evaluation is required to determine if any significant impacts would result from the Project.
b) Does the project have impacts that are individually limited, but cumulatively considerable?
(“Cumulatively considerable” means that the incremental effects of a project are considera ble when
viewed in connection with the effects of past projects, the effects of other current projects, and the
effects of probable future projects?)
Potentially Significant Impact. As mentioned in the analysis above, further evaluation is required to
state the level of significance for several impacts. In order to discuss cumulatively considerable
impacts, further evaluation is required.
c) Does the project have environmental effects which will cause substantial adverse effects on human
beings, either directly or indirectly?
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Potentially Significant Impact. As mentioned in the analysis above, further evaluation is required to
state the level of significance for several impacts. In order to discuss substantial adverse effects on
human beings, further evaluation is required.
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SECTION 5.0 – REFERENCES
The following is a list of references used in the preparation of this document.
CalFire
2011 CalFire Fire Hazard Severity Zones Maps, Los Angeles County, Rancho Palos Verdes.
Available online at: https://osfm.fire.ca.gov/media/5839/rancho_palos_verdes.pdf.
California Geological Survey
2010 Update of Mineral Land Classification for Portland Cement Concrete-Grade Aggregate in
the San Gabriel Valley Production-Consumption Region, Los Angeles County, California,
2010 Special Report 209. Available online at:
https://maps.conservation.ca.gov/cgs/informationwarehouse/index.html?map=mlc.
Caltrans
2020 Scenic Highways. Available online at: https://dot.ca.gov/programs/design/lap-landscape-
architecture-and-community-livability/lap-liv-i-scenic-highways.
City of Rancho Palos Verdes
1975 General Plan Land Use Map. Adopted June 26, 1975. Available online at:
http://www.rpvca.gov/DocumentCenter/View/5911/General-Plan-Land-Use-Map-
adopted-1975-PDF.
1978 General Plan Land Use Map Adopted December 19, 1978. Available online at:
https://www.rpvca.gov/DocumentCenter/View/5901/Coastal-Specific-Plan-Map-PDF.
2012 Official Zoning Map, February 21, 2012. Available online at:
http://www.rpvca.gov/DocumentCenter/View/5912/Zoning-Map-adopted-2012-PDF.
Department of Conservation (DOC)
2016 California Important Farmland Finder, Los Angeles 2016. Available online at:
https://maps.conservation.ca.gov/DLRP/CIFF/
2019 The Williamson Act Status Report 2016-2017, August 2019. Available online at:
https://www.conservation.ca.gov/dlrp/wa/Documents/stats_reports/2018%20WA%20S
tatus%20Report.pdf
2020 Maps. Available online at: https://maps.conservation.ca.gov/cgs/DataViewer/
2020 California Office Tsunami Inundation Maps. Available online at:
https://www.convservation.ca.gov/cgs/tsunami/maps.
2020 Division of Oil, Gas, and Geothermal Resources (DOGGR) Well Finder,
https://maps.conservation.ca.gov/doggr/wellfinder/#openModal/-
118.36105/33.74492/15, accessed August 11, 2020.
Department of Toxic Substances Control
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2020 Envirostor. Available online at:
https://www.envirostor.dtsc.ca.gov/public/map/?myaddress=rancho+palos+verdes,
accessed August 11, 2020.
State Water Resources Control Board (SWRCB)
2020 Geotracker. Available online at:
https://geotracker.waterboards.ca.gov/profile_report.asp?global_id=T0603705391,
accessed August 11, 2020.
United States Fish and Wildlife (USFSW)
2020 National Wetlands Inventory. Available online at:
https://www.fws.gov/wetlands/data/mapper.html, accessed August 11, 2020.
United States Geological Survey
2020 U.S Quaternary Faults. Available online at:
https://usgs.maps.arcgis.com/apps/webappviewer/index.html?id=5a6038b3a1684561a
9b0aadf88412fcf, accessed August 11, 2020.
APPENDIX A – A-49
RANCHO PALOS VERDES CITY COUNCIL MEETING DATE: 12/17/2019
AGENDA REPORT AGENDA HEADING: Regular Business
AGENDA DESCRIPTION:
Consideration and possible action to accept and file the design drawings and hydrologic
analysis associated with Portuguese Bend Landslide Mitigation Project
RECOMMENDED COUNCIL ACTION:
(1) Accept and file the design drawings and hydrologic analysis associated with
Portuguese Bend Landslide Mitigation Project;
(2) Authorize Staff to proceed with preparing the environmental document pursuant
to the California Environmental Quality Act (CEQA) for the project including
requesting and receiving proposals as needed; and,
(3) Authorize Staff to identify funding opportunities for construction from county,
state, and federal agencies to augment local funds for consideration by the City
Council at a later date.
FISCAL IMPACT: The recommended action, if approved, will require funding for the
preparation of the environmental document since this is a new
project and funding for this Capital Improvement construction is not
included in the approved Fiscal Year 2019-20 budget. The cost to
prepare the environmental document is unknown at this time and
an additional appropriation will be brought to the City Council at a
later date when costs are identified as part of the professional
services agreement for the environmental consultant.
Amount Budgeted: $0
Additional Appropriation: $0
Account Number(s): 330-400-8304-8001 (CIP – Portuguese Bend Landslide/Professional Services)
ORIGINATED BY: Nasser Razepoor, PE, Associate Engineer
REVIEWED BY: Elias Sassoon, PE, Director of Public Works
APPROVED BY: Ara Mihranian, Interim City Manager
ATTACHED SUPPORTING DOCUMENTS:
A. Geotechnical Evaluation Report (page A-1)
B. Project Construction Cost Estimate (page B-1)
C. Background – August 7, 2019 City Council Staff Report (page C-1)
B-1
D. NCCP/HCP - Acreage (page D-1)
BACKGROUND AND DISCUSSION:
On January 16, 2018, after a series of public workshops, Staff presented the City
Council with a draft copy of a feasibility study for extensive work to stabilize the
Portuguese Bend Landslide complex. The City Council received and filed the feasibility
study on August 7, 2018 as summarized in the attached staff report (Attachment C). On
December 18, 2018, the City Council approved the award of a professional services
agreement to Daniel B. Stephens & Associates, Inc. for design services associated with
the Portuguese Bend Landslide Mitigation Project. The scope of work included
hydrologic analysis, evaluation, and design for drainage and dewatering (hydraugers)
improvements in the Portuguese Bend Landslide area.
The design consultant has completed the hydrologic analysis and design drawings
associated with the project. Prior to completing the analysis and drawings, the City held
two public outreach meetings, which took place on May 29, 2019 and October 7, 2019.
At those meetings, the design consultant provided information regarding the hydrologic
analysis, water balance, and mitigation design. The consultant also participated in
discussions with residents and answered their questions. Staff reviewed the design
drawings and hydrologic analysis with the Palos Verdes Peninsula Land Conservancy
(PVPLC), Infrastructure Management Advisory Committee (IMAC) Landflow
Subcommittee, City Council subcommittee and interested members of the community to
receive input and comments for consideration in the project design.
The submitted report consists of the hydrology study, which includes the water balance
analysis and engineering plans recommending certain improvements intended to
significantly reduce land movement associated with the landslide. These proposed
improvements are categorized in three design components to occur in phases which
are: Phase I, the repair of existing ground fractures; Phase II, the installation of surface
drainage improvements; and Phase III, the installation of below-grade hydraugers. The
effectiveness of the each phase will be examined to determine whether to proceed with
next phase of the project. The following is a summary for each design component of
the Portuguese Bend Landslide Mitigation Project:
1. Design Components
Phase 1 - Repair of the Existing Fractures
Surface fractures (also known as fissures) in the Portuguese Bend area are the result of
land movement. These existing fractures are a few feet wide and some are as deep as
150 feet. The fractures intercept stormwater runoff where this water discharges into the
ground. The proposed mitigation improvements include filling these fractures with slurry
material that is easily placed in them. The slurry consists of 95-97% fly ash and 3-5%
cement. Fly ash is a fine powder that is a byproduct of burning pulverized coal in electric
B-2
power-generating plants. It is inert and its use has been proven to be very safe in these
applications.
This will be the first phase of the project and is intended to eliminate storm runoff from
easily becoming part of the groundwater and is an important component in efforts to
minimize landslide-related ground movement. This construction of this phase could be
completed in approximately four months.
Phase II - Surface Drainage Improvements
The surface drainage improvements include the refurbishment of existing swales and
pipes, and construction of a reduction flow area, which essentially serves as a detention
basin near the bottom of the hill landward of Palos Verdes Drive South (PVDS)
(Attachment A - Appendix A). In summary, over the years, the existing swales have
eroded and the drainage pipes have clogged, resulting in inadequate performance. In
some areas, sections of the drainage pipes have been disconnected, displaced or are
missing. Further, as a direct result of landslide movement and land displacement, a few
low areas have formed. During rainfall events, stormwater runoff is trapped in these
areas. Since there is no outlet, the collected stormwater runoff creates ponds and
eventually, the water percolates into the ground and exasperates the landslide.
Over the years, Staff has learned that there is a direct correlation between water
percolating into the ground and landslide movements. In the case of the Abalone Cove
area, the installation of dewatering wells combined with the construction of a sanitary
sewer system to remove existing septic tanks, thereby minimizing the amount of water
seeping into ground, resulted in land movement in the area slowing significantly.
Therefore, a big component of this landslide mitigation project is to significantly reduce
surface water from percolating into the ground by establishing a functioning and
maintainable network of pipes and surface swales so that positive drainage can be
established.
The project will no longer result in stormwater ponding because runoff will be conveyed
through newly establish/refurbished pipes and swales to the ocean in a controlled
manner. The area where ponding most often occurs is just north of PVDS because the
roadway acts as a dam with respect to the stormwater runoff after a significant rainfall
event. It should be noted that the capacity of the existing 60-inch steel pipe under PVDS
is fairly limited, and it originally was recommended that four additional 60-inch pipes
under PVDS, extending to the ocean, be constructed in order to adequately convey the
quantity of stormwater runoff associated with a 100-year rainfall event. The construction
of four pipes would be a significant and costly undertaking. Thus, in order to minimize
costs, a flow reduction area (also known as a detention basin) is proposed to allow
stormwater runoff to be detained and released at a gradual rate through a controlled
outlet mechanism into the existing single, 60-inch diameter pipe under PVDS. A
Bentoliner blanket will be installed under this area to alleviate any water percolation.
B-3
As part of this design, the existing pipe under Burma Road, which is completely clogged
and is no longer functioning properly, will be replaced with a new 36-inch pipe.
Additionally, the existing eroded surface swales will be repaired and in the areas where
runoff velocity is excessive, the swales will be lined with a GeoWeb material, which will
be filled with gravel and/or rock depending on the velocity of runoff. This will alleviate
erosion of these newly-repaired swales. It should be noted that no concrete will be used
in this stabilization method for strengthening the swales.
The design of this project was conducted with continuous public input. Surface swales
were modified to soften the impacts brought forward through the public input process
that are more in line with the surrounding setting of the Palos Verdes Nature Preserve.
Specifically, the original design of the swales was m odified and the use of natural
energy dissipaters has been incorporated into the design in favor of concrete armament.
Controlling the runoff and minimizing infiltration is required as a step toward lessening
ground movement associated with groundwater in this landslide. Similar to filling
fractures, the installation of the surface drainage features is an important design
component to minimize landslide-related ground movement. Accordingly, Staff
recommends installing the swales, pipes and flow reduction area as Phase II of the
project. This phase will follow sealing the fractures as a continuation of efforts to
successfully manage runoff, minimize infiltration, and convey cleaner water with less
velocity (and consequently, less erosion) to the ocean. Construction of this phase could
be completed in approximately 10 months.
Phase III - Below-Grade Hydraugers
Hydraugers, to be constructed below grade, are designed to alleviate artesian water
pressure underground in the Portuguese Bend Landslide area. Their function is similar
to vertical dewatering wells, but they are installed horizontally, beneath the active
movement zone of the landslide. The City’s consultant believes that vertical dewatering
wells are not sustainable in this area because of the land movement. The landslide is
active, with annual movement measured in feet, and consequently, vertical dewatering
wells shear quickly due to the land movement. Until this land movement is minimized,
vertical wells will continue to shear. The high rate of land movement in Portuguese
Bend has resulted in the rapid failure of vertical wells in the areas that will be targeted
with hydraugers.
The exact length, location and number of hydraugers that will be installed is unknown at
the moment, but generally are expected to run up to 1,200 feet in length and are
generally grouped in sets of 5 hydraugers per area. Moreover, the exact parameters for
accessing and staging the hydraugers will be determined during the environmental
review phase of the project, but the staging area measures approximately 100’ by 100’.
The general location of the hydraugers is shown on the plans, but these locations can
change somewhat to accommodate a minimized impact to the habitat located in the
City’s open space. The number of hydraugers to be installed will also be determined
during construction. The consultant is recommending beginning, as a pilot program, the
B-4
hydrauger installation at location A2 (Attachment A – see Appendix A, Drawing No.11)
to intercept groundwater as it enters the landslide. The actual number of hydraugers
installed at this single location will depend on production of the first well. If the initial
hydrauger produces significant dewatering flow, perhaps all 5 hydraugers at this initial
location will be installed. The City’s consultant will evaluate information obtained during
the installation and guide the contractor to obtain favorable results on subsequent
hydraugers at this location. Accordingly, the exact number of hydraugers planned to be
installed is not easily determined. This process will be very dynamic and may require
modifications to previously assumed installation locations. That said, typical to most
environmental documents, a worst case scenario of total buildout will be examined to
estimate the scope of potential impacts.
This third phase of construction involves the installation of the hydraugers which will
follow the installation of surface drainage features. This phase of the project will only
proceed after an examination of Phases I and II to determine if further groundwater
removal is warranted to reduce land movement.
Based on the above, Staff recommends the City Council accept and file the design
drawings and hydrologic analysis associated with Portuguese Bend Landslide Mitigation
Project.
2. Environmental Document
The CEQA process must occur prior to commencing any work. Thus, if the City Council
accepts the design as described above, this essentially would be the defined project
description to be studied in the environmental document pursuant to CEQA. In order to
complete the CEQA process, a request for proposals (RFP) will be issued to
environmental consultants to prepare the appropriate environmental document. The City
Council will be asked to enter into a professional services agreement with the selected
consulting firm. Costs associated with preparing the environmental document will not be
known until proposals are received, at which time, the City Council will be asked to
appropriate the funds.
As part of the CEQA process, the public and other government agencies will be
engaged including, but not limited to, the U.S. Department of Fish and Wildlife and
California Department of Fish and Wildlife (Wildlife Agencies) and the California Coastal
Commission. Furthermore, through this process, project modifications may be needed
prior to obtaining the required permits. Lastly, the preparation of the environmental
document may take approximately one year.
3. Funding Options
A cost estimate (Attachment B) was prepared including all components of this design as
though they would be installed through a single project. However, it is recommended to
complete the various components of the project based on phases, as described above,
to evaluate the effectiveness of each phase prior to proceeding with the next phase, if
B-5
warranted. The estimated costs associated with the proposed mitigation improvements
are itemized below based on either lump sum (LS) or each (Ea.) unit:
Improvement Unit Cost
Phase I
Fracture infilling LS $500,000
Subtotal $500,000
Phase II
New 36” pipe below Burma Road (trenchless installation) LS $500,000
Refurbishment of existing 60” pipe below PVDS LS $250,000
New surface swales, flow reduction area and incidental
drainage items
LS $2,750,000
Subtotal $3,500,000
Phase III
Horizontally-drilled hydraugers Ea. $350,000
Directionally-drilled hydraugers Ea. $500,000
The costs shown above are presented in order of the construction phasing
recommended by the consultant. A cost estimate was prepared including all
components of this design, which totals $21,000,000 (Attachment B). However, the
installation of all hydroaugers may not occur if Phases I and II prove to be effective
thereby significantly reducing the overall cost of the project.
In order to reduce costs borne by the City for this project which serves as a regional
benefit, Staff will continue to work with the City’s grant funding consultant in an effort to
locate and apply for grant funding that may be eligible for this project. Staff also believes
funding may be available from county, state, and federal agencies that could be used
for this project, as well as the following agencies and utilities who are impacted by the
current landslide movement:
Cal Water
Los Angeles County Sanitation District
Southern California Gas Company
Southern California Edison
Rep. Ted Lieu is aware of the need for this project. Staff will continue to work with his
office to secure any funding that may be or become available.
ADDITIONAL INFORMATION:
Septic Systems in the City of Rolling Hills
B-6
According to the Portuguese Bend Feasibility Report, water from Rolling Hills’
residential septic system discharge may contribute, but is not exactly known, to pore
pressure above the landslide slip surface, but the impact below the landslide slip
surface is likely negligible due to the presence of the low hydraulic conductivity
Portuguese Tuff.
The City Manager’s office has been working with the Landslide Subcommittee (Mayor
Cruikshank and Councilman Dyda) and the City of Rolling Hills to address the issue of
groundwater generated through septic systems in their city. As a result of meetings
between representatives of the two city councils, Rolling Hills has agreed to fund half of
a feasibility study to determine if a connection between the septic systems in Rolling
Hills and the Abalone Cove Sewer System would be possible. Staff has retained a
consulting firm, NV5, to conduct the feasibility study and prepare the associated report.
Completion of this report is anticipated in February 2020.
Natural Communities Conservation Plan/Habitat Conservation Plan (NCCP/HCP)
On November 19, 2019, the City Council adopted the final NCCP/HCP, which, among
other things, streamlines permitting for City projects, including the Portuguese Bend
Landslide Mitigation Project. The City is in the process of obtaining permits from the
Wildlife Agencies and anticipates permit approval in February 2020.
The NCCP/HCP permit allows habitat loss to occur for City projects (Attachment D).
The City project categories that may be covered under the Council-adopted NCCP/HCP
pertaining to Portuguese Bend Landslide Mitigation Project are: Dewatering W ells,
Landslide Abatement Measures, Misc. Drainage Repair in Landslide Areas, and Utility
Maintenance and Repair. According to Daniel B. Stephens, an initial estimate of the
work area to be impacted by the project consists of approximately 15.8 acres of coastal
sage scrub, 16.9 acres of grassland, and 5.7 acres of unrestricted vegetation/land
(developed, disturbed, etc.). Of these estimates, the following acreages are within the
Palos Verdes Nature Preserve: 11.9 acres of coastal sage scrub, 2.9 acres of
grassland, and 1.8 acres of unrestricted area. The initial estimates fall with the City’s
habitat loss allowances under the NCCP/HCP and will be further refined during the
preparation of the environmental document. City projects are subject to the Habitat
Impact Avoidance and Minimization Measures defined in Section 5.5 of the NCCP/HCP.
Timeline
The following flow chart has been prepared to visually describe the basic steps involved
prior to commencing project construction. The project is currently at the end of Step 3,
the design phase of the project (highlighted in yellow).
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If the City Council accepts the project design, the next step will be to complete the
environmental document pursuant to CEQA (Step 4) as described earlier in the staff
report, which may generally take approximately one year. Upon completing the
environmental document, the design will be finalized and brought back to the City
Council for final approval along with the environmental document (Step 5). Funding
sources will be required to build these improvements (Step 6) and once identified, the
project phasing can be established and solicitation for contractors’ proposals for
construction will begin (Step 7).
ALTERNATIVES:
In addition to the Staff recommendations, the following alternative action is available for
the City Council’s consideration:
1. Discuss and provide recommendations on other options that may be
appropriate.
2. Direct Staff not to proceed with the Portuguese Bend Landslide Mitigation
Project.
B-8
RANCHO PALOS VERDES CITY COUNCIL MEETING DATE: 12/18/2018
AGENDA REPORT AGENDA HEADING: Regular Business
AGENDA TITLE:
Consideration and possible action to award a Professional Services Agreement to
Daniel B. Stephens & Associates, Inc. for design services associated with the
Portuguese Bend Landslide mediation work.
RECOMMENDED COUNCIL ACTION:
(1) Award a Professional Services Agreement to Daniel B. Stephens & Associates,
Inc. in the not-to-exceed amount of $479,918;
(2) Authorize the City Manager or Director of Finance to execute changes to this
agreement, and a not to exceed contingency of $40,000 to accommodate
unforeseen requirements; and,
(3) Authorize the Mayor and City Clerk to execute the Professional Services
Agreement, contingent on the City Attorney’s approval of the Agreement as to
form.
FISCAL IMPACT: The recommended action will result in a total authorized
expenditure of up to $519,918. This is a new project and funding for this Capital
Improvement design is not included in the approved FY18-19 budget. An additional
appropriation of $519,918 is requested.
Amount Budgeted: $0
Additional Appropriation: $519,918
Account Number(s): 330-400-xxxx-xxxx
ORIGINATED BY: Ron Dragoo, PE, Principal/City Engineer
REVIEWED BY: Elias Sassoon, PE, Director of Public Works
APPROVED BY: Doug Willmore, City Manager
ATTACHED SUPPORTING DOCUMENTS:
A. Agreement for Professional Services (page A-1)
B. Request for Proposals (page B-1)
C. Proposal – Daniel B. Stephens (page C-1)
BACKGROUND AND DISCUSSION:
C-1
The City Council approved the update to the Portuguese Bend Feasibility Study at its
August 7, 2018, meeting. The City Council Subcommittee for the Landslide Feasibility
Study Update reviewed and edited the Request for Proposals (RFP) document for
Engineering Analysis, Evaluation, and Design for improvements in the Portuguese Bend
Landslide to include Drainage and Dewatering (hydro-augers). The RFP document
(Attachment B) was released October 11, 2018. Several consultants were directly
contacted by Staff and the RFP was published on the City’s website in an extended
effort to solicit qualified consultants to submit proposals for the proposed project.
The RFP document asked consultants to provide proposals to the City for their services
including:
• Perform a hydrology study of the watershed including specific hydrologic and
engineering analysis of the watershed to identify as to where, what quantity, how,
and to what extent the stormwater runs off and/or infiltrates into the landslide and
becomes part of the groundwater in the Portuguese Bend Landslide Complex;
• Perform engineering analysis, evaluation, and designs for the lower portion of the
Portuguese Bend Landslide that would convey the drainage runoff to the ocean
directly;
• Design groundwater extraction horizontal drains (hydro-augers) for the lower
area of the landslide, including a cost benefit analysis for the hydro-augers and
any alternatives; and,
• Analyze and design repair plans if sealing fractures in the landslide area between
Palos Verdes Drive South and Burma Road is determined to be needed.
Two proposals were received by the November 12, 2018, submittal deadline. Both
proposals were reviewed and Daniel B. Stephens (Attachment C) was determined to be
the most qualified for the project and required process, including public input and
reviews. Following this determination, Staff entered into negotiations for the fee and to
further refine and narrow the final scope of work for the project.
If this Professional Services Agreement (Attachment A) is approved, the work will only
include: (1) the design of the drainage system at the bottom portion of the landslide
located to the south of Burma Road; (2) the design of any necessary fracture infill in
this area; (3) the design of the underground hydro-augers at the bottom of the slide;
and, (4) the hydrology/hydraulic analysis in the canyons. Any design work to potentially
line any or all of the canyons north of Burma Road is not included in this proposal.
Environmental review work associated with any part of the designs that will be
developed will be undertaken following City Council approval of the designs. As the
Consultant develops engineering designs, they will meet with Staff and applicable
State/Federal agencies as well as the Palos Verdes Peninsula Land Conservancy
(PVPLC) and the City Council Subcommittee to review those designs. A community
outreach meeting will follow to solicit comments on the initial conceptual design of
mitigation efforts, and a 30-day public comment period will be provided to review
proposed design concepts and siting of proposed designed improvements.
Modifications to the design and locations, if needed, will be completed prior to
C-2
proceeding with the ensuing design of the Portuguese Bend Landslide Mitigation
Project. A final public outreach meeting will be conducted and the review and plan
update process repeated prior to bringing the final design plans to the City Council for
review and approval.
Based on their clear understanding of project constraints, local geology, movement and
general characteristics of the landslide, along with the results of the negotiations
associated with project scope and cost, Staff is recommending approval of the
Professional Services Agreement with Daniel B. Stephens & Associates, Inc. to perform
design services for this project.
ALTERNATIVES:
In addition to the Staff recommendations, the following alternative action is available for
the City Council’s consideration:
1. Discuss and provide recommendations on other options that may be
appropriate.
C-3
GEOTECHNICAL EVALUATION REPORT
PORTUGUESE BEND LANDSLIDE COMPLEX MITIGATION MEASURES
RANCHO PALOS VERDES, CALIFORNIA
PREPARED FOR:
City of Rancho Palos Verdes
30940 Hawthorne Boulevard
Rancho Palos Verdes, California 90275
PREPARED BY:
Geo-Logic Associates, Inc.
3150 Bristol Street, Suite 210
Costa Mesa, California 92626
714.465-8240
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TABLE OF CONTENTS
EXECUTIVE SUMMARY .......................................................................................................... iii
1.0 Introduction ............................................................................................................... 1
1.1 Site Locations and Limits of Evaluation .................................................................. 1
1.1 “Preferred” Mitigation Options based on Feasibility Study ................................... 1
1.2 Purpose of this Report ............................................................................................ 2
2.0 Background and Selected Site Conditions ................................................................... 3
2.1 Selected Geologic Features ..................................................................................... 3
2.2 Landslide Reactivation Sequence and Ongoing Displacement Rate ...................... 4
2.3 Groundwater Recharge ........................................................................................... 4
2.4 Note on Artesian Groundwater Conditions ............................................................ 5
2.4.1 General ........................................................................................................ 5
2.4.2 Evidence of Artesian Pressure within the PBLC .......................................... 6
3.0 Conceptual Model for Engineering Evaluation ............................................................. 7
3.1 General .................................................................................................................... 7
3.2 Basis for the Conceptual Model and a Note on Data Gaps .................................... 7
3.3 Subslides and Basal Rupture Surface ...................................................................... 8
3.4 Groundwater ........................................................................................................... 8
3.5 Site Constraints ....................................................................................................... 9
4.0 Geotechnical Evaluations ........................................................................................... 9
4.1 General .................................................................................................................... 9
4.2 Factor of Safety Values for Back-Analysis ............................................................. 10
4.3 Basal Rupture Surface – Shear Strength Evaluation ............................................. 11
4.4 Evaluation of Displacement Rate with Static Factor of Safety ............................. 11
4.5 Evaluation of Dewatering Effect on Displacement Rate ....................................... 12
5.0 Proposed Mitigation Measures and Phased Implementation .................................... 13
5.1 General .................................................................................................................. 13
5.2 Permitting ............................................................................................................. 14
5.3 Preparatory Field Work ......................................................................................... 14
5.4 Construction Phase I - Surface Fracture Infilling................................................... 15
5.5 Construction Phase II – Surface Water Improvements ........................................ 15
5.6 Construction Phase III – Groundwater Mitigation Drains .................................... 16
5.6.1 Sub-Phase III-A – Confirmatory Exploration and Instrumentation ........... 16
5.6.2 Sub-Phase III-B –Up-Gradient “Interceptor” Drains ................................. 16
5.6.3 Sub-Phase III-C – Down-Gradient “Relief” Drains ..................................... 17
5.7 Maintenance and Future Construction Phases .................................................... 17
6.0 LIMITATIONS ............................................................................................................ 17
7.0 REFERENCES ............................................................................................................. 19
D-2
LIST OF FIGURES
Figure 1 – Aerial Photography with Landslide Limits
Figure 2 – Topography with Landslide Limits
Figure 3 – Geology Map
Figure 4 – Landslide Reactivation Sequence
Figure 5 – Measured Horizontal Displacement 2015-2017
Figure 6 – Data Points
Figure 7A – Active Basal Rupture Contour Map
Figure 7B – Ancient Basal Rupture Contour Map
Figure 8 – Groundwater Contour Map
Figure 9 – Isopach Map, Active Basal Rupture vs. Groundwater
Figure 10 – Approximate Areas of Restriction
Figure 11 - Mobilized Shear Strength versus Factor Of Safety
Figure 12 – Cross-Section A-A’
Figure 13 – Cross-Section B-B’
Figure 14 - Cross-Section C-C’
Figure 15 - Cross-Section D-D’
Figure 16 - Shear Strength Evaluation Schematic
Figure 17 - Back-Calculated versus Leighton (2000) Shear Strength
Figure 18 - Displacement Rate versus Estimated Factor of Safety
LIST OF APPENDICES
Appendix A – Plan Set for Proposed Mitigation
Appendix B - Slope Stability Computer Program Output
Appendix C - Hydrology / Hydraulics Calculation Outputs
Appendix D – “Order-of-Magnitude” Cost Estimate
D-3
EXECUTIVE SUMMARY
This report has been prepared by Geo-Logic Associates, Inc. (GLA). It serves as a basis for
development of proposed mitigation measures for a landslide complex within the City of
Rancho Palos Verdes (City) commonly referred to as the Portuguese Bend Landslide Complex
(PBLC). The PBLC is a relatively large (approximately 239 acres, with dimensions approximately
0.9 miles in the east-west direction x 0.8 miles in the north-south direction) active landslide
complex, with ground movement varying across the site but ranging up to approximately 11
feet per year.
GLA developed a conceptual model of the PBLC site to be used for evaluation of proposed
mitigation options. The conceptual model which provides the basis for GLA’s evaluations is
based upon the results of past environmental, geologic, hydrogeologic, and geotechnical
engineering work performed within and beyond the PBLC and a Feasibility Study by DBS&A
(2018). In accordance with City direction and GLA’s approved scope of services, no additional
site-specific subsurface exploration was performed for this study.
Based on the results of GLA’s evaluations, we proposed a mitigation approach to address the
ongoing landslide movement. We note that development of the proposed mitigation approach
considered various site constraints (e.g., minimization of surface impacts to the extent
practicable, cost-effectiveness, support of the public, permitting, etc.), as well as observed
ongoing movement of nearby, “successfully” mitigated landslides (e.g., Abalone Cove
landslide). Given these factors, the objective of the proposed mitigation approach is to reduce
the movement rate of the PBLC, not to “stabilize” the landslide (i.e., in GLA’s opinion, a
mitigation design which achieved commonly accepted geotechnical stability criteria would be
infeasible, as it would not satisfy the various site constraints).
The mitigation measures proposed in this report are, in order of currently envisioned
construction phasing: (i) infilling of existing surface fractures to reduce infiltration; (ii)
construction of surface water improvements to reduce ponding and convey storm water to the
ocean; and (iii) installation of hydrauger arrays to lower hydrostatic and piezometric surfaces.
These mitigation measures should be preceded by permitting and pre-construction preparatory
field work. Long-term maintenance should be conducted, and additional mitigation measures
(i.e., vertical dewatering wells) should be considered in the event that PBLC movement is
slowed significantly.
We note that seismic loading was not considered in the evaluations discussed here. There is an
existing risk that a seismic event may accelerate PBLC movement significantly and/or may cause
rapid failure of a significant portion of the PBLC. The mitigation measures proposed in this
report, if implemented, would not eliminate this risk but might conceivably reduce the risk by a
small amount relative to the existing condition.
D-4
1.0 INTRODUCTION
This report has been prepared by Geo-Logic Associates, Inc. (GLA), in accordance with our
proposal to the City of Rancho Palos Verdes, California (City), dated November 12, 2018. The
work was approved by City Purchase Order 20190286 dated January 21, 2019.
The scope of services documented in this report includes engineering evaluations required for
development of plans (enclosed herewith as Appendix A) and specifications for the proposed
Portuguese Bend Landslide Complex (PBLC) tentative mitigation measures. This report further
presents preliminary recommendations for phased implementation of the mitigation measures
and for post-implementation monitoring.
The conclusions, recommendations, plans, and specifications attached to this report should not
be extrapolated to other areas of this site or used for other projects, at the site or at others,
without GLA review, concurrence, and written approval.
1.1 Site Locations and Limits of Evaluation
The site considered in this report is the PBLC, an existing active landslide complex located on
the Palos Verdes Peninsula in the City of Rancho Palos Verdes, California. The approximate
location of the PBLC footprint, as well as approximate limits of subslides (i.e., relatively
coherent component masses within the PBLC), are shown in Figures 1 and 2 (superimposed on
aerial photograph and topographic map, respectively). Also shown in Figures 1 and 2, and
consistently throughout this report, are the approximate limits of this project.
As shown in Figures 1 and 2, the PBLC is irregularly shaped in plan view but generally resembles
an acute triangle, widening from north to south. For reference, the PBLC has approximate
dimensions on the order of 0.9 miles wide (east-west direction, i.e., generally across movement
direction) x 0.8 miles long (north-south direction, i.e., generally along movement direction), has
a plan area of approximately 239 acres, and contains a volume on the order of approximately
38 million cubic yards of earth materials.
We note that the PBLC has several adjacent or nearby landslides, some of which are also shown
for reference in Figures 1 and 2 (i.e., Abalone Cove, Klondike Canyon, Beach Club, and Flying
Triangle Landslides). We also note that a portion of the PBLC may be situated above (i.e.,
underlain by) a portion of another “ancient” landslide complex. The existence of this ancient
landslide complex was postulated Leighton (2000), suggesting that multiple, nested landslides
may be present at the site and in its vicinity.
The assessment and/or mitigation of nearby landslides and potentially underlying landslides is
outside the scope of this project.
1.1 “Preferred” Mitigation Options based on Feasibility Study
DBS&A (2018) prepared a Feasibility Study (FS), which presented five “preferred” options to
mitigate the ongoing PBLC movement. Note that the objective of the proposed mitigation is to
reduce the movement rate of the PBLC, not to “stabilize” the landslide (i.e., in GLA’s opinion, a
D-5
mitigation design which achieved commonly accepted geotechnical stability criteria would be
infeasible, as it would not satisfy various site constraints, including environmental restrictions
and budget for implementation). In general, these “preferred” options proposed to slow the
landslide movement by: (i) lowering the piezometric surfaces and artesian pressure within and
below the landslide complex; and (ii) reducing groundwater (including artesian pressure)
recharge from stormwater and septic system infiltration. The five “preferred” options outlined
in the DBS&A (2018) FS are as follows:
1. Seal Surface Fractures - Relatively large surface fractures would be mapped and infilled
before the rainy season each year using a long-reach pumping truck, conventional
pumping rig, or other method.
2. Directional Subsurface Drains - Directional drains for groundwater removal would be
installed in a phased manner using a drill rig capable of performing directional drilling to
maintain the drain alignments below the landslide slip surface. This technique would
provide for longer service life for the drains because drains that cross the landslide slip
surface would be quickly compromised by landslide movement.
3. Flexible Liner System and Components - The canyon liner would be used to reduce
stormwater infiltration and percolation to groundwater along Portuguese, Paint Brush,
and Ishibashi Canyons.
4. Groundwater Extraction Wells - Supplemental groundwater extraction wells would be
installed in the project area. Groundwater monitoring wells will also need to be
installed to routinely monitor groundwater levels in the PBLC area.
5. Centralized Sewer System - Approximately 2 miles of new subsurface sewer lines and
associated manholes and junctions would be installed in the Portuguese Bend
neighborhood east of lower Altamira Canyon and west of lower Portuguese Canyon.
The new sewer line installation would be coordinated with private lateral installation
and connection, as well as septic system removal in both neighborhoods.
Of these five “preferred” options proposed in the FS, this report includes evaluation and/or
preliminary construction plans and specifications for items 1, 2, and 3. Item 4 might be
addressed in a future phase of work (e.g., long-term maintenance and monitoring plan). Item
5, in our opinion, is not predominantly a geotechnical concern.
1.2 Purpose of this Report
The purpose of this report is to document engineering evaluations for the predominantly
geotechnical “preferred” mitigation measures (i.e., items 1, 2, and 3 above) and to convey
construction plans and specifications.
D-6
2.0 BACKGROUND AND SELECTED SITE CONDITIONS
Instability and ongoing movement of the PBLC are generally attributable to several factors,
including: (i) the geology of the site and vicinity; (ii) natural groundwater conditions above and
below the PBLC slip surface; and (iii) and human-modified surface and groundwater conditions.
Selected background information regarding these factors is provided here for reference.
2.1 Selected Geologic Features
Geology of the PBLC has been studied since the first reported landslide movement in 1956.
Approximately 500 (or, potentially, more) maps, reports, technical papers and technical
presentations are on-file with the City. A map showing the surficial geology of the PBLC site as
interpreted by GLA is enclosed as Figure 3. This surficial geologic map is generally based on that
prepared by Dibble (1999) with modification based on interpreted landslide limits by Leighton
(2000). Site geologic conditions are summarized in the FS by DBS&A (2018) and are
paraphrased below.
The Palos Verdes Peninsula extends along the southwest-dipping Palos Verdes fault (Douglas,
2013). It is generally elevated due to uplift and formation of a doubly plunging Wilmington
anticline. The PBLC is located on the southern flank of the fold, which generally slopes
downward in a southwesterly direction toward the Pacific Ocean. The head of the PBLC is
located near the crest of the anticline, and the PBLC movement direction generally follows the
downward slope of the anticline in the seaward direction because the landslide slip surface
follows a weak layer within the sedimentary stratigraphic section.
The sedimentary rocks that form the Palos Verdes Peninsula include the Catalina Schist,
Monterey Formation, marine terrace deposits, alluvium, and landslide deposits. Mesozoic-age
Catalina Schist generally forms the core of the anticline (Ehlig, 1992) and is not known to be
involved in subsurface movement. Miocene-age marine sediments of the Monterey Formation,
containing mudstone, shale, chert, and altered volcaniclastic sediments, overlie the schist
(Conrad and Ehlig, 1983; Douglas, 2013).
According to Conrad and Ehlig (1983), the Monterey Formation may be classified into three
members, the stratigraphically lowermost and oldest of which is referred to as the Altamira
Shale. Douglas (2013) further subdivides the lowermost member (i.e., Altamira Shale) into
lower tuffaceous shales and upper cherty and phosphatic lithofacies. The tuffaceous shales in
the lower portion of the Altamira Shale member contain volcanic ash-derived bentonite beds,
which form the slip surfaces of many of the landslides on the Palos Verdes Peninsula (Ehlig,
1992; Douglas, 2013), including the PBLC (i.e., much of the PBLC basal rupture surface lies
within these tuffaceous shale zones). The Portuguese Tuff is one of the most laterally
continuous and thickest of the bentonite beds in the Altamira Shale. In addition to having a low
internal shear strength, the bentonite beds are also have a very slow hydraulic conductivity
which may act as an aquitard, resulting in confined groundwater. There is some evidence of
artesian conditions underlying the landslide slip surface which result when the pore pressure
results in a potentiometric surface that is higher than the local ground elevation. This can result
in groundwater flowing on the ground surface if the aquitard is compromised.
D-7
There is also some evidence of east-west trending anticlinal folding and north-south trending
faulting within the footprint of the PBLC. The anticlinal features, which trend approximately
perpendicular to the PBLC direction of movement, result in undulations of the basal rupture
surface of the PBLC, and facilitate propagation of tension cracks toward the ground surface as
the landslide moves across these undulations.
2.2 Landslide Reactivation Sequence and Ongoing Displacement Rate
Reportedly, the PBLC was dormant for some span of time until reactivated in August 1956
(Ehlig / BYA, 1997). The reactivation sequence, illustrated in Figure 4, reportedly occurred in
relatively discrete stages, as follows: (i) initial triggering near the northeast portion of the PBLC
(area “A”) during construction of the Crenshaw Boulevard extension (now called the Burma
Road); (ii) propagation down-slope (area “B”); (iii) triggering of the central portion of the PBLC
and propagation up-slope (areas “C” and “D,” respectively); and (iv) triggering of the
westernmost portion of the PBLC.
Since its reactivation in 1956, the PBLC has continued to move at various rates within relatively
discrete blocks. Figure 5 illustrates the lateral displacement as measured at GPS monuments in
and around the PBLC footprint. The displacement magnitudes (listed beside vectors) and
directions (directions of vectors) shown correspond to a period of approximately two years
from October 2015 to October 2017. The displacement vectors of largest movement during
this time interval are color-coded red.
Due to the relatively high displacement rate of the PBLC, GPS monuments are occasionally
obliterated and replaced; the period of 2015 to 2017 was selected because several replacement
GPS monuments were installed in 2015 and because 2017 was the most recent survey event
available at the time of our evaluation.
As shown in Figure 5, measured displacements rates within the PBLC range significantly higher
than those within the adjacent landslide terrains. Lateral displacements measured during the
monitoring period are as high as approximately 22 feet within the seaward subslide area,
corresponding to an annualized velocity of approximately 11 feet per year.
2.3 Groundwater Recharge
One factor which contributes significantly to the PBLC instability is persistent elevated
groundwater pore pressure above and below the basal rupture surface. The recharge is
attributed predominantly to five sources:
• Disrupted and/or poorly defined flow of natural channels, including Portuguese Canyon,
Ishibashi Canyon, and Paint Brush Canyon, which apparently terminate and/or change
slope relatively abruptly near the limits of the PBLC. These three canyons drain onto the
active landslide terrain within the upgradient graben which results from extension when
the landslide pulls away from the stable terrain upslope. This water is likely to remain
above the landslide slip surface because the low permeability Portuguese Tuff is
continuous in the area of the upslope graben.
D-8
• Ponding of water upstream of constructed embankments, including at locations of
broken and/or sediment-clogged stormwater conveyance structures (e.g., impaired pipe
and/or culvert for Portuguese Canyon along Burma Road, ponded water north of Palos
Verdes Drive South, apparently undersized and frequently disconnected drainage pipe
along Palos Verdes Drive South, etc.). Many of the storm water conveyances have been
damaged as the upslope graben has grown in response to continued movement of the
landslide. This water is unlikely to penetrate through the Portuguese Tuff due to the
relatively low hydraulic conductivity of the bentonite clay.
• Infiltration of stormwater into open fractures, where surface expressions of cracking
have developed due to differential subslide displacement. Water entering open
fractures within the landslide terrain is likely to remain above the landslide slip surface
due to the presence of the relatively low permeability Portuguese Tuff.
• Percolation from residential septic systems. According to Vonder Linden and Lindvall
(1982) there were approximately 156 residential dwellings located in the active PBLC
when movement was initiated in 1956. This number was reduced to approximately 29
by 1969 and approximately 22 by 1982. The impact of water from residential septic
system discharge on pore pressure above the landslide slip surface is unknown, but the
impact below the landslide slip surface is likely negligible due to the presence of the low
hydraulic conductivity Portuguese Tuff.
• Infiltration of stormwater into up-gradient depressions and grabens. Areas up-gradient
of the PBLC which are candidate sites for groundwater infiltration include the Valley
View Graben. This feature is located east of Crenshaw Boulevard and north of the
ancient landslide complex which includes the PBLC (Dibblee, 1999). The Valley View
Graben and similar extensional features upslope of the larger, ancient landslide may be
allowing for infiltration of surface water, precipitation, and irrigation return from
residential watering that infiltrates to bedrock stratigraphically lower than the
Portuguese Tuff.
2.4 Note on Artesian Groundwater Conditions
2.4.1 General
Groundwater within the void spaces of sediment or rock that has a direct connection to the
atmosphere (i.e., pressure is atmospheric at the top surface of the water) is commonly referred
to as having an “unconfined” or “hydrostatic” condition. When groundwater in the voids in
rock or soil underlies a low conductivity, confining layer such as solid rock or clay and enters the
aquifer from an area of higher elevation, the groundwater may be pressurized more than the
“unconfined” or “hydrostatic” condition. This pressurized condition is commonly referred to as
“confined” or “artesian.” We note that, for the purposes of this report, the terms “artesian”
and “confined” are used interchangeably, although the term “artesian” sometimes is
considered as denoting a flowing condition (i.e., piezometric surface higher than ground
surface).
D-9
Structurally, the Palos Verdes Peninsula is a double plunging dome structure which is elongated
in the northwest-southeast direction with smaller anticlinal and synclinal fold axes
superimposed over the main structure. This results in bedding planes which predominantly
plunge in the downslope direction. The presence of low strength, bentonite bedding planes
dipping downslope has resulted in numerous landslides. However, this structure also can act as
a barrier to groundwater flow because of the low conductivity characteristics of the bentonite
clay. Water percolating into bedrock that is stratigraphically below the bentonite clay beds may
be trapped stratigraphically below the slide plane resulting in an artesian or confined
groundwater condition. The Valley View Graben which overlies the ancient landslide complex
that includes the active PBLC is a closed depression that may have formed from movement of
the ancient landslide complex. Given that the Valley View Graben appears to be formed by
extension it may expose bedrock stratigraphically below the Portuguese Tuff and be a conduit
for groundwater infiltration resulting in artesian groundwater conditions under the PBLC is
likely a significant contributor to instability.
2.4.2 Evidence of Artesian Pressure within the PBLC
Available reports of artesian pressure within the PBLC footprint and in the vicinity of the site
include the following (emphasis added):
• Ehlig (1992) – “only one boring” within the PBLC footprint “has encountered artesian
pressure” within the easterly portion of the seaward subslide, “about 200 feet inland from
the beach in 1957;” the source of the water is possibly attributable to infiltration from up-
gradient septic systems; “in 1981, artesian water was encountered 700 feet further east at
the toe of the Klondike Canyon landslide;” “artesian pressure may occur locally near the
beach but there is no evidence of artesian pressure affecting movement of the slide;”
• Ehlig / BYA (1997) – of three piezometer installations within the northeasterly portion of the
PBLC, measurements from two suggest that upward flow across the basal rupture surface is
“negligible,” while the remaining location showed approximately 10 feet of artesian
pressure head above the corresponding hydrostatic condition;
• Leighton (2000) – the relatively fast rate of movement of the seaward subslide is “in part
due to the episodic excess pore water pressure below the rupture surface” and “in part due
to the continual wave erosion of the toe of the active landslide” (i.e., apparently, artesian
pressure is more significant in the southerly portion of the PBLC than elsewhere, but it is
not necessarily the only or the most important factor affecting stability);
• Hill et al. (2007), citing Ehlig / BYA (1997) – restates that Ehlig / BYA (1997) investigated the
potential for flow across the basal rupture surface by installing three multi-stage pneumatic
piezometers; two instruments in the northern portion of the landslide measured a higher
piezometric level above the rupture surface than below, suggesting negligible downward
flow across the surface; the remaining piezometer measured approximately ten feet of
hydraulic head beneath the rupture surface and none above;
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• Douglas (2013) – makes several mentions of artesian, pressurized, and/or confined flow
below the PBLC basal rupture surface as an important contributing factor to the ongoing
instability and displacement, but does not provide evidence to support such claims;
• RPV (2019) – one groundwater extraction well, of seven installed, located in the
northeasterly portion of the PBLC encountered artesian groundwater conditions at a depth
of approximately 400 feet below ground surface (i.e., at a level significantly below the basal
rupture surface); water reportedly flowed from the well for approximately six days, and,
afterward, remained at approximately the level of the surrounding ground surface.
