20201218 Late Correspondence
TO: HONORABLE MAYOR & CITY COUNCIL MEMBERS
FROM: CITY CLERK
DATE: DECEMBER 18, 2020
SUBJECT: ADDITIONS/REVISIONS AND AMENDMENTS TO AGENDA
_____________________________________________________________________
Attached are revisions/additions and/or amendments to the agenda material received through
Friday afternoon for the Saturday, December 19, 2020 City Council meeting:
Item No. Description of Material
1 Letter from Los Angeles County Sanitation Districts
Email from: Landslide Mitigation. IMAC Comments
Emails from: Brain Thompson; Sheri Hastings; Noel Park; and Sharon
Yarber
Respectfully submitted,
__________________
Emily Colborn
L:\LATE CORRESPONDENCE\2020 Cover Sheets\20201219 additions revisions to agenda thru Friday afternoon.docx
LOS ANGELES COUNTY
SANITATION DISTRICTS
Converting Waste Into Resources
Mr. Ron Dragoo, City Engineer
Public Works Department
City of Rancho Palos Verdes
30940 Hawthorne Boulevard
Rancho Palos Verdes, CA 90275-5391
Dear Mr. Dragoo:
Robert C. Ferrante
Chief Engineer and General Manager
1955 Workman Mill Road, Whittier, CA 90601-1400
Mailing Address: P.O. Box 4998, Whittier, CA 90607-4998
(562) 699-7411 • www.lacsd.org
December 15, 2020
Ref. DOC 5972522
NOP Response for Portuguese Bend Landslide Mitigation Project
The Los Angeles County Sanitation Districts (Districts) received a Notice of Preparation of a Draft
Environmental Impact Report (NOP) for the subject project on November 11. The proposed project is located
within the jurisdictional boundary of District No.5. We offer the following comments:
1. Sections of the proposed project may impact existing and/or proposed Districts' facilities (e.g. trunk sewers,
recycled waterlines, etc.) over which it will be constructed. Districts' facilities are located directly under
and/or cross directly beneath the proposed project alignment. The Districts cannot issue a detailed response
to or permit construction of, the proposed project until project plans and specification that incorporate
Districts' facilities are submitted for our review. To obtain copies of as-built drawings of the Districts'
facilities within the project limits, please contact the Districts' Engineering Counter at
engj]1eeringgm!J~!:@l~csd.org or (562) 908-4288, extension 1205. When project plans that incorporate our
facilities have been prepared, please submit copies of the same to the Engineering Counter for our review
and comment.
2. The Districts maintain sewerage facilities within the project area that may be affected by the proposed
project. Approval to construct improvements within a Districts' sewer easement and/or over or near a
Districts' sewer is required before construction may begin. For a copy of the Districts' buildover procedures
and requirements go to www.lacsd.org, under Services, then Wastewater Program and Permits and select
Buildover Procedures. For more specific information regarding the buildover procedure, please contact
Ms. Danielle Thomas at (562) 908-4288, extension 2754.
If you have any questions, please contact the undersigned at (562) 908-4288, extension 2717 or at
araza~lacsd.org.
AR:ar
cc: A. Howard
R. Paracuelles
D. Thomas
Engineering Counter
DOC 6000083.005
Very truly yours,
~ft:f
Adriana Raza
Customer Service Specialist
Facilities Planning Department
\.
Landslide Mitigation, I MAC EIR Scope comments
19 December 2020.
The following comments are provided by the I MAC and complement the I MAC Landflow Report included
in the agenda items.
1. Geographic scope.
1.1. Expand the project boundary to provide a margin of 180 feet along the easterly (up-slope)
side of Burma Road Trail. (Portuguese Bend Mitigation Project, Nov. 2020, Chambers Group, Section
1.2, p. 5 and Figure 1, Project Site Location)
Reason: This will include existing retention/catch basins in Paintbrush, Ishibashi and Portuguese
Canyons that lie up-slope to the east of Burma Road Trail. Burma Road acts as a dam to some extent for
these canyon retention/catch basins. The proposed expansion of the boundary also will include land
fissures on and adjacent to Burma Road.
