City of Manteca Well 29 TCP Treatment Project

City of Manteca Well 29 TCP Treatment Project

The project involves constructing a Granular Activated Carbon (GAC) water treatment system to treat the water produced by Well 29 located in Yosemite Village Park to remove 1,2,3-trichloropropane (TCP) to achieve a treated water concentration that complies with California State Water Resource Control Board (SWRCB) Compliance Order No. 01-10-21R-002. This Order requires compliance with California Code Regulations, Title 22, Section 64444 on or before April 10, 2024. The maximum contaminant level (MCL) for 1,2,3-Trichloropropane (TCP) is 0.005 micrograms per Liter (µg/L). The City is considering two Layout Options as described below. Layout Option A would place six new 12-foot-diameter GAC treatment vessels directly to the east of the existing well site on a concrete pad measuring 40 by 60-feet. The new GAC system would tie into the existing Well 29 raw water discharge pipe, prior to arsenic treatment, via two new 12-inch pipes that would run approximately 90-feet southwest. The new GAC vessels would discharge backwash waste into an 8-inch pipe running approximately 255-feet from the GAC vessels to the existing backwash tank located adjacent to the arsenic treatment system. The existing site fencing would be continued around the new treatment facility, and two 16-foot sliding gates would be added for maintenance access. The hypochlorite injection point for potable water disinfection would be relocated from the existing wellhead to an above-grade injection point after the GAC treatment system. A connection to the existing sanitary sewer system would be made in the street adjacent to the site with a new sanitary sewer maintenance hole. An additional maintenance hole and drain lines would be installed onsite for collecting wash water from the backwash process and excess water that must be drained during media change-outs from the GAC delivery truck. Media change outs are completed by sending a water and media slurry from the treatment vessels to the GAC delivery trucks. Excess water must be drained from the trucks after the slurry pumping operation is completed and before the truck may depart. The water utilized to generate the slurry is potable water. The existing driveway would be widened by 14-feet and additional pavement added to accommodate the truck turning radius. Option A would require removal of one ornamental tree located at the southeast corner of the existing Well 29 footprint. Layout Option B would include the majority of the same infrastructure as Layout Option A but would be located directly north of the existing well site. Due to the location of Option B, a new 16-foot-wide access driveway would be required just north of the new infrastructure. Since this layout option would be placed where the existing basketball court is located, a new basketball court is being proposed east of the existing playground. Option B would not require tree removal as a part of the Proposed Project.

Manteca

San Joaquin

Citywide

California Air Resources Board (ARB), California Department of Fish and Wildlife, Bay Delta Region 3 (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, California Public Utilities Commission (CPUC), Central Valley Flood Protection Board, Delta Protection Commission, Delta Stewardship Council, Office of Historic Preservation, 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, State Water Resources Control Board, Division of Drinking Water, California Regional Water Quality Control Board, Central Valley Sacramento Region 5 (RWQCB)

State Water Resources Control Board, Division of Drinking Water, California Regional Water Quality Control Board, Central Valley Sacramento Region 5 (RWQCB)

Other (TCP treatment system to existing well infrastructure )

Approval (Board)

Biological Resources, Transportation, Tribal Cultural Resources, archeological/Historical