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URS Ms. Lori Duncan, REHS Page 3 of 6 San Joaquin Environmental Health Department November 15, 2006 F1Well Destruction The property owner of the site, Mr. Bill Halverson,has constructed a car wash on the site.ARCO Fill coordinated the well destruction activities to occur during property development. ARCO also took advantage of these site activities to coordinate the installation of a remediation system. ARCO was asked by the owner to abandon monitoring well MW-4 to make way for the new car wash. On September 27, 28, 29 and October 3, 2005 vapor wells VW-2,VW-3, VW-4,VW-5,VW-9, VW-12, and VW-13 as well as monitoring well MW-4 were abandoned by Woodward Drilling a licensed drilling i contractor by overdrilling. Due to the presence of utilities,VW-6 was destroyed on September 28, 2005 Fby pressure grouting. Drilling and Monitoring Well Installation Four groundwater monitoring wells (MW-9 through MW-12) were installed to further define the lateral extent of petroleum hydrocarbon-impacted groundwater beneath the site. Seventeen dual completion SVEIAS wells (EW-1/SP-1 through EW-17/SP-17) and five AS wells (SP-18 through SP-22) were installed to complete the treatment system well network at the site. F From November 3, 2005 through November 15, 2005, Woodward Drilling, of Rio Vista, California, f drilled and completed a total of twenty-six wells at the site. Prior to drilling, utility clearance was obtained from Underground Service AIert (USA). Cruz Brothers Locators, a private utility location contractor, cleared proposed boring locations to ensure that private utilities would not be damaged during drilling. Boring locations were cleared to a depth of 5 feet below ground surface(bgs)with an air k knife device prior to drilling. Boring/well locations are shown on Figure 2. !� The borings were drilled using a drill rig equipped with 8- and 10-inch-outside-diameter (OD) hollow- l stem augers (HSAs) to accommodate the installation of 2-inch diameter groundwater monitoring and dual completion remediation wells.First groundwater was encountered from approximately 23 to 35 feet bgs in the borings. Soil samples were collected at - - p 5 foot intervals using a modified California split spoon sampler from 5 feet bgs to the total depth. Soils were logged by a URS geologist according to the Unified Soil Classification System. Hydrocarbon staining and/or odor were noted in samples collected in all of the ` wells installed. Soil samples were submitted for laboratory analysis from each soil boring. Soil boring samples were field preserved using EPA Method 5035 sample kits supplied by the laboratory. Soil samples collected from approximately 20 feet bgs were submitted for analysis from each boring. Preservation sample vials for SP-20 were broken following receipt by the laboratory and therefore no analytical data is included for this boring. Samples were then labeled and placed on ice in a cooler, pending delivery to Sequoia Analytical Laboratories in Petaluma, California. Soil samples were analyzed for gasoline range organics (GRO),benzene, toluene, ethylbenzene, and total xylenes (BTEX), and for fuel oxygenates/additives (including MtBE)by U.S. EPA Method 8260B. F K:\Wprocess;W BP ARC010216K200G System 6istallation\Report.doe F'