1.2 Clarify/expand the project location boundary on the north-west to conform to the limits of
the Portuguese Bend watershed as depicted in the Geo-Logic hydrology report, Drawing 1, plus a margin
of plus 100 feet for uncertainties in the watershed delineation. Reference Portuguese Bend Landslide
Mitigation, Chambers, Nov. 2020 ("Chambers 2020-11") Section 1.2 and Figure 1. (Hydrology and
Hydraulics Evaluation, Geo-Logic Associates, December 9, 2019, Appendix C, City Council page A-76,
Attachment 1, Hydrology Map) (See also Chambers, Figure 7, Hydraugers Locations, location A3.)
Reason: The northwest boundary lies in an area of complicated geology located between the currently
existing outflows of middle Portuguese Canyon and the Kelvin Canyon tributary to Alta mira Canyon.
There are unresolved issues concerning the possible existence of important water transfer underground
between what appear at the surface to be separate canyon watersheds. The expanded 100-foot margin
will allow investigation whether water infiltrating from storm run-off in this expanded area might
intrude underground into the landslide either above or below the basal rupture surface of the landslide.
This margin will allow the project to address potential sources of artesian water originating at higher
elevations that could possibly be extracted by horizontal hydraugers or wells. (See, for example" Geo-
Logic, December 2019, Section 5.6.1, Sub-phase lilA-Confirmatory Exploration and Instrumentation,
council page A-20.)
\
2. Hydrauger Implementation
Include alternative phasing (timing sequence) of construction. Installation of "down-gradient 'relief'
drains" currently is proposed only in Phase Ill, sub-phase C, construction. That is, the hydraugers are to
be installed near the end of all other construction such as fissure filling and installation of surface-water
run-off controls. (Reference Chambers, 2020-11, Sections 1.3 and 1.4, pp. 11-12.) [Geotechnical
Evaluation Report, Geo-Logic Associates, December 2019, section 5.6.3, page 17 (Council agenda page
A-21). (Geo-Logic Report of 12-2019)] Include within the EIR scope an alternative Phase 1 construction
for installation of a limited number of prototype directional hydraugers from the sea shore into the
lower landslide to test/verify the viability of the directional hydrauger concept. Advance to Phase I
some of the confirmatory exploration and instrumentation, currently specified in section 5.6.1 of the
Geologic Report of 12-2019. A similar concept appears in Geo-Logic Report, 12-2019, appendix C,
council page C-63 ("In addition, remedy construction is proposed to be completed incrementally and
iteratively starting with a pilot test program for directional subsurface drains.")
Reason: Directionally drilled hydraugers have never before been tried in the Portuguese Bend
landslide. The consultants evaluate them as the largest contributor to stabilization of the landslide.
(Geotechnical Report, Geo-Logic Associates, December, 2019, pages 12 -13, Council pages A-16-A-17,
including Table 1, estimated factors of safety.) However, their effectiveness is uncertain and the
consultants have stated that finding this high-pressure water will be a trial and error process. These
hydraugers are high risk and high reward. Prudent risk management concludes that early hydrauger
prototypes are essential. Prototypes will demonstrate their effectiveness in extracting significant
quantities of water, provide needed information on the composition of the land below the slide plane,
prove their survivability and provide the necessary information to plan the implementation of the
operational hydraugers in Phase 3. If these prototypes work well then that opens up opportunities to cut
back on some of the preventative measures if they are no longer essential. Specifically, there could be
re-evaluation of fracture infilling and upper-slope, interception hydraugers, both of which have
significant environmental impacts and substantial costs that might be saved. If the prototype lower
hydraugers don't work, then the whole program will need to be reconsidered because we already know
that all the other preventative measures combined will not achieve the defined success criteria.
3. Back Up Plan for Culvert under PVDS.
Include within the scope of the project for EIR purposes the installation of a possible new, second
culvert beneath Palos Verdes Drive South in the vicinity of Peppertree Trail on the eastern side of the
landslide.
