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s <br /> f N <br /> breakdown of results. <br /> Laboratory results of groundwater samples collected from <br /> each of the three monitoring wells indicated that groundwater <br /> has been impacted by gasoline contamination, as gasoline <br /> constituents were found in water obtained from each well <br /> (Table 3, Section 4.2) . <br /> See Appendices B and C for laboratory analysis and <br /> chain--of-custody documents, and section 4.2 for tabular <br /> breakdowns of results. <br /> 2e4 GROUNDWATER FLOW AND GRADIENT <br /> site groundwater elevations and flow direction were <br /> determined based on water level measurements made in the <br /> three on-site monitoring wells on September 17, 1991 <br /> (Appendix D, Figure 6) . Based on measurements taken at that <br /> time, the groundwater flow direction was determined to be <br /> westward, with a gradient of 0.00054 ft/ft. At that time, <br /> groundwater was measured between 79.90 feet and 81.14 feet <br /> below ground surface. <br /> The calculated groundwater flow direction appears to be <br /> consistent with regional groundwater information. Regional <br /> flow appears to be to the west or northwest flowing toward a <br /> local cone of depression, according to The ,an Joaquin County <br /> Flood Control and Water Conservation District's "Lines of <br /> r Equal Elevation of Water in Wells (Unconfined and Semi- <br /> confined Aquifer) , San Joaquin County" map of 1990 (Appendix <br /> _. D, Figure 7) . <br /> 3.0 FIELD INVESTIGATION <br /> 3.2 WELL AND BORING LOCA'T'IONS <br /> Monitoring well 2 (MW-2) was installed on July 29, 1991. <br /> MW-2 was placed northwest of the former UST pit, close to the <br /> northerly corner of the U-Haul building. MW-2 was advat,ced <br /> to a total depth of 100 feet, with groundwater first <br /> encountered at a depth of approximately 87 feet. <br /> Monitoring well 1 (MW-1) was installed on July 30, 1991. <br /> w Mw-1 was situated east of the former tank pit, in the <br /> driveway adjacent to the Sanguinetti Lane entrance gate. MW- <br /> 1 was advanced to a total depth of 100 feet, with groundwater <br /> being encroached at approximately 85 feet. <br /> Monitoring well 3 (MW-3) also was installed on July 30, <br /> 1991. MW-3 was placed southeast of the front facade of the <br /> U-Haul building, south of the former UST pit, MW-3 was <br /> advanced to a total depth of 100 feet, with groundwater <br /> ETS ENVIRONMENTAL & ASSOC. <br /> PROJECT 305,--PAGE- - --_- <br />