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A=COM —� Harlin Knoll August 13, 2010 Page 2 ..r Monitoring Well Decommissioning AECOM contracted Woodward Drilling, Inc. (Woodward), a State-of-California C-57 licensed drilling contractor located in Rio Vista, California to perform the well decommissioning activities. Y� On July 1 and July 2, 2010, AECOM oversaw well decommissioning activities performed by Woodward. Prior to pressure grouting the wells on the eastern portion of the site, each well box and apron were removed and an area 12 inches beyond the conductor casing were cleared using vacuum truck equipment or hand auger. Monitoring well conductor casing and PVC casing were severed at least 12 inches below grade because the Site has no plans to redevelop the area around the wells. This method was approved in the field by the SJCEHD. A one-inch-diameter tremie pipe was placed to the bottom of each well and cement was pumped from the base of the well to the top of the casing.The monitoring well was then pressurized with 25-30 psi for 5 minutes to ensure that the well screen was entirely encased in cement. Remaining void space in well was grouted and cement was allowed to spill over the casing to provide a mushroom cap as required by the SJCEHD. The excavated area around the wells on the eastern portion of the site were backfilled with clean gravel and capped with 3000 psi traffic r. rated concrete. Wells on the western portion of the Site had their stovepipe wellheads removed and PVC risers were �.. cutoff below grade. Wells were pressure-grouted as stated above and cement was allowed to spill over the casing to create a mushroom cap to surface level. Vapor wells were hand augered to approximately 5 feet bgs and vapor points were removed from borehole. Cement was poured into the open borehole to approximately 8 inches bgs. Excavations were then backfilled with clean gravel and capped with 3000 psi traffic rated concrete. Waste Characterization and Disposal Well decommissioning debris and soils and displaced groundwater from tremie-grouting wells were stored on site in United Nations-rated 55-gallon drums. Soil samples were collected from the drums and placed in an ice chest pending laboratory analysis for waste characterization. The soil samples were transported to CLS, a State-of-California certified analytical laboratory, located in Rancho Cordova, CA, under chain of custody(COC) protocols. The samples were composited by the laboratory and analyzed for total petroleum hydrocarbons as gasoline (TPHg) and total petroleum hydrocarbons as diesel (TPHd) by United States Environmental Protection Agency(USEPA) Method 8015M, benzene, toluene, ethyl benzene, total xylenes (BTEX USEPA Method 8260B, and total lead by USEPA Method 6010. Results were non-detect for TPHd, TPHg, and BTEX. Total lead was reported at 6.4 milligrams per kilogram. A copy of the certified laboratory analytical report is included as Attachment A. Now The wastes were removed from the Site on August 5, 2010 by Kvac. Five drums of demolition debris and soils generated during decommissioning were transported to Hay Road Landfill located near Dixon, California. Two drums of decontamination water were transported to K Pure Water Works, located in Rancho Cucamonga, California. The Certificates of Disposal are included as Attachment B. v