Reason: Due to the unresolved questions about the viability of the sole, existing culvert under Palos
Verdes Drive South and the viability of the storm-water pathway to that culvert, it would be prudent to
include a functional alternative in the project as a backup for EIR purposes. The project as currently
proposed relies exclusively upon a single, existing culvert to convey surface storm water from the
canyons beneath Palos Verdes Drive South to the sea. That existing culvert is situated on the westerly
side of the landslide at the elevation of the historic water channel of lower Portuguese Canyon. The
culvert passes beneath the roadbed at a depth about 30 feet below the elevated Palos Verdes Drive
road surface. There are well-known engineering questions:
(A) Whether the existing culvert under Palos Verdes Drive South is suitable for re-use. (See the
attached Elevation Mapping of the Proposed Landflow Retention Basin and PVDS Culvert Area which
shows that there may be little to no slope for an effective gravity-flow pathway to the existing culvert.),
(B) Whether the pathway for storm water flow from Peppertree Trail to that existing culvert will
continue to sink in the future in the same manner that destroyed the 1990 storm drain system, and
(C) Whether that existing culvert and the pathway to it will survive for an economically reasonable
useful life in the proposed new project. (See, for example, Hydrology and Hydraulics Evaluation, Geo-
Logic Associates, December 9, 2019, Conclusions and Recommendations, second bullet point, p. 3
(Council page A-78 at A-79.) If either the existing culvert or the storm-water pathway to the existing
culvert were to fail then the entire surface water control system north of the road will fail for lack of any
outlet past the roadbed to the sea.
If the existing culvert and storm water pathway prove to be unsuitable and if no alternative plan
has been evaluated in the current EIR then it might be necessary to incur the delay and expense for a
new EIR on a new second culvert.
The existing culvert was the target of the 1990 storm drain system. It has been physically
stranded because the landslide surface sank along on the pathway of storm water leading from
Peppertree Trail to that culvert. The sinking of the land reversed the water flow along the storm water
pathway to the existing culvert, thereby stranding that culvert. This failure has created an impounded
pool of storm water from Paintbrush and Ishibashi Canyons that seeps into the ground and presumably
percolates beneath the roadbed of Palos Verdes Drive South to the ocean.
The current project design includes a retention basin to be situated along the storm water
pathway to the existing culvert. The retention basin is proposed to manage high volume flows, such as a
50-year or 100-year storm. The proposed retention basin will be subject to the same land-sinking risk
along the storm-water pathway that destroyed the 1990 storm drain system.
The current EIR could be done with a conceptual design for a second culvert but without a fully
detailed engineering design. The concept is to install the new culvert with its inlet (on the north side of
the road) at least ten feet lower than the current lowest ground surface north of the road. This would
create a vertical margin of ten feet to accommodate future sinking of the land without stranding the
new culvert. If the existing culvert and pathway prove to be unsuitable, and an alternative culvert has
been included in the first EIR, then it would be easier, cheaper and quicker to perform a supplemental
environmental analysis (or possibly a mitigated negative declaration) for a fully engineered design for a
new second culvert.
4. Infilling.
Expand scope to include possible use of filler materials other than fly ash, such as screened local soil, or
imported soil or limestone. Reference Chambers, 2020-11, Section 1.4.1, Construction Phase I, Surface
Fracture Infilling and Section 4.9.
Reason: A material data safety sheet for fly ash indicates that it is highly alkaline (high pH). The
potential impact of such ash filler upon fertility of local soils should be evaluated.
5. Swale/Trail Integration. Much of the proposed swale structure parallels Peppertree Trail. We have
suggested as part of a more holistic approach that there is an opportunity to integrate the swales with
the trail.
Reason: Combining the lower swale with the existing trail would lead to a significantly reduced
additional surface area required for the swale ("take" in NCCP parlance) and be a significant
environmental and aesthetic benefit.
Attachment:
Infrastructure Management Advisory Committee Stormwater Subcommittee Report
Elevation Mapping of the Proposed Landflow Retention Basin and PVDS Culvert Area
12/14/2020
Summary:
The Portuguese Bend Landslide mitigation proposal includes a surface-water retention basin located
north of Palos Verdes Drive South (PVDS) that outlets into the culvert under PVDS near Peppertree Lane.
PVDS effectively forms a dam blocking storm water runoff from the landflow area to the ocean and the
area of the proposed retention basin has been and likely still is sinking. Therefore, I MAC has raised
concerns that the current concept of gravity flow of storm water from the proposed retention basin
through the PVDS culvert may not be viable. To better understand the situation, the I MAC Stormwater
Sub-committee conducted this study to roughly determine the elevation profile of the existing drain
pipe running from the intersection of the Peppertree/Sandbox trails, past the proposed location of the
surface-water retention basin to the culvert under PVDS and the surrounding area. This report
documents the results of the study.
