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4 C�rdr�o San Joaquin County Environmental Health Department ATC March 22,2013 Shaping the Future Planning and Permits In advance of the well destruction activities at the site,Cardno ATC will obtain all necessary permits from the EHD. Cardno ATC will schedule field personnel and equipment,notify Underground Services Alert to locate underground utilities as required,and perform other necessary field preparation and job start-up activities. The proposed work Will be performed under the direction of a California Registered Professional Engineer or Geologist. Well Destruction Activities Cardno ATC will properly abandon groundwater monitoring wells MW1, MW2, MW3, MW4,MW5,MW6, MW7,and MW8. The locations of the groundwater monitoring and remediation well networks are shown on Figure 2. Wells Abandoned by Over Drilling The groundwater monitoring wells MW1, MW2,MW4,MW5, and MW8 will be abandoned by over-drilling the casing and sand pack.A minimum 8-inch diameter hollow-stem auger will be used on MW1, MW2, MW4,and MW5,and a minimum 10-inch diameter hollow-stem auger will be used on MW8. Once the over-drilling process has been 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 EHD 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. Wells Abandoned by Pressure Grouting Groundwater monitoring wells MW3, MW6,and MW7 will be abandoned via pressure grouting. Prior to the abandonment for protection of the annular seal at the ground surface,the well boxes and locking plugs will be removed and a minimum 24-inch diameter hole will be dug out around the well box locations to a depth of approximately 36 inches. Then the top 2.5 feet of well casing will be cut,with the remaining six-inch exposed section of casing being affixed to a specialized pressure-grouting tool to deliver and emplace a neat cement grout slurry under pressure,to fill the casing and filter pack with grout. Once the casing is completely filled,the grout used to fill the wells will be made to overflow into the excavation to form a minimum 24-inch diameter"mushroom cap"like seal,with at least 12 inches of neat cement grout poured 6 inches above and 6 inches below the top of the cut-off casing.Any remaining soil voids will be backfilled compacted and resurfaced to match the surrounding surface completion. Report Preparation Upon completion of the well destruction activities,a summary report will be prepared that will include a description of all well destruction field activities associated with the site and include records of waste disposal. Cardno ATC will also submit well destruction logs to the Department of Water Resources. PROJECTED SCHEDULE Once approval of this workplan has been received,Cardno ATC will submit a well destruction permit and accompanied with the associated fees to the EHD. Once approved,Cardno ATC will confirm the schedule for drilling activities with EHD and will notify the EHD 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.cardnoate.com