Agenda

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C. 2

To:	Board of Supervisors
From:	Brian M. Balbas, Public Works Director/Chief Engineer
Date:	November 17, 2020

Contra

Costa

County

Subject:

APPROVE the Carquinez Scenic Drive Embankment Erosion and Guardrail Repair Project and take related actions under CEQA.

APPROVE	OTHER
RECOMMENDATION OF CNTY ADMINISTRATOR	RECOMMENDATION OF BOARD COMMITTEE

Action of Board On: 11/17/2020

APPROVED AS RECOMMENDED

OTHER

Clerks Notes:

VOTE OF SUPERVISORS

AYE:

John Gioia, District I Supervisor
Candace Andersen, District II Supervisor
Diane Burgis, District III Supervisor
Karen Mitchoff, District IV Supervisor
Federal D. Glover, District V Supervisor

Contact:	Shrav Sundaram, 925-313-2366
cc:	Shrav Sunderam Ave' Brown

I hereby certify that this is a true and correct copy of an action taken and entered on the minutes of the Board of Supervisors on the date shown.
ATTESTED: November 17, 2020
David Twa,

BY:	, Deputy

RECOMMENDATION(S):

APPROVE the Carquinez Scenic Drive Embankment Erosion and Guardrail Repair Project (Project) and AUTHORIZE the Public Works Director, or designee, to advertise the Project, Carquinez Strait area. [County Project No. 0672-6U2341, DCD-CP#20-16] (District V).


DETERMINE the Project is a California Environmental Quality Act (CEQA), Class 1(c) Categorical Exemption, pursuant to Article 19, Section 15301 of the CEQA Guidelines, and

RECOMMENDATION(S): (CONT'D)

DIRECT the Director of Department of Conservation and Development to file a Notice of Exemption with the County Clerk, and

AUTHORIZE the Public Works Director or designee to arrange for payment of a $25 fee to the Department of Conservation and Development for processing, and a $50 fee to the County Clerk for filing the Notice of Exemption.

FISCAL IMPACT:

Estimated Project cost: $940,000. 100% Local Road Funds.

BACKGROUND:

The purpose of this project is to reconstruct the road embankment and guardrail along the westbound lane of Carquinez Scenic Drive. The erosion of the westbound lane and embankment occurred during the 2017 winter storms. Traffic has been reduced from a two-way road to a single lane road with stop signs installed on both sides of the erosion, and the westbound lane has been closed off with concrete k-rails. The embankment repair is necessary to prevent further deterioration of the roadway and to restore the westbound lane. The project will repair an approximately 130-foot stretch of Carquinez Scenic Drive. The embankment will be stabilized by installing rows of soil nails into the slope in a grid pattern. The roadway and shoulder will be reestablished with a concrete-form retaining wall (approximately 120-ft long and 10-ft tall) that is backfilled with low-density cellular concrete. The wall will be further supported by a single row of self-driving micropiles that is covered with reinforced structural shotcrete. The micropiles will be drilled in; no pile driving will occur. The retaining wall will be downslope from the roadway and not visible to drivers. The guardrail will be reconstructed along the entire length of the project. Heavy equipment will be operated from the roadway. The anticipated maximum depth of excavation is 25 feet for installing the rows of soil nails.

Concrete k-rails and channelizers will limit the roadway to one-way traffic for the duration of construction. Temporary construction easements may be required. Equipment staging will likely occur just to the west of the project site on a paved or gravel area. Some debris and eroded soil removal may be required. Roadway surface drainage will be restored to previous conditions, and the retaining wall will incorporate features to promote drainage. Tree removal (approximately four oaks) and vegetation removal may be necessary to prepare the eroded embankment area for the repair work. Construction is currently anticipated to occur in the summer of 2021 and take approximately 25 days to complete.

CONSEQUENCE OF NEGATIVE ACTION:

Delay in approving the project may result in a delay of design and construction.