The measurements indicate that the local low spot where storm water runoff naturally accumulates, on
the connector trail between the Ishibashi Farm Trail and the Peppertree Trail near PVDS, is roughly the
same elevation as the inlet to the culvert under PVDS. Additionally, there is a ridge with almost a 30
foot rise in terrain height between the culvert and the identified low point on the pathway to the
culvert. While this study was conducted using a smartphone for elevation measurements and should not
be considered accurate enough on its own to support engineering decisions, it does provide sufficient
evidence that a full elevation survey of the area is needed prior to finalizing the design of this aspect of
the landflow mitigation effort.
Elevation Measurements:
This aerial view of the area shows the locations of elevation measurements taken with a smartphone
GPS on the morning of 10/22/20. Points #1, #2, #8, #3, #4 and #6 are at locations on the existing, but no
longer functioning, drain pipe that once carried storm water from the landflow area to the PVDS culvert.
Point #1 is the PVDS culvert inlet, #8 is a local high point and #4 is a local low point (where the area is
covered in silt and the pipe is not visible-presumably buried.
Point GPS (tJ§bl Delta H Estimate Elev(~bl Description
1 147 -8 -6 133 On tra il at c u'~te n . Estimate bonom of culvert is 6' l>elow traij .
2 159 -8 151 0 n tra~ tO CIJ~tert , local nig h point. p 1pe bottom IS level 'IJ!h tra il.
3 150 -8 -2 140 C ulven tra~ 30' from ~l)jgs§!JJ T rail intersec t iOn , local lowpoint . BO P IS 2' belowtra1l.
4 142 -8 134 ).s~ to ~.P.R.~ conn ecto r , local [owspot 1n s itt. C a n ~ see pipe he re .
5 162 -8 154 LovJfiat a rea 10n t rail nea r bon om . D id not v.alk th is vJlole trail.
6 199 -8 191 Dra in pipe 90" l>end . Pipe is same level a s tra il .
7 181 -8 -20 153 Lov.ell 's lo>.vspot o n LWOO§!Jl T ra il
8 169 -8 161 Local high point on culvert trail
9 177 -8 169 local low point on traJl heading tov.ard ~
10 19D -8 182 Blaok •)(" o n tra il in from ~
D ena H = D 1stance fro m Phone antenna to ground vJlen read 1ng
Estimate = M}' estimate o f the height differe nce l>etv.een g round and point of interest (usually the pipe bottom).
Elevation Measurements Along the Existing Drain Pipe:
The profile below shows the elevation change between the go• bend in the drain pipe at the Peppertree
Trail (Point #6) and the PVDS culvert (Point #1)_ It indicate s that the contiguous fall line between point
#6 and the culvert is a myth and a retention basin located around points #4 and #5 would probably not
drain through to the culvert using gravity feed alone, especially if there is more sinking in the area.
200
191
190 '
180 I
170 1
::;
"' :;.<
~· £
~ ..
~
Ul
130
120 ,
ll0 1
100 -~---,
0 2 3 4 5 6 7 8 9 10
Other Points of Interest:
Point #7 is the location of an estimated overall low point in the area. The trail in that area is at 173ft
MSL. Given all the brush etc., it's very hard to estimate the elevation distance from the trail to the
ground below. We estimated about 20ft which would make this spot above the silty area on the trail
(Point #4) -153ft vs. 134ft.
Points #5 and #9 could be used to support the idea of a culvert under PVDS on the south/east side of the
landslide area. However, there is a substantial rise between this area and PVDS which would require a
long tunnel or trench to get water under the road from this point.
Elevation Measurement Errors:
Two sources contributed to errors in the measurement of elevations presented in this report:
1. GPS Error:
This study was conducted using a smartphone and an App (ForeFiight) showing GPS altitude in feet
above Mean Sea Level. The Smartphone GPS receiver is generally accurate to about 5 meters which does
not provide the accuracy necessary to support the elevation profiles given in this report. However, the
study was conducted under conditions and in a way that reduces many of the large errors inherent to
GPS measurements. GPS receiver errors contributing to the 5 meter accuracy claim are dominated by:
Cause of Errors Study Specific Consideration
Objects in the field of view of the GPS satellites. The entire study location is open space and there are
no trees, buildings etc. that would obstruct the view of
the GPS satellites.