3.0 CONCEPTUAL MODEL FOR ENGINEERING EVALUATION
3.1 General
To provide a basis for stability evaluation of the PBLC, GLA developed a conceptual model of the
site. The model is exclusively developed based on previous work performed by others (e.g.,
Ehlig / BYA, 1997; Leighton, 2000) and considers information provided by the City on the
direction and intensity of landslide movement, as presented in Figure 5. In accordance with
City direction and GLA’s approved scope of services, GLA has not performed additional field
investigation to evaluate the accuracy of the interpretations by others.
Limited modification of the geologic and hydrogeologic information developed by others has
been performed. This modification was necessary in order to allow for input to three-
dimensional (3D) stability calculations. This includes a provision for artificially daylighting basal
rupture surface within the PBLC footprint, extrapolating groundwater elevation contours to
model domain limits, etc.).
Key elements of the conceptual model for engineering evaluations include interpretation of the
PBLC footprint within the project limits (including postulated daylight of block and complex
rupture surfaces), the elevation of the basal rupture surface, the elevation of the hydrostatic
groundwater table, and the elevation of the artesian piezometric surface. These elements are
presented in Figures 6 through 8.
3.2 Basis for the Conceptual Model and a Note on Data Gaps
Figure 6 shows approximate locations of selected test holes (i.e., borings, piezometers, wells,
etc.) previously advanced by others within and near PBLC, as reported by Ehlig / BYA (1997) and
Leighton (2000). As shown in the figure, numerous test holes were advanced within the PBLC
footprint during the period of 1956 through 1996. We understand that the active basal rupture
surface and the hydrostatic groundwater table locations developed by Leighton (2000), upon
which GLA’s conceptual model is substantially based, considers available geotechnical
information.
While numerous testing locations appear in Figure 6, for the purpose of stability evaluation and
development of remedial measures against landsliding, significant data gaps exist. These
presently include: (i) geotechnical information is limited within the western portion of the
PBLC, particularly within the Western Subslide area, and (ii) due to the significant movement of
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the PBLC, site conditions at the boring locations may have changed significantly (i.e., while the
approximate boring locations shown in Figure 6 are fixed spatially, the ground into which the
borings were advanced has moved significantly, possibly on the order of one hundred feet in
the direction of movement shown in Figure 5).
The results of our preliminary evaluations suggest that artesian pressure is the most significant
contributor to the instability of the PBLC. However, GLA is not aware of any existing study
which characterizes the artesian piezometric surface in a quantitative manner (spatial
distribution of the intensity of artesian pressure). This is a significant data gap. Given that
addressing data gaps is outside the scope of this study (i.e., additional exploration and site
characterization have been excluded from the project scope), GLA relied on observational (i.e.,
qualitative) data and engineering judgment, as discussed below.
3.3 Subslides and Basal Rupture Surface
Leighton (2000) divided the PBLC into five subslides, designated as the Seaward, East-Central,
West-Central, Landward, and Westward Subslides. The conceptual PBLC geometry and the
associated subslide geometries in this study (Figures 1-10) were generated based on the
subslide boundaries and the basal rupture surface developed by Leighton (2000). GLA
subdivided one of the subslides (the Seaward Subslide) into two components. These
components are designated as the East Seaward and West Seaward Subslides (Figures 1-10).
Note that this division between East Seaward and West Seaward Subslides is conceptual and
does not necessarily reflect a judgement by GLA about materially different geological
conditions but, rather, was included to facilitate stability modeling.
Elevation contours of the assumed PBLC active basal rupture surface are shown in Figure 7. The
elevation contours are generally based on those developed by Leighton (2000) plan view figures
and cross-section P-P’. Modifications to the Leighton (2000) contours include: (i) addition of
assumed basal rupture surface contours within the Western Subslide area, (ii) adjustment of
discontinuous contours along East-Central / West-Central Subslide boundary, and (iii)
daylighting of the basal rupture surface around the PBLC perimeter.
3.4 Groundwater
Two groundwater surfaces were included in GLA’s conceptual model: (i) the hydrostatic
groundwater table; and (ii) the piezometric surface of the artesian groundwater. Contours of
hydrostatic groundwater table elevation are shown in Figure 8. These contours are based on
the groundwater table elevations developed by Leighton (2000), with modification to
extrapolate the contours to the model domain limits.
Quantitative information regarding artesian conditions are generally unknown at this time.
Where data exist, standpipe piezometers and/or wells in the area often cross over the
Portuguese Tuff, yielding a hybrid piezometric pressure condition. The artesian piezometric
surface elevation was assumed based on the one measurement in the northeasterly portion of
the PBLC reported by Ehlig / BYA (1997). Based on this measurement, the artesian piezometric
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surface was assumed to be 10 feet above the hydrostatic groundwater table across the PBLC
footprint.
Figure 9 shows an interpretation of groundwater information at the site. It shows an isopach
map relating the anticipated height of the hydrostatic groundwater above the basal rupture
surface. This information may be used, for example, to identify target locations for vertical
dewatering wells during future phases of work, if any (e.g., highest priority dewatering well
locations could be placed in areas of highest hydrostatic water level above the basal rupture
surface).
3.5 Site Constraints
Figure 10 shows GLA’s understanding of potential environmental constraints on the project site.
In general, the categories of restricted site area are: (i) unrestricted (green), (ii) restricted
grassland (yellow), and (iii) restricted coastal sage scrub (red). It is GLA’s understanding that
construction may be performed freely (i.e., without restraint) in unrestricted areas, but that
proposed disturbance areas of grassland and coastal sage scrub are to be quantified and may
be subject to restrictions in the permitting stage.
4.0 GEOTECHNICAL EVALUATIONS
4.1 General
Geotechnical evaluations were performed in support of development of landslide mitigation
measures. Note that the objective of the proposed mitigation is to reduce the movement rate
of the PBLC, not to “stabilize” the landslide (i.e., in GLA’s opinion, a mitigation design which
achieved commonly accepted geotechnical stability criteria would be infeasible, as it would not
satisfy various site constraints). The models used in these evaluations were based upon the
conceptual model of site geologic and hydrogeologic conditions discussed above. Selected
computer program outputs are enclosed as Appendix B.
To accommodate complex geologic and hydrogeologic conditions at the site, as well as the
observed pattern of ongoing landslide movement, the evaluations were performed in two
stages. The following was evaluated / established in the first stage:
• Delineate blocks within the PBLC that move quasi-independently;
• Assign a Factor of Safety (FS) for each quasi-independent block;
• Perform back-analysis to estimate shear strength along basal rupture surface of each quasi-
independent block.
• Based on assigned FS value and observed pattern of landslide movement, assign rate of
movement to each block.
This first stage of evaluation was performed to establish a baseline for forward analyses.
Evaluations for this stage were performed using relatively simple two-dimensional (2D) slope
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stability analysis methods but with multiple cross-sections to address the relatively complex
geometry and groundwater flow conditions.
The forward analyses were performed using relatively advanced 3D slope stability evaluation
methods. The more detailed engineering model was required to allow for key remedial design
considerations, namely, number, length, orientation and diameter of hydraugers (relief wells
advanced by directional drilling). The material parameters (i.e., basal rupture surface shear
strength) used for this stage were evaluated in the first stage.
We note that seismic loading was not considered in the evaluations discussed here. There is an
existing risk that a seismic event may accelerate PBLC movement significantly and/or may cause
rapid failure of a significant portion of the PBLC. The mitigation measures proposed in this
report, if implemented, would not eliminate this risk but might conceivably reduce the risk by a
small amount relative to the existing condition.
4.2 Factor of Safety Values for Back-Analysis
For the actively moving PBLC, it was assumed that the FS varies across the site but is generally
within the range of FS = 1.0 to 1.15. For a “typical” landslide, FS = 1.0 is commonly interpreted
as “failure” (i.e., that the landslide mass is on the verge of moving or is anticipated to move by
several feet before stopping). In the case of the PBLC, the landslide has been moving over an
extended period of time; for such a condition, a FS value more than 1.0 is considered
appropriate. The assumed FS value and the geometry of the basal rupture surface are
commonly used for a back analysis approach to evaluate (residual) shear strength.
Given that this landslide complex is moving, GLA distinguishes two general failure mechanisms:
(i) “creep”-type; and (ii) “catastrophic”-type. The former (i.e., “creep”) generally involves
continuous deformation under sustained loading, while the loading is typically less than the
controlling strength of the resisting system (e.g., slope stability evaluation shows factor of
safety higher than 1). The latter (i.e., “catastrophic”) generally involves relatively rapid failure
under loading which reaches or exceeds the controlling strength of the resisting system (e.g.,
slope stability evaluation shows FS = 1.0).
As shown schematically in Figure 11, the FS estimated by slope stability evaluation may also be
considered in terms of the proportion of shear strength mobilized along the critical failure
surface. The proportion of mobilized shear strength ranges between zero (i.e., no loading
applied) and 1 (i.e., applied loading results in “catastrophic”-type failure). Commonly, a
stability criterion of FS ≥ 1.25 is used for temporary stability of slopes, suggesting that “creep”-
type deformation is uncommon when 80% or less of the available shear strength is mobilized.
Additionally, it might be assumed that, within the range for “creep”-type failure, the rate of
displacement increases with an increase in proportion of mobilized shear strength.
In light of the long-term, ongoing movement of the PBLC over a period of several decades, as
well as the characterization of the movement as creep/creeping/etc. by several previous
consultants (e.g., Ehlig / BYA, 1997; Leighton, 2000; Douglas, 2013) GLA categorizes the failure
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mechanism of the PBLC observed to date as “creep”-type. This observation suggests that the
factor of safety assumed for back-analysis should be more than unity but less than
approximately 1.25. Based on the decreasing rates of movement from south to north (i.e.,
fastest nearest the coastline), it was assumed for back-analysis that the factor of safety
increases in the same direction, from approximately 1.05 for seaward subslides to
approximately 1.15 for the landward subslide.
4.3 Basal Rupture Surface – Shear Strength Evaluation
Back-analysis for shear strength evaluation of the basal rupture surface was performed for four
cross-sections through the PBLC, designated as cross-sections A-A’ through D-D’. Locations of
cross-sections are shown in plan view in Figures 2 through 10. Profile views of the sections are
shown in Figures 12 through 15.
GLA performed back-analysis using stability analysis software SLOPE/W (www.geo-slope.com).
In particular, GLA used the Morgenstern and Price (1965) limit equilibrium-based approach, as
implemented in SLOPE/W, for the evaluation. The landslide material was modeled as
“Crossbed Slide Debris” based on the material types presented by Leighton (2000), with a total
unit weight of 127 pounds per cubic foot, friction angle of 20 degrees, and cohesion of 600
pounds per square foot. The basal rupture surface was divided into up to three material types
at the subslide limits, as illustrated schematically in Figure 16. Material properties for basal
rupture surface included total unit weight of 127 pounds per cubic foot and zero cohesion.
Friction angles for the subslides were evaluated sequentially. Seaward subslides were
evaluated by back-calculation first; then central subslides, then landward subslide. The input
friction angle for a segment of basal rupture surface was varied in increments of 0.2 degrees
until the calculated factor of safety was within approximately 0.01 of the assumed factor of
safety value for that subslide.
The estimated friction angle values for the basal rupture surface ranged from approximately 5.2
degrees to 11.8 degrees, with averages of approximately 7.7 degrees, 7.2 degrees, and 8.3
degrees for seaward, central, and landward subslides, respectively. As shown in Figure 17, the
range of estimated values is comparable to the range of values estimated by Leighton (2000)
for the east-central subslide, west-central subslide, and Abalone Cove Landslide basal rupture
surfaces. This range is also in reasonable agreement with laboratory test results of drained
residual strength of remolded bentonite from the PBLC reported by Watry and Lade (2000).
4.4 Evaluation of Displacement Rate with Static Factor of Safety
GLA developed a conceptual relation between assumed factor of safety and landslide
movement rate (i.e., velocity). The purpose of this conceptual relation is to aid in prediction of
the effectiveness (i.e., reduction in movement rate) which might be expected for a particular
mitigation approach. We note that, due to factors including relatively complex mechanics of
the PBLC movement and relatively few data points, predictions based on this conceptual
relation should be assumed to have low accuracy and low precision and should not be relied
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upon. Implementation of mitigation measures should be accompanied by instrumentation of
the PBLC to assess effectiveness in the field.
Figure 18 shows the conceptual landslide movement rate / factor of safety relation developed
for the site. Three each data points were generated cross-sections A-A’ through C-C’, and one
data point was generated for cross-section D-D’. One data point was generated for each
subslide traversed by a cross-section. Movement rates were estimated by selecting movement
vectors (Figure 5) near the cross-sections and averaging the magnitudes of the vectors within
each of the subslide footprints. Factor of safety values correspond to the assumed values used
in the back-analysis.
The “best estimate” line shown in Figure 18 represents the conceptual relation of movement
rate with estimated factor of safety. As shown in the figure, the predicted movement rate
approaches large values as the factor of safety approaches unity and asymptotically approaches
zero as the factor of safety increases. Based on this conceptual relation, GLA considers it
plausible that the movement rate can be reduced significantly if the factor of safety can be
increased to approximately 1.2 or more.
4.5 Evaluation of Dewatering Effect on Displacement Rate
As discussed in the DBS&A (2018) feasibility study, the preferred mitigation measures for the
PBLC movement generally involve modification of the site groundwater conditions. The site
modifications proposed here may be categorized generally as follows: (i) measures to reduce
surface water infiltration through surface cracks, surface depressions, and unlined channels;
and (ii) measures to relieve artesian pressure along the basal rupture surface. Proposed
mitigation measures are shown in the enclosed plan set (Appendix A).
GLA performed evaluations to assess the anticipated impacts of the proposed surface water
and groundwater modification measures on movement rate of the PBLC. Evaluations were
performed for cross-sections A-A’ through C-C’ through the PBLC using the slope stability
analysis software SLOPE/W (www.geo-slope.com). Note that lowering of the assumed
groundwater levels along cross-section D-D’ apparently would not provide a significant benefit
for slope stability, although additional exploration is warranted for cross-section D-D’ and the
western subslide area more broadly. GLA used the Morgenstern and Price (1965) limit
equilibrium-based approach, as implemented in SLOPE/W, for the evaluation. The material
properties used for the evaluation were as described in Section 4.2 (Shear Strength Evaluation)
of this report (i.e., landslide material was modeled as “Crossbed Slide Debris” based on
Leighton, 2000, and basal rupture surface segments were assigned shear strength based on
back-analysis).
Four scenarios were considered in the evaluation: (i) existing conditions, i.e., pre-mitigation; (ii)
lowered hydrostatic groundwater table only; (iii) lowered artesian piezometric surface only; and
(iv) lowered hydrostatic groundwater table and artesian piezometric surface. Results of the
evaluation are shown in Table 1. Note that factor of safety values listed in Table 1 are
estimated for the seaward subslides.
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TABLE 1
ESTIMATED FACTOR OF SAFETY FOR SEAWARD SUBSLIDES PRE- AND POST- MITIGATION
Scenario Evaluated Cross-Section A-A’ Cross-Section B-B’ Cross-Section C-C’
1 - Existing Conditions
(pre-mitigation) 1.06 1.04 1.04
2 - Lowered Hydrostatic
Groundwater Table
Only
1.09 1.05 1.04
3 - Lowered Artesian
Piezometric Surface 1.16 1.10 1.13
4 - Lowered Hydrostatic
Groundwater Table
And Artesian
Piezometric Surface
1.25 1.11 1.13
Based on the estimated factor of safety values listed in Table 1, the following observations are
made:
• Lowering the hydrostatic groundwater table in isolation apparently does not have adverse
stability impacts and modestly increases factor of safety for one of three cross-sections
considered;
• Lowering the artesian piezometric surface in isolation apparently does not have adverse
stability impacts and increases factor of safety relatively significantly for three of three
cross-sections considered; and
• Lowering the hydrostatic groundwater table in addition to lowering the artesian
piezometric surface apparently does not have adverse stability impacts and results in
modest additional increase of factor of safety for two of three cross-sections considered.
Based on the estimated factor of safety values shown in Table 1, as well as the estimated
displacement rates shown in Figure 18, it is conceivable that implementation of the surface
water and groundwater mitigation measures could slow the movement of the PBLC to rates
ranging from less than 0.1 to approximately 0.6 feet per year, considerably slower than the
annualized rates of approximately 2 to 11 feet per year measured between 2015 and 2017.
Note that this finding suggests that, even if the proposed mitigation measures were
implemented, the PBLC would not be “stabilized” (i.e., would not meet commonly accepted
geotechnical design criteria) and would continue to move (although likely at a slower rate).
5.0 PROPOSED MITIGATION MEASURES AND PHASED IMPLEMENTATION
5.1 General
Proposed mitigation measures are shown in the plan set enclosed as Appendix A. Supporting
hydrology and hydraulics calculations for the surface water components are enclosed as
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Appendix C. A notional cost estimate for the proposed mitigation measures is enclosed as
Appendix D.
The sequence of the recommended mitigation measures has been organized in this report to
provide a phased-approach to construction and installation. The general sequence through
construction is anticipated be as follows: (i) permitting; (ii) preparatory field activities;
(iii) phased construction. The construction may be implemented in stages, which may be
awarded separately, if needed. At this time, GLA envisions the construction phasing as follows:
(i) surface fracture infilling; (ii) surface water improvements; and (iii) groundwater mitigation
improvements. Continuous field observation should be performed during construction under
the supervision of a California registered Geotechnical Engineer. Post-construction items are
anticipated to include long-term maintenance, landslide monitoring, and possible future
construction phases. Additional discussion on these items is provided below.
5.2 Permitting
The City should obtain all required permits before beginning construction activities. The City
should require the contractor to accommodate, to the extent practicable, all conditions of the
permits, environmental mitigation plans, and similar documents. The contractor should make
all reasonable efforts to minimize impacts to site flora and fauna.
At this time, we anticipate that the Palos Verdes Peninsula Land Conservancy will be involved in
the permitting process and that the California Coastal Commission may become involved at
some point during permitting. Additional agencies which may assert jurisdiction (although GLA
is not aware of such a jurisdictional claim at this time) and/or may become involved during
permitting include the California Department of Fish and Wildlife, the U.S. Army Corps of
Engineers, California Department of Water Resources, and/or the Los Angeles County
Department of Public Works.
5.3 Preparatory Field Work
We recommend that the City immediately increase the frequency of its landslide displacement
survey from approximately annual to approximately monthly. This increased frequency of
monitoring should be maintained through the end of construction. Monthly monitoring should
continue for approximately one year after construction, and the frequency should be
reevaluated at the end of this period. We anticipate that the data developed from the more
frequent monitoring program may be used to assess items including effectiveness of the
proposed mitigation measures and the seasonal variability of landslide movement.
The PBLC site is an active landslide and is moving. The topography and existing improvements
shown in the plans and figures should be considered approximate. We recommend that the
City require the contractor to perform a pre-construction topographic survey of the PBLC
footprint, with a margin of several hundred feet outside the PBLC limits. This survey should
include establishment of control points for the construction. We note that the topographic
information provided by the City, which GLA relied upon in evaluation and design, may differ
significantly from topography at the time of the future construction. The City should anticipate
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that discrepancies are likely to be identified and that some redesign may be necessary to
accommodate these discrepancies.
Before the start of construction, the City should require the contractor to perform a pipe
condition survey for the existing 60-inch-diameter pipe below Palos Verdes Drive South. The
contractor should field verify the existing pipe’s location, flowline elevations, diameter,
functionality, structural integrity, and remaining useful life. The deliverable for the pipe
condition survey should be a report conveying findings as to these items, as well as
recommendations for retrofit and restoration, as necessary; the report should be prepared
under the supervision of a California registered Professional Engineer.
The City should require the contractor to provide access roads, working platforms, staging
areas, and other temporary site features as needed to perform the construction. The
contractor should establish these items in the field during the construction mobilization.
5.4 Construction Phase I - Surface Fracture Infilling
We anticipate surface fracture infilling will be performed during the first phase of construction.
For the purpose of estimating infill quantities, GLA evaluated lengths of visible fractures and
assumed regular (i.e., standardized) fracture width and depth. The City should require the
contractor to field verify fracture locations and dimensions. The identified fractures should be
infilled with a flowable/pumpable fly ash-based slurry.
After the initial fracture infilling event, the City should perform periodic observation to identify
fractures which may open in the future due to ongoing landslide movement. Fractures
identified during periodic observation should be infilled as part of post-construction
maintenance.
5.5 Construction Phase II – Surface Water Improvements
We anticipate surface water improvements will be installed during the second phase of
construction. Recommended surface water improvements, as shown in the enclosed plan set
(Appendix A) include the following:
• Engineered swales;
• Flow reduction area;
• Installation of new 36-inch-diameter pipe below Burma Road using trenchless
techniques;
• Removal and disposal of existing 36-inch-diameter plastic pipe south of Palos Verdes
Drive South and replacement with thick-walled fusion-welded plastic pipe;
• Refurbishment (i.e., cleanout, lining with smooth polymeric material, and structural
retrofit if needed) of existing 60-inch-diameter pipe below Palos Verdes Drive South.
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5.6 Construction Phase III – Groundwater Mitigation Drains
We anticipate groundwater mitigation improvements will be installed during the third phase of
construction. Types and locations of recommended groundwater mitigation improvements are
shown in the enclosed plan set.
The groundwater mitigation program is planned to be implemented in three sub-phases, as
discussed below. The sub-phases generally consist of: (i) preparatory work and
instrumentation; (ii) installation of up-gradient drains using horizontal drilling; and (iii)
installation of down-gradient drains using directional drilling. The pace and sequence of
construction within each sub-phase is likely to require adjustment based on field observations
(i.e., field observations during construction should inform the work going forward so that
appropriate design and construction adjustments may be made).
5.6.1 Sub-Phase III-A – Confirmatory Exploration and Instrumentation
We anticipate that drain installation may pose safety hazards due to uncertainties associated
with the hydrostatic and artesian groundwater elevations. Before installing the hydraugers, the
City should require the contractor to perform a program of confirmatory subsurface exploration
to evaluate soil and groundwater conditions in the areas of proposed hydrauger installation.
The City should require the contractor to develop and submit a workplan for exploratory work.
Subsurface exploration should be performed under the supervision of a California registered
Geotechnical Engineer and/or Certified Engineering Geologist. A report should be prepared
conveying findings of the exploration and providing recommendations for installation of
grouted conductor and/or surface casing with adequate capacity to prevent blowout and/or
other potential adverse events related to hydrauger installation, operation, and/or
maintenance.
We recommend that an instrumentation program also be performed during the confirmatory
exploration. The purpose of the instrumentation program is to assess the effectiveness of the
mitigation measures, particularly of the groundwater improvements. Anticipated effects of the
proposed mitigation measures include lowered hydrostatic groundwater surface, lowered
artesian piezometric surface, and reduced movement rate of the landslide; adequate
instrumentation should be installed so that these effects can be measured, if achieved. We
anticipate that instrumentation will include a combination of nested piezometers and survey
monuments installed at various locations, particularly around hydrauger arrays.
5.6.2 Sub-Phase III-B –Up-Gradient “Interceptor” Drains
The first stage of hydrauger installation is planned to focus on the two up-gradient drain arrays
(i.e., Arrays 2 and 3 in the enclosed plan set). Access to these locations is anticipated to be
more readily available for these locations, and the horizontal drilling technique is anticipated to
be simpler and significantly less expensive than with the directional technique. Additionally, as
a water wash is planned to be used for horizontal drilling, drain development is anticipated to
be simpler for these arrays than for directionally drilled arrays (for which bentonite-based
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drilling fluid is anticipated to be used). Information collected during installation of the each
horizontal drain (e.g., soil conditions, pore water pressure, discharge rate, etc.) should be
recorded and may be used to adjust plans for subsequent drain installation.
5.6.3 Sub-Phase III-C – Down-Gradient “Relief” Drains
The second stage of hydrauger installation is planned to focus on the four down-gradient drain
arrays (i.e., Arrays 1 and 4 through 6 in the enclosed plan set). Due to access constraints and
relatively complicated installation, the City may choose to retain a specialty contractor for these
drains. Information collected during installation of each horizontal drain (e.g., soil conditions,
pore water pressure, discharge rate, etc.) should be recorded and may be used to adjust plans
for subsequent drain installation.
5.7 Maintenance and Future Construction Phases
The City should plan and implement a post-construction maintenance program to allow for
long-term functionality of the proposed improvements. Potential sources of maintenance
issues include build-up of silt and vegetation in the channels, pipes, and flow reduction area;
buildup of silt and mineral deposits in the subsurface wells; and continued landslide movement
(at a reduced but measurable rate). Potential periodic monitoring and maintenance operations
include field observation of the improvements, infilling of reopened and newly observed
fractures, silt removal from channels and flow reduction area by grading, and jetting of pipes
and drains.
In the event that the proposed mitigation measures are observed to slow the landslide
movement significantly (e.g., by approximately an order of magnitude), we recommend the City
consider additional dewatering to reduce movement rate further. In particular, we recommend
the City consider installation of vertical dewatering wells arranged in a grid pattern. The slowed
landslide movement would allow for longer design life of vertical wells penetrating the basal
rupture surface, as it would extend the time until landslide movement caused shearing (i.e.,
failure) of the well casing.
6.0 LIMITATIONS
In preparing the findings and professional opinions presented in this report, Geo-Logic
Associates (GLA) has endeavored to follow generally accepted principles and practices of the
engineering geologic and geotechnical engineering professions in the area and at the time our
services were performed. This report and the enclosed plans and calculations were peer
reviewed internally in accordance with GLA’s peer review policy. No warranty, express or
implied, is provided.
The conclusions and recommendations contained in this report are based, in part, on
information that has been provided to us. In the event that the general development concept
or general location and type of improvements are modified, our conclusions and
recommendations shall not be considered valid unless we are retained to review such changes
and to make any necessary additions or changes to our recommendations. To remain as the
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project geotechnical engineer-of-record, GLA must be retained to provide geotechnical field
observation services during construction.
Subsurface exploration is necessarily confined to selected locations and conditions may, and
often do, vary between these locations. Should conditions different from those described in
this report be encountered during project development, GLA should be consulted to review the
conditions and determine whether our recommendations are still valid. Additional exploration,
testing, and analysis may be required for such evaluation.
Should persons concerned with this project observe geotechnical features or conditions at the
site or surrounding areas which are different from those described in this report, those
observations should be reported immediately to GLA for evaluation.
It is important that the information in this report be made known to the design professionals
involved with the project (if other than GLA), that our recommendations be incorporated into
project drawings and documents, and that the recommendations be carried out during
construction by the contractor and subcontractors. It is not the responsibility of GLA to notify
the design professionals and the project contractors and subcontractors.
The findings, conclusions and recommendations presented in this report are applicable only to
the specific project development on this specific site. These data should not be used for other
projects, sites or purposes unless they are reviewed by GLA or another qualified geotechnical
professional.
Geo-Logic Associates
Alan F. Witthoeft, PE, GE Mark W. Vincent, PG, CEG, CHg
Project Engineer III Senior Geologist
Neven Matasovic, PhD, PE, GE
Principal
nmatasovic@geo-logic.com / 714-465-8240
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7.0 REFERENCES
Conrad, C.L. and Ehlig, P.L. (1983), “The Monterey Formation of the Palos Verdes Peninsula,
California - An Example of Sedimentation in a Tectonically Active Basin within the California
Continental Borderland,” In Cenozoic Marine Sedimentation, Pacific Margin, U.S.A., Pacific
Section, Soc. Econ. Paleontologists and Mineralogists (Larue, D.K. and Steel, R.J., eds.),
pp. 103 116.
DBS&A (2018), “Feasibility Study Update, Portuguese Bend Landslide Complex, Rancho Palos
Verdes, California,” Technical Report, Daniel B. Stephens & Associates, Inc., Costa Mesa,
California (Project No. DB17.1171.00).
Douglas, R. (2013), “The Creepy (Slow Moving) Landslides of Portuguese Bend,” AEG Special
Publication No. 24, Association of Environmental & Engineering Geologists, Los Angeles,
California.
Dibblee, T.W. (1999) “Geologic Map of the Palos Verdes Peninsula and Vicinity Redondo Beach,
Torrance, and San Pedro Quadrangles, Los Angeles County, California,” Dibblee Geology
Center Map #DF-70 (eds. Ehrenspeck, H.E., Ehlig, P.L., and Bartlett, W.L., 1999; ed. Minch,
J.A., 2011).
Ehlig, P.L. (1992), “Evolution, mechanics and mitigation of the Portuguese Bend Landslide, Palos
Verdes Peninsula, California,” In AEG Special Publication No. 4, Association of
Environmental & Engineering Geologists, Los Angeles, California.
Ehlig / BYA (1997), “Feasibility of Stabilizing Portuguese Bend Landslide,” Technical Report,
Perry Ehlig, Consulting Engineering Geologist, South Pasadena, California, and Bing Yen &
Associates, Inc., Irvine, California (BYA Project No. G-940989).
Hill, C.A., Douglas, R.G., and Hammond, D.E. (2007), “A Hydrological Assessment of
Groundwater Sources in the Portuguese Bend and Abalone Cove Landslide Areas, California:
Implications for Landslide Movement,” In Geology and Paleontology of Palos Verdes Hills,
California, A 60th Anniversary Revisit to Commemorate the 1946 Publication of U. S.
Geological Survey Professional Paper 207, Book 103, pp. 271-292, Pacific Section SEPM
(Society for Sedimentary Geology), Walnut, California.
Leighton (2000), “Updated Feasibility Study for the Portuguese Bend Landslide Remediation
Project at Peacock Hill and Portuguese Bend, City of Rancho Palos Verdes, California,”
Technical Report, Leighton and Associates, Inc., Irvine, California (Project No. 1881922-26).
Morgenstern, N.R. and Price, V.E. (1965), “The Analysis of the Stability of General Slip Surfaces,”
Géotechnique, Vol. 15, pp. 70-93.
RPV (2019), “Dewatering well,” Email Communication, Mr. James Flannigan to Dr. Neven
Matasovic, City of Rancho Palos Verdes, California.
D-23
Vonder Linden, K. (1972), “An Analysis of the Portuguese Bend Landslide, Palos Verdes Hills,
California,” PhD Dissertation, Stanford University, Stanford, California.
Vonder Linden, K. and Lindvall, C.E. (1982), “The Portuguese Bend Landslide,” In Landslides and
Landslide Abatement, Palos Verdes Peninsula, Southern California, Guidebook for the 78th
Annual Meeting of the Geological Society of America, Anaheim, California (compiled by John
D. Cooper) pp. 49-56.
Watry, S. M., and Lade, P. V. (2000), “Residual Shear Strengths of Bentonites on Palos Verdes
Peninsula, California.” In Slope Stability 2000, pp. 323-342. ASCE.
D-24
FIGURES
D-25
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MOBILIZED SHEAR STRENGTH VERSUS FACTOR OF SAFETY
PORTUGUESE BEND LANDSLIDE MITIGATION
RANCHO PALOS VERDES, CALIFORNIA
DATE: November 2019
FIGURE NO 11 PROJECT NO. DB19.1055.00
D-37
3150 Bristol Street, Costa Mesa, California 92626geo-logic.com│657.218.4708ISSUED FOR REVIEWCROSS SECTION A-A'D-38
3150 Bristol Street, Costa Mesa, California 92626geo-logic.com│657.218.4708ISSUED FOR REVIEWCROSS SECTION B-B'D-39
3150 Bristol Street, Costa Mesa, California 92626geo-logic.com│657.218.4708ISSUED FOR REVIEWCROSS SECTION C-C'D-40
3150 Bristol Street, Costa Mesa, California 92626geo-logic.com│657.218.4708ISSUED FOR REVIEWCROSS SECTION D-D'D-41
SHEAR STRENGTH EVALUATION SCHEMATIC
PORTUGUESE BEND LANDSLIDE MITIGATION
RANCHO PALOS VERDES, CALIFORNIA
DATE: November 2019
FIGURE NO 16 PROJECT NO. DB19.1055.00
Notes:
1. Schematic illustration. Not to scale.
2. Friction angles shown are averages for cross-sections A-A’ through D-D’ (as
applicable) as evaluated for each segment by back-calculation.
D-42
BACK-CALCULATED VERSUS LEIGHTON (2000) SHEAR STRENGTH
PORTUGUESE BEND LANDSLIDE MITIGATION
RANCHO PALOS VERDES, CALIFORNIA
DATE: November 2019
FIGURE NO 17 PROJECT NO. DB19.1055.00
D-43
DISPLACEMENT RATE VERSUS ESTIMATED FACTOR OF SAFETY
PORTUGUESE BEND LANDSLIDE MITIGATION
RANCHO PALOS VERDES, CALIFORNIA
DATE: November 2019
FIGURE NO 18 PROJECT NO. DB19.1055.00
D-44
APPENDICES
D-45
APPENDIX A
PLAN SET FOR PROPOSED MITIGATION
D-46
REV. NO.DATE DESCRIPTION APPROVED BY
3150 BRISTOL STREET
SUITE 210
COSTA MESA, CA 92626
(714) 465-8240
www.geo-logic.com
DWG NO.
LOS ANGELES COUNTY, CA
30940 HAWTHORNE BLVD.
RANCHO PALOS VERDES,CA 90275
NOT FOR CONSTRUCTION-PENDING ENVIRONMENTAL REVIEW
PORTUGUESE BEND LANDSLIDE MITIGATION
CITY OF RANCHO PALOS VERDES
THE CITY OF
RANCHO PALOS VERDES
FINAL-REV 1
TITLE SHEET
1
UTILITY COMPANY CONTACT INFORMATION PHONE
CITY OF RANCHO PALOS VERDES (310) 544-5252
SOUTHERN CALIFORNIA EDISON COMPANY (310) 783-1156
SOUTHERN CALIFORNIA GAS COMPANY (310) 687-2020
VERIZON (310) 793-4159
CALIFORNIA WATER SERVICE COMPANY (310) 541-2438
COX COMMUNICATIONS (310) 551-5020 X30
COUNTY OF LOS ANGELES, DEPARTMENT OF PUBLIC WORKS
(STORM DRAIN)(626) 458-3109
COUNTY OF LOS ANGELES, DEPARTMENT OF PUBLIC WORKS
(SEWER)(626) 458-4357
SANITATION DISTRICT OF LOS ANGELES COUNTY (562) 699-7411 X1205
USA (800)227-2600
NOTICE: ACTUAL EXISTING SITE CONDITIONS MAY DIFFER FROM THOSE SHOWN. THE CONTRACTOR SHALL VERIFY SITE CONDITIONS PRIOR TO BIDDING. LOCATION OF EXISTING
AND ABANDONED UTILITIES IS UNKNOWN OR FROM RECORD DATA ONLY. THE CONTRACTOR SHALL VERIFY TO HIS SATISFACTION LOCATIONS OF ALL UTILITIES PRIOR TO BIDDING
AND CONSTRUCTION. CONTRACTOR SHALL MAINTAIN AS-BUILT RECORDS OF EXISTING UTILITIES AND INFORM THE ENGINEER IN CASE OF DISCREPANCIES.
THE CONSTRUCTION CONTRACTOR AGREES THAT IN ACCORDANCE WITH GENERALLY ACCEPTED CONSTRUCTION PRACTICES, CONSTRUCTION CONTRACTOR WILL BE REQUIRED
TO ASSUME SOLE AND COMPLETE RESPONSIBILITY FOR JOB SITE CONDITIONS DURING THE COURSE OF CONSTRUCTION OF THE PROJECT, INCLUDING THE SAFETY OF ALL
PERSONS AND PROPERTY; THAT THIS REQUIREMENT SHALL BE MADE TO APPLY CONTINUOUSLY AND NOT BE LIMITED TO NORMAL WORKING HOURS, AND CONSTRUCTION
CONTRACTOR FURTHER AGREES TO DEFEND, INDEMNIFY, AND HOLD DESIGN PROFESSIONAL HARMLESS FROM ANY LIABILITY, REAL OR ALLEGED, IN CONNECTION WITH THE
PERFORMANCE OF WORK ON THIS PROJECT, EXCEPTING LIABILITY ARISING FROM THE SOLE NEGLIGENCE OF DESIGN PROFESSIONAL.
THE ENGINEER PREPARING THESE PLANS WILL NOT BE RESPONSIBLE FOR, OR LIABLE FOR, UNAUTHORIZED USE OF THESE PLANS. ALL CHANGES TO THE PLANS MUST BE IN
WRITING AND MUST BE APPROVED BY THE PREPARER OF THESE PLANS.
THE CONTRACTOR SHALL VERIFY THE PRESENCE, LOCATION, AND MATERIAL OF ALL AFFECTED OR CONFLICTING UTILITIES AS NECESSARY FOR CONSTRUCTION. UTILITY
VERIFICATION AND NOTIFICATION SHALL BE MADE IN A TIMELY MANNER SO AS TO ALLOW FOR ALTERNATIVE PLANNING WITHOUT AFFECTING THE CONSTRUCTION SCHEDULE
MATERIALLY.
NOVEMBER, 2019
PORTUGUESE BEND LANDSLIDE COMPLEX MITIGATION MEASURES
CITY OF RANCHO PALOS VERDES, CALIFORNIA
DRAWING INDEX:
GENERAL INFORMATION
• Grading Permit Application No. GR_____________________________ *
• Earthwork Volumes Cut (cy), Fill (cy) *
• Over Excavation/ Alluvial Removal & Compaction _______ (cy)*
• Export (cy), Export Location: __________ *
• Total Disturbed Area (Acres)*
• Total Proposed Landscape Area Square Feet *
PROPERTY INFORMATION
• Property Address ______________________________________ (If exist *)
• Record of Survey Book ___ Pages ____
• Property Owner ___________ *
• Assessors ID Number(s) __________________________________
BENCHMARK:
HORIZONTAL COORDINATE SYSTEM: NAD 83, CALIFORNIA STATE PLANE, ZONE 5, NAVD 88
NOT TO SCALE
NOT TO SCALE
SHEET NUMBER SHEET TITLE
1 TITLE SHEET
2 GENERAL NOTES
3 SURFACE WATER - CHANNELS
4 SURFACE WATER PROFILES
5 LINE A CROSS SECTIONS
6 CULVERT A-1 PROFILE
7 CULVERT A-2 PROFILE
8 FLOW REDUCTION AREA GRADING
9 LINES A-1 AND A-2 REMEDIAL GRADING
10A SURFACE WATER DETAILS
10B ENGINEERED SWALE DETAILS
11 GROUNDWATER- HYDRAUGERS
12 GROUNDWATER- HYDRAUGERS- ARRAY 1
13 GROUNDWATER- HYDRAUGERS- ARRAY 2
14 GROUNDWATER- HYDRAUGERS- ARRAY 3
15 GROUNDWATER- HYDRAUGERS- ARRAY 4
16 GROUNDWATER- HYDRAUGERS- ARRAY 5
17 GROUNDWATER- HYDRAUGERS- ARRAY 6
18 HYDRAUGERS DETAILS- DIRECTIONAL
19 HYDRAUGER DETAILS- HORIZONTAL
20 FRACTURE INFILLING LOCATIONS
21 FRACTURE INFILLING LOCATION 1
22 FRACTURE INFILLING LOCATION 2
23 FRACTURE INFILLING LOCATION 3
24 ACCESS, STAGING, AND STOCKPILE LOCATIONS
D-47
REV. NO. DATE DESCRIPTION APPROVED BY
3150 BRISTOL STREET
SUITE 210
COSTA MESA, CA 92626
(714) 465-8240
www.geo-logic.com
DWG NO.
LOS ANGELES COUNTY, CA
30940 HAWTHORNE BLVD.
RANCHO PALOS VERDES,CA 90275
NOT FOR CONSTRUCTION-PENDING ENVIRONMENTAL REVIEW
PORTUGUESE BEND LANDSLIDE MITIGATION
CITY OF RANCHO PALOS VERDES
THE CITY OF
RANCHO PALOS VERDES
FINAL-REV 1
GENERAL NOTES
2
GENERAL NOTES
1. ALL WORKS SHALL CONFORM TO THE CITY OF RANCHO PALOS VERDES STANDARD
PLANS FOR PUBLIC WORKS CONSTRUCTION, THE STATE OF CALIFORNIA DEPARTMENT
OF TRANSPORTATION STANDARD PLANS & SPECIFICATIONS, & PROJECT SPECIAL
PROVISIONS, EACH OF THE MOST RECENT DATE.
2. THE CONTRACTOR SHALL NOTIFY THE CITY OF RANCHO PALOS VERDES AT LEAST TWO
WORKING DAYS (48 HOURS) PRIOR TO STARTING CONSTRUCTION, AT (310) 544-5252.
3. ALL UNDERGROUND FACILITIES SHALL BE INSTALLED PRIOR TO SURFACING OF STREETS.
THE INSTALLATION OF ALL UNDERGROUND FACILITIES CROSSING EXISTING ARTERIAL
HIGHWAYS REQUIRES BORING OR JACKING, UNLESS OTHERWISE APPROVED BY THE
CITY OF RANCHO PALOS VERDES.
4. TRAFFIC CONTROL AND SAFETY DEVICES SHALL BE INSTALLED PER THE 2012 EDITION OF
THE CALIFORNIA MUTCD, AND TO SATISFACTION OF THE CITY OF RANCHO PALOS
VERDES.
5. EXISTING PAVEMENT DISTURBED BY THE CONSTRUCTION OF UNDERGROUND
INSTALLATIONS SHALL BE REPLACED IN KIND & RESTRIPED. A PERMIT ISSUED BY THE
CITY OF RANCHO PALOS VERDES IS REQUIRED.
6. IT SHALL BE THE CONTRACTOR'S RESPONSIBILITY TO ARRANGE FOR AND COORDINATE
THE RELOCATION OF ANY EXISTING UTILITIES DEEMED NECESSARY BY THE PROPOSED
IMPROVEMENTS.
7. THE CONTRACTOR SHALL BE RESPONSIBLE FOR PROTECTION OF EXISTING UTILITIES.
ANY DAMAGE TO SUCH FACILITIES CAUSED BY HIS WORK SHALL BE REPAIRED BY THE
CONTRACTOR AT HIS EXPENSE.
8. THE CONTRACTOR SHALL MAINTAIN ADJACENT STREETS IN A NEAT, CLEAN, DUST FREE
AND SANITARY CONDITION TO THE SATISFACTION OF THE CITY'S INSPECTION. THE
ADJACENT STREETS SHALL BE KEPT CLEAN OF DEBRIS, WITH DUST AND OTHER
NUISANCES BEING CONTROLLED AT ALL TIMES. THE CONTRACTOR SHALL BE
RESPONSIBLE FOR ANY CLEAN UP ON ADJACENT STREETS AFFECTED BY HIS
CONSTRUCTION. STOCKPILE OF MATERIALS WITHIN THE PUBLIC RIGHT-OF-WA IS NOT
ALLOWED WITHOUT PRIOR WRITTEN APPROVAL OF THE CITY INSPECTOR.
9. ALL CONCRETE WORK SHALL BE 560-C-3250.
10. CONTRACTOR SHALL OBTAIN ALL REQUIRED O.S.H.A. PERMITS PRIOR TO CONSTRUCTION
OF UNDERGROUND FACILITIES.
11. WHEELCHAIR RAMPS, DRIVEWAY APRONS, CURBS, OR GUTTERS DISTURBED BY
CONSTRUCTION SHALL BE REPLACED AT THE CONTRACTOR'S EXPENSE. A PERMIT
ISSUED BY THE CITY OF RANCHO PALOS VERDES IS REQUIRED.
12. ALL SAWCUTS SHALL BE DONE BY THE WET-CUT METHOD, UNLESS OTHERWISE
APPROVED BY THE CITY ENGINEER, AND ALL SLURRY SHALL BE VACUUM REMOVED.
13. NEW CONCRETE SHALL MATCH EXISTING CONCRETE IN COLOR, FINISH, AND TEXTURE,
TO THE APPROVAL OF THE ENGINEER.
14. CONSTRUCTION SHALL BE ADJUSTED AS NECESSARY TO MATCH EXISTING CONDITIONS,
USES, AND PROVIDE POSITIVE SURFACE DRAINAGE. EXACT LIMITS AND CONFIGURATION
OF WORK TO BE ADJUSTED AS DIRECTED BY THE ENGINEER IN THE FIELD.
15. TOPOGRAPHIC INFORMATION SHOWN HEREIN HAS BEEN PROVIDED BY THE CITY OF
RANCHO PALOS VERDES, DATED 2017. THE CONTRACTOR SHALL BE RESPONSIBLE FOR
VERIFYING THE CORRECTNESS OF TOPOGRAPHIC INFORMATION FOR HIS OWN
PURPOSES.
