2023 Large Diameter Sewer Renovations, District Project 100007


SCH Number
Public Agency
Central Contra Costa Sanitary District
Document Title
2023 Large Diameter Sewer Renovations, District Project 100007
Document Type
NOE - Notice of Exemption
Document Description
Main Trunk No. 1 is currently exposed across Grayson Creek due to erosion activities over the last 70 years, so the span across the creek is no longer structurally sound. Therefore, removal of this 39- inch pipe is environmentally beneficial since it reduces the possibility of a sewage event into waters of the State. Additionally, the routine desilting maintenance activities of the Flood Control District are limited with this pipe crossing, so removal provides a public benefit by, potentially, allowing improvements to the channel' s capacity. As central Contra Costa County was developed, two additional interceptors, the A -Line (90-inch diameter) and A -Line Relief Interceptor (102-inch diameter), were constructed in the early 60s and 90s, respectively; therefore Main Trunk No. 1 is not needed for influent capacity since the two interceptors provide sufficient hydraulic capacity to accommodate peak dry weather flows (PDWF) and average wet weather flows AWWF), which been re -verified with the updated hydraulic model in 2023.During their construction, junction structures were installed to divert flow from Main Trunk No. 1 near, current -day, Target and Buchanan Golf Course, and which will be the upstream limit for abandonment of Main Trunk No. 1. However, Main Trunk No. 1 was not abandoned at that time since staff were aware of the Contra Costa Transportation Authority's interchange improvement project and anticipated needing Main Trunk No. 1 for bypassing when the 84-inch portion of the A -Line along Berry would have to be relocated. As the final phase of the interchange improvement project is imminent, preparations to abandon Main Trunk No. 1 may now proceed.

Contact Information

Agency Name
Central Contra Costa Sanitary District (Central San)
Job Title
Environmental Coordinator
Contact Types
Lead/Public Agency / Project Applicant / Parties Undertaking Project


Contra Costa
Northern California, San Francisco Bay Area, Unincorporated
Cross Streets
Berry Drive and Center Avenue, Pacheco
Grayson Creek

Notice of Exemption

Exempt Status
Categorical Exemption
Type, Section or Code
CEQA Guidelines Section 15302
Reasons for Exemption
At its November 2, 2023, meeting, the Central San Board of Directors independently found this project is exempt from the California Environmental Quality Act (CEQA) under Central San's CEQA Guidelines Section 15302, since it involves replacement of existing public facilities at the same location and with the same purpose.
County Clerk
Contra Costa


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