Changes in GPS satellites in view of the receiver This is minimized because the readings were all taken
(active) and their relative position to the receiver. in nearly the same geographic location and within an
hour of each other.
Differences in modeling (earth ellipsoid, absolute MSL The study measurements compare locations relative to
height etc.). each other to create a profile. The results are relative
and not dependent on absolute altitude that these
modeling inaccuracies affect.
To further improve confidence, the GPS elevation of some of the data points was taken twice during the
measurement period to confirm that the readings weren't "jumping around". In all cases, measurements
taken at the same point minutes apart yielded results within a few feet of each other increasing the
confidence of the accuracy of the technique.
Measurement 1 Measurement 2
Point 1: 147' MSL 151' MSL
Point 2: 159' MSL
Point 3: 150' MSL 155' MSL
Point 4: 142' MSL 140' MSL
Point 5: 162' MSL
Point 6: 199' MSL 198' MSL
Point 7: 181' MSL
Point 8: 169, MSL
Point 9: 177' MSL
Point 10: 190' MSL 184' MSL
Measurement 1: Obtained elevation measurement of each point in the point number order.
Measurement 2, About 20 minutes later, after completing all other points, returned to selected points
and measured elevation again.
Only Measurement 1 points were reported because they were taken within the shortest time span.
2. Vertical Distance Estimate Error ("Estimate" in the data table):
Most measurements were taken while standing safely on a trail near the point of interest (such as the
bottom of the drain pipe surveyed or a culvert inlet). In many instances, it was necessary to estimate the
vertical distance from the trail surface to the point of interest. While care was taken to do this as
accurately as possible, the use of proper surveying equipment would enhance the accuracy of the
measurements a few more feet.
Enyssa Momoli
From:
Sent:
To:
Subject:
Late carr
-----Original Message-----
Teresa Takaoka
Friday, December 18, 2020 11 :06 AM
Enyssa Momoli
FW: Please preserve access to the Portugese Bend Reserve
From: Brian Thompson <brianthompson3@gmail.com>
Sent: Monday, December 14, 2020 11:23 AM
To: CC <CC@rpvca.gov>
Subject: Please preserve access to the Portugese Bend Reserve
Palos Verdes City Council,
The Portugese Bend Reserve is one of the most beautiful outdoor spaces in the county of Los Angeles and it's access to
a II residents needs to be protected.
Please, I beg of you, protect meaningful access to this beautiful outdoor public space. For our children, and future
generations, we need this meaningful access to be protected.
Thank you,
Brian Thompson
1
\ '
Enyssa Momoli
From: Ron Dragoo
Sent:
To:
Monday, December 14, 2020 2:19PM
Sheri Hastings
Cc: CC; Katie Lozano; CityCierk
Subject: RE: Portuguese Bend Trail Network
Dear Ms. Hastings,
Thank you for your comments. Public comments received will be provided to the City Council as late correspondence in
advance of Saturday's meeting.
Best regards,
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: Ara Mihranian <AraM@rpvca.gov>
Sent: Monday, December 14, 2020 11:10 AM
To: Ramzi Awwad <rawwad@rpvca.gov>; Ron Dragoo <RonD@rpvca.gov>
Subject: FW: Portuguese Bend Trail Network
Please respond.
Ara Michael Mihranian
City Manager
CITY OF RANO!O PALOS VERDES
30940 Hawthorne Blvd.
Rancho Palos Verdes, CA 90275
31 0-544-5202 (telephone)
31 0-544-5293 (fax)
1
aram@rpvca.gov
www.rpvca.gov
Do you really need to print this e-mail?
Thi:; H11ilil rnessage contains information belonging to the City of Rand1o Palos Verdes, which may be privile\Jed, confidential and/or protected from
cli:;closure. The information is intended only for usc of the individual or entity narncd. Unauthorized diss('mination, distribution, or copyinq is strictly prohibited. If
vou received this crnail in error, or me not an intended recipient, please notify the sender irnmediately. Thank you for your assistance and cooperation.
