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Former Discovery Chevrolet March 20, 1998 Tracy,California Problem Assessment Report The soil borings were drilled to a depth of approximately 20 feet bsg, except for borings GP- 6 and GP-10, which were drilled to 25 feet bsg and 14 feet bsg, respectively. The locations of the borings are shown on Figure 2. Upon completion of sampling, the borings were backfilled with a bentonite/neat cement grout to existing grade. Sediments encountered during drilling consisted primarily of silty clay and clayey sand. The sediments from the borings were classified using the Unified Soil Classification System (USCS). A copy of the USCS is shown on the Boring Log Symbol Key in Appendix G. 4.2 WellInventory A review of California Department of Water Resources (DRW) well records was conducted by Horizon. Records were searched to identify wells within a one-half mile radius of the site. According to DWR records, five wells, both public and private, were identified within this radius (historical Figure 4 and Table 4 in Appendix D). There were no recorded wells downgradient from this site. The nearest well, #1, is 700 feet north-northeast of the site and is completed to 427 feet bsg. During the Horizon February 19, 1998 site drilling, an apparent water well was discovered outside of the northwest corner of the service bay area (Figure 2). An approximately 6-inch diameter steel casing was noted with a 2-inch diameter galvanized pipe extending above ground level from inside the casing. The apparent well was measured with an electronic well sounder to a depth of approximately 145 feet bsg, where the sounder appeared to encounter soft sediments. 5.0 LABORATORY RESULTS Analytical ReNults- Soil Soil samples were collected from borings GP-1 through GP-9 at depths of approximately 5, 10, 15, and 20 feet bsg. At the request of the SJC DHS/EHD inspectors, boring GP-6, the deepest boring, was also sampled at 25 feet bsg. No soil samples were collected from boring GP-10. The soil samples were submitted under chain-of-custody (COC) to Kiff Analytical i' 3001-12.par 6 HORIZON ENVIRONMENTAL INC.