SR-303-009 (9)
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Council Meeting: April 27, 2004 Santa Monica, California
TO: Mayor and City Council
Chairperson and Redevelopment Agency
FROM: City Staff
SUBJECT: Presentation of Mitigation Strategies for the Santa Monica Palisades Bluff
Improvement Project
Introduction
This study session describes the findings of the geotechnical study conducted by URS
Corporation for the Santa Monica Palisades Bluff Improvement Project and presents
mitigation strategies for the project.
Background
The Palisades Bluffs rise 30 to 150 feet above Pacific Coast Highway from the McClure
tunnel to the northerly city limits. The slope of the bluff is steep to near vertical at
various locations with deeply eroded gullies and areas of landslide debris. After the
January 17, 1994 Northridge earthquake, various sections were impacted by earth falls,
debris and mudflows, fractures and slides. Further sloughing after the disaster level
storms of 1995 and 1998 exacerbated the damage.
At that time the City retained the services of Dames and Moore, geotechnical engineers,
to conduct an evaluation of the earthquake and storm damaged areas of Palisades Park
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and the bluffs. Several remedial measures were taken as a result of the
recommendations from the studies including relocating portions of the fence in
Palisades Park; installing subsurface drains in the face of the bluff; landscaping
restoration; and grading Palisades Park to direct the existing surface drainage into
underground storm drain devices in Ocean Avenue to reduce the amount of surface
runoff.
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In 1998, Congress passed the Transportation Equity Act for the 21 Century. One of
the high priority projects approved under that Act was the Santa Monica Palisades Bluff
Improvement Project. The federal funding authorized for the construction of the project
amounts to $6,000,000.
On February 12, 2002, the City Council approved a professional services contract with
URS Corporation to provide a geotechnical study for the Santa Monica Palisades Bluff
Improvement project. The intent of the geotechnical study was to evaluate the current
conditions of the soils within the existing bluff area and to provide recommendations to
mitigate existing damage and potential future deterioration of the bluffs.
Discussion
The geotechnical study conducted by URS Corporation, included a comprehensive
review of the following:
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Existing geotechnical data;
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Geologic mapping;
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Field reconnaissance;
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Drilling of vertical and horizontal exploratory borings along the Santa Monica
Palisades Park and the easterly side of the Pacific Coast Highway from the
McClure tunnel to the northerly City Limits respectively;
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Installation of observation wells and horizontal drains; and
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Laboratory and field testing of soils
Based on the URS Corporation findings, staff proposes non-intrusive improvement
elements that can be applied individually or in combination for different areas of the
Bluffs as needed. The proposed mitigation strategies include: subsurface drainage to
improve the overall stability of the Bluffs through the application of dewatering systems;
surface improvement such as surface grouting, filling of erosion pockets, ground cracks
and deep gullies; and micro piles to support areas of marginal stability.
Implementation of these strategies would result in the following temporary impacts to
the public:
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Dewatering systems such as hydraugers along PCH will result in lane closures
during the construction period;
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Construction of a dewatering tunnel below Palisades Park will require installation
of two temporary access shafts in the Palisades Park that will produce noise at
the shaft locations and traffic impact on Ocean Avenue during construction;
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Vertical Interceptor drains along Ocean Avenue will impact traffic by lane
closures on Ocean Avenue during construction
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Budget / Financial Impact
Currently there is $1.3 million in Redevelopment Funds and an additional $6 million
Federal grant budgeted for this project. Staff will report to Council with additional
budget/financial impact information when recommending award of the design and
construction contracts.
Next Steps
With the input received from Council at this meeting, staff will proceed with public
outreach and a California Department of Transportation (Caltrans) field review, as
required for the Federal grant. Staff will return to Council in Fall 2004 with award of the
design and environmental clearance contracts. As part of the next steps, staff will
prioritize areas of the Bluff for treatment as funds become available on the project.
Subsequent steps include Council certification of the environmental clearance
document, board and commission approvals, Council concurrence on final design and
award of a construction contract to implement the Bluff improvements.
Prepared by: Kate Vernez, Asst. to the City Manager, Government Relations
Craig Perkins, Director, Environmental and Public Works Management
Anthony Antich, P.E., City Engineer & Architecture Manager
Jeff Mathieu, Director, Resource Management
Tina Rodriguez, Redevelopment Administrator
Barbara Stinchfield, Director, Community and Cultural Services
Karen Ginsberg, Assistant Director at CCS Administration
Dave Britton, P.E., Principal Civil Engineer
Spiros A. Lazaris, P.E., Civil Engineer
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