What is the Sewer Trunk Main Replacement Project?

The Sonoma Valley County Sanitation District (SVCSD) Sewer Trunk Main Replacement Project is a multi-year project that will replace the existing sewer trunk pipeline that services the City of Sonoma and the unincorporated areas of Agua Caliente, Boyes Hot Springs, Eldridge, Fetters Hot Springs, Glen Ellen, Schellville, Telemec, and Vineburg. Construction on the next phase of the multi-year replacement project is set to begin this year. This next phase of the sewer trunk main replacement project is known as Phase 5B and will be completed in two separate sections. 

The SVCSD Sewer Trunk Main Replacement Phase 5B (Johson Avenue) project will install approximately 562 linear feet (0.1 miles) of 24-inch diameter trunk sewer main the intersection of Johnson Avenue and Lichtenberg Avenue and the terminus of Johnson Avenue. During planning and design SVCSD and Public Infrastructure identified additional efficiencies could be realized by combining construction efforts to minimize construction impacts to residents, reduce duplicate work and unnecessary expenditures for paving, and consolidate construction contract administration costs. The project, led by SVCSD, will complete full-depth restoration and paving of Johnson Avenue in accordance with the County’s ongoing Pavement Preservation Program. The remaining segment of Phase 5B between Johnson Avenue and Las Flores Drive will be constructed before October 2029.  

After Phase 5B (Johson Avenue) project is completed, close to 33,600 linear feet of sewer trunk main will have been constructed since the first replacement project in 2003.

When is Project construction expected to start?

Phase 5B (Johnson Avenue) is expected to begin in July 2026. Construction activities will begin near the intersection of Johnson Avenue and Lichtenberg Avenue and progress northward along the construction path indicated on the map.

Project work hours are Monday through Friday 7 am to 7 pm, excluding holidays.

How will this Project affect my neighborhood?

If you live or have a business along the corridor, the construction may create additional noise, dust, and cause some traffic disruptions. See the map for Phase 5B (Johnson Avenue) project limits. We will make every effort to minimize any traffic delays or detours. The project will not affect sewer service.

Why is the Project needed?

• The trunk sewer main to be replaced is approximately 60 years old and at the end of its life expectancy.
• The project will improve the sewer trunk main’s ability to reliably handle dry and wet weather flows.
• The project will help to prevent leaks in the system and reduce sanitary sewer overflows, which occur during heavy rains and can result in wastewater entering creeks.

• Reach 4A: From the intersection of 6th Street West and Studley Street, continue north to Highway 12, continue north along State Highway 12, and continue west and north along Highway 12, ending in Ramon Street.
• Reach 4B.1: Within Maxwell Farms Regional Park, is being advanced in coordination with Sonoma County Regional Parks to replace a portion of the existing sewer main that is under the baseball field. Improvements were planned as a part of the Maxwell Farms Regional Park Master Plan.
• Reach 4B.2: Beginning at the intersection of Ramon Street and Highway 12 in Sonoma, crossing through Maxwell Farms Regional Park, and ending just north of Verano Avenue. This phase begins where Phase 4A ended in 2019 and worked its way north to tie into the Agua Caliente Siphon Project, which was constructed in 2016.
• Phase 4C: The SVCSD Trunk Main Replacement Phase 4C project included installation of 2,200 feet (0.4 miles) of 27-inch diameter sewer line along Happy Lane between Fairview and Orchard in Boyes Hot Springs.
• Reach 5A: The SVCSD Sewer Trunk Main Replacement Phase 5A project included installation of approximately 3,100 linear feet (0.6 miles) of 24-inch diameter trunk sewer main running between the north end of Happy Lane and the intersection of Johnson Avenue and Lichtenberg Avenue.

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