Canal Levee Elimination and Flood Protection Project, Segments 3 and 4, Contra Costa Water District, Project Number 416054 (Subcontractor to Garney Construction)

The Contra Costa Canal Replacement Project is a drinking water supply protection and flood management project to replace four miles of unlined Contra Costa Canal with reinforced concrete pipeline from the Discharger’s Pumping Plant 1 (PP1) to the Rock Slough Headworks. The first phase was completed in 2009 and replaced approximately 1,900 feet of unlined Canal
from PP1 to Marsh Creek (Segment 1). The second phase was completed in 2015 and included
the installation of approximately 5,500 feet of pipeline replacing the unlined Canal from Marsh
Creek to Sellars Avenue and 200 feet of pipe installed at the end of Contra· Costa Canal near
Rock Slough that supports a Flood Isolation Structure (Segment 2).

This contract provides coverage for the current phase of construction (Segments 3 and 4) that will be constructed in 2018 – 2019 and Includes replacement of approximately 5,500’ of unlined canal from Sellers Avenue to a location about 1,000’ upstream (west) of Jersey Island Road and East Cypress Road with a 10-foot diameter pipeline.

Our portion of the project consists of constructing an Access Structure and Culvert Transition Structure in Oakley, CA. The first order of work will be to construct the Access Structure starting in June, 2018. The construction of the Access Structure will take careful planning with Garney Construction to tie-in the 10-foot diameter Ameron pipe. The Access Structure is a 26’ tall box that will require engineered form drawings in order to ensure that the forms are supported during the pour for the walls.

The roof of the Access Structure is to be constructed separately from the walls and requires the installation of long lead items that will need to be ordered in preparation of the concrete pour. Once the roof is constructed, it will set onto the structure and tied in. The Culvert Transition Structure will allow for the continuation of Little Dutch Slough over the installation of the 10-foot pipe. Prior to the installation of the culvert, Garney Construction will install dewatering wells and then install the 10’ RCP along with a sheet pile shoring system. After installation and backfill is complete, we will construct the Culvert Transition Structures on either end of the slough.