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3.3 Subsurface Utility Clearance Prior to field activities, ATC marked out all drilling locations in accordance with the Underground Service Alert (USA) guidelines, and notified USA North of upcoming subsurface activities so existing underground utilities in the areas of work could be located and avoided. ATC also contracted with a private utility locator to confirm the locations of the underground utilities in the vicinity of the work and identified any other subsurface conflicts within the work locations. 3.4 Well Destruction Activities Of the 15 monitoring wells destroyed, 11 monitoring wells were destroyed by pressure grouting and four monitoring wells were destroyed by over-drilling using hollow-stem augers followed by grouting. Table 1 summarizes the well construction details and proposed destruction methods. Note that the originally proposed method of destruction for five of the monitoring wells (MW-3, MW-8, MW-9, AMW-5, and AMW-6) was changed from over drilling to pressure grouting due to subsurface utility conflicts. This variation was approved by the EHD via email correspondence with ATC on January 11, 2013. The 11 monitoring wells destroyed by pressure grouting were destroyed by removing the well vaults and clearing an area around the well casing to 124% of the original diameter and three feet bgs, cement grout was then emplaced in the bottom of each well casing via tremmie pipe. Once cement extended to the top of the well casing, an air pressure of 25 PSI was applied to the well casing. Additional cement was poured into the top of the well casing as necessary. Each well was deemed successfully destroyed when a pressure of 25 PSI could be maintained for 5 minutes with the grout dropping less than one foot. Upon completion of pressure grouting, the well casing was cut at two and a half feet and cement grout was poured into the space cleared around the former well casing to facilitate a mushroom cap. Once the mushroom cap was in place, the surface was repaired to match the surrounding pavement. The remaining four monitoring wells at the site were over-drilled utilizing hollow-stem auger drilling equipment. Upon completion of drilling, the boreholes were backfilled with cement grout emplaced via tremmie pipe, the well vaults removed, and the surface pavement repaired to match the surrounding pavement. Department of Water Resources DWR-188 Forms are included in Appendix C. 3.5 Waste Disposal Investigation derived waste (IDW) including soil cuttings and construction debris generated during well destruction activities were contained in 55-gallon drums and temporarily stored on site. The IDW was profiled and was removed by a licensed waste disposal contractor on December 4, 2012 and January 29, 2013 and disposed of at the Keller Canyon Landfill in Pittsburgh, California. Documentation of IDW disposal is included in Appendix D. 2 76(Former BP)Service Station No.11194 ATC Project Number 75.75118.1750 Tracy,California March 5,2013