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1.0 INTRODUCTION i GHH Engineering, Inc (GHH) is currently providing USA Gasoline Corporation(USA) Professional environmental services to conduct groundwater monitoring at their retail gasoline station#110 located at 21.32 East Manposa Road, Stockton, California, as shown on Figures 1, 2 Iand 3 Mr Srikanth Dasappa of USA authorized GHH to prepare this"First Quarter, 2000, Groundwater Monitoring Report" (QMR) for the site This report has been prepared for subnuttal to the San Joaquin County Public Health Services,Environmental Health Division(County), the Ilead regulatory agency overseeing environmental issues at the site. The County Site Code is #1669 ' 1.1 Scope of Work Groundwater monitoring was conducted at the site on January 13, 2000 The following is a brief summary of the scope of work authorized by USA I Locate and measure depths to groundwater in wells MW 1-P through MW-6-P, MW-1, and MW-2 I Purge a minimum of three equivalent well volumes of groundwater from each of the wells and monitor pH, temperature and conductivity Collect groundwater samples from the monrtonng wells • Analyze water samples for total petroleum hydrocarbon in the gasoline range(TPH G, ' EPA Method 8015 modified), benzene, toluene, ethylbenzene, total xylenes, and methyl- tert-butyl-ether(BTEX and MTBE;EPA Method 8020) • Analyze groundwater sample with the highest concentration of MTBE for all oxygenates, including MTBE, tertiary butyl alcohol (TBA), di-isopropyl ether(RIPE), ethyl tertiary ' butyl ether(ETBE), tertiary amyl methyl ether (TAME), and ethanol using EPA Method 8260B • Prepare this QMR for submittal to USA and the regulatory agencies 2.0 GROUNDWATER MONITORING 1 The following section discusses field protocol used during data collection for this QMR I2.1 Groundwater Elevations Prior to gauging depths to groundwater, the eight groundwater monitoring wells (MW-1-P Ithrough MW-6-P, MW-1, MW-2) were checked for the presence of free floating hydrocarbon compounds using an interface probe No free product was present in any of the wells Depths to groundwater measurements were then taken from each well from surveyed marks on the casing using an electric water level sensor Calculated groundwater elevations are summarized in Table 1, and shown on Figure 4