16. THE CONTRACTOR SHALL REMOVE ALL CONSTRUCTION MARKINGS FROM THE PROJECT
BY POWER WASHING, INCLUDING THOSE PLACED FOR UTILITY LOCATING AND
CONSTRUCTION SURVEYING. WASTE FROM POWER WASHING MUST BE DISCHARGED IN
COMPLIANCE WITH NPDES.
17. THE CONTRACTOR SHALL BE RESPONSIBLE FOR PROVIDING ACCESS ROADS, WORKING
PLATFORMS, STAGING AREAS, AND OTHER TEMPORARY SITE FEATURES AS NEEDED TO
PERFORM THE CONSTRUCTION.
18. THE CONTRACTOR SHALL BE RESPONSIBLE FOR PREVENTING DISCHARGE OF SEDIMENT,
CONTAMINATED WATER, DRILLING MUD AND OTHER CONTAMINANTS TO DRAINAGE
FEATURES AND/OR THE OCEAN.
19. THE CONTRACTOR SHALL ACCOMMODATE ALL REQUIREMENTS SPECIFIED BY PERMITS,
ENVIRONMENTAL MITIGATION PLANS, AND OTHER SIMILAR DOCUMENTS. ALL
REASONABLE EFFORTS SHALL BE MADE TO MINIMIZE IMPACTS TO SITE FLORA AND
FAUNA.
20. THE SITE IS AN ACTIVE LANDSLIDE AND IS MOVING. ALL LOCATIONS SHOWN IN THE
PLANS ARE APPROXIMATE. THE CONTRACTOR IS RESPONSIBLE FOR IDENTIFYING AND
CORRECTING DISCREPANCIES BETWEEN PLANS AND FIELD CONDITIONS.
BEST MANAGEMENT PRACTICE NOTES:
1. EVERY EFFORT SHOULD BE MADE TO ELIMINATE THE DISCHARGE OF NON-STORMWATER FROM THE PROJECT SITE AT ALL TIMES.
2. ERODED SEDIMENTS AND OTHER POLLUTANTS MUST BE RETAINED ON-SITE AND MAY NOT BE TRANSPORTED FROM THE SITE VIA
SHEET FLOW, SWALES, AREA DRAINS, NATURAL DRAINAGE COURSES OR WIND.
3. STOCKPILES OF EARTH AND OTHER CONSTRUCTION RELATED MATERIALS MUST BE PROTECTED FROM BEING TRANSPORTED FROM THE
SITE BY THE FORCES OF WIND OR WATER.
4. FUELS, OILS, SOLVENTS, AND OTHER TOXIC MATERIALS MUST BE STORED IN ACCORDANCE WITH THEIR LISTING AND ARE NOT TO
CONTAMINATE THE SOIL AND SURFACE WATERS. ALL APPROVED STORAGE CONTAINERS ARE TO BE PROTECTED FROM THE WEATHER.
SPILLS MUST BE CLEANED UP IMMEDIATELY AND DISPOSED OF IN A PROPER MANNER. SPILLS MAY NOT BE WASHED INTO THE
DRAINAGE SYSTEM.
5. EXCESS OR WASTE CONCRETE MAY NOT BE WASHED INTO THE PUBLIC WAY OR ANY OTHER DRAINAGE SYSTEM. PROVISIONS SHALL
BE MADE TO RETAIN CONCRETE WASTES ON-SITE UNTIL THEY CAN BE DISPOSED OF AS SOLID WASTE.
6. TRASH AND CONSTRUCTION RELATED SOLID WASTES MUST BE DEPOSITED INTO A COVERED RECEPTACLE TO PREVENT
CONTAMINATION OF RAINWATER AND DISPERSAL BY WIND.
7. SEDIMENTS AND OTHER MATERIALS MAY NOT BE TRACKED FROM THE SITE BY VEHICLE TRAFFIC. THE CONSTRUCTION ENTRANCE
ROADWAYS MUST BE STABILIZED SO AS TO INHIBIT SEDIMENTS FROM BEING DEPOSITED INTO THE PUBLIC WAY. ACCIDENTAL
DEPOSITIONS MUST BE SWEPT UP IMMEDIATELY AND MAY NOT BE WASHED DOWN BY RAIN OR OTHER MEANS.
8. ANY SLOPES WITH DISTURBED SOILS OR DENUDED OF VEGETATION MUST BE STABILIZED SO AS TO INHIBIT EROSION BY WIND AND WATER.
9.“I CERTIFY THAT THIS DOCUMENT AND ALL ATTACHMENTS WERE PREPARED UNDER MY DIRECTION OR SUPERVISION IN ACCORDANCE
WITH A SYSTEM DESIGNED TO ENSURE THAT QUALIFIED PERSONNEL PROPERLY GATHER AND EVALUATE THE INFORMATION SUBMITTED.
BASED ON MY INQUIRY OF THE PERSON OR PERSONS WHO MANAGE THE SYSTEM OR THOSE PERSONS DIRECTLY RESPONSIBLE FOR
GATHERING THE INFORMATION, TO THE BEST OF MY KNOWLEDGE AND BELIEF, THE INFORMATION SUBMITTED IS TRUE, ACCURATE, AND
COMPLETE. I AM AWARE THAT SUBMITTING FALSE AND/ OR INACCURATE INFORMATION, FAILING TO UPDATE THE ESCP TO REFLECT
CURRENT CONDITIONS, OR FAILING TO PROPERLY AND/ OR ADEQUATELY IMPLEMENT THE ESCP MAY RESULT IN REVOCATION OF GRADING
AND/ OR OTHER PERMITS OR OTHER SANCTIONS PROVIDED BY LAW.”
PRINT NAME _____________________________________________
(OWNER OR AUTHORIZED AGENT OF THE OWNER)
SIGNATURE ______________________________________________ DATE __________________
(OWNER OR AUTHORIZED AGENT OF THE OWNER)
THE FOLLOWING BMPS AS OUTLINED IN, BUT NOT LIMITED TO, THE LATEST EDITION OF THE CASQA CONSTRUCTION BMP ONLINE
HANDBOOK OR CALTRANS STORMWATER QUALITY HANDBOOKS (CONSTRUCTION SITE BMP MANUAL), MAY APPLY DURING THE
CONSTRUCTION OF THIS PROJECT (ADDITIONAL MEASURES MAY BE REQUIRED IF DEEMED APPROPRIATE BY THE PROJECT ENGINEER OR
THE BUILDING OFFICIAL)
STORMWATER IMPROVEMENTS
BID ITEM UNIT QUANTITY
EARTHWORK
CUT C.Y.54,200
FILL C.Y.2,200
PROTECTIVE COVER SOIL C.Y.44,800
ENGINEERED SWALE/FLOW
REDUCTION AREA
TYPE 1 S.F.39,000
TYPE 2 S.F.84,100
TYPE 3 S.F.22,700
SHINGLED GCL S.F.491,700
GEOTEXTILE S.F.637,500
PIPE
NEW 60" THICK WALLED HDPE L.F. 990
REFURBISHED 60"L.F. 240
NEW 36" HDPE (TRENCHLESS)L.F. 380
NEW 36" HDPE L.F. 50
NEW 48" HDPE L.F. 50
PRE-CONSTRUCTION
PRE-CONSTRUCTION TO
TOPOGRAPHIC SURVEY EA.1
PRE-CONSTUCTION PIPE CONDITION
SURVEY WITH PE CERTIFICATION
EA. 1
EROSION CONTROL
BIODEGRADABLE EROSION
CONTROL MATTING
EA.1
HYDROSEEDING EA.1
HYDRAUGERS
BID ITEM UNIT QUANTITY
HORIZONTAL DRAINS L.F.12,000
DIRECTIONAL DRAINS L.F.24,000
PRE-CONSTRUCTION
CONFIRMATORY SUBSURFACE
EXPLORATION PROGRAM
EA. 1
PORE WATER PRESSURE
INSTRUMENTATION MONITORING
PROGRAM
EA.1
PRODUCED WATER ANALYTICAL
LABORATORY TESTING AND
TREATMENT PROGRAM
EA.1
FRACTURE INFILL
BID ITEM UNIT QUANTITY
FLOWABLE FLY ASH-BASED SLURRY C.Y.1,600
D-48
CULVERT A-2
SEE SHEET 7
CULVERT A-1
SEE SHEET 6
LINE A DRAINAGE
SEE SHEET 4
LINE A-1 DRAINAGE
SEE SHEET 4 & 9
LINE A-2 DRAINAGE
SEE SHEET 4 & 9
ENGINEERED SWALE
SEE SHEET 4 AND 8
FLOW REDUCTION
AREA GRADING
SEE SHEET 8
PORTUGUESE
CANYON
(NORTH WEST)
ISHIBASHI
CANYON
(NORTH CENTRAL)
PAINTBRUSH
CANYON
(NORTH EAST)
EXISTING CITY
PROJECT
(OUT OF SCOPE;
BY OTHERS)
EXISTING
ACCESS
POINT
EXISTING
PARKING
AREA
PROPOSED FLOW
REDUCTION AREA
LINE A DRAINAGE
SEE SHEET 4
LINES A-1
AND A-2
GRADING
SEE SHEET 9
REV. NO. DATE DESCRIPTION APPROVED BY
3150 BRISTOL STREET
SUITE 210
COSTA MESA, CA 92626
(714) 465-8240
www.geo-logic.com
DWG NO.
LOS ANGELES COUNTY, CA
30940 HAWTHORNE BLVD.
RANCHO PALOS VERDES,CA 90275
NOT FOR CONSTRUCTION-PENDING ENVIRONMENTAL REVIEW
PORTUGUESE BEND LANDSLIDE MITIGATION
CITY OF RANCHO PALOS VERDES
THE CITY OF
RANCHO PALOS VERDES
FINAL-REV 1
SURFACE WATER - CHANNELS
3
APPROXIMATE LOCATION OF SHORELINE
APPROXIMATE LIMITS OF PORTUGUESE BEND LANDSLIDE
COMPLEX (BASED ON LEIGHTON, 2000)
APPROXIMATE LIMITS OF SUBSLIDES OF PORTUGUESE BEND
LANDSLIDE COMPLEX (BASED LEIGHTON, 2000)
PROPOSED FLOWLINE MODIFICATIONS
PROPOSED CULVERT LOCATIONS
PROPOSED FLOW REDUCTION AREA
LEGEND
EXISTING TOPOGRAPHY, 2 FT ELEVATION CONTOUR
NOTES:
1. EXISTING TOPOGRAPHY PROVIDED BY CITY OF RANCHO PALOS VERDES, DATED 2017.
2. CONTRACTOR IS RESPONSIBLE TO FIELD VERIFY ELEVATIONS SHOWN.
3. WHERE PROPOSED SWALES CROSS OR PARALLEL EXISTING TRAILS, MODIFY TO
MAINTAIN FULL TRAIL FUNCTIONALITY.
4. CONTRACTOR IS RESPONSIBLE TO COORDINATE AS NECESSARY WITH EXISTING CITY
PROJECT(S) WHICH MAY BE UNDER CONSTRUCTION CONCURRENTLY WITH THIS
PROJECT.
EXISTING TOPOGRAPHY, 10 FT ELEVATION CONTOUR
PRESERVE PROPERTY BOUNDARY
EXISTING TRAIL
EXISTING ROAD
D-49
RPV-ALGN-DRNG-LINE A-1 RPV-ALGN-DRNG-LINE A-2
RPV-ALGN-DRNG-LINE A
PALOS VERDES
DRIVE SOUTH
REFURBISHED
EXISTING
60" CMP
ENGINEERED SWALE
TYPE 1
SHINGLED GCL
BASIN LINING
LIMITS OF PROPOSED
FLOW REDUCTION AREA
ENGINEERED SWALE
TYPE 2
ENGINEERED SWALE
TYPE 2
PROPOSED
36" HDPE
60" HDPE
(DISPOSE EXISTING 36" HDPE)
ENGINEERED SWALE
TYPE 3
ENGINEERED SWALE
TYPE 1
ENGINEERED SWALE
TYPE 3
WITH 10" ROCK ARMORING
AS SHOWN ON SHEET 7 33+07.64 LINE A=0+00.00 LINE A-2 36+28.96 LINE A=0+00.00 LINE A-1 0+00.00 LINE A-1=36+28.96 LINE A 0+00.00 LINE A-2=33+7.64 LINE AENGINEERED SWALE
TYPE 3
WITH 10" ROCK ARMORING
ENGINEERED
SWALE
TYPE 2
ENGINEERED SWALE
TYPE 3
WITH 10" ROCK ARMORING
ENGINEERED SWALE
TYPE 2
ENGINEERED
SWALE
TYPE 2
UNLINED
UNLINED
UNLINED
THICK-WALLED
FUSION WELDED
CONTROL POINTS CONTROL POINTS
REV. NO. DATE DESCRIPTION APPROVED BY
3150 BRISTOL STREET
SUITE 210
COSTA MESA, CA 92626
(714) 465-8240
www.geo-logic.com
DWG NO.
LOS ANGELES COUNTY, CA
30940 HAWTHORNE BLVD.
RANCHO PALOS VERDES,CA 90275
NOT FOR CONSTRUCTION-PENDING ENVIRONMENTAL REVIEW
PORTUGUESE BEND LANDSLIDE MITIGATION
CITY OF RANCHO PALOS VERDES
THE CITY OF
RANCHO PALOS VERDES
FINAL-REV 1
4
SURFACE WATER PROFILES
NOTE:
SEE SHEET 10B FOR ENGINEERED SWALE
TYPE 1, 2, AND 3 SECTIONS.
D-50
5
4
5
4
GEOCELL LIMITS
DISTURBANCE LIMITS
GEOCELL LIMITS
5
4
GEOCELL LIMITS
DISTURBANCE LIMITS
10
4
GEOCELL LIMITS
DISTURBANCE LIMITS
4
3
GEOCELL LIMITS
DISTURBANCE LIMITS
4
2.5
GEOCELL LIMITS
DISTURBANCE LIMITS
4
2.5
GEOCELL LIMITS
DISTURBANCE LIMITS
4
2.5
GEOCELL LIMITS
DISTURBANCE LIMITS
4
2.5
GEOCELL LIMITS
DISTURBANCE LIMITS
5
4
GEOCELL LIMITS
DISTURBANCE LIMITS
REV. NO. DATE DESCRIPTION APPROVED BY
3150 BRISTOL STREET
SUITE 210
COSTA MESA, CA 92626
(714) 465-8240
www.geo-logic.com
DWG NO.
LOS ANGELES COUNTY, CA
30940 HAWTHORNE BLVD.
RANCHO PALOS VERDES,CA 90275
NOT FOR CONSTRUCTION-PENDING ENVIRONMENTAL REVIEW
PORTUGUESE BEND LANDSLIDE MITIGATION
CITY OF RANCHO PALOS VERDES
THE CITY OF
RANCHO PALOS VERDES
FINAL-REV 1
LINE A CROSS SECTIONS
5
NOTES:
1. AREA WITHIN DISTURBANCE LIMITS TO BE CLEARED AND GRUBBED BEFORE GRADING.
2. UPPER 12-INCHES OF SUBGRADE TO BE COMPACTED TO 90% OR HIGHER MODIFIED
PROCTOR MAXIMUM DENSITY BEFORE RECEIVING FILL OR GEOCELL.
3. FILL TO BE COMPACTED TO 90% OR HIGHER MODIFIED PROCTOR MAXIMUM DENSITY.
4. AREAS OUTSIDE GEOCELL LIMITS BUT WITHIN DISTURBANCE LIMITS TO BE COVERED
WITH BIODEGRADABLE EROSION CONTROL MATTING AND HYDROSEEDED WITH NATIVE
VEGETATION AFTER GRADING.
5. SEEDS FOR NATIVE VEGETATION TO BE SOURCED FROM AND/OR APPROVED BY PALOS
VERDES PENINSULA LAND CONSERVANCY. CONTACT PVPLC AT (310) 541-7613.
D-51
PALOS VERDESDRIVE SOUTHREFURBISHED
EXISTING
60" CMP
PROPOSED 60" THICK W
A
L
L
E
D
HDPE (FUSION WELDED)
184.88 L.F. - SINGLE 60" CMP (EXISTING)
EXISTING GRADE
W.S.E.=160.0
PALOS VERDES
DRIVE SOUTH
HYRAULIC DATA
Q100=302 cfs
V= 21.3 ftps
HGL (Q100)
PROPOSED 60" THICK WALLED HDPE (FUSION WELDED)
NOTE: MAKE CONNECTION TO NEW PIPE
ENGINEERED SWALE
TYPE 1
2' FREEBOARD
ABOVE W.S.E.
REV. NO. DATE DESCRIPTION APPROVED BY
3150 BRISTOL STREET
SUITE 210
COSTA MESA, CA 92626
(714) 465-8240
www.geo-logic.com
DWG NO.
LOS ANGELES COUNTY, CA
30940 HAWTHORNE BLVD.
RANCHO PALOS VERDES,CA 90275
NOT FOR CONSTRUCTION-PENDING ENVIRONMENTAL REVIEW
PORTUGUESE BEND LANDSLIDE MITIGATION
CITY OF RANCHO PALOS VERDES
THE CITY OF
RANCHO PALOS VERDES
FINAL-REV 1
CULVERT A-1 PROFILE
6
NOTES:
1. CONTRACTOR IS RESPONSIBLE TO FIELD VERIFY EXISTING PIPE
LOCATION, FLOWLINE ELEVATIONS, SIZE AND FUNCTIONALITY.
2. CONTRACTOR IS RESPONSIBLE TO RESTORE FUNCTIONALITY OF
EXISTING PIPE TO A STATE EQUIVALENT TO THAT OF A NEW
SMOOTH-WALLED PLASTIC PIPE OF THE SAME NOMINAL DIAMETER.
3. EXISTING TOPOGRAPHY PROVIDED BY CITY OF RANCHO PALOS
VERDES, DATED 2017.
4. CONTRACTOR IS RESPONSIBLE TO PROVIDE A "PIPE
CERTIFICATION REPORT" STAMPED BY CALIFORNIA PROFESSIONAL
ENGINEER IF THE PIPE REQUIRES ANY REFURBISHMENT AND/OR
RESTORATION, THE REPORT MUST INCLUDE RECOMMENDATIONS
FOR RETROFITTING/RESTORATION.
D-52
BURMA ROADS
W
A
L
E
10" ROCK ARMORING
EXISTING GRADE
W.S.E.=598.0
325.90 L.F. - SINGLE 36" HDPE (PROPOSED)
HYRAULIC DATA
Q100=306 cfs
V= 15.44 ftps
HGL (Q100)
BURMA ROAD
TYPE 3
ENGINEERED SWALE WITH
10" ROCK ARMORING
ENGINEERED SWALE
TYPE 1
2' FREEBOARD
ABOVE W.S.E.
REV. NO. DATE DESCRIPTION APPROVED BY
3150 BRISTOL STREET
SUITE 210
COSTA MESA, CA 92626
(714) 465-8240
www.geo-logic.com
DWG NO.
LOS ANGELES COUNTY, CA
30940 HAWTHORNE BLVD.
RANCHO PALOS VERDES,CA 90275
NOT FOR CONSTRUCTION-PENDING ENVIRONMENTAL REVIEW
PORTUGUESE BEND LANDSLIDE MITIGATION
CITY OF RANCHO PALOS VERDES
THE CITY OF
RANCHO PALOS VERDES
FINAL-REV 1
CULVERT A-2 PROFILE
7
NOTES:
1. CONTRACTOR IS RESPONSIBLE TO FIELD VERIFY EXISTING PIPE
LOCATION, FLOWLINE ELEVATIONS, SIZE AND FUNCTIONALITY.
2. CONTRACTOR IS RESPONSIBLE TO RESTORE FUNCTIONALITY OF
EXISTING PIPE TO A STATE EQUIVALENT TO THAT OF A NEW PIPE
OF THE SAME NOMINAL DIAMETER.
3. EXISTING TOPOGRAPHY PROVIDED BY CITY OF RANCHO PALOS
VERDES, DATED 2017.
4. INSTALLATION OF PIPE SHALL BE BY TRENCHLESS METHODS.
D-53
TYPE
1
1
8
0
1
7
2
1
7
2
1
8
0
1
7
0172180 172
17217417
4
174180 17418017
6
18
0
180176180
176174174176
178PROPOSED FLOW REDUCTION AREA
DISTURBED AREA: 10.1 AC
STORAGE VOLUME: 45 AC-FT
SPILLWAY
SEE DETAIL 4, SHEET 10
EXISTING 60" PIPE
PROPOSED GRADING LIMIT
PROPOSED GRADING LIMIT
PROPOSED
GRADING LIMIT
PROPOSED GRADING LIMIT
TYPE 2
ARMOR SLOPE TO ELEVATION 162
TYPE I
ENGINEERED SWALE
REV. NO. DATE DESCRIPTION APPROVED BY
3150 BRISTOL STREET
SUITE 210
COSTA MESA, CA 92626
(714) 465-8240
www.geo-logic.com
DWG NO.
LOS ANGELES COUNTY, CA
30940 HAWTHORNE BLVD.
RANCHO PALOS VERDES,CA 90275
NOT FOR CONSTRUCTION-PENDING ENVIRONMENTAL REVIEW
PORTUGUESE BEND LANDSLIDE MITIGATION
CITY OF RANCHO PALOS VERDES
THE CITY OF
RANCHO PALOS VERDES
FINAL-REV 1
FLOW REDUCTION AREA GRADING
8
PROPOSED ENGINEERED SWALE TYPE
EXISTING 60" CULVERT LOCATION
LEGEND
EXISTING TOPOGRAPHY, 2 FT ELEVATION CONTOUR
NOTES:
1. EXISTING TOPOGRAPHY PROVIDED BY CITY OF RANCHO PALOS VERDES, DATED
2017.
2. CONTRACTOR IS RESPONSIBLE TO FIELD VERIFY ELEVATIONS SHOWN.
3. FLOW REDUCTION AREA FLOOR SHOWN CORRESPONDS TO FINISHED GRADE
ELEVATIONS. FINISH GRADE INCLUDES GEOCELL AND 3-FT THICK PROTECTIVE
COVER SOIL, AS APPLICABLE, SEE DETAILS 4 & 5 ON SHEET 10.
4. AUTOCAD FILES WILL BE PROVIDED TO THE CONTRACTOR.
5. CONTRACTOR WILL BE REQUIRED PERFORM A TOPOGRAPHIC SURVEY BEFORE
AND AFTER CONSTRUCTION.
6. WHERE PROPOSED SWALES CROSS OR PARALLEL EXISTING TRAILS, MODIFY TO
MAINTAIN FULL TRAIL FUNCTIONALITY.
EXISTING TOPOGRAPHY, 10 FT ELEVATION CONTOUR
TYPE 3
EXISTING TOPOGRAPHY, 2 FT ELEVATION CONTOUR
EXISTING TOPOGRAPHY, 10 FT ELEVATION CONTOUR170
168
EXISTING TRAIL
EXISTING ROAD
PRESERVE PROPERTY BOUNDARY
KEY MAP (NOT TO SCALE)
D-54
TYPE
3
UNLINED
TYP
E
2
U
N
L
I
N
E
D
TYPE
3
UNLINED
TYPE 2TYPE 1TYPE 2
LINE
A-2
DRAINAGE
LINE A-1
DRAINAGE
ARMOR BURMA ROAD
FOOTPRINT USING TYPE 2
ENGINEERED SWALE SECTIONTYPE 3REV. NO. DATE DESCRIPTION APPROVED BY
3150 BRISTOL STREET
SUITE 210
COSTA MESA, CA 92626
(714) 465-8240
www.geo-logic.com
DWG NO.
LOS ANGELES COUNTY, CA
30940 HAWTHORNE BLVD.
RANCHO PALOS VERDES,CA 90275
NOT FOR CONSTRUCTION-PENDING ENVIRONMENTAL REVIEW
PORTUGUESE BEND LANDSLIDE MITIGATION
CITY OF RANCHO PALOS VERDES
THE CITY OF
RANCHO PALOS VERDES
FINAL-REV 1
LINES A-1 AND A-2 REMEDIAL GRADING
9
APPROXIMATE LIMITS OF PORTUGUESE BEND LANDSLIDE
(BASED ON LEIGHTON, 2000)
PROPOSED MODIFIED FLOWLINE AND ENGINEERED SWALE
LEGEND
EXISTING TOPOGRAPHY, 2 FT ELEVATION CONTOUR
NOTES:
1. EXISTING TOPOGRAPHY PROVIDED BY CITY OF RANCHO PALOS VERDES, DATED
2017.
2. CONTRACTOR IS RESPONSIBLE TO FIELD VERIFY ELEVATIONS SHOWN.
3. "UNLINED" DENOTES NATURAL CHANNEL OR SHEET FLOW IN AREAS ANTICIPATED
TO BE INACCESSIBLE.
4. WHERE PROPOSED SWALES CROSS OR PARALLEL EXISTING TRAILS, MODIFY TO
MAINTAIN FULL TRAIL FUNCTIONALITY.
EXISTING TOPOGRAPHY, 10 FT ELEVATION CONTOUR
TYPE 3
EXISTING TRAIL
EXISTING ROAD
KEY MAPKEY MAP (NOT TO SCALE)
D-55
2' MIN.
5' MIN.
PREPARED/ PROOF
ROLLED SUBGRADE
8oz/YD NON WOVEN
GEOTEXTILE
GEOCELL GW30V WITH
6 IN GRAVEL INFILL
2' MIN.
ANCHOR TRENCH
GEOSYNTHETIC
CLAY LINER (GCL)
FLOW REDUCTION AREA
LINING TERMINATION
SECTION
N.T.S.
2
-10A
TENDON
DEADMAN
ANCHOR
1
VARIES
FLOW REDUCTION AREA FLOOR
SHINGLED GCL (PLAN VIEW)
DETAIL
N.T.S.
3
-10A
CROSS-ROLL
DIRECTION
ROLL
DIRECTION
PREDOMINANT
LANDSLIDE
MOVEMENT
DIRECTION
20' MIN OVERLAP
(ROLL DIRECTION)
3' MIN OVERLAP
(CROSS-ROLL
DIRECTION)
12' MIN.
ANCHOR TRENCH
SEE SECTION 2/10
FLOW REDUCTION AREA
SPILLWAY
SECTION
N.T.S.
4
-10
1
2
TRANSITION TO
TYPE 1 TO
ENGINEERED
SWALE
1x36" CORRUGATED HDPE
1x48" CORRUGATED HDPE
8' MAX.
1
2
2' MIN.
PIPE BOOT
UNDER GCL
PREPARED
SUBGRADE
COMPACTED
FILL
3' MIN.
SEE SECTION 2/10
TYPE 3
ENGINEERED
SWALE
FLOW REDUCTION
AREA
20' MIN.
20' MIN.
GRATE
GRATE
8oz/YD NON WOVEN
GEOTEXTILE
SHINGLED GCL.
SEE DETAIL 3/10
3
PREPARED
SUBGRADE
B
B'
FL = 178
FL = 170
PROTECTIVE
COVER SOILC'
C
1
Z
T
W
H
d
ENGINEERED SWALE
SECTION
N.T.S.
1
-10A
FLOW REDUCTION AREA
GEOCELL TERMINATION
SECTION
N.T.S.
5
-10
1
VARIES
FLOW REDUCTION
AREA
20' MIN.
3
8oz/YD NON WOVEN GEOTEXTILE
GEOCELL GW40V WITH 4IN GRAVEL INFILL
GEOSYNTHETIC
CLAY LINER (GCL)
TENDON
SHINGLED GCL.
SEE DETAIL 3/10
PREPARED
SUBGRADE
PROTECTIVE
COVER SOIL
1
1
10'
2'
SECTION B-B'
N.T.S.
36" CORRUGATED HDPE
1x24" CORRUGATED HDPE
Q100 = 92 CFS
COMPACTED
FILL
FL = 180
FL = 178
48" CORRUGATED
HDPE
Q100 = 164 CFS
FL = 170
SPILLWAY
Q100 = 38 CFS
60" THICK-WALLED
HDPE PIPE
DRIVE POSTS
TO REFUSAL
EXISTING SURFACE
PIPE ANCHOR
SECTION
N.T.S.
6
-10
SECURE STRAP
SCROSS TOP
OF PIPE
NOTE: ANCHOR PIPE AT LENGTH
INTERVALS FOR
MANUFACTURER
RECOMMENDATION
1
1
10'
2'
SECTION C-C'
N.T.S.
2' MIN.2' MIN.
REV. NO. DATE DESCRIPTION APPROVED BY
3150 BRISTOL STREET
SUITE 210
COSTA MESA, CA 92626
(714) 465-8240
www.geo-logic.com
DWG NO.
LOS ANGELES COUNTY, CA
30940 HAWTHORNE BLVD.
RANCHO PALOS VERDES,CA 90275
NOT FOR CONSTRUCTION-PENDING ENVIRONMENTAL REVIEW
PORTUGUESE BEND LANDSLIDE MITIGATION
CITY OF RANCHO PALOS VERDES
THE CITY OF
RANCHO PALOS VERDES
FINAL-REV 1
SURFACE WATER DETAILS
10A
GENERAL NOTES:
1. INSTALL GEOSYNTHETIC AND OTHER COMPONENTS PER
MANUFACTURER'S RECOMMENDATIONS.
2. TOP OF COVER PROTECTIVE COVER SOIL LEVEL
CORRESPONDS TO PROPOSED GRADES SHOWN ON SHEET 8.
NOTES:
1. PROTECTIVE COVER SOIL LAYER
SHALL BE PLACED OVER ALL
INSTALLED GCL PANELS BEFORE
THE END OF EACH WORKING DAY OF
GCL INSTALLATION.
2. PROTECTIVE COVER SOIL LAYER
SHALL BE PLACED BEFORE TRUCKS
OR EQUIPMENT MAY TRAVERSE
INSTALLED GCL PANELS.
3. LOW GROUND PRESSURE
EQUIPMENT SHALL BE USED FOR
PROTECTIVE COVER SOIL
PLACEMENT AND FINAL GRADIGN
WITHIN GCL-LINED AREA.
CHANNEL DIMENSIONS
LINE A
STATION
START
STATION
END W H T d Z
GEOWEB
TYPE
12+08 16+38 5 4 21 3 2 1
25+50 32+08 5 4 21 3 2 2
32+08 33+08 5 4 21 3 2 3
33+08 36+29 10 4 26 3 2 3
36+29 37+40 4 2.5 14 1.5 2 3
37+40 45+00 4 2.5 14 1.5 2 1
45+00 58+00 4 2.5 14 1.5 2 2
58+00 60+00 4 2.5 14 1.5 2 3
LINE A1
STATION
START
STATION
END W H T d Z
GEOWEB
TYPE
0+00.00 1+50 2 3 14 2 2 3
4+13 6+63 2 3 14 2 2 2
LINE A2
STATION
START
STATION
END W H T d Z
GEOWEB
TYPE
0+00.00 1+50 2.5 3 14.5 2 2 3
3+47 6+73 2.5 3 14.5 2 2 2
NOTE:
SWALE HAUNCHES TO BE
ROUNDED. SEE SHEET 10B.
D-56
PREPARED SUBGRADE
8oz/YD NON WOVEN
GEOTEXTILE
GEOWEB GW40V OR
APPROVED EQUIVALENT,
6IN GRAVEL INFILL
TYPE 1
ENGINEERED SWALE
SECTION
N.T.S.
8
4,6,7,9,10B
6"
10A
PREPARED SUBGRADE
8oz/YD NON WOVEN
GEOTEXTILE
GEOWEB GW30V OR
APPROVED EQUIVALENT,
6IN GRAVEL INFILL
TYPE 2
ENGINEERED SWALE
SECTION
N.T.S.
9
4,6,7,9,10B
6"
10A
PREPARED SUBGRADE
8oz/YD NON WOVEN
GEOTEXTILE
GEOWEB GW20V OR
APPROVED EQUIVALENT,
8IN GRAVEL INFILL
TYPE 3
ENGINEERED SWALE
SECTION
N.T.S.
10
4,6,7,9,10B
8"
10" ROCK ARMORING
WHERE SHOW IN PLANS
10A
REV. NO. DATE DESCRIPTION APPROVED BY
3150 BRISTOL STREET
SUITE 210
COSTA MESA, CA 92626
(714) 465-8240
www.geo-logic.com
DWG NO.
LOS ANGELES COUNTY, CA
30940 HAWTHORNE BLVD.
RANCHO PALOS VERDES,CA 90275
NOT FOR CONSTRUCTION-PENDING ENVIRONMENTAL REVIEW
PORTUGUESE BEND LANDSLIDE MITIGATION
CITY OF RANCHO PALOS VERDES
THE CITY OF
RANCHO PALOS VERDES
FINAL-REV 1
ENGINEERED SWALE DETAILS
10B
EXAMPLE ENGINEERED SWALE
ISOMETRIC/CUTAWAY VIEW
SECTION
N.T.S.
11
-10B
EXAMPLE
ELECTRIC PUMP
DETAIL
N.T.S.
13
-10B
EXAMPLE WATER STORAGE TANK
DETAIL
N.T.S.
14
-10B
GEOCELL
DETAIL
N.T.S.
7
-10B
EXAMPLE ENGINEERED SWALE
CROSS-SECTION VIEW
SECTION
N.T.S.
12
-10B
VEGETATION
GEOCELL WITH
GRAVEL INFILL
GEOTEXTILE
UNDER GEOCELL
PREPARED
SUBGRADE
TOPSOIL/
SILT DEPOSIT
D-57
A6A5
A1
A4
A6A5
A1
A4
A2
A3
EXISTING
ACCESS
POINT
EXISTING
PARKING
AREA
REV. NO. DATE DESCRIPTION APPROVED BY
3150 BRISTOL STREET
SUITE 210
COSTA MESA, CA 92626
(714) 465-8240
www.geo-logic.com
DWG NO.
LOS ANGELES COUNTY, CA
30940 HAWTHORNE BLVD.
RANCHO PALOS VERDES,CA 90275
NOT FOR CONSTRUCTION-PENDING ENVIRONMENTAL REVIEW
PORTUGUESE BEND LANDSLIDE MITIGATION
CITY OF RANCHO PALOS VERDES
THE CITY OF
RANCHO PALOS VERDES
FINAL-REV 1
GROUNDWATER- HYDRAUGERS
11
LEGEND
EXISTING TOPOGRAPHY, 2 FT ELEVATION CONTOUR
APPROXIMATE LOCATION OF SHORELINE
APPROXIMATE LIMITS OF PORTUGUESE BEND LANDSLIDE
COMPLEX (PBLC)
PROPOSED HYDRAUGER ARRAY LOCATION. BOX REPRESENTS
WORK LOCATION, RED LINE REPRESENT DIRECTION AND
LENGTH OF HYDRAUGERS. FILL COLOR DENOTES TYPE OF
PROPOSED HYDRAUGER.
DIRECTIONAL / GRAVITY FLOW
DIRECTIONAL / PUMP ASSISTED FLOW
HORIZONTAL / GRAVITY FLOW
TYPE OF HYDRAUGER
A6
NOTES:
1. CONTRACTOR IS RESPONSIBLE TO PERFORM PRE-CONSTRUCTION CONFIRMATORY
SUBSURFACE EXPLORATION TO VERIFY GROUNDWATER, SOIL, AND BEDROCK
CONDITIONS.
2. CONTRACTOR IS RESPONSIBLE TO INSTALL GROUTED CONDUCTOR AND/OR
SURFACE CASING WITH ADEQUATE CAPACITY TO PREVENT BLOWOUT AND/OR
OTHER POTENTIAL ADVERSE EVENTS RELATED TO HYDRAUGER INSTALLATION,
OPERATION, AND/OR MAINTENANCE.
3. EXISTING TOPOGRAPHY PROVIDED BY CITY OF RANCHO PALOS VERDES, DATED
2017.
4. CONTRACTOR IS RESPONSIBLE TO FIELD VERIFY ELEVATIONS SHOWN.
5. CONTRACTOR TO FURNISH AND INSTALL PUMPS AND ELECTRICAL CONNECTIONS
FOR PUMP-ASSISTED DRAINS.
6. CONTRACTOR TO INSTALL PLUMBING CONNECTIONS TO EXISTING DRAINAGE LINES
AND/OR PROPOSED SWALES.
7. WHERE PROPOSED SWALES CROSS OR PARALLEL EXISTING TRAILS, MODIFY TO
MAINTAIN FULL TRAIL FUNCTIONALITY.
8. CONTRACTOR IS RESPONSIBLE TO CAPTURE WATER PRODUCED FROM DRAINS
DURING CONSTRUCTION PERIOD; PERFORM ANALYTICAL LABORATORY TESTING OF
REPRESENTATIVE WATER SAMPLES; FURNISH AND INSTALL STORAGE, TREATMENT,
AND/OR PUMPING EQUIPMENT AS NEEDED FOR COMPLIANCE WITH PERMIT
REQUIREMENTS.
EXISTING TOPOGRAPHY, 10 FT ELEVATION CONTOUR
PRESERVE PROPERTY BOUNDARY
EXISTING TRAIL
EXISTING ROAD
D-58
A1
DRAIN 1
DRAIN 2
DRAIN 3
DRAIN 4
DRAIN 5
WORK LOCATION
APPROX. LIMIT OF PBLC
APPROX. CL OF PVDS
WORK LOCATION
APPROX. CL OF PVDS
WORK LOCATION
APPROX. CL OF PVDS
REV. NO. DATE DESCRIPTION APPROVED BY
3150 BRISTOL STREET
SUITE 210
COSTA MESA, CA 92626
(714) 465-8240
www.geo-logic.com
DWG NO.
LOS ANGELES COUNTY, CA
30940 HAWTHORNE BLVD.
RANCHO PALOS VERDES,CA 90275
NOT FOR CONSTRUCTION-PENDING ENVIRONMENTAL REVIEW
PORTUGUESE BEND LANDSLIDE MITIGATION
CITY OF RANCHO PALOS VERDES
THE CITY OF
RANCHO PALOS VERDES
FINAL-REV 1
GROUNDWATER- HYDRAUGERS- ARRAY 1
12
ARRAY 1 / DRAIN 1
ARRAY 1 / DRAIN 3
ARRAY 1 / DRAIN 5
LEGEND
ACTIVE BASAL RUPTURE SURFACE
EXISTING GROUND SURFACE
GROUNDWATER SURFACE
PROPOSED DRAIN
DRAIN 1 COORDINATES TABLE
POINT STATION
N E Z COMMENT
1 0+00 1727364 6451771 50 BEGIN CURVE
2 1+26.57 1727461 6451852 29 END CURVE
3 12+00 1728283 6452542 29
DRAIN 3 COORDINATES TABLE
POINT STATION N E Z COMMENT
1 0+00 1727364 6451771 50 BEGIN CURVE
2 2+32.79 1727597 6451771 -25 END CURVE
3 12+00 1728564 6451771 -25
DRAIN 5 COORDINATES TABLE
POINT STATION N E Z COMMENT
1 0+00 1727364 6451771 50 BEGIN CURVE
2 2+11.02 1727526 6451635 -10 END CURVE
3 12+00 1728283 6450999 -10
NOTES
1. FOR DRAINS 2 AND 4 COORDINATES, INTERPOLATE BETWEEN ADJACENT DRAINS.
2. MINIMUM CURVE RADIUS 400 FEET.
APPROXIMATE LIMITS OF PORTUGUESE BEND
LANDSLIDE COMPLEX (PBLC)
APPROXIMATE CENTERLINE(CL) OF PALOS
VERDES DRIVE SOUTH (PVDS)
KEY MAP (NOT TO SCALE)
D-59
DRAIN 1
DRAIN 2
DRAIN 3
DRAIN 4
DRAIN 5
A2
WORK LOCATION
APPROX. CL OF BURMA RD
WORK LOCATION
APPROX. CL OF BURMA RD
WORK LOCATION
APPROX. CL OF BURMA RD
REV. NO. DATE DESCRIPTION APPROVED BY
3150 BRISTOL STREET
SUITE 210
COSTA MESA, CA 92626
(714) 465-8240
www.geo-logic.com
DWG NO.
LOS ANGELES COUNTY, CA
30940 HAWTHORNE BLVD.
RANCHO PALOS VERDES,CA 90275
NOT FOR CONSTRUCTION-PENDING ENVIRONMENTAL REVIEW
PORTUGUESE BEND LANDSLIDE MITIGATION
CITY OF RANCHO PALOS VERDES
THE CITY OF
RANCHO PALOS VERDES
FINAL-REV 1
GROUNDWATER- HYDRAUGERS- ARRAY 2
13
ARRAY 2 / DRAIN 1
ARRAY 2 / DRAIN 3
ARRAY 2 / DRAIN 5
DRAIN 1 COORDINATES TABLE
POINT STATION
N E Z COMMENT
1 0+00 1730146 6451713 300
2 12+00 1730280 6452906 324
DRAIN 3 COORDINATES TABLE
POINT STATION N E Z COMMENT
1 0+00 1730146 6451713 300
2 12+00 1731015 6452541 324
DRAIN 5 COORDINATES TABLE
POINT STATION N E Z COMMENT
1 0+00 1730146 6451713 300
2 12+00 1731344 6451788 324
LEGEND
ACTIVE BASAL RUPTURE SURFACE
EXISTING GROUND SURFACE
GROUNDWATER SURFACE
PROPOSED DRAIN
NOTES
1. FOR DRAINSS 2 AND 4 COORDINATES, INTERPOLATE BETWEEN ADJACENT DRAINS.
2. MINIMUM CURVE RADIUS 400 FEET.
APPROXIMATE LIMITS OF PORTUGUESE BEND
LANDSLIDE COMPLEX (PBLC)
APPROXIMATE CENTERLINE(CL) OF BURMA RD
KEY MAP (NOT TO SCALE)
D-60
DRAIN 1
DRAIN 2
DRAIN 3
DRAIN 4
DRAIN 5
A3
WORK LOCATION
APPROX. LIMIT OF PBLC APPROX. CL OF BURMA RD
APPROX. LIMIT OF PBLC APPROX. CL OF BURMA RD
WORK LOCATION
APPROX. LIMIT OF PBLCWORK LOCATION
REV. NO. DATE DESCRIPTION APPROVED BY
3150 BRISTOL STREET
SUITE 210
COSTA MESA, CA 92626
(714) 465-8240
www.geo-logic.com
DWG NO.
LOS ANGELES COUNTY, CA
30940 HAWTHORNE BLVD.
RANCHO PALOS VERDES,CA 90275
NOT FOR CONSTRUCTION-PENDING ENVIRONMENTAL REVIEW
PORTUGUESE BEND LANDSLIDE MITIGATION
CITY OF RANCHO PALOS VERDES
THE CITY OF
RANCHO PALOS VERDES
FINAL-REV 1
GROUNDWATER- HYDRAUGERS- ARRAY 3
14
ARRAY 3 / DRAIN 1
ARRAY 3 / DRAIN 3
ARRAY 3 / DRAIN 5
WELL 1 COORDINATES TABLE
POINT STATION
N E Z COMMENT
1 0+00 1730518 6451075 350
2 12+00 1731437 6451847 374
WELL 1 COORDINATES TABLE
POINT STATION N E Z COMMENT
1 0+00 1730518 6451075 350
2 12+00 1731718 6451075 374
DRAIN 5 COORDINATES TABLE
POINT STATION N E Z COMMENT
1 0+00 1730518 6451075 350
2 12+00 1731437 6450304 374
LEGEND
ACTIVE BASAL RUPTURE SURFACE
EXISTING GROUND SURFACE
GROUNDWATER SURFACE
PROPOSED DRAIN
NOTES
1. FOR DRAINS 2 AND 4 COORDINATES, INTERPOLATE BETWEEN ADJACENT DRAINS.
2. MINIMUM CURVE RADIUS 400 FEET.
APPROXIMATE LIMITS OF PORTUGUESE BEND
LANDSLIDE COMPLEX (PBLC)
APPROXIMATE CENTERLINE(CL) OF BURMA RD
KEY MAP (NOT TO SCALE)
D-61
DRAIN 1
DRAIN 2
DRAIN 3
DRAIN 4
DRAIN 5
A4
WORK LOCATION
WORK LOCATION
WORK LOCATION
REV. NO. DATE DESCRIPTION APPROVED BY
3150 BRISTOL STREET
SUITE 210
COSTA MESA, CA 92626
(714) 465-8240
www.geo-logic.com
DWG NO.
LOS ANGELES COUNTY, CA
30940 HAWTHORNE BLVD.
RANCHO PALOS VERDES,CA 90275
NOT FOR CONSTRUCTION-PENDING ENVIRONMENTAL REVIEW
PORTUGUESE BEND LANDSLIDE MITIGATION
CITY OF RANCHO PALOS VERDES
THE CITY OF
RANCHO PALOS VERDES
FINAL-REV 1
GROUNDWATER- HYDRAUGERS- ARRAY 4
15
ARRAY 4 / DRAIN 1
ARRAY 4 / DRAIN 3
ARRAY 4 / DRAIN 5
DRAIN 1 COORDINATES TABLE
POINT STATION
N E Z COMMENT
1 0+00 1728218 6448970 235 BEGIN CURVE
2 3+35.59 1728396 6449255 53 END CURVE
3 12+00 1728854 6449988 53
DRAIN 3 COORDINATES TABLE
POINT STATION N E Z COMMENT
1 0+00 1728218 6448970 235 BEGIN CURVE
2 3+35.59 1728537 6449074 53 END CURVE
3 12+00 1729359 6449341 53
DRAIN 5 COORDINATES TABLE
POINT STATION N E Z COMMENT
1 0+00 1728218 6448970 235 BEGIN CURVE
2 3+35.59 1728529 6448844 53 END CURVE
3 12+00 1729330 6448520 53
LEGEND
ACTIVE BASAL RUPTURE SURFACE
EXISTING GROUND SURFACE
GROUNDWATER SURFACE
PROPOSED DRAIN
NOTES
1. FOR DRAINS 2 AND 4 COORDINATES, INTERPOLATE BETWEEN ADJACENT DRAINS.
2. MINIMUM CURVE RADIUS 400 FEET.
APPROXIMATE LIMITS OF PORTUGUESE BEND
LANDSLIDE COMPLEX (PBLC)
APPROXIMATE CENTERLINE(CL) OF ROAD
KEY MAP (NOT TO SCALE)
D-62
DRAIN 1
DRAIN 2
DRAIN 3
DRAIN 4
DRAIN 5
A5
WORK LOCATION
APPROX. CL OF PVDS
WORK LOCATION
APPROX. CL OF PVDS
WORK LOCATION
APPROX. LIMIT OF PBLC
REV. NO. DATE DESCRIPTION APPROVED BY
3150 BRISTOL STREET
SUITE 210
COSTA MESA, CA 92626
(714) 465-8240
www.geo-logic.com
DWG NO.
