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r Well Destruction Work Plan 76(Former BP)Service Station No. 1119 CaI"Lno® 1403 West Country Club Boulevard ATC Stockton,California Shaping the Future 4 3.4 Well Destruction Activities There are 24 well structures associated with the Site slated for destruction, including the following: • 12 Monitoring Wells (MW-1, MW-3, MW-4, MW-5, MW-6, MW-7, MW-8, MW-9, MW-10, MW-11, MW-12, and MW-13) • 10 Ozone Sparge Wells(SP-A, SP-B, SP-C, SP-D, SP-E, SP-F, SP-G, SP-H, SP-J, and SP-K) • 2 Vapor Extraction Wells (VW-1 and VW-2) In February 1991, MW-2 was properly destroyed with the oversight of the SJCEHD as it was located in the area of the proposed UST excavation (IT, Underground Storage Tank Closure Report data April 1991). As per the SJCEHD Well Standard, since each of these wells had detectable amounts of contaminants present in soil or groundwater samples collected, all the wells will need to be over drilled. Well construction details and the application of the SJCEHD Well Standards are summarized in Table 1. Each well will be abandoned by first removing the well's box/vault. Then the well casing and sand pack will be overdrilled for the well's entire length, using an auger slightly larger in diameter than the original borehole. This will facilitate removing all the contents of the original borehole (i.e. conductor casing, well casing, screen, filter pack, and grout sealant). Once the over-drilling process is completed, the boreholes will be backfilled with a neat cement grout slurry mix from the base of the annulus to the surface using a tremmie pipe. Groundwater displaced to the surface during grout installation shall be pumped out of the excavation, collected, and containerized for proper disposal. This water will be available for the SJCEHD to inspect and to verify that the well has been properly destroyed. Any remaining soil voids will be backfilled, compacted, and resurfaced to match the surrounding surface completion. 3.5 Waste Disposal Investigation derived waste (IDW) including soil cuttings, groundwater, and decontamination water generated during well destruction activities will be contained in 55-gallon drums or a roll-off bin and temporarily stored on Site. The IDW will be profiled and scheduled for removal and disposal by a licensed waste disposal contractor as soon as possible after the well destruction is completed. Documentation of IDW disposal will be submitted to the SJCEHD following receipt of waste manifest copies. 3.6 Reporting Upon completion of the well destruction activities, a summary report will be prepared that will include a description of the well destruction field activities associated with the Site, including records of waste disposal. Cardno ATC will also submit well destruction logs to the Department of Water Resources. 4.0 PROJECTED SCHEDULE Once approval of this workplan has been received, Cardno ATC will submit a completed well destruction permit to the SJCEHD, accompanied by the associated fees. Once approved, Cardno ATC will confirm the schedule for drilling activities with SJCEHD and will notify the SJCEHD at least 48 hours prior to the commencement of any field activities. A summary report will be submitted within approximately 30 days following the completion of field activities. www.cardnoatc.com