RPVCCA_CC_SR_2012_12_18_05_Landslide_Mitigation_MeasuresCITY OF
MEMORANDUM
RANCHO PALOS VERDES
TO:
FROM:
DATE:
SUBJECT:
REVIEWED:
Project Manager:
HONORABLE MAYOR &CITY COUNCIL MEMBERS
JIM HENDRICKSON,INTERIM DIR.PUBLIC WORK...,Il",.n1l
DECEMBER 18,2012
LANDSLIDE MITIGATION MEASURES -REVIEW OF
PRIORITIZED LIST OF PROJECTS (Supports City
Council Goal -Public Infrastructur~n
CAROLYN LEHR,CITY MANAGER ~
Ron Dragoo,Senior Engine~
RECOMMENDATION
Receive and file the staff report.
BACKGROUND
At its March 20,2012 meeting,the City Council adopted the Goals and Priorities list
which includes an item to address Public Infrastructure,specifically an in-depth review
of the Portuguese Bend Landslide.Based on this desire to better understand the
Landslide,the City Council conducted a landslide workshop at its July 31,2012
meeting.Staff assembled a team of 3 geologists who presented information,answered
questions,offered opinions,and outlined projects that could aid in mitigating the
ongoing land movement.At the conclusion of its discussion on July 31 st,the City
Council decided to:
~Receive and file the staff report;
~Directed staff to return with a report summarizing recommendations from the
panel of geologists,including prioritizing cost v.effectiveness of the
recommendations;and
~Requested Finance staff to review sources of funding,including the creation of
new potential CIP projects.
The Portuguese Bend Landslide includes the former Abalone Cove and Portuguese
Bend project areas of the City's Redevelopment Agency (RDA)that was formed in 1984
to use restricted property tax increment revenue to fund landslide mitigation projects.
The types of projects previously installed in the landslide area and the location of these
projects was based on recommendations contained in a 1984 Technical Panel Report
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"Feasibility of Stabilizing Abalone Cove Landslide."The report identified the following
six stabilization methods which are still germane today:
~Maintenance of existing dewatering system;
~Expansion of the existing dewatering system;
~Installation of a domestic sewer system;
~To require individual lot storm drainage;
~Storm drainage,especially the Altamira Canyon drainage area;,and
~Building a 50 foot high berm along the toe of the slide at the beach.
After the installation of the domestic sewer system in Abalone Cove and the installation
of the half round pipes in the landslid~in 2002,RDA funding for projects was largely
exhausted.Projects performed since then have been limited to emergency repair
projects like the installation of a buttress fill adjacent to Palos Verdes Drive South which
was completed in 2010 and the drainage pipe reestablishment project completed in
2011.
The Improvement Authority exists to maintain the landslide mitigation infrastructure
improvements constructed by the RDA.It has been funded with the interest earnings of
the $1 Million Abalone Cove Permanent Fund established with the Horan Settlement
Agreement in 1987.However,staff has provided its caution in the Five-Year Financial
Model that the funds available for maintenance will likely decrease and could be
depleted within five years.
DISCUSSION
Portuguese Bend Landslide Workshop -July 31!2012
The workshop information provided an overview of the projects including their general
rank in terms of effectiveness in aiding the slowing of land movement within the
landslide.For example,projects that capture runoff before entering the landslide,like
storm drain systems,are believed to be the most effective.Removing groundwater
through dewatering wells closely follows in terms of the effect a project has on slowing
movement.Global Positioning Survey (GPS)measurements and updating the City's
Geographic Information System (GIS)with current aerial photographs,topographic
contour maps and files,angular pictometry view aerials and new software tools are the
basic tools needed to aid in project analysis.These systems will provide information
that is critical in determining where projects should be located to address movement in
specific areas.The priority of the GPS and updated aerial photographs is very high.
Instrument wells and an automated GPS station will provide valuable data but are not
as highly ranked.
Projects that were presented during the workshop have been further reviewed and their
scope refined,allowing staff to,in some cases,develop programming level estimates.
Many projects discussed at the workshop are unfunded and/or not included in the City's
2012 Capital Improvement Plan (CIP).The following is a listing and discussion of an
array of the most effective projects to undertake in the landslide area.They are
subdivided into 5 categories:Collection of Surface Drainage Runoff,Updated Aerial
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Photographs,Dewatering Wells,GPS Monitoring,and Instrument Wells.A project
Location Map (Attachment A)has been included depicting specific project locations.