LOS ANGELES COUNTY, CA
30940 HAWTHORNE BLVD.
RANCHO PALOS VERDES,CA 90275
NOT FOR CONSTRUCTION-PENDING ENVIRONMENTAL REVIEW
PORTUGUESE BEND LANDSLIDE MITIGATION
CITY OF RANCHO PALOS VERDES
THE CITY OF
RANCHO PALOS VERDES
FINAL-REV 1
GROUNDWATER- HYDRAUGERS- ARRAY 5
16
ARRAY 5 / DRAIN 1
ARRAY 5 / DRAIN 3
ARRAY 5 / DRAIN 5
DRAIN 1 COORDINATES TABLE
POINT STATION
N E Z COMMENT
1 0+00 1727147 6449217 8 BEGIN CURVE
2 1+37.58 1727279 6449257 -17 END CURVE
3 12+00 1728296 6449565 -17
DRAIN 3 COORDINATES TABLE
POINT STATION N E Z COMMENT
1 0+00 1727147 6449217 8 BEGIN CURVE
2 1+58.63 1727293 6449155 -25 END CURVE
3 12+00 1728251 6448746 -25
DRAIN 5 COORDINATES TABLE
POINT STATION N E Z COMMENT
1 0+00 1727147 6449217 8 BEGIN CURVE
2 1+32.38 1727207 6449099 -15 END CURVE
3 12+00 1727690 6448147 -15
LEGEND
ACTIVE BASAL RUPTURE SURFACE
EXISTING GROUND SURFACE
GROUNDWATER SURFACE
PROPOSED DRAIN
NOTES
1. FOR DRAINS 2 AND 4 COORDINATES, INTERPOLATE BETWEEN ADJACENT DRAINS.
2. MINIMUM CURVE RADIUS 400 FEET.
APPROXIMATE LIMITS OF PORTUGUESE BEND
LANDSLIDE COMPLEX (PBLC)
APPROXIMATE CENTERLINE(CL) OF PALOS
VERDES DRIVE SOUTH (PVDS)
KEY MAP (NOT TO SCALE)
D-63
DRAIN 1
DRAIN 2
DRAIN 3
DRAIN 4
DRAIN 5
A6
WORK LOCATION
WORK LOCATION
WORK LOCATION
APPROX. CL OF PVDS
REV. NO. DATE DESCRIPTION APPROVED BY
3150 BRISTOL STREET
SUITE 210
COSTA MESA, CA 92626
(714) 465-8240
www.geo-logic.com
DWG NO.
LOS ANGELES COUNTY, CA
30940 HAWTHORNE BLVD.
RANCHO PALOS VERDES,CA 90275
NOT FOR CONSTRUCTION-PENDING ENVIRONMENTAL REVIEW
PORTUGUESE BEND LANDSLIDE MITIGATION
CITY OF RANCHO PALOS VERDES
THE CITY OF
RANCHO PALOS VERDES
FINAL-REV 1
GROUNDWATER- HYDRAUGERS- ARRAY 6
17
ARRAY 6 / DRAIN 1
ARRAY 6 / DRAIN 3
ARRAY 6 / DRAIN 5
DRAIN 1 COORDINATES TABLE
POINT STATION
N E Z COMMENT
1 0+00 1727142 6449664 11 BEGIN CURVE
2 2+16.21 1727189 6449875 -53 END CURVE
3 12+00 1727403 6450835 -53
DRAIN 3 COORDINATES TABLE
POINT STATION N E Z COMMENT
1 0+00 1727142 6449664 11 BEGIN CURVE
2 2+09.02 1727308 6449791 -48 END CURVE
3 12+00 1728095 6450393 -48
DRAIN 5 COORDINATES TABLE
POINT STATION N E Z COMMENT
1 0+00 1727142 6449664 11 BEGIN CURVE
2 1+66.06 1727307 6449656 -25 END CURVE
3 12+00 1728340 6449609 -25
LEGEND
ACTIVE BASAL RUPTURE SURFACE
EXISTING GROUND SURFACE
GROUNDWATER SURFACE
PROPOSED DRAIN
NOTES
1. FOR DRAINS 2 AND 4 COORDINATES, INTERPOLATE BETWEEN ADJACENT DRAINS.
2. MINIMUM CURVE RADIUS 400 FEET.
APPROXIMATE LIMITS OF PORTUGUESE BEND
LANDSLIDE COMPLEX (PBLC)
APPROXIMATE CENTERLINE(CL) OF PALOS
VERDES DRIVE SOUTH (PVDS)
KEY MAP (NOT TO SCALE)
D-64
1
2
3
4R400.0 MINIMUM
DRILL RIG
WORKING
PLATFORM
1
SUMP TO CONTAIN DRILLING FLUIDS
AND CUTTINGS TO BE SIZED BY
DRILLING CONTRACTOR
ANGLE OF ATTACK PER PLAN BASED ON
LOCATION PER DESIGN ENGINEER
NEAT CEMENT GROUT ANNULAR SEAL
IN 12-INCH DIAM. BORE HOLE
8-INCH DIAM. LOW CARBON STEEL
CONDUCTOR CASING-DEPTH AND
LENGTH TO BE DETERMINED BEFORE
THE START OF DRILLING BY ASSESSING
THE MAXIMUM ANTICIPATED
PIEZOMETRIC PRESSURE
DRILL RIG
REV. NO. DATE DESCRIPTION APPROVED BY
3150 BRISTOL STREET
SUITE 210
COSTA MESA, CA 92626
(714) 465-8240
www.geo-logic.com
DWG NO.
LOS ANGELES COUNTY, CA
30940 HAWTHORNE BLVD.
RANCHO PALOS VERDES,CA 90275
NOT FOR CONSTRUCTION-PENDING ENVIRONMENTAL REVIEW
PORTUGUESE BEND LANDSLIDE MITIGATION
CITY OF RANCHO PALOS VERDES
THE CITY OF
RANCHO PALOS VERDES
FINAL-REV 1
HYDRAUGERS DETAILS- DIRECTIONAL
18
NOTES
CONTRACTOR TO EXCAVATE SUMP TO CONTAIN DRILLING FLUIDS AND
CUTTINGS. CONTRACTOR TO CONSTRUCT WORKING PLATFORM TO
ACCOMMODATE DRILLING OPERATION. DIMENSIONS TO BE
DETERMINED BY DRILLING CONTRACTOR. WATER USED FOR DRILLING
AND DEVELOPED FROM THE DRILL SHALL BE DISPOSED OF BY THE
CONTRACTOR WITHOUT DAMAGE TO THE PROJECT OR THE
ENVIRONMENT.
ANGLE OF ATTACK FOR THE HYDRAUGER IS PER PLAN SHEET 11
THROUGH 17 PER THE ENGINEER. THE DEPTH AND LENGTH OF THE
CONDUCTOR CASING IS TO BE DETERMINED BEFORE THE START OF
DRILLING OPERATIONS TO WITHSTAND 2 TIMES THE MAXIMUM
ANTICIPATED HYDROSTATIC PRESSURE.
THE BOREHOLE FOR THE CONDUCTOR CASING SHALL BE A MINIMUM OF
12-INCHES IN DIAMETER. THE CONDUCTOR CASING SHALL CONSIST OF
8-INCH DIAMETER, SCHEDULE 40, LOW CARBON STEEL.
CONTRACTOR TO ENSURE THAT THE PROFILE AND DIRECTION OF THE
HYDRAUGER CONFORMS TO THE DESIGN ON SHEET 11 THROUGH 17.
1
2
3
4
2
3
TYPICAL HYDRAUGER
DIRECTIONAL
CROSS SECTION
N.T.S
-
--18
SUMP AND CONDUCTOR CASING
DETAIL
N.T.S
-
--18
D-65
1
3
45
2
1
SUMP TO CONTAIN DRILLING FLUIDS
AND CUTTINGS TO BE SIZED BY
DRILLING CONTRACTOR
ANGLE OF ATTACK PER PLAN BASED ON
LOCATION PER DESIGN ENGINEER
NEAT CEMENT GROUT ANNULAR SEAL
IN 12-INCH DIAM. BORE HOLE
8-INCH DIAM. LOW CARBON STEEL
CONDUCTOR CASING-DEPTH AND
LENGTH TO BE DETERMINED BEFORE
THE START OF DRILLING BY ASSESSING
THE MAXIMUM ANTICIPATED
PIEZOMETRIC PRESSURE
2
REV. NO. DATE DESCRIPTION APPROVED BY
3150 BRISTOL STREET
SUITE 210
COSTA MESA, CA 92626
(714) 465-8240
www.geo-logic.com
DWG NO.
LOS ANGELES COUNTY, CA
30940 HAWTHORNE BLVD.
RANCHO PALOS VERDES,CA 90275
NOT FOR CONSTRUCTION-PENDING ENVIRONMENTAL REVIEW
PORTUGUESE BEND LANDSLIDE MITIGATION
CITY OF RANCHO PALOS VERDES
THE CITY OF
RANCHO PALOS VERDES
FINAL-REV 1
HYDRAUGER DETAILS- HORIZONTAL
19
NOTES
CONTRACTOR TO EXCAVATED SUMP TO CONTAIN DRILLING FLUIDS AND
CUTTING. DIMENSIONS TO BE DETERMINED BY DRILLING CONTRACTOR.
WATER USED FOR DRILLING AND DEVELOPED FROM THE DRILL SHALL BE
DISPOSED OF BY THE CONTRACTOR WITHOUT DAMAGE TO THE PROJECT
OR THE ENVIRONMENT.
SUBCONTRACTOR TO EXCAVATE AT SLOPE FACE, IF NECESSARY, AND
CONSTRUCT WORKING PLATFORM TO ACCOMMODATE DRILLING
OPERATION.
ANGLE OF ATTACK FOR THE HYDRAUGER IS PER PLAN SHEET 11
THROUGH 17 PER THE ENGINEER. THE DEPTH AND LENGTH OF THE
CONDUCTOR CASING IS TO BE DETERMINED BEFORE THE START OF
DRILLING OPERATIONS TO WITHSTAND 2 TIMES THE MAXIMUM
ANTICIPATED HYDROSTATIC PRESSURE.
THE BOREHOLE FOR THE CONDUCTOR CASING SHALL BE A MINIMUM OF
12-INCHES IN DIAMETER. THE CONDUCTOR CASING SHALL CONSIST OF
8-INCH DIAMETER, SCHEDULE 40, LOW CARBON STEEL.
CONTRACTOR TO ENSURE THAT THE PROFILE AND DIRECTION OF THE
HYDRAUGER CONFORMS TO THE DESIGN ON SHEET 11 THROUGH 17.
1
2
3
4
5
4
TYPICAL HYDRAUGER
HORIZONTAL
CROSS SECTION
N.T.S.
-
--19
SUMP AND CONDUCTOR CASING
DETAIL
N.T.S.
-
--19
D-66
SEE SHEET 21
SEE SHEET 23
SEE SHEET 22
REV. NO. DATE DESCRIPTION APPROVED BY
3150 BRISTOL STREET
SUITE 210
COSTA MESA, CA 92626
(714) 465-8240
www.geo-logic.com
DWG NO.
LOS ANGELES COUNTY, CA
30940 HAWTHORNE BLVD.
RANCHO PALOS VERDES,CA 90275
NOT FOR CONSTRUCTION-PENDING ENVIRONMENTAL REVIEW
PORTUGUESE BEND LANDSLIDE MITIGATION
CITY OF RANCHO PALOS VERDES
THE CITY OF
RANCHO PALOS VERDES
FINAL-REV 1
FRACTURE INFILLING LOCATIONS
20
APPROXIMATE LOCATION OF SHORELINE
APPROXIMATE LIMITS OF PORTUGUESE BEND LANDSLIDE
(BASED ON LEIGHTON, 2000)
APPROXIMATE LIMITS OF SUBSLIDES OF PORTUGUESE BEND
LANDSLIDE (BASED LEIGHTON, 2000)
APPROXIMATE LOCATION OF SURFACE FRACTURE
FRACTURE TOTAL
LOCATION NUMBER LENGTH (FT)VOLUME (1,2)
(C.Y.)
1 1,632 1,000
2 702 450
3 242 150
TOTAL 2,576 1,600
NOTES:
(1) ASSUMES FRACTURE WIDTH 1 FOOT AND DEPTH 15 FEET.
(2) CONTRACTOR TO FIELD VERIFY ALL FRACTURE DIMENSIONS AND
LOCATIONS.
(3) CONTRACTOR TO BACKFILL FRACTURES TO LEVEL OF ADJACENT GROUND
SURFACE.
(4) FRACTURE INFILL TO CONSIST OF FLOWABLE FLY ASH-BASED SLURRY OR
APPROVED ALTERNATIVE LOW-PERMEABILITY MATERIAL.
LEGEND
EXISTING TOPOGRAPHY, 2 FT ELEVATION CONTOUR
NOTES:
1. EXISTING TOPOGRAPHY PROVIDED BY CITY OF RANCHO PALOS VERDES, DATED
2017.
2. CONTRACTOR IS RESPONSIBLE TO FIELD VERIFY ELEVATIONS SHOWN.
EXISTING TOPOGRAPHY, 10 FT ELEVATION CONTOUR
PRESERVE PROPERTY BOUNDARY
EXISTING TRAIL
EXISTING ROAD
D-67
REV. NO. DATE DESCRIPTION APPROVED BY
3150 BRISTOL STREET
SUITE 210
COSTA MESA, CA 92626
(714) 465-8240
www.geo-logic.com
DWG NO.
LOS ANGELES COUNTY, CA
30940 HAWTHORNE BLVD.
RANCHO PALOS VERDES,CA 90275
NOT FOR CONSTRUCTION-PENDING ENVIRONMENTAL REVIEW
PORTUGUESE BEND LANDSLIDE MITIGATION
CITY OF RANCHO PALOS VERDES
THE CITY OF
RANCHO PALOS VERDES
FINAL-REV 1
FRACTURE INFILLING LOCATION 1
21
APPROXIMATE LIMITS OF PORTUGUESE BEND
LANDSLIDE COMPLEX
F1
F2
F3
F4
F5
F6
F7
F8
F9
F10
LOCATION 1
FRACTURE NUMBER
LENGTH
(FT)
VOLUME (1,2)
(C.Y.)
F1 198 -
F2 205 -
F3 217 -
F4 61 -
F5 108 -
F6 287 -
F7 213 -
F8 52 -
F9 191 -
F10 100 -
TOTAL (THIS SHEET)1,632 1,000
FRACTURE LOCATION
F8
NOTES:
(1) ASSUMES FRACTURE WIDTH 1 FOOT AND DEPTH 15 FEET.
(2) CONTRACTOR TO FIELD VERIFY ALL FRACTURE DIMENSIONS AND
LOCATIONS.
(3) CONTRACTOR TO BACKFILL FRACTURES TO LEVEL OF ADJACENT GROUND
SURFACE.
(4) FRACTURE INFILL TO CONSIST OF FLOWABLE FLY ASH-BASED SLURRY OR
APPROVED ALTERNATIVE LOW-PERMEABILITY MATERIAL.
LEGEND
EXISTING TOPOGRAPHY, 2 FT ELEVATION CONTOUR
NOTES:
1. EXISTING TOPOGRAPHY
PROVIDED BY CITY OF RANCHO
PALOS VERDES, DATED 2017.
2. CONTRACTOR IS RESPONSIBLE
TO FIELD VERIFY ELEVATIONS
SHOWN.
EXISTING TOPOGRAPHY, 10 FT ELEVATION CONTOUR
PRESERVE PROPERTY BOUNDARY
KEY MAP (NOT TO SCALE)
D-68
REV. NO. DATE DESCRIPTION APPROVED BY
3150 BRISTOL STREET
SUITE 210
COSTA MESA, CA 92626
(714) 465-8240
www.geo-logic.com
DWG NO.
LOS ANGELES COUNTY, CA
30940 HAWTHORNE BLVD.
RANCHO PALOS VERDES,CA 90275
NOT FOR CONSTRUCTION-PENDING ENVIRONMENTAL REVIEW
PORTUGUESE BEND LANDSLIDE MITIGATION
CITY OF RANCHO PALOS VERDES
THE CITY OF
RANCHO PALOS VERDES
FINAL-REV 1
FRACTURE INFILLING LOCATION 2
22
F1
F2
F3
F4
F5
F6
F7
LOCATION 2
FRACTURE NUMBER LENGTH (FT)VOLUME (1,2)
(C.Y.)
F1 66 -
F2 98 -
F3 74 -
F4 116 -
F5 99 -
F6 132 -
F7 117 -
TOTAL (THIS SHEET)702 450
APPROXIMATE LIMITS OF PORTUGUESE BEND
LANDSLIDE COMPLEX
FRACTURE LOCATION
F8
NOTES:
(1) ASSUMES FRACTURE WIDTH 1 FOOT AND DEPTH 15 FEET.
(2) CONTRACTOR TO FIELD VERIFY ALL FRACTURE DIMENSIONS AND
LOCATIONS.
(3) CONTRACTOR TO BACKFILL FRACTURES TO LEVEL OF ADJACENT GROUND
SURFACE.
(4) FRACTURE INFILL TO CONSIST OF FLOWABLE FLY ASH-BASED SLURRY OR
APPROVED ALTERNATIVE LOW-PERMEABILITY MATERIAL.
LEGEND
EXISTING TOPOGRAPHY, 2 FT ELEVATION CONTOUR
NOTES:
1. EXISTING TOPOGRAPHY PROVIDED BY CITY
OF RANCHO PALOS VERDES, DATED 2017.
2. CONTRACTOR IS RESPONSIBLE TO FIELD
VERIFY ELEVATIONS SHOWN.
EXISTING TOPOGRAPHY, 10 FT ELEVATION CONTOUR
EXISTING TRAIL
KEY MAPKEY MAP (NOT TO SCALE)
PRESERVE PROPERTY BOUNDARY
D-69
REV. NO. DATE DESCRIPTION APPROVED BY
3150 BRISTOL STREET
SUITE 210
COSTA MESA, CA 92626
(714) 465-8240
www.geo-logic.com
DWG NO.
LOS ANGELES COUNTY, CA
30940 HAWTHORNE BLVD.
RANCHO PALOS VERDES,CA 90275
NOT FOR CONSTRUCTION-PENDING ENVIRONMENTAL REVIEW
PORTUGUESE BEND LANDSLIDE MITIGATION
CITY OF RANCHO PALOS VERDES
THE CITY OF
RANCHO PALOS VERDES
FINAL-REV 1
FRACTURE INFILLING LOCATION 3
23
F1
LOCATION 3
FRACTURE NUMBER LENGTH (FT)VOLUME (1,2)
(C.Y.)
F1 242 -
TOTAL (THIS SHEET)242 150
APPROXIMATE LIMITS OF PORTUGUESE BEND
LANDSLIDE COMPLEX
FRACTURE LOCATION
F8
NOTES:
(1) ASSUMES FRACTURE WIDTH 1 FOOT AND DEPTH 15 FEET.
(2) CONTRACTOR TO FIELD VERIFY ALL FRACTURE DIMENSIONS AND
LOCATIONS.
(3) CONTRACTOR TO BACKFILL FRACTURES TO LEVEL OF ADJACENT GROUND
SURFACE.
(4) FRACTURE INFILL TO CONSIST OF FLOWABLE FLY ASH-BASED SLURRY OR
APPROVED ALTERNATIVE LOW-PERMEABILITY MATERIAL.
LEGEND
EXISTING TOPOGRAPHY, 2 FT ELEVATION CONTOUR
NOTES:
1. EXISTING TOPOGRAPHY PROVIDED BY
CITY OF RANCHO PALOS VERDES,
DATED 2017.
2. CONTRACTOR IS RESPONSIBLE TO
FIELD VERIFY ELEVATIONS SHOWN.
EXISTING TOPOGRAPHY, 10 FT ELEVATION CONTOUR
EXISTING TRAIL
PRESERVE PROPERTY BOUNDARY
KEY MAP (NOT TO SCALE)
D-70
A5
A1
A4
A6
A5
A1
A4
A2
A3
EXISTING
ACCESS
POINT
STOCKPILE AREA
PRIMARY STAGING AREA
SECONDARY STAGING
AREA
ACCESS ROUTE
ACCESS ROUTE
ACCESS ROUTE
REV. NO. DATE DESCRIPTION APPROVED BY
3150 BRISTOL STREET
SUITE 210
COSTA MESA, CA 92626
(714) 465-8240
www.geo-logic.com
DWG NO.
LOS ANGELES COUNTY, CA
30940 HAWTHORNE BLVD.
RANCHO PALOS VERDES,CA 90275
NOT FOR CONSTRUCTION-PENDING ENVIRONMENTAL REVIEW
PORTUGUESE BEND LANDSLIDE MITIGATION
CITY OF RANCHO PALOS VERDES
THE CITY OF
RANCHO PALOS VERDES
FINAL-REV 1
ACCESS, STAGING, AND STOCKPILE LOCATIONS
24
LEGEND
EXISTING TOPOGRAPHY, 2 FT ELEVATION CONTOUR
APPROXIMATE LOCATION OF SHORELINE
APPROXIMATE LIMITS OF PORTUGUESE BEND LANDSLIDE
COMPLEX (PBLC)
APPROXIMATE LIMITS OF SUBSLIDES OF PORTUGUESE BEND
LANDSLIDE
HYDRAUGER DIRECTIONAL / GRAVITY FLOW
HYDRAUGER DIRECTIONAL / PUMP ASSISTED FLOW
HYDRAUGER HORIZONTAL / GRAVITY FLOW
NOTES:
1. CONTRACTOR IS RESPONSIBLE TO PERFORM PRE-CONSTRUCTION CONFIRMATION
SUBSURFACE EXPLORATION TO VERIFY GROUNDWATER, SOIL, AND BEDROCK
CONDITIONS.
2. CONTRACTOR IS RESPONSIBLE TO INSTALL GROUTED CONDUCTOR AND/OR
SURFACE CASING WITH ADEQUATE CAPACITY TO PREVENT BLOWOUT AND/OR
OTHER POTENTIAL ADVERSE EVENTS RELATED TO HYDRAUGER INSTALLATION,
OPERATION, AND/OR MAINTENANCE.
3. EXISTING TOPOGRAPHY PROVIDED BY CITY OF RANCHO PALOS VERDES, DATED
2017.
4. CONTRACTOR IS RESPONSIBLE TO FIELD VERIFY ELEVATIONS SHOWN.
EXISTING TOPOGRAPHY, 10 FT ELEVATION CONTOUR
PRESERVE PROPERTY BOUNDARY
PLANNED ACCESS ROUTE
HYDRAUGER INSTALLATION WORK AREA (100'X100' TYPICAL)
100'
100'
D-71
APPENDIX B
SLOPE STABILITY COMPUTER PROGRAM
OUTPUT
D-72
Notes:
1.Not to scale.
2.Directions, dimensions, and locations are approximate.
3.“HS” denotes hydrostatic.
1-Back Analysis 2- Dewater HS Only
3- Dewater Artesian Only 4- Dewater HS &Artesian
STABILITY SOFTWARE OUTPUT – CROSS-SECTION A-A’
SLOPE STABILITY EVALUATION
PORTUGUESE BEND LANDSLIDE
DATE: November 2019
FIGURE NO 1 PROJECT NO. DB19.1055
D-73
Notes:
1.Not to scale.
2.Directions, dimensions, and locations are approximate.
3. “HS” denotes hydrostatic.
1-Back Analysis 2- Dewater HS Only
3- Dewater Artesian Only 4- Dewater HS &Artesian
STABILITY SOFTWARE OUTPUT – CROSS-SECTION B-B’
SLOPE STABILITY EVALUATION
PORTUGUESE BEND LANDSLIDE
DATE: November 2019
FIGURE NO 2 PROJECT NO. DB19.1055
D-74
Notes:
1.Not to scale.
2.Directions, dimensions, and locations are approximate.
3.“HS” denotes hydrostatic.
1-Back Analysis 2- Dewater HS Only
3- Dewater Artesian Only 4- Dewater HS &Artesian
STABILITY SOFTWARE OUTPUT – CROSS-SECTION C-C’
SLOPE STABILITY EVALUATION
PORTUGUESE BEND LANDSLIDE
DATE: November 2019
FIGURE NO 3 PROJECT NO. DB19.1055
D-75
APPENDIX C
HYDROLOGY / HYDRAULICS CALCULATION
OUTPUTS
D-76
December 9, 2019
Project No. DB19.1055.00
City of Rancho Palos Verdes
30940 Hawthorne Boulevard
Rancho Palos Verdes, California 90275
Attention: Mr. Elias Sassoon
HYDROLOGY AND HYDRAULICS EVALUATION
PORTUGUESE BEND LANDSLIDE COMPLEX MITIGATION MEASURES
RANCHO PALOS VERDES, CALIFORNIA
Dear Mr. Sassoon:
INTRODUCTION
Geo-Logic Associates, Inc. (GLA) is pleased to submit this letter and attachments (i.e., hydrology
map; hydrology and hydraulics computer program outputs) to the City of Rancho Palos Verdes
(City). The services documented here were performed in support of GLA’s Portuguese Bend
Landslide Complex (PBLC) mitigation design project.
GLA has provided to the City under separate cover the geotechnical design report and plan set
for proposed mitigation measures (GLA, 2019a,b). Key stormwater management features
shown in the GLA (2019b) plan set include the following:
• Proposed engineered swale, which is approximately trapezoidal in transverse cross-
section;
• Proposed “flow reduction area” (i.e., detention basin);
• Proposed 36-inch-diameter high-density polyethylene (HDPE) pipe below Burma Road
(near PBLC northern limit)
• Existing 60-inch-diameter corrugated metal pipe (CMP) below Palos Verdes Drive South
(PVDS), to be refurbished; and
• Proposed 60-inch-diameter thick-walled HDPE pipe south of PVDS.
In performing the services documented here and in the associated deliverables (i.e., GLA,
2019a,b), GLA relied upon information provided by the City. In particular, GLA relied upon City-
provided watershed topography dated 2017, existing pipe locations (including flowline
elevations), and existing pipe dimensions. Field verification (e.g., detailed topographic and pipe
D-77
condition surveys) was outside the approved scope of GLA’s services and was not performed in
the course of this project.
SCOPE OF SERVICES
GLA performed the following services under the supervision of a California registered
Professional Engineer:
• Hydrology Map Development: Based on the PBLC and surrounding area topography
provided by the City, GLA developed a hydrology map for use in hydraulics calculations.
The hydrology map shows estimated watershed limits, subdrainage limits, flowline
locations, and subdrainage parameters (i.e., area, average slope, flow path length, and
flow rate).
• Estimation of Design Flows: Using the hydrology map developed for the project, GLA
estimated design flows for the 100-year (return period) 24-hour (duration) design storm
event based on the methodology of the Los Angeles County Department of Public Works
(LACDPW, 2006) hydrology manual.
• Proportioning of Engineered Swale and Flow Reduction Area: Based on the City-
provided topography and information on existing pipes, and the estimated design flows,
GLA proportioned the proposed engineered swale and flow reduction area (i.e.,
detention basin) features.
• Evaluation of Ponding north of Burma Road: Per City request, the current construction
plan set calls for a new 36-inch-diameter pipe to be installed below Burma Road near
the northern limit of the PBLC. Based on GLA’s evaluation of design flows, such a pipe is
anticipated to be inadequate (i.e., not large enough) to accommodate the design storm
event without ponding in the existing basin-like feature north of Burma Road (i.e., at the
inlet of the proposed pipe). GLA performed a preliminary evaluation of the ponded
water volume at the proposed pipe inlet for the design storm event.
CONCLUSIONS AND RECOMMENDATIONS
As part of the PBLC mitigation design project, GLA performed hydrology and hydraulics
evaluations in support of design of proposed surface water management features. Based on
the results of these evaluations, it is GLA’s opinion that the proposed design features (with the
exception of the proposed pipe below Burma Road) can adequately accommodate the design
storm event, provided that the following recommendations are implemented:
• Before construction of the proposed surface water drainage features, a site-specific
topographic survey of the watershed including the PBLC should be performed under the
supervision of a California registered Professional Land Surveyor. The survey should
include field verification of all relevant drainage features (e.g., pipe locations and
flowline elevations). Results of this topographic survey should be used to update
D-78
hydrology and hydraulics calculations prepared by GLA, and the surface water design
(i.e., GLA, 2019b construction plan set) should be updated to reflect revised calculations.
• Before construction of the proposed PBLC mitigation measures, a detailed pipe
condition survey should be performed to evaluate feasibility of refurbishing and/or
augmenting the existing 60-inch-diameter pipe below PVDS. This pipe condition survey
should be performed under the supervision of a California registered Professional
Engineer and should include assessment of flowline elevations, obstructions, wall
integrity, remaining service life, structural design adequacy, feasibility of refurbishment,
retrofit requirements, etc. Results of this detailed pipe condition survey should be used
to update hydrology and hydraulics calculations prepared by GLA, and the surface water
design (i.e., GLA, 2019b construction plan set) should be updated to reflect the relevant
findings.
• Based on GLA’s evaluations, the proposed 36-inch-diameter pipe below Burma Road will
not provide adequate capacity to accommodate design storm flows without ponded
water north of Burma Road. GLA anticipates that the ponded water volume for the
design storm event will be on the order of approximately two acre-feet and that this
volume of ponded water will remain in place for less than one hour.
D-79
CLOSURE
This letter report is based on the data and analyses described herein. GLA should be notified of
any conditions that differ from those described herein since this may require a reevaluation of
the data, conclusions and recommendations presented. Any use of the recommendations and
conclusions contained in this report for other projects is strictly forbidden without GLA review
and approval
This letter report has been prepared in accordance with generally accepted engineering
practices in southern California, and internally peer-reviewed in accordance with GLA’s peer
review policy, and makes no other warranties, either expressed or implied, as to the
professional data presented in it.
This letter report has not been prepared for use by other parties and projects other than those
named or described above. It may not contain sufficient information for other parties or other
purposes.
Sincerely,
Geo-Logic Associates, Inc.
Alan F. Witthoeft, PE, GE
Project Engineer III
FOR Courtney Barrett, PE, QSD, QISP
Senior Engineer
Attachments
Attachment 1: Hydrology Map
Attachment 2: Hydrology and Hydraulics Computer Program Outputs
D-80
REFERENCES
LACDPW (2006), “Hydrology Manual,” Los Angeles County Department of Public Works, Water
Resources Division, 145 pp. (plus Appendices).
GLA (2019a), “DRAFT Geotechnical Evaluation Report, Portuguese Bend Landslide Complex
Mitigation Measures, Rancho Palos Verdes, California,” Technical Report, Geo-Logic
Associates, Inc., Costa Mesa, California (Project No. DB19.1055.00).
GLA (2019b), “Portuguese Bend Landslide Complex Mitigation Measures, City of Rancho Palos
Verdes, California, November, 2019,” Construction Plan Set, Geo-Logic Associates, Inc.,
Costa Mesa, California (Project No. DB19.1055.00).
D-81
ATTACHMENT 1
Hydrology Map
D-82
A1
20.29
L=1,000'
S
=
2
3
.
0
5
%
A2
26.53
A3
28.74
A4
23.54
A5
36.82
A6
18.18
A10
20.51
A9
32.71
A8
11.98
A7
17.75
A11
19.12
A16
19.02
A15
26.73
A14
16.47 A13
24.53
A12
21.36
A17
71.89
A18
52.15
A19
29.25
E1
15.61
D1
16.70
C1
41.43
B2
20.13
B3
15.78
B1
19.15
Q
=
6
1
.
1
9
c
f
s
L=1,155' S=15.71%Q=73.93cfs
L=93
0'
S
=
2
0.
6
4
%
Q
=
8
6.
5
5
C
F
S
L=742' S=
1
1
.
6
2
%
Q=70.89CF
S
L=1,427' S=16.94%Q=95.66CFSL
=
8
3
9
'
S
=
3
.
5
7%Q=
4
7
.
2
2C
FS L=1,438' S=16.76%Q=49.66CFSL=729'
S
=
2
0.09
%
Q=6
7.83
C
F
S
L=1,
4
4
0'
S
=1
7.
84
%
Q=84.99
C
F
S
L=579'
S=22.28%
Q=39.62C
F
S
L=1,
0
1
3'
S
=
2
3.
8
4
%
Q=53.
5
6
C
F
S
L=1,301'
S
=
9
.
6
1
%
Q
=
5
5
.
7
5
C
F
S
L=994' S=20.12
%
Q=73.97
C
F
S
L=1,1
9
6'
S
=
2
0.
4
0
%
Q
=
4
5.
9
0
C
F
S
L=140
0'
S
=
1
5
.
7
8
%
Q
=
6
9
.
5
4
C
F
S
L=1,0
6
4'
S
=
2
6
.
3
1
%
Q
=
5
7
.
2
7
C
F
S
L=2,326' S=5.33
%
Q=144.19
CF
S
L=1,210' S=12.89% Q=63.72CFSL=1,072' S=17.72% Q=39.07CFSL=1,845' S=15.55% Q=75.59CFSL=2,444' S=9.39% Q=78.40CFSL=1,5
8
3'
S
=
1
1.
5
9
%
Q
=
3
7.
9
2
C
F
S
L=2,629' S=15.99%Q=25.1
8
C
F
SL=1,415' S=3.39%Q=47.38CFSL=786' S=19.34%
Q=40.40CFS
1350
1225.0
1300.0
1275.0
1044.5
863.0
671.0
584.8
315.0
285.0
526.0
672.5
929.5
1058.5
1025.0
781.0
560.0
280.0
156.0
287.0
190.0
200.0
152.0
0.0
0.0
0.0
0.0
0.0
420.5
383.5
385.5
556.8
B4
7.01
150.0
0.0 L=438'S=34.24
%
Q=14.0
CF
S
EXISTING CITY PROJECT
(OUT OF SCOPE; BY OTHERS)
REV. NO. DATE DESCRIPTION APPROVED BY
3150 BRISTOL STREET
SUITE 210
COSTA MESA, CA 92626
(714) 465-8240
www.geo-logic.com
DWG NO.
