Supplemental Mitigated Negative Declaration - Keyes 1, 2, 3 TCP Mitigation Project

Supplemental Mitigated Negative Declaration - Keyes 1, 2, 3 TCP Mitigation Project

This is a Supplemental Initial Study / Mitigated Negative Declaration to the Keyes CSD’s Keyes 1, 2, 3 – TCP Mitigation Project (Approved Project), which includes a treatment system to remove the pesticide impurity 1, 2, 3 – Trichloropropane (TCP) from its water supply. The original Approved Project included two components: 1) Granular Activated Carbon (GAC) Treatment at Well 8, Well 9, and Well 10. This component will centralize TCP treatment at Wells 8, 9, and 10. Two trains and a 40,000 gallon backwash tank will be constructed at Well 8. Three trains will be constructed at Well 9. Four trains and a 60,000 gallon backwash tank will be constructed at Well 10. 2) Water Transport from Well 7 to Well 10. Because physical space at Well 7 cannot accommodate GAC infrastructure, this component involves conveying raw ground water from Well 7 to Well 10 for TCP treatment. Approximately 2,532 linear feet of 6-inch pipeline will be installed below existing roads between Well 7 and Well 10. After filing the Notice of Determination for the Approved Project, minor changes were made to the Project which included removing a previously-planned backwash holding tank at Well 9 and installing a 150,000 gallon backwash pond adjacent to the Well 9 site. Additional modifications consist of changes to tank sizes at Wells 7, 8 and 10. These additional components were evaluated in the Supplemental IS/MND. Existing water service will not be significantly impacted during construction.

Keyes (unincorporated)

Stanislaus

Citywide

California Air Resources Board (ARB), California Department of Conservation (DOC), California Department of Fish and Wildlife, Bay Delta Region 3 (CDFW), California Department of Fish and Wildlife, Central Region 4 (CDFW), California Department of Fish and Wildlife, North Central Region 2 (CDFW), California Department of Parks and Recreation, California Department of Toxic Substances Control (DTSC), California Department of Transportation, District 10 (DOT), California Department of Water Resources (DWR), California Highway Patrol (CHP), California Native American Heritage Commission (NAHC), California Natural Resources Agency, Central Valley Flood Protection Board, Delta Stewardship Council, Office of Historic Preservation, State Water Resources Control Board, Division of Drinking Water, State Water Resources Control Board, Division of Drinking Water, District 10, State Water Resources Control Board, Division of Water Rights, State Water Resources Control Board, Divison of Financial Assistance, California Regional Water Quality Control Board, Central Valley Sacramento Region 5 (RWQCB)

California Regional Water Quality Control Board, Central Valley Sacramento Region 5 (RWQCB)

Water Facilities (TCP Removal system)(Type TCP Removal , MGD 0.000001)

Site Plan

Aesthetics, Agriculture and Forestry Resources, Air Quality, Biological Resources, Cultural Resources, Drainage/Absorption, Energy, Fiscal Impacts, Flood Plain/Flooding, Geology/Soils, Greenhouse Gas Emissions, Hazards & Hazardous Materials, Hydrology/Water Quality, Land Use/Planning, Mandatory Findings of Significance, Mineral Resources, Noise, Population/Housing, Public Services, Recreation, Schools/Universities, Septic System, Sewer Capacity, Solid Waste, Transportation, Tribal Cultural Resources, Utilities/Service Systems, Vegetation, Wetland/Riparian, Wildfire