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i URS Mr. Jeffrey Wong . San Joaquin County Environmental Health Department October 4, 2002 Page 3 Soil Sampling and Analysis On August 28, 2002, three groundwater monitoring wells (MW-2 through MW-4) were installed at the site by PC Exploration of Rocklin, California. The wells were completed under the direction of a URS geologist at the locations shown on Figure 1. Well completion details are presented on the boring logs in Attachment 11. The borings were drilled using a hollow-stem auger (HSA) drill rig with 8.25-inch-outside-diameter (OD) augers. The total depth of each boring was approximately 25 feet bgs. Groundwater was first encountered at approximately 18 feet bgs. Soil samples were collected at 5-foot intervals with a modified California split-spoon sampler. The soils were logged by a URS geologist according to the Unified Soil Classification System. One soil sample from each of the three borings was collected for analysis. Because no hydrocarbon impacts were observed or detected with the PID, the three samples from the capillary fringe (collected at approximately 11 feet bgs) were retained for laboratory analysis. The soil samples were sealed in 2- inch-diameter brass sleeves with Teflon squares and plastic end caps. The samples were then labled and placed on ice in a cooler, pending delivery to Sequoia Analytical Laboratories in Sacramento, California. The three soil samples were analyzed for TPHg and BTEX by EPA Method 801518021,and MtBE, tert-butyl alcohol (TBA), di-isopropyl ether (DIPS), ethyl tert-butyl ether (ETBE), tert-amyl methyl ether (TAME), 1,2-dichloroethane (1,2-DCA), and ethylene dibromide (EDB) by EPA Method 8260B. Decontaminated augers were used for all three of the boreholes. Downhole sampling equipment was decontaminated between samples by washing in a non-phosphate detergent solution. Monitoring wells were constructed in the boreholes using 2-inch-diameter (ID), schedule 40, flush- threaded polyvinyl chloride (PVC) well casing. Fifteen feet of 0.010-inch machine-slotted well screen were set from 9 to 24 feet bgs for MW-2 and 8 to 23 feet bgs in MW-3 and MW-4. A Monterey No. 2112 silica sand filter pack was installed from the bottom of the boring to one foot above the well screen. A 2-foot bentonite seal was placed above the sand pack to approximately 6 feet bgs and neat cement was used to seal the remaining annular space to the surface. The wells were completed with flush-mounted well boxes. A locking well cap was placed on the top of the casing. Soil cuttings generated during the drilling activities were placed in six labeled 55-gallon Department of Transportation (DOT)-approved steel drums and stored on site. A composite soil sample was collected from the six drums and analyzed for TPHg and BTEX by Methods 801518021, fuel oxygenates by EPA Method 8260B, and total lead by EPA Method 6010B. Drum composite analytical results are included in Table 1. On September 5, 2002,the drums were transported by Dillard Environmental Services to the Altamont Landfill and Disposal Facility in Altamont, California, where they were disposed of as nonhazardous waste. Soil disposal documentation is included as Attachment M. 7G600-622-02/Site investigation ReportKAJ5 BP ARCO\05450\5ite Investigation Report.doc