LOS ANGELES COUNTY, CA
30940 HAWTHORNE BLVD.
RANCHO PALOS VERDES,CA 90275
NOT FOR CONSTRUCTION-PENDING ENVIRONMENTAL REVIEW
PORTUGUESE BEND LANDSLIDE MITIGATION
CITY OF RANCHO PALOS VERDES
THE CITY OF
RANCHO PALOS VERDES
FINAL-REV 1
HYDROLOGY
1
LEGEND
10 FT ELEVATION CONTOUR
PROPOSED CULVERT LOCATIONS
HYDROLOGY DRAINAGE BOUNDARY
HYDROLOGY SUB-DRAINAGE BOUNDARY
HYDROLOGY SUB-AREA
SUBDRAINAGE PATH LENGTH
SUBDRAINAGE PATH AVERAGE SLOPES
L
SUBDRAINAGE CONTRIBUTION TO SUBAREA FLOWQ
1350 FLOWLINE SPOT ELEVATION
A11
19.12
SUBDRAINAGE DESIGNATION AND AREA IN ACRES
SUBAREA A
SUBAREA B
SUBAREA C
SUBAREA D
SUBAREA E
D-83
ATTACHMENT 2
Hydrology and Hydraulics Computer Program
Outputs
D-84
Autodesk® Storm and Sanitary Analysis 2016 - Version 13.2.147 (Build 0) ----------------------------------------------------------------------------------------- ******************* Project Description ******************* File Name ................. RPV Hydrology MOD.SPF Description ............... C:\Users\cbarrett\Documents\Rancho Palos Verdes\XRPV-HYDRO- EXIST.dwg
**************** Analysis Options **************** Flow Units ................. cfs Subbasin Hydrograph Method. SCS TR-55 Time of Concentration...... SCS TR-55 Link Routing Method ....... Kinematic Wave Storage Node Exfiltration.. None Starting Date ............. NOV-01-2019 00:00:00 Ending Date ............... NOV-02-2019 00:00:00 Report Time Step ........... 00:05:00
************* Element Count ************* Number of rain gages ....... 4 Number of subbasins ........ 8 Number of nodes ............ 13 Number of links ............ 13
**************** Raingage Summary **************** Gage Data Data Recording ID Source Type Interval ------------------------------------------------------------
min
100-YR 100-YR CUMULATIVE 6.00 10-YR 10-YR CUMULATIVE 6.00 2-YR 2-YR CUMULATIVE 6.00 50-YR 50-YR CUMULATIVE 6.00
****************
Subbasin Summary **************** Subbasin Total Peak Rate
Area Factor ID acres
------------------------------------------ {Site 1}.A12-16 208.70 484.00 {Site 1}.A1-4 171.20 484.00 {Site 1}.A-17 76.00 484.00 {Site 1}.A18 51.46 484.00 {Site 1}.A19 6.00 484.00 {Site 1}.A20 7.27 484.00 {Site 1}.A5-6 67.80 484.00
{Site 1}.A7-11 174.40 484.00
************
Node Summary ************ Node Element Invert Maximum Ponded External ID Type Elevation Elev. Area Inflow
ft ft ft²
------------------------------------------------------------------------------ BURMA_PIPE_INLET JUNCTION 584.80 587.80 0.00
D-85
BURMA_PIPE_OUTLET JUNCTION 556.76 559.76 0.00 DK_BLUE_CHANNEL JUNCTION 120.00 122.00 0.00 JUNCTION_ORANGE-DK_GREEN_LT_BLUEJUNCTION 278.00 281.50 0.00 JUNCTION_PURPLE-ORANGE-LT_GREENJUNCTION 285.00 288.50 0.00 LT_BLUE_INLET JUNCTION 458.00 460.00 0.00 LT_GREEN_INLET JUNCTION 475.00 477.00 0.00 OCEAN_OUTLET JUNCTION 0.00 3.00 0.00 ORIFICE_OUTLETS JUNCTION 166.10 170.10 0.00 PALOS_VERDE_PIPE_INLETJUNCTION 154.71 160.71 0.00 PALOS_VERDE_PIPE_OUTLETJUNCTION 150.44 156.44 0.00 WEIR_OUTLET JUNCTION 175.95 183.95 0.00 BASIN STORAGE 170.00 178.00 0.00
************ Link Summary ************ Link From Node To Node Element Length Slope Manning's ID Type ft % Roughness -------------------------------------------------------------------------------------------- 36-IN-PIPE_BURMABURMA_PIPE_INLETBURMA_PIPE_OUTLETCONDUIT 325.9 8.6039 0.0130 60-IN_CMP_PALOS_VERDESPALOS_VERDE_PIPE_INLETPALOS_VERDE_PIPE_OUTLETCONDUIT 184.9 2.3096 0.0150 DK_GREEN JUNCTION_ORANGE-DK_GREEN_LT_BLUEBASIN CHANNEL 904.5 11.3322 0.0300 DKBLUE PALOS_VERDE_PIPE_OUTLETDK_BLUE_CHANNEL CHANNEL 260.0 11.7072 0.0320 Link-20 WEIR_OUTLET ORIFICE_OUTLETS CHANNEL 13.8 71.8954 0.0130 LT_BLUE LT_BLUE_INLET JUNCTION_ORANGE-DK_GREEN_LT_BLUECHANNEL 609.6 29.5290 0.0300 LT_GREEN LT_GREEN_INLET JUNCTION_PURPLE-ORANGE-LT_GREENCHANNEL 681.4 27.8834 0.0300 ORANGE JUNCTION_PURPLE-ORANGE-LT_GREENJUNCTION_ORANGE-DK_GREEN_LT_BLUECHANNEL 320.7 2.1827 0.0300 PURPLE BURMA_PIPE_OUTLETJUNCTION_PURPLE-ORANGE-LT_GREENCHANNEL 1873.8 14.5028 0.0300 RED ORIFICE_OUTLETS PALOS_VERDE_PIPE_INLETCHANNEL 451.3 2.4597 0.0300 Outfall_36-INCH BASIN ORIFICE_OUTLETS ORIFICE Outfall_48-INCH BASIN ORIFICE_OUTLETS ORIFICE Spillway BASIN WEIR_OUTLET WEIR
********************* Cross Section Summary ********************* Link Shape Depth/ Width No. of Cross Full Flow Design ID Diameter Barrels Sectional Hydraulic Flow Radius Capacity
ft cfs
Area
ft ft ft²
---------------------------------------------------------------------------------------------- ------------ 36-IN-PIPE_BURMA CIRCULAR 0.75 195.64 60-IN_CMP_PALOS_VERDES CIRCULAR 1.25 343.03 DK_GREEN TRAPEZOIDAL 2.10 1244.71 DKBLUE TRAPEZOIDAL 1.34 385.92 Link-20 TRAPEZOIDAL 1.53 3092.49 LT_BLUE TRAPEZOIDAL 1.14 380.95 LT_GREEN TRAPEZOIDAL 1.10 333.74
3.00 3.00 1 7.07
5.00 5.00 1 19.63
3.50 20.00 1 45.50
2.00 14.00 1 20.00
2.00 14.00 1 24.00
2.00 10.50 1 13.00
2.00 10.00 1 12.00
D-86
ORANGE TRAPEZOIDAL 3.50 22.00 1 52.50 2.22 653.75 PURPLE TRAPEZOIDAL 2.00 12.00 1 16.00 1.24 347.62 RED TRAPEZOIDAL 3.00 17.00 1 33.00 1.79 378.20
************************** Volume Depth Runoff Quantity Continuity acre-ft inches ************************** --------- ------- Total Precipitation ...... 395.888 6.228 Surface Runoff ........... 20.004 0.315 Continuity Error (%) ..... -0.000
************************** Volume Volume Flow Routing Continuity acre-ft Mgallons ************************** --------- --------- External Inflow .......... 0.000 0.000 External Outflow ......... 197.420 64.332 Initial Stored Volume .... 0.000 0.000 Final Stored Volume ...... 0.747 0.243 Continuity Error (%) ..... 0.000
****************************************** Composite Curve Number Computations Report ****************************************** --------------------------- Subbasin {Site 1}.A12-16 --------------------------- Area Soil Soil/Surface Description (acres) Group CN ---------------------------------------------------------------------------------------- Paved parking & roofs 13.73 C 98.00 Brush, Fair 94.39 C 70.00 Composite Area & Weighted CN 108.12 73.56
-------------------------
Subbasin {Site 1}.A1-4 -------------------------
Area Soil
Soil/Surface Description (acres) Group CN ---------------------------------------------------------------------------------------- Paved parking & roofs 6.94 C 98.00 Brush, Fair 92.17 C 70.00 Composite Area & Weighted CN 99.11 71.96
-------------------------
Subbasin {Site 1}.A-17 -------------------------
Area Soil Soil/Surface Description (acres) Group CN ---------------------------------------------------------------------------------------- Paved parking & roofs 0.69 C 98.00 Brush, Fair 68.08 C 70.00 Composite Area & Weighted CN 68.77 70.28
------------------------
Subbasin {Site 1}.A18 ------------------------
Area Soil
Soil/Surface Description (acres) Group CN ---------------------------------------------------------------------------------------- Paved parking & roofs 6.84 C 98.00 Brush, Fair 44.62 C 70.00 Composite Area & Weighted CN 51.46 73.72
------------------------
Subbasin {Site 1}.A19
D-87
------------------------
Area Soil Soil/Surface Description (acres) Group CN ---------------------------------------------------------------------------------------- Paved parking & roofs 0.04 C 98.00 Brush, Fair 3.83 C 70.00 Composite Area & Weighted CN 3.87 70.28
------------------------
Subbasin {Site 1}.A20 ------------------------
Area Soil
Soil/Surface Description (acres) Group CN ---------------------------------------------------------------------------------------- Paved parking & roofs 0.41 C 98.00 50 - 75% grass cover, Fair 6.86 A 49.00 Composite Area & Weighted CN 7.27 51.79
-------------------------
Subbasin {Site 1}.A5-6 -------------------------
Area Soil
Soil/Surface Description (acres) Group CN ---------------------------------------------------------------------------------------- Paved parking & roofs 1.10 C 98.00 Brush, Fair 53.90 C 70.00 Composite Area & Weighted CN 55.00 70.56
--------------------------
Subbasin {Site 1}.A7-11 --------------------------
Area Soil Soil/Surface Description (acres) Group CN ---------------------------------------------------------------------------------------- Paved parking & roofs 8.17 C 98.00 Brush, Fair 93.90 C 70.00 Composite Area & Weighted CN 102.07 72.24
***************************************************
SCS TR-55 Time of Concentration Computations Report
***************************************************
Sheet Flow Equation ------------------- Tc = (0.007 * ((n * Lf)^0.8)) / ((P^0.5) * (Sf^0.4)) Where: Tc = Time of Concentration (hrs) n = Manning's Roughness Lf = Flow Length (ft) P = 2 yr, 24 hr Rainfall (inches) Sf = Slope (ft/ft) Shallow Concentrated Flow Equation ---------------------------------- V = 16.1345 * (Sf^0.5) (unpaved surface) V = 20.3282 * (Sf^0.5) (paved surface) V = 15.0 * (Sf^0.5) (grassed waterway surface) V = 10.0 * (Sf^0.5) (nearly bare & untilled surface) V = 9.0 * (Sf^0.5) (cultivated straight rows surface) V = 7.0 * (Sf^0.5) (short grass pasture surface) V = 5.0 * (Sf^0.5) (woodland surface) V = 2.5 * (Sf^0.5) (forest w/heavy litter surface) Tc = (Lf / V) / (3600 sec/hr) Where: Tc = Time of Concentration (hrs)
D-88
Lf = Flow Length (ft) V = Velocity (ft/sec) Sf = Slope (ft/ft) Channel Flow Equation --------------------- V = (1.49 * (R^(2/3)) * (Sf^0.5)) / n R = Aq / Wp Tc = (Lf / V) / (3600 sec/hr)
Where:
Tc = Time of Concentration (hrs) Lf = Flow Length (ft) R = Hydraulic Radius (ft) Aq = Flow Area (ft²) Wp = Wetted Perimeter (ft) V = Velocity (ft/sec) Sf = Slope (ft/ft) n = Manning's Roughness
--------------------------- Subbasin {Site 1}.A12-16 --------------------------- Sheet Flow Computations ----------------------- Subarea C
Subarea A Subarea B
0.00 0.00
0.00
2.30 0.00 0.00
Manning's Roughness: 0.30 0.00
Flow Length (ft): 100.00 0.00 Slope (%): 16.80 0.00
2 yr, 24 hr Rainfall (in): 2.30 2.30
Velocity (ft/sec): 0.19 0.00
Computed Flow Time (minutes): 8.59 0.00
Shallow Concentrated Flow Computations --------------------------------------
Subarea C
Subarea A Subarea B
0.00 0.00 Unpaved
0.00
0.00
Flow Length (ft): 5283.20 0.00 Slope (%): 16.60 0.00
Surface Type: Bare & untilled Unpaved
Velocity (ft/sec): 4.07 0.00
Computed Flow Time (minutes): 21.63 0.00
============================================================================================== == Total TOC (minutes): 30.22 ============================================================================================== ==
------------------------- Subbasin {Site 1}.A1-4 ------------------------- Sheet Flow Computations -----------------------
D-89
Subarea C
0.00
0.00 0.00 2.30 0.00 0.00
Subarea A Subarea B Manning's Roughness: 0.30 0.00 Flow Length (ft): 100.00 0.00 Slope (%): 17.60 0.00
2 yr, 24 hr Rainfall (in): 2.30 2.30
Velocity (ft/sec): 0.20 0.00
Computed Flow Time (minutes): 8.43 0.00
Shallow Concentrated Flow Computations -------------------------------------- Subarea C
Subarea A Subarea B
0.00 0.00
Unpaved
0.00
0.00
Flow Length (ft): 3817.00 0.00
Slope (%): 17.60 0.00
Surface Type: Grassed waterway Unpaved
Velocity (ft/sec): 6.29 0.00
Computed Flow Time (minutes): 10.11 0.00
============================================================================================== == Total TOC (minutes): 18.54 ============================================================================================== ==
------------------------- Subbasin {Site 1}.A-17 ------------------------- Sheet Flow Computations ----------------------- Subarea C Subarea A Subarea B
0.00 Manning's Roughness:
Flow Length (ft):
0.30
100.00
0.00
0.00 0.00 Slope (%): 30.10 0.00 0.00 2 yr, 24 hr Rainfall (in): 2.30 2.30 2.30 Velocity (ft/sec): 0.25 0.00 0.00 Computed Flow Time (minutes): 6.80 0.00 0.00
Shallow Concentrated Flow Computations --------------------------------------
Subarea C Flow Length (ft):
Subarea A
1882.60
Subarea B 0.00 0.00 Slope (%): 30.10 0.00 0.00 Surface Type: Unpaved Velocity (ft/sec):
Bare & untilled
5.49
Unpaved
0.00 0.00 Computed Flow Time (minutes): 5.72 0.00
D-90
0.00 Channel Flow Computations ------------------------- Subarea C Subarea A Subarea B
Manning's Roughness: 0.30 0.00 0.00
Flow Length (ft): 478.00 0.00 0.00
Channel Slope (%): 13.00 0.00 0.00
Cross Section Area (ft²): 50.75 0.00 0.00
Wetted Perimeter (ft): 23.15 0.00 0.00
Velocity (ft/sec): 3.02 0.00 0.00
Computed Flow Time (minutes): 2.64 0.00 0.00
============================================================================================== == Total TOC (minutes): 15.15 ============================================================================================== ==
------------------------ Subbasin {Site 1}.A18 ------------------------ Sheet Flow Computations ----------------------- Subarea C Subarea A Subarea B
0.00 Manning's Roughness:
Flow Length (ft):
0.35
100.00
0.00
0.00 0.00 Slope (%): 9.40 0.00 0.00 2 yr, 24 hr Rainfall (in): 2.30 2.30 2.30 Velocity (ft/sec): 0.14 0.00 0.00 Computed Flow Time (minutes): 12.26 0.00 0.00
Shallow Concentrated Flow Computations -------------------------------------- Subarea C Flow Length (ft):
Subarea A
2344.10
Subarea B 0.00 0.00 Slope (%): 9.40 0.00 0.00 Surface Type: Unpaved Velocity (ft/sec):
Grassed waterway
4.60
Unpaved
0.00 0.00 Computed Flow Time (minutes): 8.49 0.00 0.00
============================================================================================== == Total TOC (minutes): 20.75
============================================================================================== ==
D-91
------------------------ Subbasin {Site 1}.A19 ------------------------ Sheet Flow Computations ----------------------- Subarea C
0.00
0.00 0.00 2.30
0.00 0.00 Shallow Concentrated Flow Computations -------------------------------------- Subarea C
Subarea A Subarea B
Subarea A Subarea B
0.00 0.00 Unpaved
0.00
0.00
Flow Length (ft): 352.70 0.00
Slope (%): 12.40 0.00
Surface Type: Grassed waterway Unpaved
Velocity (ft/sec): 5.28 0.00
Computed Flow Time (minutes): 1.11 0.00
Channel Flow Computations ------------------------- Subarea C
Subarea A Subarea B
0.00 0.00 0.00
0.00
0.00
0.00
0.00
Manning's Roughness: 0.03 0.00
Flow Length (ft): 451.30 0.00
Channel Slope (%): 5.10 0.00
Cross Section Area (ft²): 36.00 0.00
Wetted Perimeter (ft): 19.42 0.00
Velocity (ft/sec): 16.93 0.00 Computed Flow Time (minutes): 0.44 0.00
============================================================================================== == Total TOC (minutes): 11.26
============================================================================================== ==
------------------------ Subbasin {Site 1}.A20 ------------------------
Sheet Flow Computations -----------------------
Subarea C
Subarea A Subarea B
Manning's Roughness: 0.30 0.00
Flow Length (ft): 100.00 0.00
Slope (%): 12.40 0.00
2 yr, 24 hr Rainfall (in): 2.30 2.30
Velocity (ft/sec): 0.17 0.00
Computed Flow Time (minutes): 9.70 0.00
D-92
0.00 Manning's Roughness:
Flow Length (ft):
0.30
100.00
0.00
0.00 0.00 Slope (%): 15.70 0.00 0.00 2 yr, 24 hr Rainfall (in): 2.30 2.30 2.30 Velocity (ft/sec): 0.19 0.00 0.00 Computed Flow Time (minutes): 8.83 0.00 0.00
Shallow Concentrated Flow Computations --------------------------------------
Subarea C Flow Length (ft):
Subarea A
860.50
Subarea B
0.00 0.00 Slope (%): 15.70 0.00 0.00 Surface Type: Unpaved Velocity (ft/sec):
Grassed waterway 5.94
Unpaved 0.00 0.00 Computed Flow Time (minutes): 2.41 0.00 0.00
============================================================================================== == Total TOC (minutes): 11.24 ============================================================================================== ==
------------------------- Subbasin {Site 1}.A5-6 ------------------------- Sheet Flow Computations ----------------------- Subarea C Subarea A Subarea B
0.00 Manning's Roughness:
Flow Length (ft):
0.30
100.00
0.00
0.00 0.00 Slope (%): 20.70 0.00 0.00 2 yr, 24 hr Rainfall (in): 2.30 2.30 2.30 Velocity (ft/sec): 0.21 0.00 0.00 Computed Flow Time (minutes): 7.90 0.00 0.00
Shallow Concentrated Flow Computations -------------------------------------- Subarea C Flow Length (ft):
Subarea A 839.10
Subarea B 0.00 0.00 Slope (%): 20.70 0.00 0.00 Surface Type: Unpaved Velocity (ft/sec):
Grassed waterway
6.82
Unpaved
0.00 0.00 Computed Flow Time (minutes): 2.05 0.00 0.00
D-93
============================================================================================== == Total TOC (minutes): 9.95
============================================================================================== ==
-------------------------- Subbasin {Site 1}.A7-11 -------------------------- Sheet Flow Computations -----------------------
Subarea C
0.00
0.00 0.00 2.30
0.00
0.00
Shallow Concentrated Flow Computations --------------------------------------
Subarea C
0.00
0.00 Unpaved
0.00
0.00
Subarea A Subarea B
Subarea A Subarea B
============================================================================================== == Total TOC (minutes): 19.56
============================================================================================== ==
*********************** Subbasin Runoff Summary *********************** -------------------------------------------------------------------------- Subbasin ID Total Total Precip Runoff in in
Peak Weighted Runoff Curve cfs Number
Time of Concentration days hh:mm:ss -------------------------------------------------------------------------- {Site 1}.A12-16 6.20 3.31 314.83 73.560 0 00:30:13 {Site 1}.A1-4 6.20 3.15 305.69 71.960 0 00:18:32 {Site 1}.A-17 6.20 2.99 137.08 70.280 0 00:15:09 {Site 1}.A18 6.20 3.33 93.63 73.720 0 00:20:45 {Site 1}.A19 6.20 2.99 11.74 70.280 0 00:11:15 {Site 1}.A20 6.20 1.38 4.55 51.790 0 00:11:14 {Site 1}.A5-6 6.20 3.02 137.69 70.560 0 00:09:57 {Site 1}.A7-11 6.20 3.18 307.77 72.240 0 00:19:33 --------------------------------------------------------------------------
Manning's Roughness: 0.30 0.00
Flow Length (ft): 100.00 0.00
Slope (%): 18.50 0.00
2 yr, 24 hr Rainfall (in): 2.30 2.30
Velocity (ft/sec): 0.20 0.00
Computed Flow Time (minutes): 8.26 0.00
Flow Length (ft): 4371.00 0.00
Slope (%): 18.50 0.00
Surface Type: Grassed waterway Unpaved
Velocity (ft/sec): 6.45 0.00
Computed Flow Time (minutes): 11.29 0.00
D-94
****************** Node Depth Summary ****************** ----------------------------------------------------------------------------------------- Node Average Maximum Maximum Time of Max Total Total Retention ID Depth Depth HGL Occurrence Flooded Time Time Attained Attained Attained Volume Flooded ft ft ft days hh:mm acre-in minutes hh:mm:ss ----------------------------------------------------------------------------------------- BURMA_PIPE_INLET 0.55 3.00 587.80 0 10:01 20.43 20 0:00:00 BURMA_PIPE_OUTLET 0.55 3.00 559.76 0 10:02 0 0 0:00:00 DK_BLUE_CHANNEL 1.51 2.00 122.00 0 05:55 0 0 0:00:00 JUNCTION_ORANGE-DK_GREEN_LT_BLUE 0.72 3.37 281.37 0 10:10 0 0 0:00:00 JUNCTION_PURPLE-ORANGE-LT_GREEN 0.71 3.38 288.38 0 10:10 0 0 0:00:00 LT_BLUE_INLET 0.43 1.82 459.82 0 10:15 0 0 0:00:00 LT_GREEN_INLET 0.42 1.93 476.93 0 10:10 0 0 0:00:00 OCEAN_OUTLET 0.00 0.00 0.00 0 00:00 0 0 0:00:00 ORIFICE_OUTLETS 1.18 2.66 168.76 0 10:55 0 0 0:00:00 PALOS_VERDE_PIPE_INLET 1.62 3.81 158.52 0 10:49 0 0 0:00:00 PALOS_VERDE_PIPE_OUTLET 1.54 3.81 154.25 0 10:49 0 0 0:00:00 WEIR_OUTLET 0.06 0.19 176.14 0 10:55 0 0 0:00:00 BASIN 1.80 7.04 177.04 0 10:55 0 0 0:00:00
***************** Node Flow Summary *****************
------------------------------------------------------------------------------------
BURMA_PIPE_OUTLET JUNCTION 0.00 205.22 0 10:19 0.00
DK_BLUE_CHANNEL JUNCTION 0.00 318.66 JUNCTION_ORANGE-DK_GREEN_LT_BLUE JUNCTION 0.00 0 10:49 883.73 0.00 0 10:10 0.00 JUNCTION_PURPLE-ORANGE-LT_GREEN JUNCTION 136.99 LT_BLUE_INLET JUNCTION 312.28 312.28 608.13 0 10:15 0 10:10 0.00 0.00
LT_GREEN_INLET JUNCTION 307.37 307.37 0 10:10 0.00 OCEAN_OUTLET JUNCTION 4.31 4.31 0 10:05 0.00 ORIFICE_OUTLETS JUNCTION 0.00 294.54 0 10:55 0.00 PALOS_VERDE_PIPE_INLET JUNCTION 103.12 318.67 0 10:49 0.00 PALOS_VERDE_PIPE_OUTLET JUNCTION 0.00 318.66 0 10:49 0.00 WEIR_OUTLET JUNCTION 0.00 37.92 0 10:55 0.00
BASIN STORAGE 132.45 1008.84 0 10:11 0.00
******************** Storage Node Summary ********************
---------------------------------------------------------------------------------------------- --------------------------------------- Storage Node ID Maximum Maximum Time of Max Average Average Maximum Maximum Time of Max. Total
Ponded Ponded Exfiltration Exfiltration Exfiltrated Ponded Ponded Ponded Storage Node
Volume Volume Volume Volume Volume Outflow Rate Rate Volume
1000 ft³ (%) days hh:mm 1000 ft³ (%) cfs cfm hh:mm:ss 1000 ft³
---------------------------------------------------------------------------------------------- ---------------------------------------
Node Element Maximum Peak Time of Maximum Time of Peak
ID Type Lateral Inflow Peak Inflow Flooding Flooding
Inflow Occurrence Overflow Occurrence
cfs cfs days hh:mm cfs days hh:mm
------------------------------------------------------------------------------------ BURMA_PIPE_INLET JUNCTION 305.53 305.53 0 10:10 107.99 0 10:10
D-95
BASIN 1591.794 83 0 10:55 266.848 14 294.54 0.00 0:00:00 0.000
***************** Link Flow Summary *****************
---------------------------------------------------------------------------------------------- ---------------------------------- Link ID Element Time of Maximum Length Peak Flow Design Ratio of Ratio of Total Reported Type Peak Flow Velocity Factor during Flow Maximum Maximum Time Condition Occurrence Attained Analysis Capacity /Design Flow Surcharged
Flow Depth minutes
days hh:mm ft/sec cfs cfs
---------------------------------------------------------------------------------------------- ---------------------------------- 36-IN-PIPE_BURMA CONDUIT 0 10:19 31.93 1.00 205.22 195.64 1.05 1.00 18 SURCHARGED 60-IN_CMP_PALOS_VERDES CONDUIT 0 10:49 19.83 1.00 318.66 343.03 0.93 0.76 0 Calculated DK_GREEN CHANNEL 0 10:11 25.02 1.00 882.92 1244.71 0.71 0.85 0 Calculated DKBLUE CHANNEL 0 10:49 18.30 1.00 318.66 385.92 0.83 0.91 0 Calculated Link-20 CHANNEL 0 10:55 26.09 1.00 37.92 3092.49 0.01 0.07 0 Calculated LT_BLUE CHANNEL 0 10:15 27.86 1.00 312.13 380.95 0.82 0.91 0 Calculated LT_GREEN CHANNEL 0 10:10 27.28 1.00 306.33 333.74 0.92 0.96 0 Calculated ORANGE CHANNEL 0 10:10 12.22 1.00 607.18 653.75 0.93 0.96 0 Calculated PURPLE CHANNEL 0 10:21 19.16 1.00 200.64 347.62 0.58 0.76 0 Calculated RED CHANNEL 0 10:56 10.73 1.00 294.54 378.20 0.78 0.89 0 Calculated Outfall_36-INCH ORIFICE 0 10:55 92.38 Outfall_48-INCH ORIFICE 0 10:55 164.24
Spillway WEIR 0 10:55 37.92
0.00
******************************** Highest Flow Instability Indexes ******************************** All links are stable. WARNING 002 : Max/rim elevation (depth) increased to account for connecting conduit height dimensions for Node WEIR_OUTLET. Analysis began on: Thu Nov 07 16:44:52 2019 Analysis ended on: Thu Nov 07 16:44:54 2019 Total elapsed time: 00:00:02
D-96
APPENDIX D
“ORDER-OF-MAGNITUDE” COST ESTIMATE
D-97
December 9, 2019
Project No. DB19.1055.00
City of Rancho Palos Verdes
30940 Hawthorne Boulevard
Rancho Palos Verdes, California 90275
Attention: Mr. Elias Sassoon
“ORDER-OF-MAGNITUDE”-LEVEL COST ESTIMATE
PORTUGUESE BEND LANDSLIDE COMPLEX MITIGATION MEASURES
RANCHO PALOS VERDES, CALIFORNIA
Dear Mr. Sassoon:
Geo-Logic Associates, Inc. (GLA) is pleased to submit this “order-of-magnitude”-level cost
estimate to the City of Rancho Palos Verdes (City). The information presented here was
prepared in support of GLA’s Portuguese Bend Landslide Complex (PBLC) mitigation design
project.
GLA has provided to the City under separate cover the geotechnical design report and plan set
for proposed mitigation measures (GLA, 2019a,b). Key features of the mitigation design, as
shown in the GLA (2019b) plan set, include the following:
• Proposed 36-inch-diameter high-density polyethylene (HDPE) pipe to be installed below
Burma Road (near PBLC northern limit) using trenchless techniques;
• Existing 60-inch-diameter corrugated metal pipe (CMP) below Palos Verdes Drive South
(PVDS), to be refurbished;
• Various proposed stormwater management features, including engineered swales,
“flow reduction area” (i.e., detention basin), new 60-inch-diameter thick-walled HDPE
pipe from PVDS to the ocean, and other incidental items (e.g., energy dissipator, trail
armoring, etc.);
• Two proposed arrays of hydraugers (five hydraugers per array) in the northerly portion
of the site to be installed by horizontal drilling; and
• Four proposed arrays of hydraugers (five hydraugers per array) in the southerly and
central portions of the site to be installed by directional drilling.
At City request, GLA prepared an “order-of-magnitude”-level cost estimate for the proposed
construction. Cost figures were developed based on our experience with similar projects (i.e.,
previous projects in the southern California region including elements similar to those included
D-98
in the PBLC mitigation design), discussions with the City, and discussions with contractors. An
itemized list of estimated costs is provided in Table 1.
Table 1. Itemized “order-of-magnitude”-level cost estimate.
Cost Item Number Unit Unit Cost Cost
New 36" Pipe below Burma Road
(Trenchless Installation) 1 Ea. $ 500,000 $ 500,000
Refurbishment of Existing 60" Pipe
below Palos Verdes Drive South 1 Ea. $ 250,000 $ 250,000
New Swales, Flow Reduction Area,
and Incidental Drainage Items 1 Ea. $ 2,750,000 $ 2,750,000
Horizontally Drilled Hydraugers 10 Ea. $ 350,000 $ 3,500,000
Directionally Drilled Hydraugers 20 Ea. $ 500,000 $ 10,000,000
Fracture Infilling 1 Ea. $ 500,000 $ 500,000
Subtotal $ 17,500,000
“Contingency” (20 percent of subtotal) $ 3,500,000
Total $ 21,000,000
Note that actual bids and/or construction costs may depart significantly from this “order-of-
magnitude”-level estimate. Bid and construction costs may be significantly influenced by
numerous factors, including but not limited to (in no particular order) fluctuations in material
costs, regional and/or local economic conditions, seasonal fluctuations in cost and/or
availability, permit conditions, labor market conditions, and/or prevailing wage requirements.
We recommend that, after the permitting process but before the bidding process, the City
prepare an updated cost estimate. This updated cost estimate should reflect the changes made
to the design during the permitting process.
D-99
CLOSURE
This letter report is based on the data and analyses described herein. GLA should be notified of
any conditions that differ from those described herein since this may require a reevaluation of
the data, conclusions and recommendations presented. Any use of the recommendations and
conclusions contained in this report for other projects is strictly forbidden without GLA review
and approval
This letter report has been prepared in accordance with generally accepted engineering
practices in southern California, and internally peer-reviewed in accordance with GLA’s peer
review policy, and makes no other warranties, either expressed or implied, as to the
professional data presented in it.
This letter report has not been prepared for use by other parties and projects other than those
named or described above. It may not contain sufficient information for other parties or other
purposes.
Sincerely,
Geo-Logic Associates, Inc.
Alan F. Witthoeft, PE, GE
Project Engineer III
Neven Matasovic, PhD, PE, GE
Principal
nmatasovic@geo-logic.com / 714-465-8240
D-100
REFERENCES
GLA (2019a), “DRAFT Geotechnical Evaluation Report, Portuguese Bend Landslide Complex
Mitigation Measures, Rancho Palos Verdes, California,” Technical Report, Geo-Logic
Associates, Inc., Costa Mesa, California (Project No. DB19.1055.00).
GLA (2019b), “Portuguese Bend Landslide Complex Mitigation Measures, City of Rancho Palos
Verdes, California, November, 2019,” Construction Plan Set, Geo-Logic Associates, Inc.,
Costa Mesa, California (Project No. DB19.1055.00).
D-101
IMAC Landflow Report Approved 9.21.2020
1
Infrastructure Management Advisory Committee Landflow Report
Summary of IMAC Recommendations
The IMAC generally supports the current Portuguese Bend Landslide mitigation
proposals by the City’s geologic consultants and makes the following
recommendations in the enclosed report:
1.Determined efforts to slow the landslide are warranted to protect
residents and the environment. Even though science cannot predict timing or
magnitude, there is danger that a sudden, major slide will cause catastrophic
damage to Palos Verdes Drive South and the twin sewage trunk lines. (Sections
1 and 2).
2.To reduce overall risk, the proposed prototyping of hydraugers should be
done as a first step in the process. It is prudent to validate the geologic
consultants’ design model before money is spent on less effective supplementary
measures. The ability of hydraugers to extract large quantities of high-pressure
water is uncertain and can only be determined by trial. If hydraugers fail then
the whole mitigation plan should be re-evaluated because other mitigation
measures are unlikely to achieve project goals on their own. (Section 3).
3.There should be immediate and continuing surveys (a) of the existing
culvert under Palos Verdes Drive South and (b) of the surface-water flow
lines to that culvert through the area proposed for the flood-water
retention basin. Historic sinking of the landslide surface destroyed the earlier
surface-water flow lines to the existing culvert and is likely to continue until the
slide has been controlled. This raises questions about the long-term viability of
the existing culvert, of surface-water flow lines to the culvert, and of the
proposed floodwater retention basin. The alternative of a second, deeper culvert
under PVDS should be retained as a backup design option until the existing
culvert and its flow lines are shown to have viable useful lives. (Section 4)
4.Risk management should be an integral part of future phases of design and
construction of this uniquely challenging, mitigation project. We offer these
recommendations during the environmental impact study and prior to final
design of the project. Recommendations 2 and 3 above should resolve known
data gaps concerning the effectiveness of hydraugers and the likely useful life of
the surface-water collection system. Armed with that knowledge the remainder
of the proposed mitigation program can be designed with more confidence.
5.Additional issues merit evaluation as the mitigation project proceeds.
(Section 5)
IMAC 11/16/20 Mtg Item A- page 1 E-1
IMAC Landflow Report Approved 9.21.2020
2
Infrastructure Management Advisory Committee Landflow Report
Summary
The Portuguese Bend landslide has plagued the city of RPV for over 60 years. Many
attempts to slow the slide have failed, primarily because they were destroyed by the
slide itself before they could demonstrate their effectiveness. There is now a
proposal before the City Council that offers a multi-faceted approach to reducing
water content in and around the surface on which the slide moves. We believe that
the proposed engineering measures to slow the slide are promising. But, the
proposed engineering design is based on a simplified model of the slide’s basic
causes and there is really very little data to support such a hypothetical model for
Portuguese Bend. The experts cite the model as a plausible explanation of the slide
dynamics rather than a model validated by actual data. We accept that
characterization. With the past history of failures and the level of uncertainty in
critical factors buried 100 feet or more beneath the surface, we can only conclude
the proposed program is high risk. Nonetheless, the public necessity to preserve
Palos Verdes Drive South and the twin trunk sewage lines gives powerful motivation
to face the risks and manage the landslide. We provide analysis showing that there
are no low-risk alternatives to preserve the road and sewage lines, including the
continuation of current practices.
The IMAC Landflow Subcommittee conducted a needs/risk analysis in 2019 and
identified a few areas where proactive risk management was recommended to help
mitigate the risks. Subsequently, at three separate city council meetings, a council
member suggested that our risk assessment be expanded to evaluate the risk of
continuing current repair practices without attempting to slow the slide. We looked
at the possibility of the slide changing from its “creep” mode to a rapid slip of a mass
large enough to wreck PVDS and the adjacent sewer lines. We identify some
potential conditions that could lead to such an event and analyze the potential
consequences on residents’ quality of life if that should happen. We conclude that
the final decision making process should include a reasoned assessment of the
consequences of a catastrophic event, not just a comparison of the cost of the
proposed project versus the cost of continuing to repair the road and sewage trunk
lines. The first part of this report addresses this risk analysis in detail.
We have studied the experts’ final report. We concur with most of their
recommendations and we have identified two areas we deem to be critical to short-
and long-term success. The first involves what we determined was the highest risk
component, namely the directionally drilled drains, known as down-gradient
hydraugers (installed from the sea shore near the base of the slide). This is a unique
approach that has not been attempted before in Portuguese Bend. By the experts’
analysis, it represents the highest contributor to improving stability of the slide. We
suggested in our 2019 risk analysis that these hydraugers should first be prototyped
to gain experience and understanding of how effective they are going to be and how
well they survive the hostile environment that destroyed previous attempts. We
IMAC 11/16/20 Mtg Item A- page 2 E-2
IMAC Landflow Report Approved 9.21.2020
3
acknowledge that the experts’ final report incorporates hydrauger prototyping. We
also accept the experts’ analysis that both the hydraugers and the surface water
management system are important to success and neither will achieve it on their
own. Based on these premises, we recommend a different phasing that would help
to understand the hydrauger risks and benefits much earlier. Rather than leaving
the hydraugers to the last implementation phase of the program, we respectfully
suggest that they be prototyped in the first phase. They are the highest risk and
highest return. If they work, then the potential for program success will be more
encouraging. If they don’t relieve high-pressure water or fail to survive the
environment, then we suggest it’s much better to know that before spending tens of
millions of dollars on other program elements that are unlikely to be enough on
their own to meet the program goal. We believe this is a more cost-effective
approach. If testing of hydraugers succeeds then that will increase future program
flexibility to reduce total costs.
The proposed surface water management approach will rely on an existing culvert
running under PVDS. This culvert has survived over 20 years because it was located
in a relatively stable area. The experts’ plan proposes a surface-water retention
basin that will lead to the existing culvert. However, that basin is to be constructed
at least partially on land that has been sinking for decades and likely will continue to
sink with the slide. In such a case, it won’t be long before that existing culvert
becomes stranded because the outlet from the retention basin may sink below the
inlet to the culvert. We don’t know the life expectancy of the culvert but today’s
elevations of the potential flow lines to that culvert appear to leave very little
margin for sinking along those flow lines. The experts suggested something similar
in their report and recommended surveys to understand the area and its movement
before proceeding. We fully endorse that recommendation. Any reasonable risk
management approach integrates a back-up plan in case the risk is ultimately found
to be insurmountable. Late program changes are expensive which is why prudent
program managers carry a baseline and back-up(s) through early phases until such
time as the risk is mitigated or the back-up is found to be the only viable way
forward. Typically, during this period, design decisions are made to accommodate
all options so that a later change to the back up doesn’t become overly onerous. We
believe a deeper, second-culvert alternative should be carried as a back-up
component of the baseline design so that it could be readily accommodated should it
be found to be necessary. We understand it is likely to be an expensive alternative,
but not as expensive as failure of the whole system because this risk was not
considered early when it needed to be. We believe a second culvert offers a larger
margin to tolerate sinking land and design freedom that could potentially integrate
the retention basin, reduce the overall footprint and have a much lower
environmental impact.
IMAC 11/16/20 Mtg Item A- page 3 E-3
IMAC Landflow Report Approved 9.21.2020
4
1. Introduction
First, let us be very clear that, while we have met and consulted with the City Public
Works Department, this report is our work product. Any errors are our
responsibility. Neither Public Works nor any City employee has any responsibility
for its contents. We have tried to render an objective assessment of the proposed
plan. Nothing in this report should be read to imply any criticism of any City
employee or official, past or present, nor of the consultants.
Many tens of millions of dollars have been spent in unsuccessful efforts to control
the Portuguese Bend landslide in the 64 years since it re-activated in 1956. All of
the failed efforts were designed by licensed professionals who had outstanding
credentials. The experts designed and implemented successful controls on the
nearby Abalone Cove landslide but failed to control the Portuguese Bend landslide.
With this history, any new proposal must be critically reviewed.
The Landflow subcommittee of the IMAC has studied the Portuguese Bend Landslide
complex and reviewed the mitigation plan proposed by Daniel B. Stephens &
Associates, Inc., (DB Stephens) and its subcontractor Geo-Logic Associates (Geo-
Logic) under contract with the City. Hereafter, we refer to them collectively as the
“Geo Consultants.” Some IMAC members conducted numerous site visits to get a
better understanding of the landslide and the engineering measures being proposed
to slow its movement. Our Landflow Subcommittee presented an earlier risk
analysis to the IMAC (reproduced in Appendix 1) that identified key risk areas and
recommended that the program plan incorporate proactive risk management. The
City’s Geo Consultants subsequently issued their final report (Reference 1) and the
City Council forwarded that report for an environmental impact assessment. A
detailed history of the landslide may be found in the City’s online portal (Reference
2).
Our most recent efforts have focused on addressing three fundamental questions in
more detail, the first of which was posed in the council meetings. These questions
are:
1) What are the risks and consequences of not even attempting to mitigate the
landslide?
2) Should we expect success where all previous attempts have failed?
3)What steps can be taken to improve the likelihood of success?
Since none of us is a geology or drainage expert, we approached these questions
from a customer perspective. We asked ourselves as citizens “Has the proposed
plan and its inherent risks been explained clearly enough for us to understand
t he basic slide mechanics?” and “Does it convincingly explain how the approach
can succeed”? We do have engineering and management backgrounds so we
have attempted to utilize our past experience and knowledge of fundamental
physics to gain a better understanding of the geology and mechanics of the
IMAC 11/16/20 Mtg Item A- page 4 E-4
IMAC Landflow Report Approved 9.21.2020
5
Portuguese Bend landslide. We do not have the depth of knowledge of the
experts but we have done our best to effectively and accurately describe what
we think the experts are telling the City. Our goal is to faithfully relay that in a
less-technical manner to City officials and residents. Where the experts think
we have misunderstood, we welcome a clarifying explanation of their rationale
for their model and their proposal. If we have misunderstood then we suspect
that others also may have.
The draft of this report was published in the agenda for the 20th July, 2020
IMAC meeting. We received encouraging and instructive comments from the
Public Works Director Sassoon, both members of the City Council’s Landflow
Subcommittee, members of the IMAC and one member of the public. The report
was discussed in detail at that meeting. We were very fortunate to have Dr.
Neven Matasovic, of the Geo Consultants, call in and provide some excellent
insight and clarification of the proposed plan. We incorporated into this final
version comments by others that help clarify the report or add to the
arguments presented. For the few comments where we perceive an alternate
interpretation, we have included our understanding of the comment and our
perspective on the issue. These discussions are included in the relevant
sections.
Based upon our analysis stated above, we support active measures to mitigate
the slide. We concur with comments expressing the need to avoid “paralysis by
analysis.” We understand this to mean that informed, calculated risks must be
taken. Reasonable risks should not be avoided with an excuse that further
study is needed. This does not mean suspension of continuing risk
management calculated to improve likelihood of success. We recommend that
continuing risk management be integrated into program management. The Geo
Consultants’ report identifies a number of “data gaps” that are critical to project
success. They recommend, and we support, measures to close these data gaps.
The project is still in design stage and under environmental review. Early
attention to these data gaps is likely to provide guidance in final design and
implementation. It is in this spirit that we recommend early focus upon
prototype hydraugers, early evaluation of the suitability of the existing culvert,
and early survey of the location for the proposed retention basin.
1.1 Model Basics
There appears to be a long-standing consensus that (1) water in the soil enables
landslides; (2) reduction of water will slow a slide by any effective combination of
prevention, drainage and active de-watering; and (3) too much water currently
infiltrates into Portuguese Bend, collects below the surface, does not drain naturally
and causes chronic sliding. It is an old idea that high water pressure in soil pores
weakens resistance of the soil to sliding. The idea appears to be well respected by
experts. Further, it is an old idea to remove water by drilling a hole and inserting a
pipe into the vicinity of, or below, the basal slide surface. That is the proven
IMAC 11/16/20 Mtg Item A- page 5 E-5
IMAC Landflow Report Approved 9.21.2020
6
rationale for vertical, de-watering wells which have been successful with the
Abalone Cove slide, but have failed in Portuguese Bend.
The Geo Consultants’ postulated model of the Portuguese Bend landslide taken from
Reference 3 is shown in Figure 1.1. It shows four primary causes behind the
landslide, two of which relate to the water in the soil that they propose to reduce by
specific engineering measures. The first, second and third causes of sliding depicted
in Figure 1.1 interact with each other. Pressurized water in soil pores below the
slide slip surface weakens the ability of the soil at the slip surface to resist sliding.
Water under pressure both above and below the slip surface hydrates the soil
comprising the slip zone thereby reducing its ability to resist sliding forces. These
ideas are consistent with past expert opinion. The Geo Consultants’ proposed
engineering measures aim (1) to reduce the level of perched water above the slip
surface, and (2) to reduce the pore pressure of water below the slip surface. The
experts predict that these measures will combine to improve stability and slow the
land movement. Please note that in their final Geotechnical Evaluation Report, the
Geo Consultants use the term “basal rupture surface” rather than “slip surface.”
“Basal rupture surface” is a more complex idea than the simplified term “slip
surface.” The experts do not propose to do anything about the fourth cause of
sliding, erosion at the toe of the slide.
There are four primary components of the proposed engineering measures. Where
there is high surface water flow, such as canyon bottoms, selected fractures will be
in-filled to prevent direct intrusion. Swales, a collection area and large pipes will
intercept as much surface flow as possible and transport it to the ocean. The other
two techniques involve inserting slotted pipes, called hydraugers, into drill holes
Figure 1.1 Consultants’ Simplified Model of Slide Drivers (Geo-Logic, 2019)
IMAC 11/16/20 Mtg Item A- page 6 E-6
IMAC Landflow Report Approved 9.21.2020
7
bored into zones where they expect to encounter water. Arrays of hydraugers
higher up the hill are intended to intercept and drain intruded water and arrays
lower down the slope will penetrate beneath the basal rupture surface and relieve
the pressure by draining water from below the slide
All of these engineering measures come with a fairly sizeable capital outlay. It is
expected that some return on the investment will come from reducing the
maintenance costs for repairing the road and associated storm drains.
1.2 What if we Just Continue Current Practice?
Just looked at from a financial perspective, there is an argument that favors
continuing to repair the road and sewage lines as surface cracks and sinking
appear. Current practice appears to be based upon this argument. It saves a
big capital investment on a program with an uncertain likelihood of success.
Unfortunately, that is not the complete picture. Even slow moving landslides
like Portuguese Bend can change their behavior and speed up. Soil conditions
vary significantly throughout the landslide complex. There will always remain
an inherent risk that in a localized area there could be a rapid slide due to a
combination of adverse conditions acting together to eliminate a precarious,
temporary, local stability between the driving force and the resisting force.
Such dramatic slides are not uncommon in the recent history of the Palos
Verdes Peninsula. If such a slide were to happen near Palos Verdes Drive South
(PVDS) then it could be large enough to disable both the road and the sewer
lines beside it. This not only could inflict financial disaster but also could
severely impair the quality of life in Rancho Palos Verdes and Palos Verdes
Estates. We analyze this scenario in depth in Section 2.
1.3 Can We Achieve Success After 60 Years of Failure?
Given the history, it is reasonable to question why this new approach has any more
chance of success than all of its predecessor failures. One such example is a system
installed in Portuguese Bend (circa 1990) for surface water interception and
transportation to the ocean. Unfortunately it wasn’t constructed robustly enough to
survive the land flow. It was quickly destroyed before it had enough rainy seasons
to demonstrate whether or not it would be effective. Figure 1.2 shows some of that
damaged system beside one of the gullies carved by surface water from a heavy
storm. Another failure is the system of dewatering wells that were drilled vertically
into Portuguese Bend over the years. Unlike the success of vertical wells in Abalone
Cove, most of those in Portuguese Bend did not survive long enough to demonstrate
whether they could extract enough water to be effective.
IMAC 11/16/20 Mtg Item A- page 7 E-7
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Figure 1.2 The Destroyed Surface Water Collection and Transportation System
(Wedemeyer, 2019)
This question prompted the needs/risk analysis that was presented to the IMAC in
October 2019. That presentation is attached as Appendix 1. Essentially that study
looked at two specific issues concerning the proposed plan – will it work and will it
last long enough to learn if it will be effective? The study focused primarily on the
hydrauger solution for high-pressure water removal and the surface water
collection system. It identified the risks and recommended specific mitigation
efforts. The overall conclusions from this earlier needs/risk analysis are briefly
summarized below.
The IMAC believes that the Geo Consultants’ model has sufficient merit to guide the
initial search for solutions. We accept the Geo Consultants’ characterization of its
model as plausible and we heed their warning not to rely on the model alone,
(Reference 1, Section 4.4, pp. A-15, A-16.) We accept that the landslide is much
more complex than the simple model. We know that the soil of the landslide mass is
not even close to homogenous. It comprises numerous sedimentary layers of rock,
shale and volcanic deposits, some of which are bentonite layers formed from
volcanic ash. One only has to look at nearby cliffs to see the complex makeup of the
peninsula’s geology. Figure 1.3 is an example taken from the beach below the sea
cliffs of Vanderlip Park. This photo illustrates the chaotic structures underground
and the widely varying thickness of layers of volcanic materials. In Portuguese Bend
the slide is thought to have shattered and tumbled the layers that once existed so
the soil now is called “slide debris.” The key geologic parameters of porosity and
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permeability vary both vertically and horizontally. Although we accept that the
simple model may apply to the slide in a macroscopic sense, the extensive variability
in the makeup of the land both above and below the basal rupture surface suggests
local zones may exist where behavioral deviations from the simple model are in
play. We believe that extrapolating the simple model to describe geologic
properties everywhere in the slide zone is too broad an assumption for engineering
design.
We would have more confidence in the model if there were data to directly support
it but we haven’t located any and doubt that much relevant data even exists any
more despite the numerous geologic studies conducted over the years. The data
scarcity, which the Geo Consultants call “data gaps”, means that the model has yet to
be validated. Thus, we think it essential to organize a search for data to validate,
modify or invalidate the simple model before settling on a final engineering design
for such a large project. We conclude that the most practical solution is to try a few
prototype hydraugers to see if they actually find and relieve high pressure below the
basal rupture surface. We also recommend that robust risk identification and
management should be an integral part of both the final design and the
implementation. There are well-established techniques, such as prototyping and
data collection, that could be adopted early in the life cycle of this program so that
concerns can be allayed before the budget is spent on less effective measures.
Figure 1.3 Illustrative Peninsula Geology, before sliding (Shaw, 2020)
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Section 3 addresses in more detail our current perspectives on model validation and
the uncertainty surrounding the hydrauger approach.
We conclude that construction of the surface water system likely is lower risk but it
requires close attention to maintenance to ensure that it remains functional in the
presence of land movement. Of more concern is the single, existing culvert that is a
single point of potential failure of the entire surface water system. We perceive a
substantial probability that the existing culvert could again be stranded by the land
sinking along the route for delivery of storm water to the culvert. Section 4
addresses these culvert issues in more detail.
2. Risk Identification for Continuing Current Practices
We start by identifying three potential paths forward along with a brief summary of
their advantages and disadvantages. We then look at the potential consequences of
not pursuing the mitigation program. Finally, we address the likelihood of
catastrophic damage by a major landslide using our own rationale supported by
research into past events that we believe to be relevant.
Mother Nature does not respect jurisdictional boundaries. Portions of the Cities of
Palos Verdes Estates and Rancho Palos Verdes are served by the sewage trunk lines
that are the responsibility of the County Sanitation District. Gas, power and water
utilities are all affected as well. The road serves San Pedro, Palos Verdes Estates and
Rancho Palos Verdes. CalTrans also has some jurisdiction over it. We are informed
that Palos Verdes Drive South is a designated emergency evacuation route for the
San Pedro area of the City of Los Angeles. Such cross-jurisdictional issues are
beyond the scope of this report.
2.1 Future Options
2.1.1 The “Absolutely Do Nothing” Option
In this hypothetical option, all expenditures by the City on the road and roadbed
would terminate and storm water would be left uncontrolled. Based upon decades
of experience, fissures would open and widen and the roadbed would continue to
sink in active zones of slide movement. There is near certainty that the roadbed and
the twin sewage trunk lines that cross the slide zone would fail due to loss of
vertical and lateral support. The road surface initially might remain passable for
some months, albeit potentially dangerous, but within just a few years it would
become impassable. Access would be lost to the sewage trunk lines for repair and
adjustment, likely leading to loss of those sewage lines. Emergency access routes for
fire, police, ambulance, and evacuation would be lost. We do not believe this end
state would be acceptable to any reasonable person. The option would only be
feasible if alternative solutions for both transportation and sewage disposal already
are in operation. We have seen a preliminary evaluation prepared in 2009 by
Sanitation District engineers for re-routing the twin trunk sewer lines (Reference 4).
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We are not aware of any currently active proposals to re-route either the sewage
lines or the road. We recommend investigation of alternative routes, in part
because of the risk of catastrophic damage to the road and sewage lines and in part
because the likely end state of the on-going sliding probably will eventually become
intolerable even with the current annual repair.
2.1.2 The “Continue Current Practice” Option.
Current practice amounts to managed accommodation of continuing, progressive
sliding of the roadbed structure. Current practice accepts slow sliding and gradual
collapse of the roadbed structure. Current Practice makes frequent repairs of the
paving, paving base and surface drainage of the road to maintain short-term
functionality; makes no provision for alternative or replacement systems; and
makes no provision for potentially catastrophic collapse. In our view, this approach
is simply slowing down the process of eventually coming to approximately the same
end state for the roadbed structure as the “Absolutely Do Nothing” option. Of course
we cannot predict precisely how or when this complex slide might move. We think
it possible that Current Practice might defer final failure for one or more decades,
especially if there are one or more major projects to rebuild that roadbed structure.
In that timeframe we cannot exclude the possibility that the roadbed structure
might no longer be salvageable and an alternate route might become a necessity.
For decades the City has routinely filled fissures across, and adjacent to, the road
surface; made grading cuts in the paving base; repaved the road surface; and
modified drainage for the road surface to adjust to continuing slide movement. The
City budgets approximately $660,000 per year, every year. Every 10 to 20 years
major re-grading and realignment of the roadbed and road surface has cost
additional millions of dollars, including moving more than a million cubic yards of
soil in a massive re-alignment and re-grading of the roadbed that was done in the
1986 – 1990 era. There is a current project in 2020-2021 CIP budget plan to re-
align the “S-curve” in Palos Verdes Drive South at the eastern margin of the slide
zone near Portuguese Bend Club at an estimated cost of $1.2 million. Additionally,
the County Sanitation District spends a similar annual sum on continual
readjustment of the two sewer lines to accommodate their “stretching” as the land
in between the east and west fixed points moves southwards and downwards.
Sanitation District crews routinely pack additional soil under the sewage lines as the
supporting land sinks away. We are not aware of any planning for response to
catastrophic failures of these sewer lines other than a comment in Reference 4
recommending possible addition of storage capacity upstream of the slide area to
provide a “few hours of response time”. Beyond that, it would have to be massive to
store flow of 1.36 million gallons per day.
From a resident’s quality of life standpoint, the current situation is a nuisance for
users. Driving and bicycle riding are awkward and require reduced speed. Vehicles
experience rapid changes in the road surface that require extreme caution. The
current practice of chronic repairs regularly causes one-way traffic, with extended
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backups, for road repairs and emergency access is severely degraded. It is very
difficult to maintain separate bicycle lanes. There are no sidewalks or maintained
pedestrian paths for a distance of nearly a mile along Palos Verdes Drive South.
Fissures and repair work on the road and sewage lines regularly disrupt the
informal paths that do exist. The paths do not accommodate handicapped, elderly
or very young people. Many of these issues could be reasonably resolved if the slide
were successfully slowed. They cannot be reliably or permanently resolved as long
as the slide continues in its current modes.
