Los Vaqueros Dam Toe Drain Rehabilitation Project

Summary

SCH Number
2025060377
Public Agency
Contra Costa Water District
Document Title
Los Vaqueros Dam Toe Drain Rehabilitation Project
Document Type
NOE - Notice of Exemption
Received
Posted
6/9/2025
Document Description
CCWD proposes to rehabilitate the Los Vaqueros Dam’s toe drain outfall that discharges seepage water into Kellogg Creek. The existing 24-inch diameter toe drain outfall is located on the western bank of Kellogg Creek as shown in Figure 2 and was installed in the late 1990’s as part of the original Los Vaqueros Reservoir construction project. Over time, vegetation growth and sedimentation into Kellogg Creek has raised the elevation of the creekbed, leading to the submergence of the toe drain outlet. Currently, there remains positive flow through the toe drain, but the outlet remains at risk of complete blockage due to ongoing sedimentation and vegetative growth. Rehabilitation of the toe drain outfall to remove this obstruction is a requirement of the California Division of Safety of Dams (DSOD). At the project site, the existing toe drain outfall is nearly completely submerged in sediment within Kellogg Creek. CCWD proposes to redirect the alignment of the toe drain outfall into an underground pump package system/vault that would pump seepage water out of a new 10-inch pipeline alignment that outfalls into Kellogg Creek. The new outfall pipeline would exit the creek’s embankment at a higher elevation than the existing outfall and curve downwards, eliminating the sedimentation issue. The new pump package system will consist of 3 concrete structures (valve vault, manhole, and sump) extending a maximum of 15 feet underground. The structures will be constructed using a combination of pouring concrete in place and using pre-cast vaults. The exposed surface area of the concrete pump station vault is expected to be 10 ft by 10 ft, the vault will have a 6 ft diameter, and the valve vault will be 4 ft by 6 ft. In addition, an aboveground pump control panel adjacent to the pump system will be installed that will have a 6 ft by 8 ft concrete base. The new 10-inch outfall discharge pipe will be trenched underground at a depth of 3 ft. CCWD will install a concrete base pad underneath where the new discharge pipeline to prevent erosion issues. Before installing the concrete pad, vegetation within the top of bank and within Kellogg Creek will need to be removed using weed whackers and other hand tools. The use of excavators or backhoes may be needed to remove vegetation from the channel, but this equipment will only be operated from the bank of Kellogg Creek. Once vegetation is removed and the work area is dewatered, the area will be excavated to a depth of 1.5 feet. Afterwards, approximately 30 ft by 30 ft of concrete will be poured in place at a depth of 6 inches over a layer of aggregate base consisting of small rocks and gravel. The total volume of both aggregate base and concrete is approximately 50 cubic yards (17 cubic yards of concrete and 33 cubic yards of aggregate base). Once the project is completed, the existing 24-inch outfall pipeline will be disconnected from other drainage facilities, plugged, and remain in place.

Contact Information

Name
Cody Ericksen
Agency Name
CCWD
Job Title
Associate Planner
Contact Types
Lead/Public Agency / Project Applicant / Parties Undertaking Project

Location

Counties
Contra Costa
Regions
Unincorporated
Cross Streets
Walnut Blvd
Parcel #
005-100-002-0
Waterways
Kellogg Creek, Tributaries to Kellogg Creek, Frisk Creek, Horseshoe Creek, Mariposa Creek
Other Location Info
This project is in the Los Vaqueros Watershed on property owned by CCWD, along the first 150 feet of the Los Vaqueros Dam outfall area within Kellogg Creek. The project site is in unincorporated Contra Costa County. Access to the site will occur from Walnut Boulevard, which leads into a paved access road to the base of the dam.
Other Information
Nearest city is Brentwood, CA.

Notice of Exemption

Exempt Status
Categorical Exemption
Type, Section or Code
Section 15301 (b)
Reasons for Exemption
This project involves the operation, repair, maintenance...or minor alternation of existing public or private structures and facilities, "existing facilities" are defined as "facilities of both investor-and publicly owned utilities that are used to provide public utility services."
County Clerk
Contra Costa

Attachments

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