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Grotwotm er Monkorft Repon <br /> 707 East Yosemite Ave Manwa camma <br /> In June 1993, Aegis conducted a subsurface investigation that included drilling three soil <br /> borings (SB-1 through SB-3) to 15 feet below grade (bg) in the vicinity of the pump <br /> islands and UST basin (Figure 2) This investigation was prompted by the SJCEHD <br /> requesting soil borings around the original pipeline repair area to asses the presence of <br /> petroleum hydrocarbons Soil sample analytical results indicated no petroleum <br /> hydrocarbons were present, except 0 008 ppm of xylenes at 15 feet bg adjacent to the <br /> western dispenser island (SB-1) <br /> Because of the xylenes detected in the soil boring investigation, SJCEHD requested <br /> monitoring wells to asses groundwater conditions On August 13, 1993, Aegis conducted <br /> a subsurface investigation that included drilling three soil borings to 30 to 35 bg and <br /> completing them as 2-inch-diameter groundwater monitoring wells MW-1, MW-2 and MW- <br /> 3 (Figure 2) On August 17, 1993 Aegis personnel monitored and sampled groundwater <br /> from the three wells The results of the subsurface investigation and monitoring were <br /> compiled in Aegis' report, "Groundwater Monitoring Well Installation Results Report", <br /> dated September 14, 1993 No petroleum hydrocarbons were detected in the <br /> groundwater samples <br /> This sampling event was requested by SJCEHD to confirm the absence of petroleum <br /> hydrocarbons in the groundwater Based on the results, site closure may be granted by <br /> SJCEHD <br /> GROUNDWATER MONITORING <br /> Groundwater Level Measurements <br /> On October 11, 1993, Aegis personnel collected measurements of depths to groundwater <br /> in wells MW-1, MW-2, and MW-3 All groundwater elevation measurements were <br /> conducted according to the Aegis standard operating procedures (SOP) included as <br /> Attachment 1 Groundwater elevation data are summarized in Table 1 A groundwater <br /> elevation hydrograph is included as Figure 3 A potentiometric surface map of the current <br /> data is presented in Figure 4 <br /> Since the last monitoring event in August 1993, groundwater levels have increased an <br /> average of 0 66 feet (Figure 3) On the basis of the October 11, 1993, measurements, <br /> groundwater is estimated to flow to the northeast (Figure 4) at an average gradient of <br /> 0 001 ft/ft On August 17, 1993, the estimated flow direction was to the northeast, at an <br /> average gradient of 0 002 ft/ft <br /> 93-042A QMR 2 <br />