Collecting Surface Drainage Runoff has been determined to be the highest priority of
the projects discussed during the workshop.This proactive approach to runoff
management will help minimize runoff from entering cracks or fissures,where it will
ultimately increase the groundwater table.Accordingly the runoff collected will not
further exacerbate the landslide.Three projects were introduced to cO,lIect surface
drainage runoff at the workshop that will help minimize the amount of runoff entering
the landslide..
The Paintbrush Canyon Drainage-System project would capture runoff at the head of
the Portuguese Bend landslide in three locations,transfer that runoff via surface
mounted High Density Polyethylene (HOPE)pipe under Palos Verdes Drive South,
through an existing steel pipe,and continue along the existing storm drain pipe
al!gnment to the ocean.This project is not funded and is not included in the City's 2012
CIP.The preliminary estimated cost of the Paintbrush Canyon Drainage System
Project could be as much as $2,400,000.
The Beach Club Landslide Drainage System project would capture runoff at the head of
the Beach Club Landslide and transfer that runoff via buried HOPE pipe to the Klondike
Canyon Storm Drain.This project is located within the Klondike Geological Hazard
Abatement District.The District has indicated that at this point they are taking the lead
with this project.This project is not funded and is not included in the City's 2012 CIP.
However,the City is a property owner and pays about 60%of the total assessment
collected by the Klondike Geological Hazard Abatement District.The estimated
preliminary construction cost could be as much as $205,000.
The Ski Jump Drainage project would aid in the passive drainage of runoff that is now
trapped due to ground movement.A Steel pipe would be installed under the roadway
to correct the elevation difference that currently prohibits drainage flowing from the
north side of the road to the ocean.The corrugated metal pipe (CMP)located adjacent
to the roadway needs to be adjusted to facilitate flow from nearby runoff collection
points.This solution is very important but will require ongoing maintenance that will
likely include adjustment of the under-road and CMP pipes connections from time to
time to reestablish drainage as the ground continues to move.This project is not
funded and is not included in the City's 2012 CIP.The preliminary estimated
construction cost of this project is $416,000.
The update to the City's Geographic Information System (GIS)with current electronic
aerial photographs,topographic contour maps,angular pictometry aerials and new
software tools to provide analysis is a level two priority.They are needed to provide a
visual baseline making it possible to visually compare iterative movement in the landslide.
Additionally,Staff is at the beginning stages of organizing storm drain files,including the
storm drain inventory,project plans,inspection photos and videos,for storm drain master
planning using the GIS system.The upgrade of the GIS system is essential to successful
transition of storm drain project data.The Annual Report issues by the Oversight
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Committee for the storm drain program,dated June 27,2012,stated:
"The Committee concurs that it is prudent to upgrade the Geographic Information
System before further integration of the Drainage Master Plan into that system."
The FY12-13 budget includes a provision for $75,000 for the GIS upgrade.The City's
use of the Los Angeles Region Imagery Acquisition Consortium (LAR-IAC)is the most
cost effective solution for the GIS upgrade.Through the LAR-IAC pro"gram,aerial
photographs were taken in 2006,2008 and 2011.These aerials would be available for.
reference by staff once incorporated into the City's existing GIS platform.
City staff and Palos Verdes on the Net (PVNET)have developed a robust GIS system
that includes maps of sewers,storm drains and other city facilities and project
management data that is hosted on hardware and software owned and support~d by
PVNET in accordance with the Professional Services Agreement.Staff elected to defer
bringing the recommendation to enroll in'LAR-IAC to the City Council while NexLevel
conducted their recent IT review.In light of the City Council direction to conduct a bid
process for IT services (including GIS)in early 2013 and the fact that PVNET hosts GIS
services,Staff felt it was prudent to continue to defer the GIS upgrade.Staff believes
the bid process should require that any successor GIS provider have the capability to
host and support the City's data-rich GIS system.Staff and Palos Verdes on the Net
are currently working together towards the development of an interim solution.