2.1.3 The “Proceed with the Proposed Engineering Measures” Option
The necessity to preserve the road and sewage lines provides powerful motivation
to mitigate the landslide. The Geo Consultants’ report proposes Engineering
Measures to mitigate the sliding of the roadbed structure. The goal is to slow down
the land movement by an order of magnitude to eliminate continual road repairs to
PVDS and to minimize the risks that a significant slide could destroy the road and
the sewer lines.
Currently, there are rough cost estimates prepared by the Geo Consultants.
However, there are no definitive costs available for the proposed project. We are
informed that investigations are ongoing to determine whether federal, state or
county grants or other affected agencies could help defray some of the costs. The
Sanitation District clearly has a vested interest in success of the program. Sister city
residents are also negatively affected by the current situation and would be
impacted if a major slide happened. It is possible that the final designs could be
significantly altered based upon the results of efforts to fill “data gaps” identified in
the report of the Geo Consultants. A preliminary return on investment analysis of
the Geo Consultants’ proposal may be feasible, but a final analysis is premature.
Such an analysis should be done before final project approval is considered, after
the costs are better defined and other financial sources are resolved. It will be a
major project for the city but not entirely unique. The city has implemented similar
major infrastructure improvements such as the San Ramon Canyon and McCarrell
Canyon storm drain projects.
The IMAC Landflow Subcommittee conducted a needs/risk analysis of the proposed
mitigation measures and made recommendations on how to address the significant
risks we identified. We refer the reader to Appendix 1 for the specifics that define
the consequences of each risk, the level of risk associated with each and how to
mitigate the risk via a formal risk management approach.
2.2 Consequences of the “Continue Current Practice” Option.
The Current Practice seeks to delay the potential end state by decades through
mandatory annual expenditures for repairs and adjustments while accepting
continuing slide movement of the roadbed structure. Current Practice does not
mitigate the risk of a major slide that would cause catastrophic damage.
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First, let’s define what we mean by a major slide and catastrophic damage. We are
not aware of any expert who can eliminate concerns that the whole slope of the
Portuguese Bend Landslide Complex will suddenly and rapidly flow to the ocean,
but for the purposes of this report we treat that as a more remote possibility. Based
upon recent history discussed below, we are more concerned that a smaller slide
mass could break loose and slide seaward, more or less as a unit. This likely would
result in the surface of the roadbed sinking and moving seaward. This would
remove support for the twin sewage trunk lines. It is readily apparent from visual
inspection that in some places within the Portuguese Bend landslide area the
roadbed structure is roughly thirty feet higher than the adjacent land, on both the
north and south sides of the roadbed. One example of a potential, local slide
location is about 150 yards east of Inspiration Point ridge (near where the existing
culvert passes through the roadbed). A persistent fissure zone crosses the roadbed
and forces chronic repairs of the road surface in this area. Figure 2.1 shows a
landslide fissure very close to the road and sewage lines in this area. The fissure
recently became visible after brush clearance. Another potential local slide is the
western flank of Inspiration Point ridge (in Sacred Cove) where sheer landslide
scarps stand about 40 feet tall on the seaward side of the roadbed within about 60
feet of the roadbed – see Figure 2.2. A third area of concern is the nearby east flank
of Portuguese Point ridge, also shown in Figure 2.2, where the “ski jump” has
formed. The roadbed already has sunk more than 20 feet, forcing repeated grading
of a steep ramp. The area north of the road below the slide scarp in Figure 2.2
collects large volumes of rainwater that would be transported to the ocean if the
broken storm drain system were rendered operational. At the IMAC meeting, Public
Works Director Sassoon stated a concern about the large pool of water that
accumulates after a heavy rainstorm in the area just north of the road where the
retention basin is planned. The roadbed acts as a dam but was never constructed
for such a purpose. He opined that pooled water from a very large storm, with no
Figure 2.1 Landslide Fissure Near Roadbed and Sewage Lines, 150 yards east of
Archery Club entrance (Wedemeyer, 2020)
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outlet past the road, could cause catastrophic failure of the road. We concur with
this potential failure mode and thank Director Sassoon.
If a localized mass were to rapidly slide, similarly to the Paseo Del Mar and Ocean
Trails events, then the road will be unusable until it is repaired, assuming that
repair is feasible. The two sewer lines could be left suspended in midair, bridging a
gap where the roadbed has sunk. At some point the size of the gap would exceed the
structural capacity of the sewage lines to bridge it. To avoid or limit an
environmental disaster, the sewage lines likely would have to be removed from
service until a safe and secure solution is found and implemented. As discussed
below, removal of the sewage lines from service would cause massive disruptions.
Depending upon the size of the gap and the extent of instability of surrounding soils,
a massive, emergency reconstruction of the roadbed structure might be required
that could exceed available public financing. Almost certainly, the cost of emergency
road repair is likely to be at least an order of magnitude greater than the current
annual City budget of $660,000 for chronic repairs under Current Practice.
Depending upon the scope and nature of the slide, there is the potential that the
roadbed structure could not be restored as a practical matter, or would take
months.
Loss of the road would mean that there would no longer be an east-west corridor on
the ocean side of RPV without leaving the city. There would be a significant
disruption not only to residents but also to commuters and business traffic from
adjacent cities that use the road on a daily basis. Traffic patterns to the two
Peninsula High Schools would be especially disrupted. There will be a much longer
commute for many parents and teens living on the east side. All this diverted traffic
will naturally migrate to Western Ave.; Palos Verdes Drive, East, West and North;
Crenshaw Blvd; and Hawthorne Blvd, all busy arteries in their own right. There are
already significant traffic issues with these arteries during rush hour. They have
limited capacity to handle the extra traffic. For example, traffic light sequences at
both Crenshaw and Hawthorne Boulevards would need to be adjusted to give PVDN
longer green traffic light time which would detract from the flow on these two
north/south arteries used by most commuters from the west side of RPV. Nearly
every resident of RPV would be negatively impacted. There would also be
Figure 2.2 “Ski Jump,” Landslide Scarps and Fissures Near Road and Sewage Lines,
Sacred Cove (Wedemeyer, 2020)
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substantial impacts in adjacent communities of San Pedro, Lomita, Rolling Hills
Estates, Rolling Hills, Torrance and Palos Verdes Estates. The duration of such
traffic issues would depend on how quickly the damaged roadbed section can be
repaired, assuming it is even possible. Rerouting the roadbed a little further north
but still within the landslide would simply inherit risks of a repeat.
The road issue will be a nuisance but the sewer lines, pictured in Figure 2.3, are
actually more worrying. Their loss could be a catastrophe for many residents. First,
if the lines actually break then raw sewage will spill at rates between 343 and 1496
gallons per minute, depending on the time of day, for as long as it takes to halt the
flow. Discharge into the ocean is likely. The environmental impact of a raw sewage
spill would be felt everywhere seaward of Palos Verdes Drives South and easterly
from Portuguese Bend through San Pedro due to ocean currents. If the sewage
pipes are not broken but are suspended over a sunken section of the road, then it is
likely the Sanitation District will have to turn off the flow, at least temporarily, to
avoid a spill. Although the pipes are fairly strong steel, there are hundreds of
connectors that conform the pipes to follow the ground contours, as Figure 2.3
depicts. Such connectors likely are weaker points in the sewage lines. According to
the Sanitation District, each coupler can withstand only a 2° angular distortion
Figure 2.3 Sewer Lines Beside PVDS (Shaw, 2020)
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before failure. There also are expansion connectors that can slide at each end to
allow for about 24 inches of “stretch” before the whole pipe is held in place by just
four threaded rods and nuts.
As they did at Ocean Trails, the Sanitation District might be able to install by-pass
lines and pumps to temporarily transport the sewage effluent around a rapid, major
slide. But that will depend on whether a viable route for the by-pass lines survives
such a slide. If there is no viable reroute, then the city will be faced with a
nightmarish dilemma of either allowing sewage to spill into the ocean or shutting off
the trunk lines. We have already covered the environmental disaster consequences;
now we look briefly at the alternative.
According to information from the Sanitation District these sewage trunk lines serve
8400 parcels in the southwest section of RPV south of Crest Road and in a sizeable
section of southern Palos Verdes Estates. A typical weekly flow profile provided by
the County Sanitation District is shown in Figure 2.4. The average daily flow rate is
945 gallons per minute.
Figure 2.4 Sewer Lines Flow Rate (LA County Sanitation District, 2020)
Once these trunk sewer lines are turned off, sanitation service would be eliminated
for those 8400 parcels. There is little storage capacity in the system so the sewer
lines would quickly be overloaded. Properties on lower slopes that don’t have back-
flow prevention valves in their lines would have sewage flowing into their
properties from higher elevations. If emergency sewage lines and pumps cannot by-
pass the slide then the only method of mitigating these sewage discharges may be to
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turn off the fresh water supply to those 8400 parcels for as long as it takes to
recover some sewage disposal capability.
Recovery from loss of the twin trunk lines will be a difficult, expensive and
potentially a long-term problem for the Sanitation District. If it cannot be repaired
quickly like it was after the Ocean Trails landslide, the only recourse we can
envision in the interim would be a circulating, truck convoy to remove the 1.36
million gallons per day. Typical heavy-duty sewage vacuum trucks range in capacity
from 2,500 to 5,000 gallons. This would mean from 272 to 550 truckloads per day,
every day, until sanitation is restored. They would have to collect the sewage on the
west side of the slide area and transport it to a viable disposal access point. The
only viable routes are 1) Hawthorne Blvd or 2) PVDS and PVDW through Palos
Verdes Estates to find a suitable disposal access point. Traffic will be severely
impacted and the roadway surfaces would be degraded.
In response to a request for information, the County Sanitation District sent us an
internal report (Reference 4) identifying that they perceived the concerns expressed
above. They also worry about a traffic accident damaging the surface-laid lines. In
the 2009 report they looked at two alternative routes for pipes to avoid the
landslide. One route was along PVDW and the other over Hawthorne Boulevard.
Neither was an easy nor inexpensive option and both had risks. As far as we know
the idea never progressed beyond the study phase.
The impact of losing these sewer lines for a protracted period of time on residents
would be dire. Untold property damage would be the most likely outcome along
with a catastrophic impact on quality of life. There likely would be many refugees
from uninhabitable, unsanitary, water-deprived residences and public buildings
(including City Hall, numerous schools, churches and shopping areas).
2.3 Likelihood of Significant Failure of the “Continue Current Practice” Option.
In any risk analysis, it is much more straightforward to identify the consequences of
a risk than it is to place a probability on the likelihood of occurrence. Often, the
likelihood is just characterized as High, Medium or Low and the assessments are
more intuitive than scientifically calculated. We are not capable of placing a
probability on a catastrophic failure of the Portuguese Bend landslide. What we can
do, through analysis of the landslide mechanics, is identify the potential conditions
under which it might happen and use analogies with recent local events to highlight
that the risk should not be neglected.
The core objective of the proposed mitigation plan is to increase land stability by
intercepting and extracting water. The essence of the hypothesis is that if adding
water (rainfall) reduces stability and increases sliding then removing water will
increase stability and decrease movement. Experience shows this to be generally
true.
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Previous and current experts consistently express belief that excess water is a
primary cause of the landflow. Many residents have stated that they have noticed
increases in landflow rate after heavier than average rain seasons. Unfortunately,
we cannot locate readily available, quantified data relating landflow rates to rainfall
quantities for the Portuguese Bend Landslide Complex, but we did find Figure 2.5,
taken from Reference 5, that shows a location near the Beach School recorded for
the adjacent Abalone Cove slide. This chart shows a very strong correlation
between rainfall amounts and the rate of land movement, which is consistent with
experience. The Abalone Cove landslide has been slowed, though not halted, by
constant operation of a series of de-watering wells, although similar de-watering
wells failed rapidly in Portuguese Bend.
Rainfall in California tends to vary greatly. We recently went through drought
lasting a decade. The landflow rate in Portuguese Bend reduced during this
drought but it didn’t stop. High rainfall years tend to happen when high-
pressure zones sit to the northeast pushing the jet stream south and creating
what has been termed an “atmospheric river”. Based upon the Geo Consultants’
Figure 2.5 – Rainfall and Slide Movement Correlation at Abalone Cove (City
Landslide Workshop, 2010)
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model, which is the underpinning of the proposed engineering measures, heavy
rainfall over a protracted length of time will cause two critical parameter
changes that define land stability. Significant water percolation into the ground
above the basal rupture zone affects the basal rupture surface in a manner that
increases the tendency of the land to slide. A possible source of high-pressure
water below the basal rupture surface is thought to be percolation into the
higher ground north of the landslide. It has been proposed that water intrusion
into the soil at higher elevations increases the pressure or “head” of water
located down-slope beneath the basal rupture surface of the landslide. The Geo
Consultants propose that such increased water pressure below the basal
rupture surface reduces slide stability by lowering the capacity of the basal
rupture surface to resist the force driving the downward slippage. If
Portuguese Bend were to experience several consecutive years of high rainfall
then it is reasonable to conclude that increased saturation from above the
rupture surface and pressure from below the rupture surface could create
localized, unstable zones. Adjacent zones could remain barely stable but
sufficient to restrain rapid movement of the unstable area. Now add the stress
of a significant seismic event. That could be enough to tip a delicate balance,
driving the adjacent zones into a similar unstable state and creating a major
rapid slide. We do not believe such a combination of events is impossible
though we cannot predict the timing or magnitude of either earthquakes or
landslides.
In the last twenty two years there have been two destructive landslides: one on
Ocean Trails golf course just over a mile from Portuguese Bend and another on
Paseo Del Mar in San Pedro some three miles away. We think it would be
instructive to briefly summarize these events.
Ocean Trails golf course had just been constructed and was due to open when,
on 2nd June, 1999, a 980 foot long section of the 18
th fairway and green
(approximately 17 acres) collapsed and slid about 50 feet towards the ocean
(Reference 6) spawning the infamous headline in the local newspaper “Nature
Takes its Course” (Reference 7). Reports stated that this landslide came after
unusually heavy rains overnight that set records in Los Angeles. A 27-inch
sewer line carrying 1,500 gallons per hour was severed. Per the Sanitation
engineer, “You can’t shut off these trunk sewers because it will back up sewage
into people’s homes”. The Sanitation District reportedly had a bypass line
constructed and operational within 24 hours (Reference 8). The same report
stated there was no ocean spillage because the slide created a dam that
captured the effluent, which gradually soaked into the ground. Afterwards, it
was argued that the rains, plus likely additional water from other alleged
causes such as the broken sewer, over-irrigation and leaking water features,
saturated the soil sufficiently to trigger an ancient landslide in which the
stratified geological accumulations slid over a thin bentonite layer. This layer
was reported to be visible at the base of the slide and was up to 3 inches thick
(Reference 9). Repairing the 18th hole involved shear pins, reinforced backfill
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and various buttresses. The overall repair cost was $61 million (circa 2002
dollars) (Reference 10).
In July 2011, tension cracks formed in Paseo Del Mar in San Pedro, just east of
the White Point Nature Reserve. The cracks were up to 25 feet long and three
inches wide. After investigation, the street was closed and utility relocation
began. Then, on 20th November 2011, 420 feet of the road slid 53 feet towards
t he ocean (Reference 11). Figure 2.6 taken from Reference 4 shows the extent
of the damage. Emergency anchoring and drainage measures costing $9.14
million have stabilized the area. Longer-term solutions are still under
consideration and a preliminary construction cost of $27 million has been
established although later reports are suggesting the cost will be around $50
million. Per Reference 12, unusual amounts of groundwater saturated the
bentonite layers, which together with coastal erosion and gravity caused the
slide. The reference concludes with a quote from Jeff Miller, president of the
South Coast Geologic Society: “Landslides have been occurring in Palos Verdes
for a long time before development, and landslides will continue to occur in Palos
Verdes. The most important thing is to be as prepared as you can be. It doesn’t
mean the whole place is going to slide away.”
Figure 2.6 – Paseo Del Mar Landslide Damage (City Landslide Workshop, 2010)
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2.4 Conclusions and Recommendations
We included these past events because they are representative of what can
happen on the Peninsula. One could argue that the Portuguese Bend Landslide
Complex is different from Ocean Trails and Paseo Del Mar because they were
closer to steep cliffs. But, as we researched them, excess water and b entonite
layers are obvious commonalities. Whether our catastrophic scenario could
materialize we simply do not know, but all the similarities with nearby events
suggests it is not too far removed from becoming a reality. And simply looking
at the damage in photographs of the nearby slides, could we handle such
damage on PVDS? There is an excellent statement in the recently published
paper on landslide hazard protection (Reference 13): “Slow-moving landslides,
places where the land creeps sluggishly downhill over long periods of time, are
relatively stable - until they aren't.”
An objective of the proposed mitigation measures is to reduce the possibility of
a major slide and catastrophic damage. They won’t eliminate the possibility but
if successful in slowing down the slide then land stability likely will increase
and the risk should decrease. The Geo Consultants stated something similar in
their report.
We recommend that the City Council consider the financial costs of a
catastrophic failure in addition to the impacts upon the quality of life of
residents. The return on investment analysis should not, in our opinion, simply
focus on the financial balance between the costs of continuing current practices
versus the capital improvement costs of the proposed mitigation. It should
include some reasoned evaluation of the risks and costs of a potential
catastrophic slide. We also recommend prompt expert investigation of the
potential for catastrophic damage to the road and sewage trunk lines and inclusion
of the results in the City’s Emergency Preparedness efforts.
We received more than one comment questioning what return on investment
means. The analytical premise is that any major capital outlay should be justified by
the potential income or cost savings that the capital item is expected to generate
over its estimated lifetime. The net gain from the capital project then is compared
with an alternative strategy such as, for example, investing the money in an interest-
bearing account for the expected life of the capital project. The objective is to
integrate financial metrics into the decision-making process at early stages of
project design. We invite the City’s Finance Advisory Committee to cooperate with
IMAC to provide a more sophisticated analysis of return on investment. There has
long been a rationale that spending about $660K per year for maintenance is more
prudent than investing tens of millions on a project with an uncertain outcome. This
rationale arises from a return on investment analysis. We reach a different
conclusion because we include in the analysis the high risk of major failure of the
roadbed and sewer lines if we do not make the investment necessary to mitigate this
risk by slowing the slide.
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3. Model Validation and Hydrauger Risk Mitigation
This section focuses on the deep, high-pressure, artesian water trapped below the
basal rupture surface that poses the most difficult engineering problem and also
offers the most potential for slide mitigation.
3.1 De-Watering Hydraugers
The key de-watering problem in Portuguese Bend can be stated with deceptive
simplicity:
Can pipes be drilled into the active landslide that will find and drain high
pressure water that lies beneath the basal rupture surface upon which the
landslide moves, survive shear stress from slide movement long enough to
effectively de-water soil below the basal rupture surface and not clog up
with silt?
The answer is not nearly so simple as the question. We have concluded that
analytical science and engineering models can take us only part of the way to a
solution. The Geo Consultants state, “We note that, due to factors including relatively
complex mechanics of the PBLC movement and relatively few data points, predictions
based on this conceptual relation (between assumed factor of safety and landslide
movement rate) should be assumed to have low accuracy and low precision and should
not be relied upon.” The Geo Consultants later state, “Based on this conceptual
relation, GLA considers it plausible that the movement rate can be reduced
significantly if the factor of safety can be increased to approximately 1.2 or more.”
(Reference 1, Section 4.4, pages A-15, A-16.)
Because the Geo Consultants characterize their model as merely plausible and warn
against reliance upon that model, we do not focus upon theoretical details of
landslide models. Instead, we strongly endorse the recommendation of the
geotechnical consultants that surveys and tests be implemented (Reference 1
Sections 5.3, 5.6.1 & 5.6.3; report internal pages 14 to 17; Pages A-18, A-19 & A-21
in Report filed with City Council.) However, we recommend that critical surveys
and tests be performed before, and in aid of, final engineering design, not deferred
until contracts are let for major construction. Further, we strongly support the Geo
Consultants’ recommendation that “information [be] collected during installation of
each horizontal drain (e.g., soil conditions, pore water pressure discharge rate, etc.)
and used to adjust plans for subsequent drain installation” (Reference 1, Section 5.6.3;
internal pp. 16 – 17; City Council pages A-20, A-21). However, we also recommend that
this confirmatory exploration and instrumentation of prototype “down-gradient”
hydraugers (installed from the seashore) be performed before major construction is
done in reliance upon the Geo Consultants’ “plausible” model. If prototype down-
gradient hydraugers do not validate the Geo Consultants’ model, then the
geotechnical evaluation does not provide any basis to expect achievement of the
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most significant element of proposed mitigation (relief of high-pressure, artesian
water in the vicinity of the basal rupture surface). That could radically reduce
expectation of return on investment for the whole mitigation project. We do not
believe that tens of millions of dollars should be spent on other aspects of the
proposed mitigation before the key metrics of the hypothesized, high-pressure
water in the vicinity of the roadbed have been validated by prototype hydraugers
installed in the vicinity of the roadbed structure.
The Geo Consultants report that numerous vertical wells have been tried in
Portuguese Bend and did find some high-pressure, artesian water. (Reference 1,
Section 2.4.2; report internal p. 6; City Council report A-10.) It is our understanding
that some vertical wells survived in slower moving, upper reaches of the Portuguese
Bend Landslide Complex, but that no vertical de-watering wells survived in the
lower portions of the Portuguese Bend Landslide Complex (even though successful,
vertical, de-watering wells have been operating for years in the Abalone Cove slide).
The Geo Consultants propose that the trapped, high-pressure water can be tapped
and released by specialized pipes called hydraugers, a technology that has not
previously been used in Portuguese Bend. Hydraugers are to be drilled
approximately horizontally, not vertically, into the hypothesized high-pressure
zones beneath the basal rupture surface of the slide, employing directional drilling
technology developed for petroleum fracking. The insertion path is designed to
minimize exposure to the shear forces that destroyed vertical wells by passing
beneath not through the basal shear zone. Steel sleeve pipe, resistant to shear
stress, will be installed on the first sections to cocoon the hydrauger pipe, thereby
removing any shear stress from the hydrauger pipe itself. We believe this is a
credible approach but only time will tell if it is effective enough to protect the
hydrauger line for many years.
Another potential failure mode that has been leveled at hydraugers is silting in
which the narrow slots get blocked by particles, thereby reducing and ultimately
preventing their ability to absorb water from their surroundings (Reference 14).
This likely is a very common problem for which we would anticipate experts have
effective remedies. However, we infer that the solutions depend upon the
composition and structure of the soil – a topic on which there is a critical data gap.
If one thinks of the drilled hydrauger as an equivalent of a long core sample, then
with knowledge of the core sample the hydrauger configurations could be
optimized. Instrumentation of the hydrauger-drilling process will also enable
analysis of the geology and may effectively provide enough data over multiple
hydraugers to map out a three-dimensional model of the geologic properties under
the surface. Such data could be very useful especially if the hydraugers are not the
success we hope. If that is the case, then we will need to understand why and this
type of data could facilitate such analysis. Extensive instrumentation and sampling
will add program cost but we believe it prudent to reduce this crucial data gap
before major expenditures on other aspects of the plan that have only poor
prospects of success if the hydraugers do not succeed. We suggest that the City
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might seek opportunities to partner with academia who could provide the necessary
laboratory facilities, data reduction and the post graduate doctoral student(s) to do
the work. What an opportunity for a doctoral thesis on one of the most active
landslides in North America?
3.2 Program Scheduling
In our analysis of the benefits of program scheduling, we accept the qualification
stated by the Geo Consultants, “Note that the objective of the proposed mitigation is
to reduce the movement rate of the PBLC, not to “stabilize” the landslide (i.e., in GLA’s
opinion, a mitigation design which achieved commonly accepted geotechnical stability
criteria would be infeasible, as it would not satisfy various site constraints)”
(Reference 1, Section 4.1, internal p. 9, City Council p. A-13)
As part of their analysis, the Geo Consultants showed that current stability margins
are low and it doesn’t require more than 4% - 6% degradation to create a potential
catastrophic slide failure situation. They also calculated that hydraugers and
surface water removal would collectively improve stability margins by 7% - 19%. A
further breakdown shows that lowering the water table provides 0% to 3%
improvement in stability margin while the pressure reducing hydrauger arrays
contribute a much larger 6% to 10%. Doing both adds another 1% to 6%. We share
the Geo Consultants’ caution not to take these results too literally. They only
represent three cross sections of the slide extrapolated from very limited, decades-
old, data points. However, we can infer that the Geo Consultants’ model predicts
that the hydraugers will be considerably more effective than the surface water
interception, but together they will provide the biggest benefit. More significantly,
to achieve the desired endpoint stability, both measures are needed for project
success.
We do not see in the Reference 1 report any analysis of the potential effect that
fracture infilling or higher-elevation interceptor drains will have upon slide velocity,
apart from the proposed surface drainage structures. We see only an estimate of
combined potential benefit of surface water controls as a whole. In the absence of
such an analysis, we view such measures as supplemental and recommend that they
not be done before prototype hydraugers validate (or invalidate) the Geo
Consultants’ model for pressure reduction at the basal rupture surface.
The program implementation recommendation (Section 5 of Reference 1) shows a
phased approach as follows:
Phase I – Surface Fracture Infilling
Phase II – Surface Water Improvements
Phase III Groundwater Mitigation Drains
Phase IIIA – Confirmatory Exploration and Instrumentation
Phase IIIB – Up-Gradient “Interceptor” Drains
Phase IIIC – Down Gradient “Relief” Drains.
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Our impression is that this phasing approach is designed to implement the least
effective but lower risk items first and to leave the most effective but higher risk
components until the end. If the Geo Consultants expect other benefits then it
would be helpful if those benefits were plainly articulated. We understand from the
Reference 1 Staff Report, that one rationale behind this plan is cost based, i.e., do the
lowest cost items first and see how well they perform and maybe the higher cost
elements won’t be necessary. We understand and respect the motivation to
minimize the cost to the taxpayer. But the model suggests that the crux of this
landslide problem is high-pressure water below the basal rupture surface.
According to the Geo Consultants’ model, it appears that the best result one could
reasonably expect by doing the fracture infill and surface water improvements first
(Phases I & II) is to lower the rate of land movement to movement rates that were
experienced during the drought years. While that may be significant, it is clear from
the Geo Consultants’ analysis that it will not be sufficient. Therefore, we conclude
that it is essential to first tackle the high-pressure zone below the basal rupture
surface with the hydraugers. That “hydrauger-prototyping-first” approach could
promptly validate or invalidate the Geo Consultants’ model and may not require a
heavy-rain season to observe the effectiveness. We know of no data that tests
whether high pressure below the basal rupture surface near the roadbed persists
into drought years, or varies relatively quickly with rain intensity. We note that it is
common knowledge that natural springs in mid-level elevations in the Kelvin
Canyon area of Portuguese Bend continue to flow during long droughts, though with
some reduced volume. This implies that higher-elevation sources of deep, high-
pressure water may persist during years of drought. Prototype hydraugers could
probe this issue before massive capital investment is committed to other water-
control measures. If prototype down-gradient hydraugers inserted from the
seashore beneath the roadbed structure under the slide mass north of the roadbed
do demonstrate capacity to extract water then the measures for draining surface
stormwater through a culvert to the ocean could work cooperatively with
hydraugers. However, if those surface stormwater measures have to stand on their
own, because down-gradient hydraugers do not work, then the cost-benefit analysis
shifts substantially for the surface stormwater measures. This is because the Geo
Consultants predict lower effects for stormwater controls than for the hydraugers.
We believe that there is insufficient scientific data to characterize the environment
in which the basal rupture surface develops and operates. That is why we
recommend that prototype hydraugers be used to test their operation and to collect
design data before large expenditures are made on other components of the
proposed project. We recommend that the hydrauger experts be required to define
written, test protocols that specify in advance of testing what will constitute
favorable results from the prototype hydraugers. The protocols should be designed
to demonstrate whether or not the test results justify proceeding with the next steps
in the proposed mitigation plan. After all, if the hydraugers do not provide the
anticipated results, wouldn’t it be better to know this early on before spending a
sizeable part of the budget? Based on the program management experience of one
of the aouthors (PS), programs very rarely under-run their costs. It’s usually the
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opposite, especially ones where significant risk is involved. If the costs of the early
work overrun significantly, there might not be any finances remaining to execute
the most effective component of the solution.
Furthermore, we think that leaving the hydrauger prototyping to the last phase of
the implementation plan runs counter to well-established program management
approaches to manage risk. All significant risks in a program need to be
systematically addressed early on before they become massive problems for both
customer and contractor. Nobody wants to see this fail. The only way we know how
to minimize the risk of project failure is to identify the key risks up front and
embrace a proactive risk management approach. We believe that is what is needed
here.
More specifically, we recommend that the Phase IIIA Confirmatory Exploration and
Instrumentation be executed first in conjunction with hydrauger prototypes. These
would be installed at the seashore to test whether or not (A) they can actually find
and drain high-pressure water from beneath the basal rupture surface in the vicinity
of the PVDS roadbed, (B) they demonstrate capability to survive shear stress from
slide movement and (C) they don’t stop working because of silting. We strongly
endorse the Geo Consultants’ recommendation that the drilling equipment and
prototype hydraugers should be instrumented and monitored with state-of-the-art
technology to learn as much as is feasible about soil conditions encountered during
drilling, drain installation and operation. We caution that the City should expect
some failures during prototype testing but this is normal; it’s better to have a
prototype fail and then remedy the cause than have them all fail in ignorance of the
problem. The important first step is to see if the prototypes find high-pressure
water in enough quantity in the vicinity of the basal rupture surface to provide real
data in support of the model. Only then does it make sense to us to install additional
hydraugers to monitor the ability of an array of hydraugers to relieve high-pressure
water from a substantial area of the basal rupture surface near the roadbed. We
don’t think the higher-elevation hydraugers should be part of this first step because
there is no analysis to support expectation of substantial effect on the roadbed from
their early installation. Whether they are successful or not in finding water in
quantity, they will provide little confidence or data on whether relieving high-
pressure water below the slide surface will be effective. Indeed, failure of higher-
elevation hydraugers might inappropriately tarnish the hydrauger concept before
we see the real benefits at the roadbed.
We understand that the Geo Consultants plan to use data from early hydrauger
installations to guide subsequent installations. However, as we understand it, they
propose to perform other major phases of construction before prototype, down-
gradient hydraugers. Based upon the analyses in the Reference 1 Geotechnical
Evaluation Report, we conclude the relatively lower expectation of benefits from
other phases of construction compels a much harder look at the project if the
prediction of benefit from hydraugers cannot be validated.
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We believe our recommended approach has other programmatic benefits. For the
pessimists who have doubts about the predicted effectiveness of hydraugers, if the
results of the prototypes do not support the model then all that is “wasted” is the
cost of the first few prototypes. Prototyping should not be a complete waste
because we gain the data from which to formulate an alternate approach. If the
hydraugers do not validate the fundamental model, then the cost-benefit analysis
becomes far less attractive. For the optimists who see hydraugers as potentially the
key difference from prior attempts, if the prototype hydraugers do drain significant
quantities of water then the remainder of the proposed project can be approached
with greater confidence based upon real data.
3.3 Fracture Infilling and Interception Drains
We do not find in the Geo Consultants’ report any data suggesting how effective
fracture infilling and higher-elevation interception drains may be in slowing
the slide. If the lower-elevation hydraugers live up to their projected potential
for slowing the slide, it likely will mean they will be extracting significant
quantities of high-pressure water to satisfy the success criteria we recommend
be established. In this case, we question whether it matters if water continues
to percolate from high up to beneath the basal rupture surface as long as the
hydraugers are successfully relieving the high-pressure zone. U ntil we see the
results of the lower hydraugers, we pose the question whether fracture-filling
or higher-elevation interception drains will still be needed. That possibility,
along with its significant cost avoidance, further supports the “hydrauger-
prototyping-first” recommendation.
We conclude that the need for fracture infilling with hardening slurry has not
been adequately justified. The Geo Consultant reports that fracture filling
won’t stop fractures from reappearing and that additional infilling likely will be
required on an annual basis. If fractures simply form in soil adjacent to the
hardened, fracture-filling material, then one asks why not just fill the fissures
with surrounding dirt in the first place and repeat that as needed? Dirt could
be slurried so that it flows into the gaps if deep penetration is the goal. Section
5 discusses some potential future study on the use of fly ash and possible
alternatives to fly ash. If the land flow has significantly slowed due to the
hydraugers, then the fissures ought to lessen in size and number. Filling
fractures with native soil might be less expensive and much more acceptable
from an environmental and preservation standpoint. While filling fractures
with local soil may not be easy, the proposed importation and injection of
slurried materials cannot be easy either. We note that similar, fracture filling
with local soil has been employed by the Portuguese Bend Club for decades,
though we have been informed that other solid materials from off-site may also
have been used.
Even with the uncertainty in the factor-of-safety analysis, one only has to observe
the damage surface water does during heavy rain seasons to conclude that surface
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water control is an essential component of a system-wide approach. Hydraugers
and surface water controls are likely to be interactive and synergistic. If the
hydraugers significantly slow land movement, then the environment in which the
surface system has to survive is less hostile and its longevity prospects are much
higher. Similarly, effective surface drainage should help hydraugers survive.
3.4 Conclusions and Recommendations
We recommend that prototype lower-elevation hydraugers be installed first,
before final design of other phases of construction. The objective is to validate,
modify or invalidate the core hypothesis of the Geo Consultants’ model. We
recommend deferral of higher elevation hydraugers, fracture in-filling, and
construction of surface water structures pending results of prototype, lower-
elevation hydraugers. The results from lower-elevation hydraugers should be
used to guide the final engineering designs for all other measures. The Geo
Consultants’ analysis predicts that the greatest slowing of the landslide is likely
to result from reduction of high-pressure water below the basal rupture
surface. The analysis suggests that other measures will provide only smaller
incremental benefits. We accept this analysis as sufficiently plausible to guide
the initial prototype testing. We believe that structuring the program plan
along our recommended lines presents the best opportunity for achieving the
most cost-effective solution.
At the IMAC meeting discussion, Dr. Matasovic confirmed our assessment on
the effectiveness of the lower hydraugers saying that they were the “best bang
for the buck”, that relieving pressure was the key, and that all other measures
were secondary. No one disagreed with the need for prototyping of the lower
(“down gradient”) hydraugers. All who responded on the topic concurred that
the most productive area to prototype them is where the land is moving the
fastest, namely the area south of the proposed retention basin. With respect to
hydrauger survival when passing through the basal rupture surface, Dr.
Matasovic stated that he had no intention of drilling through the basal rupture
surface. His plan is to employ three-dimensional, directed-drilling techniques
that have evolved from the oil fracking industry to drill under the basal rupture
surface without penetrating through it. When visualizing the drill head
trajectory in three dimensions one can see that it is possible for the hydraugers
to avoid the basal rupture surface if they start at a location outside of the
moving slide mass. This is easier to visualize with the two proposed arrays A5
and A6 that start in stable areas on either side of Inspiration Point. T wo other
arrays, A1 and A4, start near the outer edge of the Portuguese Bend Landslide
boundary so it seems feasible there as well. That clarification significantly
changes our risk assessment of the hydrauger vulnerability to damage from
land movement since they will be located in relatively stable landmass
throughout their length. Dr. Matasovic also allayed our silting concern, saying
that the high-pressure a rtesian water will flow so fast that the hydrauger will
“self flush”. This implies that a hydrauger likely will silt up only if it is not
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extracting significant quantities of high-pressure water. T hat case could arise if
either (1) the hydrauger failed to tap artesian water but then silting would
make little material difference, or (2) the hydrauger did find high-pressure
water and effectively drained it but a slow steady-state flow must be drained to
prevent pressure from re-building. In the latter case there would have to be a
maintenance program established to occasionally flush the hydraugers.
Mitigation of the survivability risk simplifies the hydrauger issue. The
principal, remaining uncertainty is whether a hydrauger will encounter
artesian water in areas of sufficiently high permeability to effectively drain the
water from below the landslide. Dr. Matasovic emphasized from his past
experience that hydrauger drilling is a trial and error process to find the best
locations for water extraction. We understand that funding limitations may
delay installation of the operational hydraugers, after prototype hydraugers
provide proof of principle. We have no issue with that. I f the hydrauger
prototyping is done first, it could be advantageous to have a few years
experience with the prototypes to see if the water flow continues and how it
changes when there is heavy rain. It also gives time to confirm that the land
movement doesn’t destroy the hydraugers. Public Works Director Sassoon
stated the current plan, to do the hydraugers last, including the prototyping,
was based on doing the easier and less costly measures first, assess their
effects, and then factor those results into deciding how many hydraugers might
be needed. We understand that rationale, but respectfully maintain that
because of the inherent uncertainty, it is critical to program success to confirm
the effectiveness of the lower hydraugers with prototypes before expending
resources on all of the other secondary measures. We think it is important to
emphasize that all the other measures are preventative in that they try to minimize
future water intrusion. Only the lower hydraugers are proactive in that they will
extract the water that is in place now, as well as future water. If the prototype
hydraugers fail to release high-pressure, artesian water as expected, then the
question remains: Of what value can the preventative measures be on their own?
4. Surface Drainage Survival
The public routinely sees the broken, scattered remains of the failed 1990
stormwater controls in the Portuguese Bend slide area. The public routinely deals
with the disruption of the road that results from continuing land movement. Any
project must address that public perception to gain approval. Past failure increases
the burdens of explanation and justification for a new project. The consultants who
design and propose a new project must carry much of that increased burden. Where
many licensed experts have failed before, citation of credentials (though important)
is no substitute for plain explanation and convincing justification. During public
meetings, residents expressed concerns about reliance upon the existing culvert
under PVDS as the sole culvert to port storm water past the roadbed. We share
those concerns. This section addresses our rationale and recommendations.
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4.1 Current and Historic Drainage.
The roadbed of Palos Verdes Drive South currently acts as a dam for surface
water that flows down-slope towards the ocean from the major canyons.
Currently, there is only one known, surviving culvert that passes beneath the
Palos Verdes Drive South roadbed between Inspiration Point and the eastern
edge of the landslide area. The culvert appears to have been sited at the best
point for transporting water from lower Portuguese Canyon beneath the road
to the sea. It is located about one hundred yards east of the relatively stable,
north-south trending ridge that forms Inspiration Point. The culvert inlet’s
elevation is about 25 feet below the surface of the road. It is roughly at the
same elevation as the natural water channel of lower Portuguese Canyon. The
date of installation of the culvert is unverified. It is possible that the culvert
already existed before it became the target of the major storm drain system
that was installed circa 1990 in the landslide area. It may be that the 1990
storm drain system was configured to utilize the already-existing culvert. The
1990 storm drain system bypassed lower Portuguese Canyon, and instead
diverted canyon flow into surface-laid, corrugated steel pipes along what is
now known as Peppertree Trail. About 100 yards north of the PVDS roadbed,
the 1990 storm drain line has a sharp elbow of nearly 90 degrees that diverts
flow from southward to westward. This elbow aims the 1990 storm drain line
back towards the existing culvert at lower Portuguese Canyon.
This layout was fatal to the 1990 storm drain system. As the PVDS roadbed slid
seaward a swale evolved about 100 yards north of the roadbed, between what
is now Peppertree Trail and Ishibashi Farm Trial. The landslide surface
progressively sank in that swale. The storm drain pipes rode the sinking
landslide surface of the swale, sinking an estimated 15 to 18 feet since 1990.
The sinking swale reversed the slope, or “fall”, of the storm drain pipes so that
water no longer could flow through the pipes to the only culvert. The culvert
was isolated, or stranded, by the sinking of the storm drainpipes as they
traversed that sinking swale. Currently, surface waters from major canyons,
including Paintbrush and Ishibashi, pool in the swale and percolate into the soil
where the water is thought to destabilize the roadbed. Dense wildlife habitat
has developed in and around the swale. Key terrain features are identified in
the photograph in Figure 4.1, which illustrates the current state of the 1990
pathway to the culvert.
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4.2 Rationale for an Additional Culvert
The existing culvert has survived for at least 20 years, and possibly more than
30 years. It appears to be located in a relatively stable point in the landslide
complex. Due to this favorable location it is potentially useful in the new
surface water collection system. In the Geo Consultants’ plan for the surface
water collection and transportation system, a new swale will be constructed
southward from the canyons roughly following Peppertree Trail. When the
proposed new swale reaches the flood sink area (known as Lake Ishibashi
before the 1986 – 1990 grading) the new swale will merge into a large
collection (or retention) basin that will be graded to provide overload capacity
for heavy rainfall conditions. Figure 4.2 is a photograph of the area on which
the proposed retention basin will be constructed just beyond Peppertree Trail
in the foreground. Figure 4.3 is the engineering drawing extracted from the
Geo Consultants final report (Reference 1) showing the proposed retention
basin, the primary flowline across it and the existing culvert. The photograph
in Figure 4.2 was taken from Sandbox Trail just outside the top right hand
corner of the enlarged Geo-Logic drawing reproduced as Figure 4.3 below. The
aspect of the photo looks approximately across Figure 4.3’s diagonal from
upper right to lower left.
Figure 4.1 Existing Culvert Location (Wedemeyer, 2019)
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Figure 4.3 Engineering Drawing of Proposed Retention Basin (Geo-Logic, 2020)
The outfall from the proposed collection basin will connect to the existing
culvert that will port the water beneath the roadbed to the ocean. We infer that
the sinking which formed the existing swale is caused by downhill, seaward
sliding of the roadbed. Our concern is that the location of the proposed
collection basin likely will continue to sink due to continuing sliding of the
roadbed. The continuing sinking under the proposed collection basin could
again strand the existing culvert before other measures succeed in slowing the
Figure 4.2 Location of Proposed Retention Basin (Wedemeyer, 2020)
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sliding of the roadbed. This would be as fatal to the new storm drain system as
it was to the 1990 system.
It appears to our inspection that major grading likely will be necessary to fill
much of the existing, sunken swale to create a complete path with slope
sufficient to drain a new collection basin through the existing culvert. We
endorse a recommendation of the Geo Consultants that the sole existing culvert
under Palos Verdes Drive should be thoroughly evaluated for suitability and
viability before a final engineering design relies on that culvert. We recommend an
early, detailed survey of the entire proposed pathway through the existing
sunken swale from Peppertree Trail to Ishibashi Farm Trail and onward to the
inlet of the existing culvert at lower Portuguese Canyon. Deriving an average
sink rate along this entire pathway will tell us roughly the life expectancy of the
proposed collection basin before it sinks below the culvert inlet. While
estimation of future land-sinkage may pose some difficulties due to lack of
measurements contemporaneous with the sinking, we think clever engineers
can evaluate the lie of existing remains of the 1990 system to achieve an
estimate of past land-sinkage and then make reasonable projections of future
sinkage. Starting promptly, significant monitoring measurements could be very
helpful. We fully support the Geo Consultants’ recommendation to increase the
land movement measurement frequency from annually to monthly. As stated
above, we strongly endorse the Geo Consultants’ recommendation that “flowline
elevations” and “remaining useful life” be verified before major construction.
(Reference1, Sec. 5.3; internal pages 14 – 15; City Council pp. A-18 to A-19.)
This estimate of the life expectancy of the “flowline elevations” to the existing
culvert could and should be made as soon as possible because they may
substantially affect the final engineering design. Because of the failure of the
1990 flowlines to the existing culvert, we think there already is sufficient doubt
about the life expectancy of that culvert and its flowline elevations to merit
parallel evaluation of a second culvert. We do endorse the Geo Consultants’
recommendation that major construction should not be implemented upstream
before the viability of that existing culvert has been established.
We recommend that a new, second culvert be considered as a continuing
option, in parallel with the evaluation of the existing culvert, so that we have a
backup if the worst case materializes after examination of the existing culvert’s
long-term viability. Addition of another culvert beneath Palos Verdes Drive
South, nearer to the eastern edge of the Portuguese Bend Landslide, and
perhaps in the vicinity of Peppertree Trail, could have the following advantages
and disadvantages:
Advantages:
1.It could be installed deeper than the sole existing culvert and provide
more advantageous flowline elevations and life expectancy. This would
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make the new culvert capable of surviving further sinking of the
landslide surface without becoming stranded.
2. It would produce a shorter pathway to deliver storm water from
Portuguese, Ishibashi and Paintbrush Canyons under the Palos Verdes
Drive South roadbed while traversing a shorter distance through an area
of relatively rapid land movement than does the pathway to the existing
culvert. Further, the pathway to a second culvert could be aligned with
the seaward flow of land movement, rather than crossing nearly
perpendicularly to the land flow as does the flowline from the 90° elbow
at Peppertree Trail westerly past Ishibashi Farm Trail to the existing
culvert
3. A second outlet beneath the roadbed to the sea would create
redundancy, so that failure of a single culvert or culvert-access storm
drain would not cause failure of the entire landslide storm drain system.
Redundancy is not a design requirement, but given the past history of
failures, it’s a feature that could be beneficially exploited in the final
design. For example, it could reduce the surface area required for
development of a collection basin. The reduction of basin area would be
proportional to the added carrying capacity of the additional culvert.
This would reduce construction and maintenance costs of the retention
basin and have a reduced environmental impact by lowering the “take”
for the collection basin.
4. There might be enough design freedom to eliminate the collection basin
by integrating it into the swale structure along Peppertree Trail. The
new swale along Peppertree Trail could be constructed gradually wider
and deeper as it approaches the new culvert to simply provide the
needed overflow capacity in heavy rain situations.
Disadvantages:
1. A second culvert would increase the capital cost of installation of the
new storm drain system, though there would be some off-setting
reduction of installation and maintenance cost of a smaller collection
basin. It will be expensive, but not nearly as expensive as failure of the
entire surface water storm drain system, with resulting failure of the
entire project to slow sliding of the roadbed structure.
