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15 August 2002 <br /> AGE-NC Project 02-0946 <br /> Page 2 of 7 <br /> quantified as gasoline (TPH-g), diesel (TPH-d) and/or motor oil (TPH-mo). The highest <br /> detected concentrations were found in soil samples collected from borings B-2 and B-5 at <br /> depths of 10 and 15 feet below surface grade (bsg), respectively, however, additional <br /> laboratory analysis of the 15-foot sample from boring B-5 did not detect volatile organic <br /> compounds (including BTEX and MTBE) or polychlorinated biphenyls. Analytical results <br /> of soil samples collected during the May 2002 investigation are summarized in Table 1; <br /> laboratory results are included in Appendix C. <br /> • Subsequently, a geophysical(magnetometer) survey of a portion of the site was performed <br /> to locate potential anomalies(underground storage tanks [USTs] or other buried structures). <br /> A copy of the magnetic survey is included in Appendix B. <br /> 2.2. GROUND WATER DEPTH AND FLOW DIRECTION <br /> Based on information obtained during soil probe boring, ground water depth beneath the site is <br /> approximately 30 feet bsg. <br /> Based on the map Lines of Equal Elevation of Groundwater,Fall 1999 published by the San Joaquin <br /> County Flood Control District and Water Conservation District,regional ground water flow direction <br /> in the area is generally towards the east. <br /> 3.0. PROCEDURES <br /> During July 2002,four exploratory trenches were excavated and three soil probe borings(PB-1,PB-2 <br /> and PB-3) were advanced at the site. The work was performed as outlined in the AGE-prepared <br /> Additional Subsurface Investigation, dated 19 July 2002. <br /> 3.1. EXPLORATORY EXCAVATIONS <br /> On 09 July 2002, four exploratory trenches (T-1 through T-4) were excavated at the site utilizing a <br /> backhoe; the trenches were excavated at locations identified during the CTE magnetic survey as <br /> possible USTs or buried structures. Trenches T-1, T-2 and T-4 were excavated to depths of <br /> approximately 12 feet below surface grade (bsg); trench T-3 was excavated to approximately 6 feet <br /> bsg. Following excavation, the trenches were backfilled to surface grade utilizing the excavated <br /> material. Approximate trench locations are illustrated on Figure 2. <br /> Advanced GeoEnvironmental,Inc. <br />