Dewatering Wells are also a level two priority and are considered to be the next most
effective method of minimizing runoff from entering the landslide,which helps slow land
movement within the landslide.All runoff that is allowed to percolate into the ground
eventually becomes part of the groundwater and will cause an increase in the depth of
the groundwater table.Removing groundwater through dewatering wells helps to lower
the groundwater table,relieving soil pressures at depth and minimizing the negative
effects groundwater has on the landslide.Up to sixteen existing wells in Abalone Cove
and three wells in Portuguese Bend require routine maintenance and will likely need to
be rehabilitated over the next fifteen years.Expanding the existing dewatering system
has been recommended previously'and continues to be a viable solution.Staff
believes three new upslope wells in Portuguese Bend and two new wells in Abalone
Cove are a good start towards expanding the system.These new wells should improve
the system's effectiveness by increasing the system's water removal capacity and by
removing water more rapidly.The rehabilitation of existing wells and installation of new
wells are not funded projects and are not included in the City's CIP.Costs to
rehabilitate a well are estimated to be $70,000;the cost to install each new well is
currently estimated to be $85,000.As described further in the Analysis section below,
the City should consider cooperation with the Abalone Cove Landslide Abatement
District (ACLAD)in the development of a long-range dewatering well rehabilitation plan.
GPS Monitoring is a valuable tool used by scientists,engineers,and the community to
determine differential movement within the landslide complex.This year the City
Council authorized expanding the annual survey to include an additional mini survey.
Continuing a twice yearly monitoring program will further our understanding of the
response times between rainfall and land movement.Staff recommended expanding
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the GPS Monitoring program at the workshop.The cost of the program was negotiated
at $50,000,which is within this year's budgeted funds of $56,000 within the
Improvement Authority.The City Council authorized this activity on September 4,2012
when the GPS Monitoring Program was authorized.
An Automatic GPS monitoring station would be used to collect land movement data
independent of the GPS surveys.The Specific data collected could be valuable in
determining and evaluating engineering solutions. Placing an automat-ed GPS
monitoring station next to an instrument well would continuously provide data that could
be compared to measurements taken at depth providing the opportunity to compare
movement on different landslide planes.The purchase of an automatic GPS
monitoring station is not funded and i~not included in the City's 2012 CIP.The cost to
purchase an automatic GPS monitoring station is estimated to be $35,000.
Instrument Wells would be used to monitor,groundwater and landslide movement.
Tbese wells will provide information that can be valuable to engineers and scientists
when a project to minimize land movement is designed or when movement is analyzed
to help determine where potential projects would be most useful.The cost to install a
piezometer and/or inclinometer in a well at depth is currently estimated to be $100,000
is not funded and is not included in the City's 2012 CIP.
The Altamira Canyon project is included in the 2012 CIP as an unfunded project
ranging between $1.25 Million and $5 Million and was discussed during the workshop.
Staff has advised the Oversight Committee that the storm drain user fee will sunset in
2016 prior to any prospect of completing the Altamira Canyon project,due to its
complexities and other project demands,This project has been studied and analyzed
over the past decades;however the need to minimize runoff from entering the ground in
Altamira Canyon still remains.
Following is a chart that shows the projects discussed above,the estimated cost to
construct the projects and their funding status.
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Project Cost and Funding
$3,000,000 -,---------------------------------,
$2,500,000
~$2,000,000
~r $1,500,000
'5l~
~$1,000,000
$500,000 +--------
$-+--------,---------,---
LAR-IAC Expanded
GPS
Monitoring
Paintbrush
Canyon
Drainage
System
Beach Club
Landslide
Drainage
System
Ski Jump
Drainage
Project
New Refurbish Automatic Insturment
Dewatering Dewatering GPS Station Wells
Wells Wells
ANALYSIS
Funded
Project Name
Unfunded
Staff believes collecting water prior to it entering the ground is one of the key
components to slowing movement in the landslide.The Ski Jump Drainage project
should be programmed in the City's 2013 CIP and engineering design work should
begin as soon as possible.
At the time this report was written,The Beach Club Landslide Drainage System is
anticipated to be funded by the Klondike Canyon Geological Hazard Abatement District.
The cost of the Paintbrush Canyon Drainage System project will be considerable.
Engineering design,a hydrologic conditions study,and environmental approvals/permits
from the resource agencies may be required.Accordingly a preliminary project study
report'should be developed to further explore project requirements,available materials
and construction costs.Staff believes a preliminary project study report should be
programmed in the City's 2013 CIP for funding and begun as soon as possible.
The City's participation in LAR-IAC will provide benefits that will extend beyond the
landslide.Staff suggests that it provide the City Council with a detailed report about the
City's GIS and its recommendation regarding the participation in LAR-IAC and the
update of the GIS system.
