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YVAfC ATC Associates Inc. ]1]7 Lone Palm Avenue, Suite 201 Modesto,California 95351 209-579-2221 ASS O C 1 ATE S IN C. Fax:209-579-2225 Wells Abandoned by Over Drilling The groundwater monitoring wells MW2 and MW3 will be abandoned by over-drilling the casing and sand pack using 8-inch diameter hollow-stem augers. Groundwater samples collected from these wells during the last groundwater sampling event in April 2010 contained detectable concentrations of chemicals of concern, therefore are required by SJCEHD to be abandoned by completely removing the well casing, screen, sand pack and grout sealant. These wells have been completed to total depths of 45 to 50 feet bgs. Once the over-drilling process has been completed, the wells will be backfill with a neat cement grout slurry mix from the base of the annulus to the surface using trem7e' pipe. Wells Abandoned by Pressure Grouting Groundwater monitoring wells MW1, MW4, MW5, and MW6 will be abandoned via pressure grouting. Prior to the abandonment, the well boxes and locking plugs and top three feet of casing will be removed from each well. The groundwater monitoring wells will be abandoned using pressure grouting methods, filling each well casing and filter pack with a neat cement grout slurry from the bottom via tremmie pipe. Well construction logs are provided as Attachment 1. The wells to be destroyed by pressure grouting processes will be completed using a specialized pressure-grouting tool. For protection of the annular seal at the land surface, a 24-inch diameter hole will be dug out around the well box locations to a depth of approximately 36 inches. The top 2.5 feet of well casing will be cut. During the sealing operation, the grout used to fill the wells will be made to overflow into the excavation and fill it to a thickness of one foot and form a cap which has a diameter of at least 24 inches. After the sealing material has set, the excavations will be filled to near surface grade with clean backfill material and the excavation will be capped with asphalt patch or concrete to restore the appearance of the paved surfaces at the site. 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. ATC will also submit well destruction logs to the Department of --` w�'er Rescutces. Projected Schedule Once approval of this workplan has been received, ATC will submit a well destruction permit and associated fees and confirm the schedule for drilling activities. ATC 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. S:\Enviromental\62605-Thiemanns\REPORTS\WP-Well Abandonment 5