Calaveras County Water District – La Contenta Wastewater Treatment Facility Phase 3 Project

Calaveras County Water District – La Contenta Wastewater Treatment Facility Phase 3 Project

The Project proposes to replace and/or improve facilities at the existing approximately 26.4-acre La Contenta WWTF due to existing age deterioration and limited capacity. See Appendix A for the Preliminary Design Report and Appendix B for the La Contenta Wastewater Treatment Facility Phase 3 Improvement Plans. Details of the Proposed Project improvements are listed below. 2.2.1 Proposed Treatment Process Upgrades The existing aeration and clarification process for the treatment plant is a Biolac system, located immediately east of the existing holding pond, and north of the UESP. The Proposed Project would add a new extended aeration activated sludge basin with an integral clarifier to provide additional treatment capacity to the existing Biolac treatment system for projected flows. This would include excavation, shoring, and backfill. The Proposed Project would also include a new UESP pump station to allow the full volume of the UESP to be utilized for seasonal storage of final effluent. The pump station would include floating pump platforms, pipe floats, submersible pumps, valves, flow meter, instrumentation, piping, and appurtenances. Additionally, the Proposed Project would include new aeration system blowers in the existing treatment plant building for the new active sludge aeration basin. This would include a new concrete equipment pad in the existing blower room and the required piping, power, and controls tie-ins. 2.2.2 Proposed Electrical The Proposed Project would include improvements to yard piping, power distribution utility power supply, instrumentation, and PLC/Supervisory Control and Data Acquisition System controls. The improvements would include a new masonry electrical building to house the new Motor Control Center (MCC) equipment with provisions for future expansion. The electrical portion of the Proposed Project would include a replacement of the existing power distribution and standby power systems for the entire La Contenta WWTF. 2.2.3 Proposed Treated Effluent Pipeline The existing pipeline consists of a 12-inch pipeline exiting the Parshall flume and transitions to an 8-inch pipeline that is outside the perimeter berm of the UESP. The 8-inch pipeline interconnects with the UESP valve assembly located south of the UESP, comprising approximately 1,100 foot of piping. The effluent is conveyed south to the LESP across approximately 2,700 feet of pipeline. To accommodate existing and future peak hour flows, the Proposed Project would install a replacement pipeline that has been designed to convey a minimum of 2.00 million gallons per day (MGD) to the LESP, Draft Initial Study and Mitigated Negative Declaration ECORP Consulting, Inc. 2-3 April 2026 CCWD La Contenta WWTF Phase 3 Project 2025-018 which increases capacity from the existing 0.73 MGD. The total run of the new pipeline would be approximately 3,800 feet. Installation of the pipeline would include dewatering, flow bypassing, temporary piping/valves, pipe stubs, tie-ins of new piping to existing piping and structures. Some existing pipeline segments deviating from the alignment of the replacement pipe would be abandoned in place.

Valley Springs

Calaveras

Countywide

California Air Resources Board (ARB), California Department of Conservation (DOC), California Department of Fish and Wildlife, North Central Region 2 (CDFW), California Department of Forestry and Fire Protection (CAL FIRE), 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 Fish and Game Commission (CDFGC), California Governor's Office of Emergency Services (OES), California Highway Patrol (CHP), California Native American Heritage Commission (NAHC), California Natural Resources Agency, California Regional Water Quality Control Board, Central Valley Sacramento Region 5 (RWQCB), California State Lands Commission (SLC), Central Valley Flood Protection Board, Delta Protection Commission, Delta Stewardship Council, Department of General Services (DGS), 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 Quality, State Water Resources Control Board, Division of Water Rights, State Water Resources Control Board, Divison of Financial Assistance

Water Facilities (Water treatment plant)(Type Utilities, MGD 2)

Site Plan

Biological Resources, Noise, Tribal Cultural Resources, archeological/Historical, Geologic/Seismic