HomeMy WebLinkAboutAGENDA REPORT 2017 0405 CCSA REG ITEM 09A ITEM 9.A.
CITY OF MOORPARK,CALIFORNIA
City Council Meeting
of 1-5-G20/I
BY:
MOORPARK CITY COUNCIL
AGENDA REPORT
TO: Honorable City Council
FROM: Sean Corrigan, City Engineer/Public Works Director 72,41`' 71177'.
DATE: March 24, 2017 (CC Meeting of 04/05/17)
SUBJECT: Consider Retaining Wall Design for Princeton Avenue Widening
Project
BACKGROUND/ DISCUSSION
Capital Improvement Program Project No. 8012 (CIP C0020) - Princeton Avenue
Widening includes 3,052 linear feet of retaining wall along the north side of the road.
While much of the wall is only two to three foot high, there are several higher sections
with the tallest reaching approximately eleven feet above the new pavement opposite
the National Ready Mixed Concrete site. The City's consulting engineers considered
several structural design approaches for these walls, including: formed in place
concrete; precast concrete crib; and masonry wall. A concrete masonry wall design
was chosen because it offers an economic, durable, reinforced structure that requires
no complicated formwork and finishing. Other wall systems have different advantages
and disadvantages. For example, precast systems may be initially less costly but need
more right of way and are not as effective holding back sandy soils. Cast in place
concrete walls are durable but more expensive and _the forming process is labor
intensive. Concrete masonry walls can be built with a number of systems. In staffs
opinion they offer the best fit of cost, schedule, durability and aesthetics.
Staff is recommending that a tan colored slumpstone block system be used for the
walls. This block will blend well with the native soils above Princeton Avenue and is
reminiscent of historical adobe construction while providing superior strength and
durability. A photo simulation of this type of wall, near the freeway bridge, is attached.
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Honorable City Council
April 5, 2017
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Because of the mass of these walls staff has identified an option of adding irrigation
and vines to all or some of the walls. The south facing exposure of these walls should
foster rapid growth if Council selects this option.
Staff will submit the design to Caltrans for approval after two right of way matters are
resolved. As soon as Caltrans approvals are received; an authorization to proceed with
construction, staff will return to Council for permission to seek bids. Since this is a
relatively straightforward street reconstruction project the State's approval should be
received in early summer but it is extraordinarily difficult to predict how long Caltrans will
take with any review. Optimally, the project would be bid in the summer and
construction begun in early fall, 2017.
FISCAL IMPACT
- The 2016 CIP Budget for construction is based on the use of concrete masonry retaining
walls, estimated to cost $1.7 million. Other wall options would vary in cost and have
advantages and disadvantages as discussed above. Addition of irrigation and vines for
the walls will add approximately $ 75,000, available from Los Angeles Avenue AOC Fund
as part of the project budget, not a standalone project.
STAFF RECOMMENDATION
Authorize staff to proceed with the current design and approve the option of adding
irrigation and vines to the walls.
Attachment: Retaining Wall photo simulation
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Photo simulation of slumpstone retaining wall on North side
of Princeton Avenue, just west of 118 Freeway bridges
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