The Abalone Cove Landslide Abatement District (ACLAD)assesses property owners
within the district a fee which is used almost exclusively for maintaining the existing
wells and dewatering drainage lines.If the City funds additional wells staff believes
ACLAD will need to increase its assessment to allow for the increased cost to maintain
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its system.Annual maintenance for each well is approximately $2,250.The City is a
member in ACLAD in that we own approximately 50%of the land within the district.
Accordingly,if ACLAD is able to increase its assessment,the City would be required to
fund our portion of the increase.The City will be responsible for 100%of the
maintenance for wells placed in upslope in the Portuguese Bend portion of the
landslide.The installation of new dewatering wells will provide additional safeguards in
the Abalone Cove Landslide and begin removing ground water upslope from the
Portuguese Bend Landslide.Ongoing additional maintenance of the n,ew City owned
wells is estimated to be approximately $6,750 per year.Staff believes these very
important groundwater removal projects should be programmed in the City's CIP with
the first project to begin in FY 2013/14 at a cost of about $170,000.To accelerate the
program,two wells could be programmed for installation in each year beginning FY
2013/14 again in 2014/15,at a cost of about $170,000 respectively.Following years
could include the installation of the remaining wells and rehabilitation of one welJ each
fiscal year.Staff should work together with the ACLAD Board to develop a long-range
fupding and project plan for ongoing rehabilitation and construction of any additional
new dewatering wells.
Staff is recommending continuing programming funds in future years for the GPS
survey program with the addition of a mini area survey as was performed this year.
Information provided through data collection obtained from piezometers and/or
inclinometers installed in wells could be used in developing reports and possibly assist
in making decisions about mitigation project placement.This project is not funded and
is not included in the City's 2012 CIP.Staff-believes this project should be placed in the
City's unfunded CIP and programmed as funding is available.
Funding any of the remediation projects will likely require a designated funding source.
General Funds could be used for this purpose or reprogramming existing projects in the
City's CIP could be considered to accommodate additional projects the City Council
may wish to program.The chart on the following page depicts projects and possible
programming years:
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$1,400,000 ,.------------------------------------------,
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FY 2014-15 FY 2015-16 ($1,355M)FY FY Unfunded
($1 ,37M)2016-17 2017-18
($70K)($70K)
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FY 2013-14 ($646,000)
$-
$200,000 -t---------
$600,000 -+=~---------~---
$400,000 -j---------
$800,000 -t----------~-=--
$1 ,200,000 -t---------~=-=,.-=~--
$1,000,000 -j---~~----------
FISCAL IMPACT
Understanding that staff has not conducted project designs,and project scoping will
likely change to accommodate environmental and design requirements,a table
summary of the possible cost of the projects described herein follows:
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FY2013-14
GIS update,including imagery (included in FY 2012-13 budget)$0
2 Dewatering Wells $170,000
Preliminary Study for Paintbrush Canyon $60,000
Ski Jump Drainage $416,000
Annual Total $646,000
FY 2014-15
2 Dewatering Wells $170,000
Paintbrush Canyon $1,200,000
Annual Total $1,370,000
FY 2015·16
Dewatering Well $85,000
Dewatering Well Rehabilitation $70,000
Paintbrush Canyon $1,200,000
Annual Total $1,355,000
FY 2016-17
Dewatering Well Rehabilitation $70,000
FY 2017-18
Dewatering Well Rehabilitation $70,000
After FY 2017-18
(12)Remaining Dewatering Well Rehabilitation $840,000
Automatic FPS monitoring Station $30,000
(2)Instrument Wells $200,000
$1,070,000
TOTAL $4,581,000
With the exception of the GIS Imagery,none of the projects are included in FY12-13
budget or 2012 CIP.Notwithstanding the recommendations offered in this Analysis,
staff expects to begin working with the City's Financial Advisor in early January 2013 to
develop funding alternatives for the San Ramon Canyon Stabilization project,as well as
other funded and unfunded CIP projects.The analysis will include Portuguese Bend
Landslide projects and present funding alternatives in conjunction with the proposed
2013 CIP Plan.This task has been commonly referred to as the Phase 1 -(funding
analysis for the)San Ramon Canyon Stabilization project.Upon completion of Phase
1,Staff expects that the City's Staff and the Financial Advisor will present an early
version of the 2013 CIP during spring 2013,including alternatives and
recommendations of funding options using available grants,Reserves and/or debt for
future infrastructure projects.
No budget adjustment is requested at this time.
Attachment:A)Project Location Map
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