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06 December 1995 AGE-NC Project No. 95-0100 Page 2 of 13 the former fuel dispenser island by GAS. Low concentrations of BTE&X were detected in one sample — from boring 134. Results of the site assessment indicated that hydrocarbon-impacted soil is present only in the immediate area of the former dispenser island. 2.4. GROUND WATER DEPTH AND FLOW DIRECTION The Well Completion Report for a domestic water well drilled near the site in January of 1992 states that water was encountered at a depth of 54 feet. According to the San Joaquin County Flood Control Map (Fall 1990), the prevailing ground water flow direction is toward the north. No site- specific ground water investigation has been performed. — 3.0. SOIL VAPOR EXTRACTION WELL INSTALLATION 3.1. DRILLING AND SAMPLING On 2 October 1995, two soil borings were drilled at the site under the supervision of AGE. Each boring was drilled using a truck-mounted IIT-55 drill rig equipped with hollow-stem augers. The drill rig and a two-man crew were supplied by Soil Exploration Services (SES) of Benicia, California. Borings VE1 and VE2 were advanced to depths of 40 and 35 feet bsg, respectively. Soil samples were collected from ahead of the drill bit using a split-tube sampler loaded with three pre-cleaned 2 by 6-inch brass sleeves. Samples were collected at five-foot intervals, using a 140- pound hammer to advance the sampler IS inches. The number of blows required to advance the sample in 6-inch increments was recorded on the boring log. To avoid cross-contamination, the sampling equipment was washed in an alconox solution and rinsed twice with water prior to each sample run. The augers were steam-cleaned prior to initiating each boring. Each sample was preserved by covering both ends of the lead sleeve with a Teflon sheet, capping with a plastic endcap, and sealing with tape. The samples were stored on ice and relinquished to Alpha Analytical Laboratory, Inc. (AAL) of Ukiah, California. Selected samples were analyzed for TPH-g and BTE&X in accordance with EPA methods 503018015m, 80201602, respectively. One sample(VE 1-10) was transported to an independent microbiologist, Mr. A. Keith Kaufman of Culver City, California, and analyzed for physicochemical properties and microbiological enumeration. During drilling, auger returns were monitored for the presence of organic vapors using a photo- ionizing detector (PID: Thermo Environmental 580A, 10.OeV calibrated with Isobutylene).