From: Sheri Hastings <sherihastings@yahoo.com>
Sent: Monday, December 14, 2020 9:14AM
To: CC <CC@rpvca.gov>; Katie Lozano <KatieL@rpvca.gov>; CityCierk <CityCierk@rpvca.gov>
Subject: Re: Portuguese Bend Trail Network
Dear Rancho Palos Verdes City Council Members:
As a resident of Portuguese Bend and as a hiker and equestrian in the Portuguese Bend community and as someone
who cares deeply about preserving local wildlife, I am writing to express concern over the impacts of the Landslide
Mitigation Project as well as the parking and access projects.
Any proposed landslide mitigation project impacts us. Parking and access projects impact us.
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
Since the Conservancy took over the land near me there have been more hikers and more large groups of hikers on the
trails. Large loud groups of people impacts the nesting birds and other wildlife on the trails. This puts more people on
fewer trails which affects us all, the habitat and public safety. Many hikers and bikers are unaware of safe behavior around
horses, so forcing all trail users into the same small space is extremely dangerous not only for equestrians, but also for
other trail users. And heavy usage it also impacts wildlife along those trails. Expand the trails but have fewer people on
them.
An expanded and managed trail network is crucial to safety. Please include the 1984 Trails Network plan in your plans.
Sincerely,
Sheri Hastings
Portuguese Bend Resident and Portuguese Bend Trail User
2
Enyssa Momoli
From:
Sent:
To:
Cc:
Subject:
Noel,
Ron Dragoo
Tuesday, December 15, 2020 1:21 PM
Noel Park
CC; Ramzi Awwad; imac
RE: IMAC Landflow report
Thank you for your comments. In addition to the electronic format they have received, they will be provided as late
correspondence to the City Council at the Saturday 12-19-2020 seeping meeting.
Best regards,
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.
-----Original Message-----
From: Noel Park <noelparkone@gmail.com>
Sent: Tuesday, December 15, 2020 11:05 AM
To: CC <CC@rpvca.gov>; Ramzi Awwad <rawwad@rpvca.gov>; Ron Dragoo <RonD@rpvca.gov>; imac
<imac@rpvca.gov>
Subject: IMAC Landflow report
The Infrastructure Management Advisory Committee (I MAC) has done extensive work and analysis concerning the
proposed landflow mitigation project. They have submitted a comprehensive report to you, raising many credible
questions and offering many credible suggestions. I strongly urge you to carefully consider the report. The success of any
project is at stake.
As a matter of primary urgency, a professional survey should been made of the alignment of the channel from the
proposed retention basin to the existing culvert under Palos Verdes Drive South. It seems highly likely that the elevation
of the retention basin is lower than that of the culvert. If so, the whole design may be called into question, or extensive
grading may be necessary to raise the elevation of the retention basin high enough to achieve gravity flow.
The idea that this survey would be left to the construction contractor is extremely dangerous. If the design is found to be
infeasible after a construction contract is let, the potential for large cost overruns is clear.
Finally, I would like to compliment the IMAC for its diligence and commitment in creating their extremely relevant and
valuable report.
Sincerely,
1
\ '
Noel Park
6715 El Rodeo Road
Rancho Palos Verdes CA 90275
562-413-5147
Sent from my iPhone
2
Enyssa Momoli
From:
Sent:
To:
Subject:
Dear Members of the I MAC,
sharon yarber <momofyago@gmail.com>
Saturday, December 12, 2020 1 :51 PM
PublicWorks; Katie Lozano; CC
Portuguese Bend Landslide Project
Thank you for your service to the community and your excellent and comprehensive report.
I wish to express my support for the position you have taken that the first order of business should be to install the
hydraugers and determine their efficacy before expending large sums of money on other measures which, without
effective underground water extraction by the hydraugers, will not be particularly successful. I hope the City Council
listens to your recommendation!
I also encourage you to vigorously promote efforts by the City to engage with Rolling Hills to eliminate septic systems
that surely contribute to the landslide problems.
Please include this email as late correspondence for the meeting on December 14th.
Sharon Yarber
1
\ .