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i 1 12 February 2020 AdvdllCeddGeo An Project No. 14-3154 ruin. Page 2 of 3 AGI prepared a Low-Threat CIesure Request (dated 11 July 2019) concluding that that site conditions meet the closure criteria presented in the State Water Resource Control Board 's Law Threat Underground Storage Tank Case Closure Policy (LTCP). The CVRWOCB is waiting to comment on the closure request until AGI performs the work proposed in the Confirmation Sampling Work Plan dated 18 December 2019 and approved by CVRWOCB letter dated 31 January 2020 (Appendix A); the work will be performed in February 2020. Due to the time constraints of this project, AGI has prepared this Work Plan to be ready for potential site cosure activities and to expediate the closure process. This Work Plan provides procedures for the destruction of all groundwater monitoring and mediation wells associated with the diesel fuel leak at the site. All wells will be destroyed by over-drilling methods and in accordance with San Joaquin County Well Standards. Well construction details am summarized! in Table 1 ; groundwater elevation and analytical data a reed in Tables 2 and 3, respectively; and Soil analytical data is summaritced in Table 4. PROCEDURES As required, a health and safety plan will be prepared in accordance with Occupational Safety and Health Guidance Manual for Hazardous Waste Site Activities (National Institute for Occupational Safety and Health Administration, U.S. Coast Guard and U.S. Environmental Protection !Agency, 1985). Prior to drilling acivgies, each proposed drilling location will be clearly marked, and utility clearance obtained through Underground Service Alert. Well abandonment1destruction permits will be obtained from the San Joaquin County Environmental Health Deparkment (EHD); additionally, the EHD will be notified a minimum of 48-hours prior In commencement of well destruction activities. Prior to well destruction activities, all wells will be checked for total depth and well integrity using a Solinst water level meter. Any obstructions found in the wells will be removed. AGI proposes to destroy wells MW-1 through MWa and RW-1 through RWE by over- drilling. The wags will be drilled-out to the tool depth of the wells utilizing a hollow-stern auger drill rig equipped with 8.25-inch diameter augers for wells MW-1 through MWd and 10.25-inch diameter augers far wells RW-1 through RW-8. All original well construction materials will be removed (including wall casing, screen, filter pack, and annular seal) by the drill rig to ensure that no residual contamination is sealed within the abandoned borehole and a vertical conduit doesn't remain The borings will be completely backfilled to surface grade with a cement grout mixture (Portland type II) and finished at the surface with native soil or concrete to match the existing surface. The grout mixture will consist of ratio of not more than six gallons water for every 84-pound sack of Portland type II cement. The drill rig hollow stem augers will be utilized as atremie pipe during deployment of the grout mixture. Any groundwater displaced by the grant mixture will be muted into properly labeled Department of Transportation (DOT)approved 55-gallon drums. All