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CPSA GWET and SVE Systems Decommissioning Activities Work Plan Page 3 Lodi Central Plume Source Area,Lodi,California March 4,2021 ■ A Notification of Soil Excavation from the Water Board to be distributed to the residential and commercial property residents and owners prior to commencement of soil excavation activities; and, ■ Site access agreements with nearby private property owners, if needed. • Underground Utility Survey Prior to initiating excavation or subsurface investigation work, the Contractor will mark all excavation areas in white paint and contact Underground Service Alert (USA)at least 72-hours prior to the start of fieldwork to notify local utilities of the planned work. Additionally, a private utility locator will search for other on-Site subsurface utilities and/or obstructions that may or may not be marked by USA. B. GWET and SVE System Decommissioning — The above-ground components of the GWET and SVE systems, including granular activated (GAC) carbon vessels / tanks, filters, and aboveground piping and valves will be dismantled and removed for disposal or recycling, and spent GAC will be profiled for proper disposal to an appropriate off-site disposal facility. The piping for the GWET and SVE systems, as well as any utility lines associated with the CPSA remedial systems (Figure 3), will either be removed, and/or grouted, capped, and abandoned in place,as per City of Lodi requirements. Additionally, the Treatment System compound will be dismantled and all its relevant components including fencing,concrete pad,control and instrumentation panels,manifolds, and sumps will be dismantled and removed for recycling or disposal to an appropriate off-site disposal facility. C. Well Abandonment—Prior to abandonment of the groundwater extraction and soil vapor extraction and monitoring wells, the driller will obtain all the necessary permits for well abandonment from the San Joaquin Department of Environmental Health (SJDEH). Appropriate methodologies will be adopted for abandoning the SVE and vapor monitoring (VMW)wells and the groundwater extraction wells. a. All SVE and VMW wells will be properly abandoned by over-drilling using an oversized hollow stem augur drills based on the diameter of the wells. For the 2- inch diameter SVE and vapor monitoring wells an 8" outer diameter(OD)auger fitted with a 9" bit will be used, while for the 4-inch diameter SVE and vapor monitoring wells, a 10" OD auger fitted with a 11" bit will be used to over drill the well casing.The over-drilled borehole will be grout sealed using the tremie system to the target depth following removal of the well casing. b. Groundwater extraction wells EW-04, EW-05, and EW-06 will be properly abandoned using the appropriate method approved by SJDEH, which will include perforation of the steel casing and pressure grouting. 175 N EL MONTE AVENUE,LOS ALTOS,CA 94022 TEL:415-424-3009