2. The new culvert through the roadbed under PVDS would be sited
within some of the faster moving parts of the landslide, raising
longevity issues, though the culvert could be aligned with the dominant
flow of the land movement to reduce shear stress. Stability issues with a
shorter, more direct, north-to-south drainage route along lower Peppertree
Trail would be balanced by avoiding the existing, severe, stability issues
experienced with the much longer, drainage route west from Peppertree
Trail along the sinking swale to the existing culvert at lower Portuguese
Canyon. The existing culvert, which is 84 inches in diameter and has ¾
inch steel walls, has proven stability, having survived for at least 20 years.
IMAC 11/16/20 Mtg Item A- page 34E-34
IMAC Landflow Report Approved 9.21.2020
35
The 1990 drainage line to the surviving culvert failed more than 15 years
ago due to sinking of the east-west swale between Peppertree Trail and the
existing culvert. Based upon visual observation of the 1990 storm drain
where it passes through the existing swale, we estimate subsidence of 15 –
18 feet since the 1990 storm drain system was installed.
4.3 Conclusions and Recommendations
We perceive a dilemma arising from lack of data other than visual observations to
calculate the current rate of sinkage. Therefore, our recommendation is conditional.
We recommend, as a matter of urgency, that the survey of the existing culvert and
flowlines to it, as recommended by the Geo Consultants, be completed immediately.
This should include estimation of the life expectancy of the path to and through the
proposed collection basin to the existing culvert. Scientific investigation to estimate
the life expectancy of the path to the existing culvert may take years to record
sufficient movement to get a highly precise, reliable answer. Measurements ideally
should include periods of heavy rain that are known to accelerate sliding.
Knowledge of life expectancy will enable an informed judgment on whether a
second culvert is essential to survival of the surface water system. We suggest that
historic sinking can be estimated by measuring the current elevations of the 1990
storm drain pipes relative to other sections of the 1990 storm drain that did not sink
very much, if at all.
If the program proceeds per our recommendation for installing prototype
hydraugers first, that will produce data to project a revised, and hopefully much
lower, rate of land movement. In turn this will lead to a revised life expectancy for
the collection basin and the pathway to the existing culvert. That may, or may not,
remove survivability of the proposed pathway from the risk analysis, depending
upon the hydrauger result. For the purposes of discussion, let’s assume the
proposed pathway to the existing culvert will remain effective for the foreseeable
future. We think there still is merit to the second culvert independent of
survivability of the pathway to the existing culvert. Because we see potential for
failure, similar to the land-sinkage that was fatal to the 1990 system, we think built-
in capacity of a new, second culvert to survive continuing land-sinkage, merits
careful, continuing consideration.
We recommend that the concept of a second culvert be retained as a viable option
while essential data is collected.
Much of the discussion on the second culvert concept at the IMAC meeting focused
on the high cost. We fully understand the cost issues, which is why our
recommendation is conditional upon a survey. Director Sassoon informed the IMAC
that survey data from 2017 identifies some margin of fall between the 90° elbow at
Peppertree Trail and the inlet to the existing culvert. However, a survey suitable for
preparation of a grading plan with cuts and fills has not yet been obtained. Director
Sassoon added that the plan is to issue a contract for the surface water management
IMAC 11/16/20 Mtg Item A- page 35E-35
IMAC Landflow Report Approved 9.21.2020
36
and the contractor’s first task will be to survey the area to ensure that the flow lines
to the existing culvert will work. Dr. Matasovic also added that any margin we have
in the available slope to the culvert when the retention basin is constructed should
last a long time if, and only if, the hydraugers have the anticipated effect of
significantly slowing the slide. We believe that comment reinforces the need to
understand the hydrauger effectiveness as soon as possible. Director Sassoon
stated that he has in his possession a current GPS map of the area including
elevations and that will be provided to the landflow subcommittee. He responded
favorably to the suggestion to conduct multiple surveys over time to enable
estimation of rates of elevation changes and the retention basin’s useful life.
Subsequently we were told that the plan for 2021 is to increase both the number of
reference points in the survey and the frequency to monthly. We support that plan
unreservedly. We highly recommend that funding be allocated for that survey effort
as a high priority for the City. We concur with the suggestion to await pending
survey results before further evaluation of a backup plan for the proposed retention
basin and the existing culvert. .
5. Future Potential Study Areas
During the development of this report, we identified some potential issues
beyond the scope of this report. These issues may or may not be resolvable by
others more expert than we are. However, we consider them important to
record and potentially to study in more detail in the future. The following
paragraphs provide a synopsis of each issue and some ideas on how they could
be addressed. We are not suggesting more study immediately, that is, analysis
paralysis should be avoided. Instead, we recommend that the City proceed
promptly with hydrauger prototyping and surveying. T hen step back to
understand the results and adjust the final design accordingly. The issues in
this Section 5 can be evaluated in due course.
5.1 Geo-Chemistry
While we are not expert in geochemistry, there appear to be geochemistry
issues that are significant to slide mechanics and therefore to slide-mitigation
risk analysis. A brief literature search discloses that there are multiple
chemical forms of bentonite clay that have significantly different functional
properties (References 15 and 16). These differences depend upon the
presence (or absence) in the bentonite clay structure o f the elements sodium,
calcium and magnesium, among others. Sodium bentonite has peculiar
properties that contribute to the landslide. Sodium bentonite can absorb large
amounts of water which results in remarkable swelling of the clay mass.
Sodium bentonite’s crystal structure forms smooth layers that are thought to
easily slide past each other and weaken resistance to slide shear forces. When
wet and swollen, sodium bentonite seals to form a barrier to water percolation.
Ions of calcium (Ca++) dissolved in water can naturally exchange with ions of
sodium (Na+), thereby converting sodium bentonite to calcium bentonite. This
IMAC 11/16/20 Mtg Item A- page 36E-36
IMAC Landflow Report Approved 9.21.2020
37
changes the crystal structure of the bentonite clay and therefore its functional
properties. The calcium bentonite forms a different structure that allows a
higher rate of water passage, which is called hydraulic conductivity. Calcium
bentonite reportedly is more resistant to shear stress.
We invite evaluation of two issues related to the existing slide-mitigation
design:
1. What is the likely useful life of the geo-fabric proposed for lining the
retention basin, given the geochemical environment in the Portuguese
Bend Landslide? The estimated useful life of the geo-fabric feeds into the
return on investment analysis. We assume that the bentonite in the geo-
fabric will be augmented with some material to protect it from calcium
ion exchange. However, we have no understanding of how well or how
long this resists the chemical reaction; hence, the question on its
expected lifetime.
2. If landslide fissures were to be filled (wholly or partially) with a slurry of
calcium-bearing materials such as crushed limestone (instead of the
proposed fly ash), would the calcium then percolate over a period of
years down through the landslide fissures to the basal slide surface?
Would conversion of the sodium bentonite to calcium bentonite
marginally increase resistance of the clay to sliding? Unlike the geo-
fabric layer where the sodium to calcium conversion is undesirable, this
potential approach to stimulate conversion could be beneficial over the
long term. We are informed that Dr. Perry Ehlig and Dr. Robert Douglas
performed an ion-exchange experiment decades ago by injecting calcium
into a vertical well. Reportedly, the landslide sheared the well and low
permeability of the clay limited the ion-conversion rate (Reference 17).
Injection of calcium bearing materials into fissures could address both of
these constraints. We make no recommendation on this topic but invite
the City to consider it.
5.2 Fracture Infilling
As discussed in Section 3.3, without any analysis to determine the effectiveness
of fracture infilling, we believe it should be delayed until after the hydrauger
prototyping at which point we will better understand the effectiveness of the
down-gradient hydraugers to slow the slide. We maintain this position for the
following reasons:
1. We accept the hypothesis of the Geo Consultants that pressure reduction
at the slide surface can be achieved by draining trapped, high-pressure
water. If water gushes at the hydrauger outlet that would suggest
significant permeability of the soil tapped by the hydrauger. If there is
an initial relief of high-pressure water that has accumulated over a long
time, then one can envision a steady state in which gushing flow reduces
IMAC 11/16/20 Mtg Item A- page 37E-37
IMAC Landflow Report Approved 9.21.2020
38
to a continuous, slow trickle matching incoming slow percolation from
higher levels. Then the hydraugers may need to function over a long
term to prevent re-building of pressure. We ask: If the flow through the
hydraugers reaches such a slow steady state, how much does it matter if
the fractures are infilled or not? Will incoming percolation from higher
elevations seasonally overwhelm the hydraugers so that pressure re-
builds and sliding accelerates seasonally? Once the flow slows to a
trickle, does the risk of silting become an issue? Hydrauger prototyping
may shed light on these questions.
2. Perhaps we could take advantage of fractures as discussed above in
Section 5.1-2 by filling (or partially filling) fractures with calcium-
bearing material such as limestone to encourage conversion of sodium
bentonite to calcium bentonite.
3. We have looked at the chemical composition of fly ash. A lthough it is
described as inert it seems to have some constituents that would not be
desirable in a nature preserve. According to a Material Safety Data
Sheet, (Reference 18), some commercial fly ash is particularly alkaline,
which could adversely affect soil pH. The ash itself likely would not
support native plants and would be barren. We suspect that it is
proposed to add cement to immobilize undesirable chemical properties
and hazardous properties of the ash. Unfortunately, that will mean we
will have numerous, unsightly masses of barren, concretized ash that
will readily become visible as the fractures reopen due to continuing
sliding. Because the concretized ash will be rigid, it likely will not
conform to changes in the fractures as the slide moves. Then yet more
slurried, concretized ash will be needed to fill re-opened fractures as the
slide moves. We invite the City to consider filling fractures with slurried,
native soil (or other plant-friendly material such as limestone). Slurried,
un-cemented, local soil with high clay content could fill fractures. Unlike
concretized ash, soil would tend to conform to fractures as they widen
and settle. Soil could be topped off as needed from time to time and
graded to shed runoff. Neither concretized ash nor clay soil will prevent
all percolation, but both should shed rapid runoff. Fractures should be
mitigated over time if hydraugers perform as hoped. In that case, why
create, permanent, concretized, barren, aesthetic scars that may harm
the habitat?
5.3 Swale/Trail Integration
An idea we have already suggested to public works is that the lower swale
design, particularly the section that roughly parallels Peppertree Trail, could be
integrated into a common swale and trail/road. For most of the year the swale
will be dry so it could easily be constructed to handle vehicles and put a multi-
use trail on one of the banks. If Peppertree Trail is in the wrong place, then it
could be moved to wherever the swale is needed for flow line reasons and the
IMAC 11/16/20 Mtg Item A- page 38E-38
IMAC Landflow Report Approved 9.21.2020
39
old unused section restored to native habitat. This will have a beneficial effect
on reducing “take” as well as being aesthetically less intrusive overall.
6.References
1.Staff Report & Geotechnical Evaluation Report to City Council 12/17/2019 -
https://rpv.granicus.com/MetaViewer.php?view_id=5&clip_id=3554&meta_i
d=77955
2.Portuguese Bend Landslide RPV City Archive:
http://www.rpvca.gov/1031/Portuguese-Bend-Landslide
3.Portuguese Bend Landslide Mitigation Project, Presented to RPV City,
December 17, 2019
4.Joint Outfall "J" Unit 1F (Abalone Cove Pumping Plant) Force Main Relocation
- Preliminary Engineering Report (PER), Sanitation Districts of Los Angeles
County, January, 2009
5.Landslide Workshop Results Presented to City Council, 31 July 2012
2013: http://www.rpvca.gov/documentcenter/view/5564
6.Trump National Golf Course
https://en.m.wikipedia.org/wiki/Trump_National_Golf_Club_(Los_Angeles)#
History
7.“Nature Takes its Course”, Daily Breeze Report, 3 June, 1999, courtesy of
Monique Sugimoto, Archivist and Adult Services Librarian, Palos Verdes
Library District
8.Ocean Trails Journal, Week 73, June 6, 1999, courtesy of Monique Sugimoto,
Archivist and Adult Services Librarian, Palos Verdes Library District
9.Golfing Atop a Landslide, https://www.tencategeo.us/media/54129420-
94ab-4926-ade3-
24c42021305f/_Apx4g/TenCate%20Geosynthetics/Documents%20AMER/I
ndustry%20Papers/Golfing%20atop%20a%20landslide
10.History of Ocean Trails/Trump National Golf Club, Maureen Megowan,
January, 2014,
11.White Point Landslide: Project Summary, https://eng.lacity.org/whitepoint
12.Slip Sliding Away: the Landslides of Palos Verdes,
https://easyreadernews.com/slip-sliding-away/
13.New 3D Mapping Technique Improves Landslide Hazard Prediction,
https://www.jpl.nasa.gov/news/news.php?feature=7672&utm_source=iCon
tact&utm_medium=email&utm_campaign=nasajpl&utm_content=uavsar202
00603-1
14.Personal telephone discussion with Kathleen Ehlig discussing the
remediation efforts at Big Rock Mesa.
15.Bentonite Resistance to Cation Exchange for Geomembrane Supported GCL
Products. GSE Technical Note;
http://www.gseworld.com/content/documents/technical-
notes/Bentonite_Resistance_to_Cation_Exchange-Tech_Note.pdf
16.Smectite clay minerals: properties and uses, The Royal Society Publishing;
I. E. Odom; https://doi.org/10.1098/rsta.1984.0036
IMAC 11/16/20 Mtg Item A- page 39E-39
IMAC Landflow Report Approved 9.21.2020
40
17. Boral Material Safety Data Sheet – Fly Ash,
https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=
&cad=rja&uact=8&ved=2ahUKEwjKr6_lidPrAhWzoFsKHet-
CQMQFjABegQIBhAB&url=https%3A%2F%2Fflyash.com%2Fwp-
content%2Fuploads%2F2018%2F09%2FSDS-Fly-Ash-All-Types-18-
0731.pdf&usg=AOvVaw0eOOimVat0bq0CXYP8YDox
18. Oral communication, the late Dr. Robert Douglas to Wedemeyer.
7. Appendices
IMAC 11/16/20 Mtg Item A- page 40E-40
IMAC Landflow Report Approved 9.21.2020
41
Appendix 1 – Reproduction of the IMAC Landflow Subcommittee Risk Analysis
Slides 1-6
IMAC 11/16/20 Mtg Item A- page 41E-41
IMAC Landflow Report Approved 9.21.2020
42
Appendix 1 – Reproduction of the IMAC Landflow Subcommittee Risk Analysis
Slides 7-12
IMAC 11/16/20 Mtg Item A- page 42E-42
IMAC Landflow Report Approved 9.21.2020
43
Appendix 1 – Reproduction of the IMAC Landflow Subcommittee Risk Analysis
Slides 13-17
IMAC 11/16/20 Mtg Item A- page 43E-43
6.Are there risks that might affect the success of ongoing or future projects?
Certainly, every project comes with a level of risk that is considered prior to onset and
re-evaluated as the individual project moves forward. The project is continuously
evaluated in its progression.
7.How are the department’s facilities insured against risks?
Facilities are insured through California Joint Powers Insurance Agency (CJPIA). Groups
using the facilities for special programs and activities are required to provide insurance
coverage naming the City as additionally insured.
8.Does the Department have disaster recovery plans?
Yes, each facility has an emergency plan as facilitated by the City Emergency Analyst.
Additionally, several parks are designated emergency evacuation centers. Caches of
emergency supplies are stored at several of these facilities.
Questions regarding future plans:
9.Are there formal short and long term plans for future projects within the Parks
Department?
Current projects include the Ladera Linda Park Master Plan, Preserve/Del Cerro area
improvements, update of the Trails Network Plan, and the Civic Center Master Plan.
10. What criteria are applied to determine recommended projects?
The criteria ranges from project to project but typically includes community
need/desire, budgetary impacts, short and long-term maintenance impacts, analysis of
community/resident impacts, time constraints, and human resources.
Questions regarding coordination:
11. What policies determine whether approved projects are managed by RPV’s Public Works
Department or some other department?
The usual division is that DPW, in coordination with DRP and other Departments,
manages larger construction and maintenance projects, while DRP manages day-to-day
operations of park and Preserve staffing, programs, activities and events.
12. What issues arise in cooperative planning, completing, managing and maintaining facilities
with other jurisdictions?
Effective and ongoing communication with other jurisdictions addresses most potential
issues that arise in managing facilities. Robust public outreach is essential at an early
stage to bring issues to light and address them in a timely fashion, especially involving
the potential budget and scope of a project.
-2-
IMAC 11/16/2020 Mtg Item 1- Page 2E-44
Questions regarding funding:
13. Are there dedicated sources of funding for parks and related infrastructure projects?
Outside of general fund money allocated to parks and related infrastructure projects in
the DRP and DPW budgets, the City receives LA County and other grants as well as
Quimby Act funds.
IMAC 11/16/2020 Mtg Item 1- Page 3E-45
Prioritization Criteria:
1.Aesthetics:
•Aesthetics # of Views: How many residents will benefit from the disappearance of the
overhead lines while at home. 0 = not visible from homes, 3=one street, 5=one
neighborhood, 7=multiple neighborhoods, 10=much of the city.
•Aesthetics Current: How unsightly are they now.
◦Wires going across the street to housed and light poles?
◦Wires on both sides of the street?
◦Both telephone and power lines and number of lines.
◦Located at a city entrance.
◦Equipment above vegetation and trees.
◦Equipment blocking the view from the road.
◦Wood vs. metal poles. Pole that are not vertical.
◦Visible or hidden by trees.
•Aesthetics # Traffic: Traffic volume (foot, bike and car) in the area that would notice.
Arterial vs collector street. Number of lanes. 10=main road (Hawthorne, PVDN), 8=almost
main (upper Crenshaw, Crest, PVDS and E), 6=feeder (Silver Spur, Montemalaga)
2.Fire Potential:
•Local fuel source and connected fuel source. General fire danger in the area including brush,
access.
•Plants and trees near the wires.
•Level of wind in the area.
3.Damage (wind, car accident etc.) Potential:
•Severity of the damage – blocked road, possible fire, outage …
•Likelihood of the event occurring.
•Type of event: wind damage, car accident
•Level of wind in the area and proximity to trees.
•Number and significance of customers served (or not served) in an outage due to damage.
4.Rule 20A area of unusual scenic interest (other topics are covered above).
IMAC 11/16/20 Mtg Item 2- Page 1 E-46
Agenda Item 3 Page 1
MEMORANDUM RANCHO PALOS VERDES
DATE: NOVEMBER 16, 2020
TO: CHAIR SWANSON AND MEMBERS OF THE INFRASTRUCTURE
MANAGEMENT ADVISORY COMMITTEE
FROM: RON DRAGOO, PE, PRINCIPAL ENGINEER
SUBJECT: AGENDA ITEM NO. 3 – DISCUSS APPROVED LIST OF 5-YEAR CIP
PROJECTS (CIP)
RECOMMENDATION
Discuss, receive and file.
DISCUSSION
This item was placed on the agenda by Chair Swanson. The purpose is to provide
an early opportunity to discuss the City’s approved list of 5-year Capital Improvement
Projects (CIP) in anticipation of the upcoming FY 21/22 budget/CIP process.
Attachment: City Approved 5-Year CIP
E-47
IMAC 11/16/2020 Mtg Item 3- Attach A page 1E-48
IMAC 11/16/2020 Mtg Item 3- Attach A page 2E-49
STATE OF CALIFORNIA-CALIFORNIA STATE TRANSPORTATION AGENCY GAVIN NEWSOM Governor
DEPARTMENT OF TRANSPORTATION
DISTRICT 7
100 S. MAIN STREET, MS 16
LOS ANGELES, CA 90012
PHONE (213) 897-8391
Serious Drought.
Making Conservation
a California Way of Life. FAX (213) 897-1337
TTY 711
www.dot.ca.gov
December 9, 2020
Mr. Ron Dragoo, City Engineer
City of Rancho Palos Verdes
30940 Hawthorne Boulevard
Rancho Palos Verdes, CA 90275-5391
Dear Mr. Dragoo:
RE: Portuguese Bend Landslide Mitigation
Vic. LA-213 PM 0.266
SCH # 2020110212
GTS # LA-2020-03421AL-NOP
Thank you for including the California Department of Transportation (Caltrans) in the
environmental review process for the above referenced project The Portuguese Bend
Landslide Mitigation Project (Project) would control the existing landslide area. The
proposed Project involves a series of recommended mitigation measures which follow
a phased-approach to construction and installation. The construction is likely to be
implemented in stages, which may occur separately. The anticipated construction
phasing as follows: (i) surface fracture infilling; (ii) surface water improvements; and (iii)
groundwater mitigation improvements. Periodic field observation should be performed
during construction under the supervision of the appropriate California registered
Engineer. Post-construction items are anticipated to include long-term maintenance,
landslide monitoring, and possible future construction phases.
The mission of Caltrans is to provide a safe, sustainable, integrated and efficient
transportation system to enhance California's economy and livability. Senate Bill 743
(2013) has been codified into CEQA law. It mandates that CEQA review of
transportation impacts of proposed developments be modified by using Vehicle Miles
Traveled (VMT) as the primary metric in identifying transportation impacts. As a
reminder, Vehicle Miles Traveled (VMT) is the standard transportation analysis metric
in CEQA for land use projects after the July 1, 2020 statewide implementation date.
You may reference The Governor's Office of Planning and Research (OPR) website for
more information.
http://opr.ca.gov/ceqa/updates/guidelines/
As a reminder, all future developments should incorporate multi-modal and complete
streets transportation elements that will actively promote alternatives to car use and
better manage existing parking assets. Prioritizing and allocating space to efficient
"Provide a safe, sustainable, integrated and efficient transportatwn system
to enhance California's economy and livability"
F-1
Mr. Ron Dragoo, City Engineer
December 9, 2020
Page 2 of 2
modes of travel such as bicycling and public transit can allow streets to transport more
people in a fixed amount of right-of-way.
Caltrans supports the implementation of complete streets and pedestrian safety
measures such as road diets and other traffic calming measures. Please note the
Federal Highway Administration (FHWA) recognizes the road diet treatment as a proven
safety countermeasure, and the cost of a road diet can be significantly reduced if
implemented in tandem with routine street resurfacing.
Also, Caltrans has published the VMT-focused Transportation Impact Study Guide
(TISG), dated May 20, 2020 and Caltrans Interim Land Development and
Intergovernmental Review (LD-IGR) Safety Review Practitioners Guidance, prepared in
July 2020.
https://dot.ca.gov/programs/transportation-planning/office-of-smart-mobility-climate-
change/sb-7 43
For future development TOM options, please refer to the Federal Highway
Administration's Integrating Demand Management into the Transportation Planning
Process: A Desk Reference (Chapter 8). This reference is available online at:
http://www.ops.fhwa.dot.gov/publications/fhwahop12035/fhwahop12035.pdf
For this project, transportation of heavy construction equipment and/or materials, which
requires the use of oversized-transport vehicles on State highways, will require a
transportation permit from Caltrans. It is recommended that large size truck trips be
limited to off-peak commute periods and idle time not to exceed 10 minutes.
If you have any questions, please feel free to contact Mr. Alan Lin the project coordinator
at (213) 897-8391 and refer to GTS # LA-2020-03421AL-NOP.
Sincerely,
~c-~~~
MIYA EDMONSON
IGR/CEQA Branch Chief
email: State Clearinghouse
"Provide a safe, sustainable, integrated and efficient transportation system
to enhance California's economy and livability"
F-2
Ron Dragoo
From:
Sent:
To:
Subject:
Katie Lozano
Katie Lozano
Friday, December 11, 2020 12:21 PM
Ron Dragoo
Fw: Trails
Senior Administrative Analyst
Recreation, Parks, and Open Space
City of Rancho Palos Verdes
310-544-5267
City Hall is open to the public during regular business hours. To help prevent the spread of COVID-19, visitors
are required to wear face coverings and adhere to physical distancing guidelines. Some employees are
working on rotation and may be working remotely. If you need to visit City Hall, please schedule an
appointment in advance by calling the appropriate department and follow all posted directions during your
visit. Walk-ups are limited to one person at a time. Please note that our response to your inquiry could be
delayed. For a list of department phone numbers, visit the Staff Directory on the City website.
From: Katie Lozano
Sent: Thursday, December 10, 2020 3:11 PM
To: Debbie Denise
Cc: CC; CityCierk
Subject: Re: Trails
Hello Ms. Denise,
Thank you for your email. The Portuguese Bend Landslide Remediation Project and Preserve
Parking and Access efforts are being prepared in compliance with the City's Trails Network Plan,
Conceptual Trails Plan and Preserve Public Use Master Plan. The Preserve Parking and Access
effort does not propose development internal to the Preserve or on open space land that would
trigger closing existing trails or implementing new conceptual trails, and at this time the Portuguese
Bend Landslide Remediation Project is not anticipated to cause any existing authorized trails to be
relocated. However, if an authorized trail is temporarily closed during construction of the project, the
City will repair and reopen the trail as part of the project. Moreover, both of these City
projects will not result in the permanent closure of the two authorized access points from the
Portuguese Bend Community to the Preserve.
It is the City's practice to identify opportunities during construction projects to implement
the conceptual trails identified within the Conceptual Trails Plan (the trails identified in the Preserve
Trails Plan of the Public Use Master Plan ((PUMP)) already exist). However, in the case of private
development projects, the City cannot require a private property owner to implement a trail on their
private property. In these cases, the City works with the private property owner at the time the
property owner submits a development application to describe the benefits of dedicating the
F-3
appropriate easements for trail access and to determine if the property owner is willing to voluntarily
dedicate land for a trail easement. Again, the City cannot require such a trail easement dedication
from a property owner.
Public safety is top priority for the City. The City works directly with the LA County Fire Department
and LA County Sheriff's Department on disaster evacuation, firefighting access, and emergency
preparedness. In fact, the City held a test operation of the Emergency Operations Center in
November in coordination with public safety agencies, and a focus was emergency response
within the Preserve. The network of existing trails throughout the City do offer access in response to
an emergency if warranted.
I hope this information is helpful. Please let me know if I can provide additional or more specific
information.
Thank you,
Katie Lozano
Senior Administrative Analyst
Recreation, Parks, and Open Space
City of Rancho Palos Verdes
310-544-5267
City Hall is open to the public during regular business hours. To help prevent the spread of COVID-19, visitors
are required to wear face coverings and adhere to physical distancing guidelines. Some employees are
working on rotation and may be working remotely. If you need to visit City Hall, please schedule an
appointment in advance by calling the appropriate department and follow all posted directions during your
visit. Walk-ups are limited to one person at a time. Please note that our response to your inquiry could be
delayed. For a list of department phone numbers, visit the Staff Directory on the City website.
From: Debbie Denise <ddmbeach@gmail.com>
Sent: Thursday, December 10, 2020 11:05 AM
To: Nathan Zweizig; Katie Lozano; CC
Cc: CityCierk
Subject: Re: Trails
Thanks so much for letting me know, I've attached a PDF version ....
2 F-4
Ron Dragoo
From: Katie Lozano
Sent:
To:
Friday, December 11, 2020 12:21 PM
Ron Dragoo
Subject: Fw: Community response to city projects
Katie Lozano
Senior Administrative Analyst
Recreation, Parks, and Open Space
City of Rancho Palos Verdes
310-544-5267
City Hall is open to the public during regular business hours. To help prevent the spread of COVID-19, visitors
are required to wear face coverings and adhere to physical distancing guidelines. Some employees are
working on rotation and may be working remotely. If you need to visit City Hall, please schedule an
appointment in advance by calling the appropriate department and follow all posted directions during your
visit. Walk-ups are limited to one person at a time. Please note that our response to your inquiry could be
delayed. For a list of department phone numbers, visit the Staff Directory on the City website.
From: Katie Lozano
Sent: Thursday, December 10, 2020 3:09 PM
To: Joan Taylor
Cc: CC; CityCierk
Subject: Re: Community response to city projects
Hello Ms. Taylor,
Thank you for your email. The Portuguese Bend Landslide Remediation Project and Preserve
Parking and Access efforts are being prepared in compliance with the City's Trails Network Plan,
Conceptual Trails Plan and Preserve Public Use Master Plan. The Preserve Parking and Access
effort does not propose development internal to the Preserve or on open space land that would
trigger closing existing trails or implementing new conceptual trails, and at this time the Portuguese
Bend Landslide Remediation Project is not anticipated to cause any existing authorized trails to be
relocated. However, if an authorized trail is temporarily closed during construction of the project, the
City will repair and reopen the trail as part of the project. Moreover, both of these City
projects will not result in the permanent closure of the two authorized access points from the
Portuguese Bend Community to the Preserve.
It is the City's practice to identify opportunities during construction projects to implement
the conceptual trails identified within the Conceptual Trails Plan (the trails identified in the Preserve
Trails Plan of the Public Use Master Plan ((PUMP)) already exist). However, in the case of private
development projects, the City cannot require a private property owner to implement a trail on their
private property. In these cases, the City works with the private property owner at the time the
property owner submits a development application to describe the benefits of dedicating the
1
F-5
appropriate easements for trail access and to determine if the property owner is willing to voluntarily
dedicate land for a trail easement. Again, the City cannot require such a trail easement dedication
from a property owner.
Public safety is top priority for the City. The City works directly with the LA County Fire Department
and LA County Sheriff's Department on disaster evacuation, firefighting access, and emergency
preparedness. In fact, the City held a test operation of the Emergency Operations Center in
November in coordination with public safety agencies, and a focus was emergency response
within the Preserve. The network of existing trails throughout the City do offer access in response to
an emergency if warranted.
I hope this information is helpful. Please let me know if I can provide additional or more specific
information.
Thank you,
Katie Lozano
Senior Administrative Analyst
Recreation, Parks, and Open Space
City of Rancho Palos Verdes
310-544-5267
City Hall is open to the public during regular business hours. To help prevent the spread of COVID-19, visitors
are required to wear face coverings and adhere to physical distancing guidelines. Some employees are
working on rotation and may be working remotely. If you need to visit City Hall, please schedule an
appointment in advance by calling the appropriate department and follow all posted directions during your
visit. Walk-ups are limited to one person at a time. Please note that our response to your inquiry could be
delayed. For a list of department phone numbers, visit the Staff Directory on the City website.
From: Joan Taylor <jtaylor@dhs.lacounty.gov>
Sent: Thursday, December 10, 2020 11:44 AM
To: CC; CityCierk; Katie Lozano
Subject: FW: Community response to city projects
From: Joan Taylor <jododge29@yahoo.com>
Sent: Thursday, December 10, 2020 11:11 AM
To: Joan Taylor <jtaylor@dhs.lacounty.gov>
Subject: Fwd: Community response to city projects
: External Email. Proceed Responsibly.
Sent from my iPhone
Begin forwarded message:
From: GRACE <jordette@msn.com>
Date: December 10, 2020 at 10:46:18 AM PST
2 F-6
To: Jododge29@yahoo.com
Subject: Community response to city projects
Hi,
Please let save our trails
• Please sign and send the attached letter or rewrite it in your own words .
• Please forward to all your contacts who share your concerns
• All e-mails need to be received no later than 12/14.
• Address your email to:
cc@rpvca.gov
cityclerk@rpvca.gov
katiel@rpvca.gov
3
F-7
Ron Dragoo
From: Katie Lozano
Sent:
To:
Friday, December 11, 2020 12:17 PM
Ron Dragoo
Subject: Fw: Concerns related to Projects: Mitigation, trails, parking
Katie Lozano
Senior Administrative Analyst
Recreation, Parks, and Open Space
City of Rancho Palos Verdes
310-544-5267
City Hall is open to the public during regular business hours. To help prevent the spread of COVID-19, visitors
are required to wear face coverings and adhere to physical distancing guidelines. Some employees are
working on rotation and may be working remotely. If you need to visit City Hall, please schedule an
appointment in advance by calling the appropriate department and follow all posted directions during your
visit. Walk-ups are limited to one person at a time. Please note that our response to your inquiry could be
delayed. For a list of department phone numbers, visit the Staff Directory on the City website.
From: Katie Lozano
Sent: Thursday, December 10, 2020 4:58PM
To: CityCierk
Subject: Fw: Concerns related to Projects: Mitigation, trails, parking
Late correspondence.
Katie Lozano
Senior Administrative Analyst
Recreation, Parks, and Open Space
City of Rancho Palos Verdes
310-544-5267
City Hall is open to the public during regular business hours. To help prevent the spread of COVID-19, visitors
are required to wear face coverings and adhere to physical distancing guidelines. Some employees are
working on rotation and may be working remotely. If you need to visit City Hall, please schedule an
appointment in advance by calling the appropriate department and follow all posted directions during your
visit. Walk-ups are limited to one person at a time. Please note that our response to your inquiry could be
delayed. For a list of department phone numbers, visit the Staff Directory on the City website.
From: Professor Ohlaker <professorohlaker@gmail.com>
Sent: Thursday, December 10, 2020 4:55PM
To: Katie Lozano
Subject: Re: Concerns related to Projects: Mitigation, trails, parking
1
F-8
Thank you Katie, I appreciate your response.
Please add my letter to those to be discussed during the upcoming meeting.
Best,
JoNeen
JoNeen Ohh1ker
Professor, Child Development I
Science & Family Consumer Studies Division
Los "-\ngeles Community College District
OHLAKEJ@LACCD.EDU
(310) 809-2425
.\djunct Faculty Issues Committee Representative I Harbor College Chapter
Los "\ngeles College Faculty Guild I c\FT Local 1521
ProfessorOhiaker@gmail.com
CPP I College of Education and Integrative Studies I Early Childhood Education
California State Polytechnic University, Pomona
National University
JOhlaker@CPP.EDU
California Faculty .\ssociation Lecturer Representative
California State Polytechnic University, Pomona
JOhlaker@CPP.EDU
Sanford College of Education I Teacher Education I Early Childhood Studies
Inspired Teaching & Learning
National University
JoNeen.Ohlaker@N"\TUNI\'.EDU
N_\EYC Higher Education _\ccreditation I Peer Review Team
National_\ssociation for the Education of Young Children
JoNeenOhlakerPBC\@Gl\L\IL.COi\1
Porh1guese Bend Community _-\ssociationBoard l\Iember I \'ice President I Board of Directors
Roadsides East & \\'est
JoNeenOhlakerPBCA@GM.AIL.COM
(31 0) 809-2425
On Dec 10, 2020, at 4:45PM, Katie Lozano <Katiel@rpvca.gov> wrote:
Hello Mr. Ohlaker,
Thank you for your email. The Portuguese Bend Landslide Remediation Project and Preserve Parking and
Access efforts are being prepared in compliance with the City's Trails Network Plan, Conceptual Trails Plan
and Preserve Public Use Master Plan. The Preserve Parking and Access effort does not propose
development internal to the Preserve or on open space land that would trigger closing existing trails or
implementing new conceptual trails, and at this time the Portuguese Bend Landslide Remediation Project
is not anticipated to cause any existing authorized trails to be relocated. However, if an authorized trail is
temporarily closed during construction of the project, the City will repair and reopen the trail as part of
2 F-9
Ron Dragoo
From:
Sent:
To:
Subject:
Katie Lozano
Katie Lozano
Friday, December 11, 2020 12:19 PM
Ron Dragoo
Fw: Saving our trails
Senior Administrative Analyst
Recreation, Parks, and Open Space
City of Rancho Palos Verdes
310-544-5267
City Hall is open to the public during regular business hours. To help prevent the spread of COVID-19, visitors
are required to wear face coverings and adhere to physical distancing guidelines. Some employees are
working on rotation and may be working remotely. If you need to visit City Hall, please schedule an
appointment in advance by calling the appropriate department and follow all posted directions during your
visit. Walk-ups are limited to one person at a time. Please note that our response to your inquiry could be
delayed. For a list of department phone numbers, visit the Staff Directory on the City website.
From: Katie Lozano
Sent: Thursday, December 10, 2020 3:27 PM
To: Matarazzo, Andrew
Cc: CC; CityCierk
Subject: Re: Saving our trails
Hello Mr. Matarazzo,
Thank you for your email. The Portuguese Bend Landslide Remediation Project and Preserve
Parking and Access efforts are being prepared in compliance with the City's Trails Network Plan,
Conceptual Trails Plan and Preserve Public Use Master Plan. The Preserve Parking and Access
effort does not propose development internal to the Preserve or on open space land that would
trigger closing existing trails or implementing new conceptual trails, and at this time the Portuguese
Bend Landslide Remediation Project is not anticipated to cause any existing authorized trails to be
relocated. However, if an authorized trail is temporarily closed during construction of the project, the
City will repair and reopen the trail as part of the project. Moreover, both of these City
projects will not result in the permanent closure of the two authorized access points from the
Portuguese Bend Community to the Preserve.
It is the City's practice to identify opportunities during construction projects to implement
the conceptual trails identified within the Conceptual Trails Plan (the trails identified in the Preserve
Trails Plan of the Public Use Master Plan ((PUMP)) already exist). However, in the case of private
development projects, the City cannot require a private property owner to implement a trail on their
private property. In these cases, the City works with the private property owner at the time the
property owner submits a development application to describe the benefits of dedicating the
appropriate easements for trail access and to determine if the property owner is willing to voluntarily
F-10
dedicate land for a trail easement. Again, the City cannot require such a trail easement dedication
from a property owner.
Public safety is top priority for the City. The City works directly with the LA County Fire Department
and LA County Sheriff's Department on disaster evacuation, firefighting access, and emergency
preparedness. In fact, the City held a test operation of the Emergency Operations Center in
November in coordination with public safety agencies, and a focus was emergency response
within the Preserve. The network of existing trails throughout the City do offer access in response to
an emergency if warranted.
I hope this information is helpful. Please let me know if I can provide additional or more specific
information.
Thank you,
Katie Lozano
Senior Administrative Analyst
Recreation, Parks, and Open Space
City of Rancho Palos Verdes
310-544-5267
City Hall is open to the public during regular business hours. To help prevent the spread of COVID-19, visitors
are required to wear face coverings and adhere to physical distancing guidelines. Some employees are
working on rotation and may be working remotely. If you need to visit City Hall, please schedule an
appointment in advance by calling the appropriate department and follow all posted directions during your
visit. Walk-ups are limited to one person at a time. Please note that our response to your inquiry could be
delayed. For a list of department phone numbers, visit the Staff Directory on the City website.
From: Matarazzo, Andrew <amatarazzo@oaktreecapital.com>
Sent: Tuesday, December 8, 2020 3:50PM
To: CC; CityCierk; Katie Lozano
Cc: sherihastings@yahoo.com
Subject: Saving our trails
Please find attached a letter outlining concerns about equestrian trail access and maintenance.
Andy Matarazzo
amatarazzo@oaktreecapital.com
1-213-830-6778 (p)
1-310-920-7013 (m)
2 F-11
the project. Moreover, both of these City projects will not result in the permanent closure of the two
authorized access points from the Portuguese Bend Community to the Preserve.
It is the City's practice to identify opportunities during construction projects to implement the conceptual
trails identified within the Conceptual Trails Plan (the trails identified in the Preserve Trails Plan of the
Public Use Master Plan ((PUMP)) already exist). However, in the case of private development projects, the
City cannot require a private property owner to implement a trail on their private property. In these cases,
the City works with the private property owner at the time the property owner submits a development
application to describe the benefits of dedicating the appropriate easements for trail access and to
determine if the property owner is willing to voluntarily dedicate land for a trail easement. Again, the City
cannot require such a trail easement dedication from a property owner.
Public safety is top priority for the City. The City works directly with the LA County Fire Department and
LA County Sheriff's Department on disaster evacuation, firefighting access, and emergency
preparedness. In fact, the City held a test operation of the Emergency Operations Center in November in
coordination with public safety agencies, and a focus was emergency response within the Preserve. The
network of existing trails throughout the City do offer access in response to an emergency if warranted.
I hope this information is helpful. Please let me know if I can provide additional or more specific
information.
Katie Lozano
Senior Administrative Analyst
Recreation, Parks, and Open Space
City of Rancho Palos Verdes
310-544-5267
City Hall is open to the public during regular business hours. To help prevent the spread of
COVID-19, visitors are required to wear face coverings and adhere to physical distancing
guidelines. Some employees are working on rotation and may be working remotely. If you
need to visit City Hall, please schedule an appointment in advance by calling the appropriate
department and follow all posted directions during your visit. Walk-ups are limited to one
person at a time. Please note that our response to your inquiry could be delayed. For a list of
department phone numbers, visit the Staff Directory on the City website.
From: Professor Ohlaker <professorohlaker@gmail.com>
Sent: Thursday, December 10, 2020 4:38 PM
To: CC; CityCierk; Katie Lozano
Cc: Sheri Hastings
Subject: Concerns related to Projects: Mitigation, trails, parking
3
F-12
Ron Dragoo
From: Katie Lozano
Sent:
To:
Friday, December 11, 2020 12:17 PM
Ron Dragoo
Subject: Fw: Save our trails
Katie Lozano
Senior Administrative Analyst
Recreation, Parks, and Open Space
City of Rancho Palos Verdes
310-544-5267
City Hall is open to the public during regular business hours. To help prevent the spread of COVID-19, visitors are
required to wear face coverings and adhere to physical distancing guidelines. Some employees are working on rotation
and may be working remotely. If you need to visit City Hall, please schedule an appointment in advance by calling the
appropriate department and follow all posted directions during your visit. Walk-ups are limited to one person at a time.
Please note that our response to your inquiry could be delayed. For a list of department phone numbers, visit the Staff
Directory on the City website.
From: Katie Lozano
Sent: Thursday, December 10, 2020 3:23PM
To: Lisa Wolf
Cc: CC; CityCierk
Subject: Re: Save our trails
Hello Ms. Wolf,
Thank you for your email. The Portuguese Bend Landslide Remediation Project and Preserve Parking and Access efforts
are being prepared in compliance with the City's Trails Network Plan, Conceptual Trails Plan and Preserve Public Use
Master Plan. The Preserve Parking and Access effort does not propose development internal to the Preserve or on
open space land that would trigger closing existing trails or implementing new conceptual trails, and at this time the
Portuguese Bend Landslide Remediation Project is not anticipated to cause any existing authorized trails to be relocated.
However, if an authorized trail is temporarily closed during construction of the project, the City will repair and reopen
the trail as part of the project. Moreover, both of these City projects will not result in the permanent closure of the two
authorized access points from the Portuguese Bend Community to the Preserve.
It is the City's practice to identify opportunities during construction projects to implement the conceptual trails
identified within the Conceptual Trails Plan (the trails identified in the Preserve Trails Plan of the Public Use Master Plan
((PUMP)) already exist). However, in the case of private development projects, the City cannot require a private
property owner to implement a trail on their private property. In these cases, the City works with the private property
owner at the time the property owner submits a development application to describe the benefits of dedicating the
appropriate easements for trail access and to determine if the property owner is willing to voluntarily dedicate land for a
trail easement. Again, the City cannot require such a trail easement dedication from a property owner.
Public safety is top priority for the City. The City works directly with the LA County Fire Department and LA County
Sheriff's Department on disaster evacuation, firefighting access, and emergency preparedness. In fact, the City held a
1
F-13
test operation of the Emergency Operations Center in November in coordination with public safety agencies, and a focus
was emergency response within the Preserve. The network of existing trails throughout the City do offer access in
response to an emergency if warranted.
I hope this information is helpful. Please let me know if I can provide additional or more specific information.
Thank you,
Katie Lozano
Senior Administrative Analyst
Recreation, Parks, and Open Space
City of Rancho Palos Verdes
310-544-5267
City Hall is open to the public during regular business hours. To help prevent the spread of COVID-19, visitors are
required to wear face coverings and adhere to physical distancing guidelines. Some employees are working on rotation
and may be working remotely. If you need to visit City Hall, please schedule an appointment in advance by calling the
appropriate department and follow all posted directions during your visit. Walk-ups are limited to one person at a time.
Please note that our response to your inquiry could be delayed. For a list of department phone numbers, visit the Staff
Directory on the City website.
From: Lisa Wolf <javelot@icloud.com>
Sent: Wednesday, December 9, 2020 8:59AM
To: CC; CC; CityCierk; Katie Lozano
Cc: Sheri Hasting
Subject: Save our trails
2 F-14
Ron Dragoo
From:
Sent:
To:
Subject:
Attachments:
l<elene and Octavia,
Ron Dragoo
Tuesday, November 24, 2020 8:12AM
Kelene Strain; Octavia Silva
Native American Heritage Commission
Letter -Native American Heritage Commission .. pdf
Attached is a letter we received form the Native American Heritage Commission. Please provide direction
regarding its significance and advise what our next steps should be if any. Thank you.
Ron Dragoo, PE
Principal Engineer
City Hall is open to the public during regular business hours. To help prevent the spread of COVID-19, visitors
are required to wear face coverings and adhere to physical distancing guidelines. Some employees are working
on rotation and may be working remotely. If you need to visit City Hall, please schedule an appointment in
advance by calling the appropriate department and follow all posted directions during your visit. Walk-ups are
limited to one person at a time. Please note that our response to your inquiry could be delayed. For a list of
department phone numbers, visit the Staff Directory on the City website.
