Sonoma Valley County Sanitation District System Protection Plan at Kohler & Sonoma Creek Crossing Project

Sonoma Valley County Sanitation District System Protection Plan at Kohler & Sonoma Creek Crossing Project

The Sonoma Valley County Sanitation District System Protection Plan at Kohler & Sonoma Creek Crossings Project would implement permanent repairs along Kohler and Sonoma creeks and establish new and expanded easements to provide access along the pipeline routes for repair and maintenance purposes. Streambank erosion and downcutting at the site has exposed pipeline segments, and streambank erosion is migrating towards existing maintenance holes in both Kohler and Sonoma creeks. The District implemented emergency repairs at the project site in 2019 to prevent further bank erosion that could expose the sewer pipeline and cause sewage spills. These emergency repairs were considered a temporary means to slow the progression of streambank erosion until a permanent repair could be completed. The Proposed Project would implement the permanent repair. The Sonoma Valley County Sanitation District System Protection Plan at Kohler & Sonoma Creek Crossings Project would stabilize streambanks and channel beds along Kohler and Sonoma creeks using a combination of rock slope protection, fabric reinforced fill material (FREF), log/rootwad revetments, brush mattress, and native vegetation. In addition, the existing siphon across Sonoma Creek would be armored with large boulders to protect against scour. Site improvements would also include revegetation with native plants and installation of habitat improvement elements for California freshwater shrimp, steelhead, Chinook salmon, and other aquatic species in Sonoma Creek. Implementation would require new temporary and permanent sewer pipeline easements.

Glen Ellen

Sonoma

Unincorporated

California Air Resources Board (ARB), California Department of Fish and Wildlife, Bay Delta Region 3 (CDFW), California Department of Forestry and Fire Protection (CAL FIRE), California Department of Parks and Recreation, California Department of Resources Recycling and Recovery, California Department of Transportation, District 4 (DOT), California Department of Water Resources (DWR), California Highway Patrol (CHP), California Native American Heritage Commission (NAHC), California Natural Resources Agency, California Regional Water Quality Control Board, San Francisco Bay Region 2 (RWQCB), Office of Historic Preservation, State Water Resources Control Board, Division of Drinking Water, State Water Resources Control Board, Divison of Financial Assistance

Other (Stream bank stabilization)

Site Plan

Aesthetics, Air Quality, Biological Resources, Cultural Resources, Drainage/Absorption, Flood Plain/Flooding, Geology/Soils, Greenhouse Gas Emissions, Hazards & Hazardous Materials, Hydrology/Water Quality, Mandatory Findings of Significance, Noise, Public Services, Recreation, Septic System, Transportation, Tribal Cultural Resources, Utilities/Service Systems, Vegetation, Wetland/Riparian