Old River Drainage/Seepage Channel Culvert Replacement Project

The purpose of the project is to provide the channel with a functional culvert to prevent local flooding and protect the integrity of the Mokelumne Aqueduct access road. The objective of the project is to replace the failed culvert and restore the original alignment of the access road. See Attachment A for additional information. Overview and Background The Project is located on the East Bay Municipal District (EBMUD) Mokelumne Aqueduct right-of-way (ROW), near Bixler in Contra Costa County. There are two drainage/seepage channels adjacent to the ROW's gravel access road, that parallel the Old River alignment. The channels store seepage water from the Delta levees, in addition to local stormwater run-off. The existing culvert on the west-side channel has failed and the edges of the overlying access road have deteriorated. Project Purpose and Objectives The purpose of the project is to provide the channel with a functional culvert to prevent local flooding and protect the integrity of the access road. The objective of the project is to replace the failed culvert and restore the access road's original alignment. Project Location The project is located on East Bay Municipal District Mokelumne Aqueduct right-of-way, near Bixler in Contra Costa County, see Figure 1a and Figure 1b. Project Characteristics The project will replace the existing 24-inch diameter corrugated metal culvert with a high-density polyethylene plastic pipeline. The 24-inch diameter will be retained, but the length will· be 30 feet, 10 feet longer than original installation. The additional length will ensure that the new installation crosses under the entire access road to prevent further erosion of the edges. The original road alignment will also be restored with a 3/4-inch aggregate base. Required heavy equipment will be staged on the access road. Permits All work will be conducted on EBMUD property, so no encroachment permits are necessary. A Lake and Streambed Alteration Agreement will be obtained from the California Department of Fish and Wildlife. Schedule Work is scheduled for after the nesting bird season, which ends on September 15th. The project is expected to be completed within five days. Work hours will be limited to weekdays with standard business hours of 7:00 a.m.to 3:00 p.m. EBMUD Practices and Procedures Standard construction environmental and safety practices applicable to all EBMUD construction projects have been incorporated into the project and will be implemented accordingly.