1
F-15
CHAIRPERSON
Laura Miranda
Luiseiio
VICE CHAIRPERSON
Reginald Pagallng
Chumash
SECRETARY
Merri Lopez-Keller
Luiseiio
PARLIAMENTARIAN
Russell AHebery
Karuk
COMMISSIONER
Marshall McKay
Win tun
COMMISSIONER
William Mungary
Paiute/White Mountain
Apache
COMMISSIONER
Julie Tumamait·
Stenslle
Chumash
COMMISSIONER
[Vacant]
COMMISSIONER
[Vacant]
EXECUTIVE SECRETARY
ChrtsHna Snider
Pomo
NAHC HEADQUARTERS
1550 Harbor Boulevard
Suite 100
West Sacramento,
California 95691
(916) 373-3710
nohc@nahc.co.gov
NAHC.ca.gov
STATE OF CALIFORNIA Gavin Newsom Goyemor
NATIVE AMERICAN HERITAGE COMMISSION
November 16, 2020
Ron Dragoo
City of Rancho Palos Verdes
30940 Hawthorne Boulevard ·
Rancho Palos Verdes, CA 90275
Re: 2020110212, Portuguese Band Landslide Mitigation Project. Los Angeles County
Dear Mr. Dragoo:
The Native American Heritage Commission (NAHC) has received the Notice of Preparation
(NOP), Draft Environmental Impact Report (DEIR} or Early Consultation for the project
referenced above. The California Environmental Quality Act (CEQA) (Pub. Resources Code
§21000 et seq.), specifically Public Resources Code §21 084.1, states that a project that may
cause a substantial adverse change in the significance of a historical resource, is a project that
may have a significant effect on the environment. (Pub. Resources Code§ 21084.1; Cal. Code
Regs., tit.14, § 15064.5 (b) (CEQA Guidelines§ 15064.5 (b)). If there is substantial evidence, in
light of the whole record before a lead agency, that a project may have a significant effect on
the environment, an Environmental Impact Report (EIR} shall be prepared. (Pub. Resources
Code §21080 (d); Cal. Code Regs., tit. 14, § 5064 subd.(a)(l) (CEQA Guidelines§ 15064 (a)( 1 )).
In order to determine whether a project will cause a substantial adverse change in the
significance of a historical resource, a lead agency will need to determine whether there are
historical resources within the area of potential effect (APE).
CEQA was amended significantly in 2014. Assembly Bill 52 (Gatto, Chapter 532, Statutes of
2014) (AB 52) amended CEQA to create a separate category of cultural resources, "tribal
cultural resources" (Pub. Resources Code §21074) and provides that a project with an effect
that may cause a substantial adverse change in the significance of a tribal cultural resource is
a project that may have a significant effect on the environment. (Pub. Resources Code
§21084.2). Public agencies shall, when feasible, avoid damaging effects to any tribal cultural
resource. (Pub. Resources Code §21084.3 (a)). AB 52 applies to any project for which a notice
of preparation, a notice of negative declaration, or a mitigated negative declaration Is flied on
or after July 1, 2015. If your project involves the adoption of or amendment to a general plan or
a specific plan, or the designation or proposed designation of open space, on or after March 1,
2005, it may also be subject to Senate Bil118 (Burton, Chapter 905, Statutes of 2004) (SB 18).
Both SB 18 and AB 52 have tribal consultation requirements. If your project is also subject to the
federal National Environmental Policy Act (42 U.S.C. § 4321 et seq.) (NEPA), the tribal
consultation requirements of Section 1 06 of the National Historic Preservation Act of 1966 ( 154
U.S.C. 300101,36 C.F.R. §800 et seq.) may also apply.
The NAHC recommends consultation with California Native American tribes that are
traditionally and culturally affiliated with the geographic area of your proposed project as early
as possible in order to avoid inadvertent discoveries of Native American human remains and
best protect tribal cultural resources. Below is a brief summary of portions of AB 52 and SB 18 as
well as the NAHC's recommendations for conducting cultural resources assessments.
Consult your legal counsel about compliance with AB 52 and SB 18 as well as compliance with
any other applicable laws.
Page 1 of 5
F-16
7. Conclusion of Consultation: Consultation with a tribe shall be considered concluded when either of the
following occurs:
a. The parties agree to measures to mitigate or avoid a significant effect, if a significant effect exists, on
a tribal cultural resource; or
b. A party, acting in good faith and after reasonable effort, concludes that mutual agreement cannot
be reached. (Pub. Resources Code §21080.3.2 (b)).
B. Recommending Mitigation Measures Agreed Upon in Consultation in the Environmental Document: Any
mitigation measures agreed upon in the consultation conducted pursuant to Public Resources Code §21080.3.2
shall be recommended for inclusion in the environmental document and in an adopted mitigation monitoring
and reporting program, if determined to avoid or lessen the impact pursuant to Public Resources Code §21082.3,
subdivision (b), paragraph 2, and shall be fully enforceable. (Pub. Resources Code §21082.3 (a)).
9. Required Consideration of Feasible Mitigation: If mitigation measures recommended by the staff of the lead
agency as a result of the consultation process are not included in the environmental document or if there are no
agreed upon mitigation measures at the conclusion of consultation, or if consultation does not occur, and if
substantial evidence demonstrates that a project will cause a significant effect to a tribal cultural resource, the
lead agency shall consider feasible mitigation pursuant to Public Resources Code §21 084.3 (b). (Pub. Resources
Code §21082.3 (e)).
10. Examples of Mitigation Measures That, If Feasible. May Be Considered to Avoid or Minimize Significant Adverse
Impacts to Tribal Cultural Resources:
a. A voidance and preservation of the resources in place, including, but not limited to:
i. Planning and construction to avoid the resources and protect the cultural and natural
context.
ii. Planning greenspace, parks, or other open space, to incorporate the resources with culturally
appropriate protection and management criteria.
b. Treating the resource with culturally appropriate dignity, taking into account the tribal cultural values
and meaning of the resource, including, but not limited to, the following:
i. Protecting the cultural character and integrity of the resource.
li. Protecting the traditional use of the resource.
iii. Protecting the confidentiality of the resource.
c. Permanent conservation easements or other interests in real property, with culturally appropriate
management criteria for the purposes of preserving or utilizing the resources or places.
d. Protecting the resource. (Pub. Resource Code §21084.3 (b)).
e. Please note that a federally recognized California Native American tribe or a non-federally
recognized California Native American tribe that is on the contact list maintained by the NAHC to protect
a California prehistoric, archaeological, cultural, spiritual, or ceremonial place may acquire and hold
conservation easements if the conservation easement is voluntarily conveyed. (Civ. Code §815.3 (c)).
f. Please note that it is the policy of the state that Native American remains and associated grave
artifacts shall be repatriated. (Pub. Resources Code §5097.991).
11. Prerequisites for Certifying go Environmentallmpqct Report or Adopting a Mitigated Negqtive Declarqtion or
Negqtive Declqrqtion with 0 Significant !mpqct on go Identified Tribal Cultural Resource: An Environmental
Impact Report may not be certified, nor may a mitigated negative declaration or a negative declaration be
adopted unless one of the following occurs:
a. The consultation process between the tribes and the lead agency has occurred as provided in Public
Resources Code § 21080.3.1 and § 21080.3.2 and concluded pursuant to Public Resources Code
§21080.3.2.
b. The tribe that requested consultation failed to provide comments to the lead agency or otherwise
failed to engage in the consultation process.
c. The lead agency provided notice of the project to the tribe in compliance with Public Resources
Code §21080.3.1 (d) and the tribe failed to request consultation within 30 days. (Pub. Resources Code
§21082.3 (d)).
The NAHC's PowerPoint presentation titled, "Tribal Consultation Under AB 52: Requirements and Best Practices" may
be found online at: http://nohc.ca.qov /wp-content /uploads/20 15/10/AB52Triba1Consultafion CaiEPAPDF.pdf
Page 3 of 5
F-17
3. Contact the NAHC for:
a. A Sacred Lands File search. Remember that tribes do not always record their sacred sites in the
Sacred Lands File, nor are they required to do so. A Sacred Lands File search is not a substitute for
consultation wit~ tribes that are traditionally and culturally affiliated with the geographic area of the
project's APE. · · . . · ..
b. A Native AmericdriTribd.i'Consultation List of appropriate tribes for consultation concerning the
project site and to assist in 'pl9n-tiing for avoidance, preservation in place, or, failing both, mitigation
measures.
4. Remember that the lack of surface evide~c'e ·of archaeological resources (including tribal cultural resources)
does not preclude their subsurface existence.
a. Lead agencies should include in their mitigation and monitoring reporting program plan provisions for
the identification and evaluation of inadvertently discovered archaeological resources per Cal. Code
Regs., tit. 14, § 15064.5(f) (CEQA .Guidelines§ 15064.5(f)). In areas of identified archaeological sensitivity, a
certified archaeologist and a culturally affiliated Native American with knowledge of cultural resources
should monjtor all ground-disturbing activities.
b. Lead agencies should include in their mitigation and monitoring reporting program plans provisions
for the disposition of recovered cultural items that are not burial associated in consultation with culturally
affiliated Native Americans.
c. Lead agencies should include in their mitigation and monitoring reporting program plans provisions
for the treatment and disposition of inadvertently discovered Native American human remains. Health
and Safety Code §7050.5, Public Resources Code §5097.98, and Cal. Code Regs., tit. 14, §15064.5,
subdivisions (d) and (e) (CEQA Guidelines§ 15064.5, subds. (d) and (e)) address the processes to be
followed in the event of an inadvertent discovery of any Native American human remains and
associated grave goods in a location other than a dedicated cemetery.
If you have any questions or need additional information, please contact me at my email address:
Andrew.Green@nahc.ca.gov.
Sincerely,
Andrew Green
Cultural Resources Analyst
cc: State Clearinghouse
Page 5 of 5
F-18
Ron Dragoo
From:
Sent:
Kelene Strain <kstrain@chambersgroupinc.com>
Monday, November 30, 2020 3:04 PM
To: Ron Dragoo; Nasser Razepoor; Ramzi Awwad; Octavia Silva
Subject: FW: Native American Heritage Commission SB 18 -Landslide Remediation Project
Team,
As previously indicated, we are fine and in compliance with AB 52. The project does not trigger SB 18. The NAHC letter
was merely a formality.
Thank you,
lVI a
00 3760
kstrain@chambersgroupinc.com www.chambersgroupinc.com
From: Green, Andrew@NAHC <Andrew.Green@nahc.ca.gov>
Sent: Monday, November 30, 2020 2:55 PM
To: Kelene Strain <kstrain@chambersgroupinc.com>
Subject: RE: Native American Heritage Commission SB 18-Landslide Remediation Project
Good Afternoon Ms. Strain,
Whether the project is subject to AB 52 and/or SB 18 is determined by the Lead Agency, not the NAHC. The Notice of
Preparation (NOP) letter you received provides a brief summary of portions of AB 52 and SB 18, however the Lead
Agency ultimately makes the determination.
Regards,
Andrew Green
Native American Heritage Commission
1550 Harbor Blvd., Suite 100
West Sacramento, CA 95691
Andrew.Green@nahc.ca.gov
Direct Line: (916) 573-1072
Office: (916) 373-3710
From: Kelene Strain <kstrain@chambersgroupinc.com>
Sent: Wednesday, November 25, 2020 9:07AM
To: Green, Andrew@NAHC <Andrew.Green@nahc.ca.gov>
Cc: Kelene Strain <kstrain@chambersgroupinc.com>
1
F-19
Subject: FW: Native American Heritage Commission SB 18-Landslide Remediation Project
Importance: High
Dear Andrew,
We received the attached letter from you, and forwarded to us by the Lead Agency, the City of Rancho Palos Verdes.
Your letter states that both AB 52 and SB 18 notifications are warranted, however, my understanding is that this
landslide remediation project triggers only AB 52 as no general plan or specific plan amendment are warranted. Would
you mind clarifying for me your position that SB 18 is also required? We completed the AB 52 process a couple months
ago shortly after we notified the Tribes. I believe one tribe has requested consultation and the City undergoing that
process at this time.
Sincerely,
li r ' [i ~~en1or i\/!anager
866.261 100 ;ws 760
kstrain@chambersgroupinc.com www.chambersgroupinc.com
From: Kelene Strain
Sent: Wednesday, November 25, 2020 8:46AM
To: 'Ron Dragoo' <RonD@rpvca.gov>; Octavia Silva <OctavioS@rpvca.gov>
Cc: Kelene Strain <kstrain@chambersgroupinc.com>; 'Ramzi Awwad' <rawwad@rpvca.gov>
Subject: RE: Native American Heritage Commission-SB 18
Importance: High
Ron,
I believe the NAHC is mistaken and they City needs only to address AB 52, which we already did a few months ago. See
attached. As a matter of fact, I believe the Tribal Chairperson, Robert Dora me, to whom the attached letter is addressed,
requested consultation. I Believe Octavia followed up with the Tribe's request. Please send me all correspondences from
this Tribe and any other tribes and also indicate where the City is in regard to the consultation process. We will want to
add these to the public record, and the EIR appendices.
That said, however, I will call the NAHC and inquire about their reasoning for SB 18. My understanding is the SB 18 is
warranted if the Lead Agency is proposing a general plan or specific plan amendment, yet, this is not the direction we
are going with this landslide mitigation project.
Please feel free to call rne if you have any questions.
Sincerely,
:100
2 F-20
kstrain@chambersgroupinc.com www.chambersgroupinc.com
From: Ron Dragoo <RonD@rpvca.gov>
Sent: Tuesday, November 24, 2020 8:12AM
To: Kelene Strain <kstrain@chambersgroupinc.com>; Octavia Silva <OctavioS@rpvca.gov>
Subject: Native American Heritage Commission
Kelene and Octavia,
Attached is a letter we received form the Native American Heritage Commission. Please provide direction
regarding its significance and advise what our next steps should be if any. Thank you.
Ron Dragoo, PE
Principal Engineer
City Hall is open to the public during regular business hours. To help prevent the spread of COVID-19, visitors
are required to wear face coverings and adhere to physical distancing guidelines. Some employees are working
on rotation and may be working remotely. If you need to visit City Halt please schedule an appointment in
advance by calling the appropriate department and follow all posted directions during your visit. Walk-ups are
limited to one person at a time. Please note that our response to your inquiry could be delayed. For a list of
department phone numbers, visit the Staff Directory on the City website.
3
F-21
Ron Dragoo
From:
Sent:
To:
Subject:
Katie Lozano
Katie Lozano
Friday, December 11, 2020 12:21 PM
Ron Dragoo
Fw: For Consideration: Landslide Mitigation and Parking and Access meetings
Senior Administrative Analyst
Recreation, Parks, and Open Space
City of Rancho Palos Verdes
310-544-5267
City Hall is open to the public during regular business hours. To help prevent the spread of COVID-19, visitors
are required to wear face coverings and adhere to physical distancing guidelines. Some employees are
working on rotation and may be working remotely. If you need to visit City Hall, please schedule an
appointment in advance by calling the appropriate department and follow all posted directions during your
visit. Walk-ups are limited to one person at a time. Please note that our response to your inquiry could be
delayed. For a list of department phone numbers, visit the Staff Directory on the City website.
From: Katie Lozano
Sent: Thursday, December 10, 2020 3:16PM
To: Lisa Gladstone
Cc: CC; CityCierk
Subject: Re: For Consideration: Landslide Mitigation and Parking and Access meetings
Hello Ms. Gladstone,
Thank you for your email. The Portuguese Bend Landslide Remediation Project and Preserve
Parking and Access efforts are being prepared in compliance with the City's Trails Network Plan,
Conceptual Trails Plan and Preserve Public Use Master Plan. The Preserve Parking and Access
effort does not propose development internal to the Preserve or on open space land that would
trigger closing existing trails or implementing new conceptual trails, and at this time the Portuguese
Bend Landslide Remediation Project is not anticipated to cause any existing authorized trails to be
relocated. However, if an authorized trail is temporarily closed during construction of the project, the
City will repair and reopen the trail as part of the project. Moreover, both of these City
projects will not result in the permanent closure of the two authorized access points from the
Portuguese Bend Community to the Preserve.
It is the City's practice to identify opportunities during construction projects to implement
the conceptual trails identified within the Conceptual Trails Plan (the trails identified in the Preserve
Trails Plan of the Public Use Master Plan ((PUMP)) already exist). However, in the case of private
development projects, the City cannot require a private property owner to implement a trail on their
private property. In these cases, the City works with the private property owner at the time the
property owner submits a development application to describe the benefits of dedicating the
appropriate easements for trail access and to determine if the property owner is willing to voluntarily
F-22
dedicate land for a trail easement. Again, the City cannot require such a trail easement dedication
from a property owner.
Public safety is top priority for the City. The City works directly with the LA County Fire Department
and LA County Sheriff's Department on disaster evacuation, firefighting access, and emergency
preparedness. In fact, the City held a test operation of the Emergency Operations Center in
November in coordination with public safety agencies, and a focus was emergency response
within the Preserve. The network of existing trails throughout the City do offer access in response to
an emergency if warranted.
I hope this information is helpful. Please let me know if I can provide additional or more specific
information.
Thank you,
Katie Lozano
Senior Administrative Analyst
Recreation, Parks, and Open Space
City of Rancho Palos Verdes
310-544-5267
City Hall is open to the public during regular business hours. To help prevent the spread of COVID-19, visitors
are required to wear face coverings and adhere to physical distancing guidelines. Some employees are
working on rotation and may be working remotely. If you need to visit City Hall, please schedule an
appointment in advance by calling the appropriate department and follow all posted directions during your
visit. Walk-ups are limited to one person at a time. Please note that our response to your inquiry could be
delayed. For a list of department phone numbers, visit the Staff Directory on the City website.
From: Lisa Gladstone <golisapv@gmail.com>
Sent: Thursday, December 10, 2020 9:34AM
To: CC; CityCierk; Katie Lozano
Subject: For Consideration: Landslide Mitigation and Parking and Access meetings
We have lived in Portuguese Bend for 20+ years. We chose this spot because ofthe direct trail access for
hiking, running and horse riding. Please read the attached letter. Thank you
2 F-23
Ron Dragoo
From:
Sent:
To:
Subject:
Katie Lozano
Katie Lozano
Friday, December 11, 2020 12:21 PM
Ron Dragoo
Fw: Save Our Trails
Senior Administrative Analyst
Recreation, Parks, and Open Space
City of Rancho Palos Verdes
310-544-5267
City Hall is open to the public during regular business hours. To help prevent the spread of COVID-19, visitors
are required to wear face coverings and adhere to physical distancing guidelines. Some employees are
working on rotation and may be working remotely. If you need to visit City Hall, please schedule an
appointment in advance by calling the appropriate department and follow all posted directions during your
visit. Walk-ups are limited to one person at a time. Please note that our response to your inquiry could be
delayed. For a list of department phone numbers, visit the Staff Directory on the City website.
From: Katie Lozano
Sent: Thursday, December 10, 2020 3:21 PM
To: Laura Feldman
Cc: CC; CityCierk
Subject: Re: Save Our Trails
Hello Ms. Feldman,
Thank you for your email. The Portuguese Bend Landslide Remediation Project and Preserve
Parking and Access efforts are being prepared in compliance with the City's Trails Network Plan,
Conceptual Trails Plan and Preserve Public Use Master Plan. The Preserve Parking and Access
effort does not propose development internal to the Preserve or on open space land that would
trigger closing existing trails or implementing new conceptual trails, and at this time the Portuguese
Bend Landslide Remediation Project is not anticipated to cause any existing authorized trails to be
relocated. However, if an authorized trail is temporarily closed during construction of the project, the
City will repair and reopen the trail as part of the project. Moreover, both of these City
projects will not result in the permanent closure of the two authorized access points from the
Portuguese Bend Community to the Preserve.
It is the City's practice to identify opportunities during construction projects to implement
the conceptual trails identified within the Conceptual Trails Plan (the trails identified in the Preserve
Trails Plan of the Public Use Master Plan ((PUMP)) already exist). However, in the case of private
development projects, the City cannot require a private property owner to implement a trail on their
private property. In these cases, the City works with the private property owner at the time the
property owner submits a development application to describe the benefits of dedicating the
appropriate easements for trail access and to determine if the property owner is willing to voluntarily
F-24
dedicate land for a trail easement. Again, the City cannot require such a trail easement dedication
from a property owner.
Public safety is top priority for the City. The City works directly with the LA County Fire Department
and LA County Sheriff's Department on disaster evacuation, firefighting access, and emergency
preparedness. In fact, the City held a test operation of the Emergency Operations Center in
November in coordination with public safety agencies, and a focus was emergency response
within the Preserve. The network of existing trails throughout the City do offer access in response to
an emergency if warranted.
I hope this information is helpful. Please let me know if I can provide additional or more specific
information.
Thank you,
Katie Lozano
Senior Administrative Analyst
Recreation, Parks, and Open Space
City of Rancho Palos Verdes
310-544-5267
City Hall is open to the public during regular business hours. To help prevent the spread of COVID-19, visitors
are required to wear face coverings and adhere to physical distancing guidelines. Some employees are
working on rotation and may be working remotely. If you need to visit City Hall, please schedule an
appointment in advance by calling the appropriate department and follow all posted directions during your
visit. Walk-ups are limited to one person at a time. Please note that our response to your inquiry could be
delayed. For a list of department phone numbers, visit the Staff Directory on the City website.
From: Laura Feldman <pbrcl@verizon.net>
Sent: Wednesday, December 9, 2020 8:29AM
To: cc@rpv.ca.gov; CityCierk; Katie Lozano
Cc: 'Sheri Hastings'
Subject: Save Our Trails
Portuguese Bend Riding Club
www.pbrcride.com
310-377-3507
2 F-25
Ron Dragoo
From: Katie Lozano
Sent:
To:
Friday, December 11, 2020 12:20 PM
Ron Dragoo
Subject: Fw: Please include the 1984 Trails Network plan in your plans.
Katie Lozano
Senior Administrative Analyst
Recreation, Parks, and Open Space
City of Rancho Palos Verdes
310-544-5267
City Hall is open to the public during regular business hours. To help prevent the spread of COVID-19, visitors
are required to wear face coverings and adhere to physical distancing guidelines. Some employees are
working on rotation and may be working remotely. If you need to visit City Hall, please schedule an
appointment in advance by calling the appropriate department and follow all posted directions during your
visit. Walk-ups are limited to one person at a time. Please note that our response to your inquiry could be
delayed. For a list of department phone numbers, visit the Staff Directory on the City website.
From: Katie Lozano
Sent: Thursday, December 10, 2020 3:25 PM
To: GRACE
Cc: CC; CityCierk
Subject: Re: Please include the 1984 Trails Network plan in your plans.
Hello Ms. Yung,
Thank you for your email. The Portuguese Bend Landslide Remediation Project and Preserve
Parking and Access efforts are being prepared in compliance with the City's Trails Network Plan,
Conceptual Trails Plan and Preserve Public Use Master Plan. The Preserve Parking and Access
effort does not propose development internal to the Preserve or on open space land that would
trigger closing existing trails or implementing new conceptual trails, and at this time the Portuguese
Bend Landslide Remediation Project is not anticipated to cause any existing authorized trails to be
relocated. However, if an authorized trail is temporarily closed during construction of the project, the
City will repair and reopen the trail as part of the project. Moreover, both of these City
projects will not result in the permanent closure of the two authorized access points from the
Portuguese Bend Community to the Preserve.
It is the City's practice to identify opportunities during construction projects to implement
the conceptual trails identified within the Conceptual Trails Plan (the trails identified in the Preserve
Trails Plan of the Public Use Master Plan ((PUMP)) already exist). However, in the case of private
development projects, the City cannot require a private property owner to implement a trail on their
private property. In these cases, the City works with the private property owner at the time the
property owner submits a development application to describe the benefits of dedicating the
appropriate easements for trail access and to determine if the property owner is willing to voluntarily
1
F-26
dedicate land for a trail easement. Again, the City cannot require such a trail easement dedication
from a property owner.
Public safety is top priority for the City. The City works directly with the LA County Fire Department
and LA County Sheriff's Department on disaster evacuation, firefighting access, and emergency
preparedness. In fact, the City held a test operation of the Emergency Operations Center in
November in coordination with public safety agencies, and a focus was emergency response
within the Preserve. The network of existing trails throughout the City do offer access in response to
an emergency if warranted.
I hope this information is helpful. Please let me know if I can provide additional or more specific
information.
Thank you,
Katie Lozano
Senior Administrative Analyst
Recreation, Parks, and Open Space
City of Rancho Palos Verdes
310-544-5267
City Hall is open to the public during regular business hours. To help prevent the spread of COVID-19, visitors
are required to wear face coverings and adhere to physical distancing guidelines. Some employees are
working on rotation and may be working remotely. If you need to visit City Hall, please schedule an
appointment in advance by calling the appropriate department and follow all posted directions during your
visit. Walk-ups are limited to one person at a time. Please note that our response to your inquiry could be
delayed. For a list of department phone numbers, visit the Staff Directory on the City website.
From: GRACE <jordette@msn.com>
Sent: Wednesday, December 9, 2020 5:28 PM
To: CC; CityCierk; Katie Lozano
Subject: Please include the 1984 Trails Network plan in your plans.
Dear Rancho Palos Verdes City Council Members:
Please see the attached/
Thank you,
Grace Yung.
2 F-27
Dear Rancho Palos Verdes City Council Members:
As a hiker, equestrian and homeowner in the Portuguese Bend community, I am writing to express
concern over the impacts of the Landslide Mitigation Project as well as the parking and access projects.
Encircled as we are by the nature preserves and the public trail systems on all sides, each proposed
project, while possibly worthy, impact us all. Each project encroaches on current trails, habitat and
public health by bringing more people to less and less space. The project mitigation plans do not address
the impact on the horse community and those who wish to continue to recreate safely on the trails. In
1984, the city approved The Trail Network Plan to enhance and maintain the trails. City staff were
directed to watch for opportunity to enhance the trail network where other projects are proposed
and initiated by staff. The plan included the need for disaster evacuation, firefighting access and other
emergency preparedness concerns. The Palos Verdes Loop trail has already been disrupted. Due to
erosion and lack of maintenance, new ways of getting through were created by trail users who then
encroached on private property, which was later closed off. These factors have led to the loss of full
segments of the trail network.
We ask that while you plan both the parking and landslide mitigation projects, as well as any future
projects, you follow the already adopted Trail Network Plan and look to enhance the trail network at
every opportunity. This includes engineering permanent trail routes, canyon crossings, erosion control
and access to trails from the Portuguese Bend Community. Access to Jack's Hat and Three Sisters is now
at risk, dependent on property owners and conservancy to make a deal. This too puts more people on
fewer trails which affects us all, the habitat and public safety. Please include the 1984 Trails Network
plan in your plans.
Sincerely,
f?~fl~
Grace Yung
F-28
Ron Dragoo
From:
Sent:
To:
Subject:
Katie Lozano
Katie Lozano
Friday, December 11, 2020 12:19 PM
Ron Dragoo
Fw: PLEASE SAVE OUR TRAILS!
Senior Administrative Analyst
Recreation, Parks, and Open Space
City of Rancho Palos Verdes
310-544-5267
City Hall is open to the public during regular business hours. To help prevent the spread of COVID-19, visitors
are required to wear face coverings and adhere to physical distancing guidelines. Some employees are
working on rotation and may be working remotely. If you need to visit City Hall, please schedule an
appointment in advance by calling the appropriate department and follow all posted directions during your
visit. Walk-ups are limited to one person at a time. Please note that our response to your inquiry could be
delayed. For a list of department phone numbers, visit the Staff Directory on the City website.
From: Katie Lozano
Sent: Thursday, December 10, 2020 3:35 PM
To: Kimberly Macy
Cc: CC; CityCierk
Subject: Re: PLEASE SAVE OUR TRAILS!
Hello Ms. Macy,
Thank you for your email. The Portuguese Bend Landslide Remediation Project and Preserve
Parking and Access efforts are being prepared in compliance with the City's Trails Network Plan,
Conceptual Trails Plan and Preserve Public Use Master Plan. The Preserve Parking and Access
effort does not propose development internal to the Preserve or on open space land that would
trigger closing existing trails or implementing new conceptual trails, and at this time the Portuguese
Bend Landslide Remediation Project is not anticipated to cause any existing authorized trails to be
relocated. However, if an authorized trail is temporarily closed during construction of the project, the
City will repair and reopen the trail as part of the project. Moreover, both of these City
projects will not result in the permanent closure of the two authorized access points from the
Portuguese Bend Community to the Preserve.
It is the City's practice to identify opportunities during construction projects to implement
the conceptual trails identified within the Conceptual Trails Plan (the trails identified in the Preserve
Trails Plan of the Public Use Master Plan ((PUMP)) already exist). However, in the case of private
development projects, the City cannot require a private property owner to implement a trail on their
private property. In these cases, the City works with the private property owner at the time the
property owner submits a development application to describe the benefits of dedicating the
appropriate easements for trail access and to determine if the property owner is willing to voluntarily
F-29
dedicate land for a trail easement. Again, the City cannot require such a trail easement dedication
from a property owner.
Public safety is top priority for the City. The City works directly with the LA County Fire Department
and LA County Sheriff's Department on disaster evacuation, firefighting access, and emergency
preparedness. In fact, the City held a test operation of the Emergency Operations Center in
November in coordination with public safety agencies, and a focus was emergency response
within the Preserve. The network of existing trails throughout the City do offer access in response to
an emergency if warranted.
I hope this information is helpful. Please let me know if I can provide additional or more specific
information.
Katie Lozano
Senior Administrative Analyst
Recreation, Parks, and Open Space
City of Rancho Palos Verdes
310-544-5267
City Hall is open to the public during regular business hours. To help prevent the spread of COVID-19, visitors
are required to wear face coverings and adhere to physical distancing guidelines. Some employees are
working on rotation and may be working remotely. If you need to visit City Hall, please schedule an
appointment in advance by calling the appropriate department and follow all posted directions during your
visit. Walk-ups are limited to one person at a time. Please note that our response to your inquiry could be
delayed. For a list of department phone numbers, visit the Staff Directory on the City website.
From: Kimberly Macy <kmacy@macyinc.com>
Sent: Tuesday, December 8, 2020 2:47 PM
To: CC; CityCierk; Katie Lozano
Cc: sherihastings@yahoo.com
Subject: PLEASE SAVE OUR TRAILS!
Dear Rancho Palos Verdes City Council Members:
As a hiker, equestrian and homeowner in the Portuguese Bend community, I am writing to express concern
over the impacts of the Landslide Mitigation Project as well as the parking and access projects.
Encircled as we are by the nature preserves and the public trail systems on all sides, each proposed project,
while possibly worthy, impact us all. Each project encroaches on current trails, habitat and public health by
bringing more people to less and less space. The project mitigation plans do not address the impact on the
horse community and those who wish to continue to recreate safely on the trails. In 1984, the city approved
The Trail Network Plan to enhance and maintain the trails. City staff were directed to watch for opportunity
to enhance the trail network where other projects are proposed and initiated by staff. The plan included the
need for disaster evacuation, firefighting access and other emergency preparedness concerns. The Palos
Verdes Loop trail has already been disrupted. Due to erosion and lack of maintenance, new ways of getting
through were created by trail users who then encroached on private property, which was later closed off.
These factors have led to the loss of full segments of the trail network.
2 F-30
We ask that while you plan both the parking and landslide mitigation projects, as well as any future projects,
you follow the already adopted Trail Network Plan and look to enhance the trail network at every opportunity.
This includes engineering permanent trail routes, canyon crossings, erosion control and access to trails from
the Portuguese Bend Community. Access to Jack's Hat and Three Sisters is now at risk, dependent on property
owners and conservancy to make a deal. This too puts more people on fewer trails which affects us all, the
habitat and public safety. Please include the 1984 Trails Network plan in your plans.
Sincerely,
Kimberly Macy Richardson
3
F-31
Ron Dragoo
From:
Sent:
To:
Cc:
Subject:
Ron Dragoo
Monday, November 16, 2020 6:04 PM
SUNSHINE
CC; CityCierk; Jesse Villalpando; Karina Banales; PublicWorks; Trails; Ramzi Awwad; Katie
Lozano
Portuguese Bend Landslide Mitigation Project
Sunshine, thank you for your comments, I appreciate all the input received from residents and concerned citizens. You
are welcome and encouraged to participate in the planned December 19, 2020 meeting. Funding for this portion of the
Portuguese Bend Mitigation Project (Environmental Review) has been included in the budget this fiscal year, and as you
know, the Trails Network Plan is a draft plan, accordingly this plan is not funded. Thank you again for your comments.
Ron Dragoo, PE
Principal Engineer
City Hall is open to the public during regular business hours. To help prevent the spread of COVID-19, visitors
are required to wear face coverings and adhere to physical distancing guidelines. Some employees are working
on rotation and may be working remotely. If you need to visit City Hall, please schedule an appointment in
advance by calling the appropriate department and follow all posted directions during your visit. Walk-ups are
limited to one person at a time. Please note that our response to your inquiry could be delayed. For a list of
department phone numbers, visit the Staff Directory on the City website.
From: SUNSHINE <sunshinerpv@aol.com>
Sent: Monday, November 16, 2020 3:38PM
To: Ron Dragoo <RonD@rpvca.gov>; PublicWorks <PublicWorks@rpvca.gov>; Trails <trails@rpvca.gov>; Ramzi Awwad
<rawwad@rpvca.gov>; Katie Lozano <KatieL@rpvca.gov>
Cc: CC <CC@rpvca.gov>; CityCierk <CityCierk@rpvca.gov>; Jesse Villalpando <jvillalpando@rpvca.gov>; Karina Banales
< kba na les@ rpvca .gov>
Subject: Funding for the Update on Portuguese Bend Landslide Mitigation Project
Hi Ron,
Have you read the draft Trails Network Plan Update yet? My environmental concern is about how
much preservation and enhancement of the Peninsula's trails network has been designed into the
landslide mitigation and storm water control considerations. In particular, the California Coastal Trail
and the Palos Verdes Loop Trail "ideal routes" have both been impacted by the land
movement. Restoring them to whatever criteria the Fire Department recommends/demands is going
to damage some "habitat".
Since the City purchased the Hon Property, Staff has not drafted an Amendment to the Conceptual
Trails Plan. Now that the Status of these trails is Category I instead of Category II, it falls to the
Public Works Department to propose how the General Plan will be complied with. The Preserve
Trails Plan (PTP) has nothing to do with the City's infrastructure maintenance. The General Plan
Update did not change that. Neither did Adopting the NCCP.
1
F-32
On your Project Site Location map, you have labeled the portion of the Crenshaw Extension Right of
Way which is at the northern edge of the Project Site as the Burma Rd. The Burma Road Trail is a
figment of the PTP no matter how the landslide moves. The Crenshaw ROW is a legal entity which
does not move. The scope of what your EIR is to address needs to be more specific.
Is all this sort or information useful before the Seeping Meeting or should I present the rest of my
comments, then? In the meantime, I suggest that you get the draft TNP Amendment into your
Budget. ... S
In a message dated 11/16/2020 10:07:01 AM Pacific Standard Time, listserv@civicplus.com writes:
Notice of Preparation of an EIR for the Portuguese Bend
Landslide Mitigation Project
The City of Rancho Palos Verdes will be the California Environmental Quality Act
(CEQA) Lead Agency and will prepare an Environmental Impact Report (EIR) for the
Portuguese Bend Landslide Mitigation Project. The City will conduct a special
meeting Seeping Meeting held on December 19, 2020, at 12:30 PM. The meeting will
be a Hybrid (in-person virtual) Meeting. Click here to view the Notice of Preparation of
an Environmental Impact Report (EIR) pursuant to the Requirements of the California
Environmental Quality Act (CEQA) for the Portuguese Bend Landslide Mitigation Project.
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F-33
Ron Dragoo
From: Katie Lozano
Sent:
To:
Friday, December 11, 2020 12:20 PM
Ron Dragoo
Subject: Fw: Request for Including Trail Updates & Repairs to RPV CC Landslide Mitigation
Direction
Katie Lozano
Senior Administrative Analyst
Recreation, Parks, and Open Space
City of Rancho Palos Verdes
310-544-5267
City Hall is open to the public during regular business hours. To help prevent the spread of COVID-19, visitors
are required to wear face coverings and adhere to physical distancing guidelines. Some employees are
working on rotation and may be working remotely. If you need to visit City Halt please schedule an
appointment in advance by calling the appropriate department and follow all posted directions during your
visit. Walk-ups are limited to one person at a time. Please note that our response to your inquiry could be
delayed. For a list of department phone numbers, visit the Staff Directory on the City website.
From: Katie Lozano
Sent: Thursday, December 10, 2020 3:24PM
To: cgardnerrpv@gmail.com
Cc: CC; CityCierk
Subject: Re: Request for Including Trail Updates & Repairs to RPV CC Landslide Mitigation Direction
Hello Ms. Gardner,
Thank you for your email. The Portuguese Bend Landslide Remediation Project and Preserve
Parking and Access efforts are being prepared in compliance with the City's Trails Network Plan,
Conceptual Trails Plan and Preserve Public Use Master Plan. The Preserve Parking and Access
effort does not propose development internal to the Preserve or on open space land that would
trigger closing existing trails or implementing new conceptual trails, and at this time the Portuguese
Bend Landslide Remediation Project is not anticipated to cause any existing authorized trails to be
relocated. However, if an authorized trail is temporarily closed during construction of the project, the
City will repair and reopen the trail as part of the project. Moreover, both of these City
projects will not result in the permanent closure of the two authorized access points from the
Portuguese Bend Community to the Preserve.
It is the City's practice to identify opportunities during construction projects to implement
the conceptual trails identified within the Conceptual Trails Plan (the trails identified in the Preserve
Trails Plan of the Public Use Master Plan ((PUMP)) already exist). However, in the case of private
development projects, the City cannot require a private property owner to implement a trail on their
private property. In these cases, the City works with the private property owner at the time the
property owner submits a development application to describe the benefits of dedicating the
1
F-34
appropriate easements for trail access and to determine if the property owner is willing to voluntarily
dedicate land for a trail easement. Again, the City cannot require such a trail easement dedication
from a property owner.
Public safety is top priority for the City. The City works directly with the LA County Fire Department
and LA County Sheriff's Department on disaster evacuation, firefighting access, and emergency
preparedness. In fact, the City held a test operation of the Emergency Operations Center in
November in coordination with public safety agencies, and a focus was emergency response
within the Preserve. The network of existing trails throughout the City do offer access in response to
an emergency if warranted.
I hope this information is helpful. Please let me know if I can provide additional or more specific
information.
Thank you,
Katie Lozano
Senior Administrative Analyst
Recreation, Parks, and Open Space
City of Rancho Palos Verdes
310-544-5267
City Hall is open to the public during regular business hours. To help prevent the spread of COVID-19, visitors
are required to wear face coverings and adhere to physical distancing guidelines. Some employees are
working on rotation and may be working remotely. If you need to visit City Hall, please schedule an
appointment in advance by calling the appropriate department and follow all posted directions during your
visit. Walk-ups are limited to one person at a time. Please note that our response to your inquiry could be
delayed. For a list of department phone numbers, visit the Staff Directory on the City website.
From: cgardnerrpv@gmail.com <cgardnerrpv@gmail.com>
Sent: Wednesday, December 9, 2020 10:23 AM
To: CC; CityCierk; Katie Lozano
Cc: sherihastings@yahoo.com
Subject: Request for Including Trail Updates & Repairs to RPV CC Landslide Mitigation Direction
Dear Rancho Palos Verdes City Council Members:
As a hiker, equestrian and homeowner in the Portuguese Bend community, I am writing to express
concern over the impacts of the Landslide Mitigation Project as well as the parking and access
projects.
Encircled as we are by the nature preserves and the public trail systems on all sides, each proposed
project, while possibly worthy, impact us all.
Each project encroaches on current trails, habitat and public health by bringing more people to less
and less space.
The project mitigation plans do not address the impact on the horse community and those who wish
to continue to recreate safely on the trails. In 1984, the city approved The Trail Network Plan to
enhance and maintain the trails. City staff were directed to watch for opportunity to enhance the
2 F-35
trail network where other projects are proposed and initiated by staff. The plan included the
need for disaster evacuation, firefighting access and other emergency preparedness concerns. The
Palos Verdes Loop trail has already been disrupted. Due to erosion and lack of maintenance, new
ways of getting through were created by trail users who then encroached on private property, which
was later closed off. These factors have led to the loss of full segments of the trail network.
We ask that while you plan both the parking and landslide mitigation projects, as well as any future
projects, you follow the already adopted Trail Network Plan and look to enhance the trail network at
every opportunity:
This includes engineering permanent trail routes, canyon crossings, erosion control and
access to trails from the Portuguese Bend Community.
Access to Jack's Hat and Three Sisters is now at risk, dependent on property owners and
conservancy to make a deal.
This too puts more people on fewer trails which affects us all, the habitat and public safety.
Please include the 1984 Trails Network plan in your plans.
Sincerely,
Dennis & Cathy Gardner
57 Narcissa Drive
Rancho Palos Verdes
3
F-36
DARYL L. OSBY
FIRE CHIEF
FORESTER & FIRE WARDEN
COUNTY OF LOS ANGELES
FIRE DEPARTMENT
1320 NORTH EASTERN AVENUE
LOS ANGELES, CALIFORNIA 90063-3294
(323) 881-2461
www.fire.lacounty.gov
"Proud Protectors of Life, Property, and the Environment"
BOARD OF SUPERVISORS
HILDA L. SOLIS
FIRST DISTRICT
MARK RIDLEY-THOMAS
SECOND DISTRICT
SHEILA KUEHL
THIRD DISTRICT
JANICE HAHN
FOURTH DISTRICT
KATHRYN BARGER
FIFTH DISTRICT c· Received
Ity of Rancho Palos Verdes
December 3, 2020
Ron Dragoo, City Engineer
City of Rancho Palos Verdes
Public Works Department
30940 Hawthorne Boulevard
Rancho Palos Verdes, CA 90275
Dear Mr. Dragoo:
DEC 11 2020
Public \Narks De Partment
NOTICE OF PREPARATION OF AN ENVIRONMENTAL IMPACT REPORT,
"PORTUGUESE BEND LANDSLIDE MITIGATION PROJECT," INVOLVES A SERIES OF
RECOMMENDED MITIGATION MEASURES WHICH FOLLOW A PHASED-APPROACH
TO CONSTRUCTION AND INSTALLATION, THE CONSTRUCTION IS LIKELY TO BE
IMPLEMENTED IN STAGES, WHICH MAY OCCUR SEPARATELY,
RANCHO PALOS VERDES, FFER 2020008897
The Notice of Preparation of an Environmental Impact Report has been reviewed by the
Planning Division, Land Development Unit, Forestry Division, and Health Hazardous
Materials Division of the County of Los Angeles Fire Department.
The following are their comments:
PLANNING DIVISION:
We have no further comments.
For any questions regarding this response, please contact Kien Chin, Planning Analyst, at
(323) 881-2404 or Kien.Chin@fire.lacounty.gov.
AGOURA HILLS
ARTESIA
AZUSA
BALDWIN PARK
BELL
BELL GARDENS
BELLFLOWER
BRADBURY
CALABASAS
SERVING THE UNINCORPORATED AREAS OF LOS ANGELES COUNTY AND THE CITIES OF:
CARSON
CERRITOS
CLAREMONT
COMMERCE
COVINA
CUDAHY
DIAMOND BAR
DUARTE
EL MONTE
GARDENA
GLENDORA
HAWAIIAN GARDENS
HAWTHORNE
HERMOSA BEACH
HIDDEN HILLS
HUNTINGTON PARK
INDUSTRY
INGLEWOOD
IRWINDALE
LA CANADA-FLINTRIDGE
LA HABRA
LA MIRADA
LA PUENTE
LAKEWOOD
LANCASTER
LAWNDALE
LOMITA
LYNWOOD
MALIBU
MAYWOOD
NORWALK
PALMDALE
PALOS VERDES ESTATES
PARAMOUNT
PICO RIVERA
POMONA
RANCHO PALOS VERDES
ROLLING HILLS
ROLLING HILLS ESTATES
ROSEMEAD
SAN DIMAS
SANTA CLARITA
SIGNAL HILL
SOUTH EL MONTE
SOUTH GATE
TEMPLE CITY
VERNON
WALNUT
WEST HOLLYWOOD
WESTLAKE VILLAGE
WHITTIER F-37
Ron Dragoo, City Engineer
December 3, 2020
Page 2
LAND DEVELOPMENT UNIT:
This project does not propose construction of structures at this time, therefore until actual
construction is proposed the project will not have a significant impact to the County of Los
Angeles Fire Department's Fire Prevention, Land Development Unit.
Should any questions arise regarding subdivision, water systems, or access, please contact
the County of Los Angeles Fire Department Land Development Unit's, Inspector Nancy
Rodeheffer at (323) 890-4243.
FORESTRY DIVISION-OTHER ENVIRONMENTAL CONCERNS:
The statutory responsibilities of the County of Los Angeles Fire Department's Forestry
Division include erosion control, watershed management, rare and endangered species,
vegetation, fuel modification for Very High Fire Hazard Severity Zones, archeological and
cultural resources, and the County Oak Tree Ordinance. Potential impacts in these areas
should be addressed.
Under the Los Angeles County Oak tree Ordinance, a permit is required to cut, destroy,
remove, relocate, inflict damage or encroach into the protected zone of any tree of the Oak
genus which is 25 inches or more in circumference (eight inches in diameter), as measured 4
1/2 feet above mean natural grade.
If Oak trees are known to exist in the proposed project area further field studies should be
conducted to determine the presence of this species on the project site.
The County of Los Angeles Fire Department's Forestry Division has no further comments
regarding this project.
For any questions regarding this response, please contact Forestry Assistant, Joseph Brunet
at (818) 890-5719.
HEALTH HAZARDOUS MATERIALS DIVISION:
The Health Hazardous Materials Division of the Los Angeles County Fire Department has no
comments or requirements for the project at this time.
Please contact HHMD senior typist-clerk, Perla Garcia at (323) 890-4035 or
Perla.garcia@fire.lacounty.gov if you have any questions.
If you have any additional questions, please contact this office at (323) 890-4330.
F-38
Ron Dragoo, City Engineer
December 3, 2020
Page 3
Very truly yours,
~~~d)~
RONALD M. DURBIN, CHIEF, FORESTRY DIVISION
PREVENTION SERVICES BUREAU
RMD:ac
F-39