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Clayton B. A copy of the well construction diagrams are included as Appendix C. The G borehole logs are included as Appendix D. � P We drilled one borehole in the parking lot east of the building near Channel Street (Figure 2). The soil cuttings were screened with an organic vapor meter (OVM) l during drilling to aid in locating any soil contamination. The only reading on the OV'_M was a very low concentration of 1.2 ppm, registered at 13 ft bgs. A soil sample was taken at a depth of 16.5 ft in the sand lensetihere contamination was noted at the car repair shop. We anticipated groundwater at approximately 35 It bgs. Beginning at 30 ft bgs, we collected soil samples at 5 ft intervals to obtain a sample just above the groundwater. We encountered groundwater at 41 ft bgs. A soil sample was collected at 40 ft bgs. 3.2 MONITORING WELL CONSTRUCTION ANI) SAMPLING On April 11, 1991, the monitoring well was constructed to a depth of 49.5 ft bgs. '.Mike: Infurna, of the San Joaquin County Environmental Health Division, inspected the well while the well box was being installed. He was also present during some of the drilling and well construction. Details of the well construction are shown in Appendix C. The monitoring well was developed on April 19, 1991. On April 22, 1991, we collected groundwater samples from the monitoring well. The sample was taken to Clayton's laboratory for analysis. The chain-of-custody form is included as Appendix E. The water sampling survey form is in Appendix F. 3.3 SITE HYDROGEOLOGY Based on a water contour map plotted during spring 1990 and data obtained from nearby monitoring wells, we estimated a depth to groundwater at the subject site of approximately 35 ft. On April 22, 1991, during well monitoring and sampling by Clayton, the depth to 00ir4walter was 36.88 ft bgs. The groundwater gradient, based on the 1990 water contour map, is toward the east. Data obtained from the installation of three monitoring wells at an adjacent site, 141 North El Dorado Street, confirmed the easterly groundwater flow direction. Groundwater levels often fluctuate seasonally or as the result of local landscape irrigation. The local flow direction beneath the site may be naturally influenced by zones of higher permeability such as buried stream channels, or artificially influenced by nearby well pumping or recharge. According to our Phase I investigation, the Stockton Deep Water Channel extends underground to the south of the subject site (Figure 2). Review of a 1968 topographic map did not indicate that this channel extends under the subject site. j lNlL.Lrep