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1 <br /> 1.0 INTRODUCTION <br /> GHH Engineering, Inc (GHH)is currently providing USA Gasoline Corporation(USA) <br /> Professional environmental services to conduct groundwater monitoring at their retail gasoline <br /> station#Ila located at 2132 East Mariposa Road, Stockton, California, as shown on Figures 1, 2 <br /> and 3 Mr Srikanth Dasappa of USA authorized GHH to prepare this"Fourth Quarter, 1998, <br /> Groundwater Monitoring Report" (QMR) for the site This report has been prepared for submittal <br /> to the San Joaquin County Public Health Services, Environmental Health Division (County), the <br />' lead regulatory agency overseeing environmental issues at the site The County Site Code is <br /> #1669 <br />' 1.1 Scope of Work <br /> Groundwater monitoring was conducted at the site on October 20, 1998 The following is a brief <br /> summary of the scope of work authorized by USA <br /> 0 Locate and measure depths to groundwater in wells MW-1-P through MW4-P, MW-6-P, <br />' S-1, MW-1, and MW-2 <br /> - Purge a minimum of three equivalent well volumes of groundwater from each of the wells <br />' and monitor pH and conductivity <br /> o Collect groundwater samples from the monitoring wells <br /> Analyze water samples for total petroleum hydrocarbon in the gasoline range(TPH G, <br /> EPA Method 8015 modified), benzene, toluene, ethylbenzene and total xylenes (BTEX, <br /> EPA Method 8020) <br /> • Prepare this QMR for submittal to USA and the County <br /> 2.0 GROUNDWATER MONITORING <br /> rThe following section discusses field protocol used during data collection for this QMR <br /> 2.1 Groundwater Elevations <br /> Prior to gauging depths to groundwater, seven groundwater monitoring wells(MW_I, MW-2, <br /> MW-1-P through MW-4-P, and MW-6-P)were checked for the presence of free floating <br /> hydrocarbon compounds using an interface probe No free product was present in any of the <br /> wells Depths to groundwater measurements were then taken from each well from surveyed <br />' marks on the casing using an electric water level sensor MW-I, MW-5-P and S-1 were damaged <br /> during station retrofit activities MW-I was repaired and re-surveyed on January 30, 1998 GHH <br /> has been unable to repair MW-5-P Repair efforts will continue until the well can be sampled <br /> Calculated groundwater elevations are summarized in Table 1, and shown on Figure 4 <br />