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1�117 Lone Palm Avenue, Suite B <br /> Modesto, CA 95351 <br /> htp llwww atcssociates comv %TC 2095792221 <br /> ASSOC IATES INC <br /> r <br /> Fax 209 579 2225 <br /> December 16, 2004 <br /> 54 26874 0001 <br /> DEC 202004 <br /> Ms Margaret Lagono <br /> San Joaquin County E `� <br /> Environmental Health Department Fc �� ,,, �S <br /> 304 E Weber Street, Third Floor <br /> Stockton, California 95202 <br /> Subject Groundwater Monitoring Report Third Quarter 2004, Tay's Mini Mart, 3302 <br /> North West Lane, Stockton, California, Site Code 1289 <br /> Dear Ms Lagorio <br /> This report presents the results of quarterly groundwater monitoring and sampling performed on <br /> July 9, 2004 by ATC Associates Inc (ATC) at the site located at 3302 North West Lane in <br /> Stockton, California (Figure 1) Sampling was performed to monitor concentrations of petroleum <br /> hydrocarbons in groundwater at the site Monitoring was performed to evaluate groundwater <br /> quality and to determine the hydraulic gradient and direction in the uppermost aquifer <br /> BACKGROUND INFORMATION <br /> In 1997, three underground storage tanks and associated piping and fuel dispensers were <br /> removed from the locations shown on Figure 2 Soil samples were collected from the bottom of <br /> the tank excavation pit at approximately 24 feet below ground surface (bgs) Analytical testing <br /> indicated detectable concentrations of petroleum hydrocarbon constituents and fuel oxygenates <br /> including methyl tert-butyl ether (MTBE) The removed USTs were replaced with new USTs in <br /> the same location and the excavation was subsequently backfilled to the ground surface <br /> In August 2000, John P Cummings & Associates (JPCA) advanced one soil boring (SB 1) via <br /> direct push at the north end of the former northern dispenser island The soil boring reached a <br /> depth of 25 feet bgs before probe refusal was encountered In September 2000, JPCA advanced <br /> a soil boring via auger at the same location as SBI to a depth of 53 feet bgs Analyses of the soil <br /> and groundwater samples from the re-bored SBI indicated that the soil samples contained <br /> detectable concentrations of MTBE and t-butanol (TBA), and the water sample contained <br /> detectable concentrations of MTBE toluene, and total petroleum hydrocarbons as gasoline <br /> (TPHg) <br /> In May 2003, GHH Engineering, Inc (GHH) supervised the advancement of three soil borings, <br /> SB2, SB3, and SB4, at the locations shown on Figure 2 Soil samples from S133 and SB4 <br /> contained detectable concentrations of MTBE, and soil samples from SB3 also contained <br /> detectable concentrations of benzene, ethylbenzene, and xylenes Groundwater samples <br /> collected from SB3 and S134 contained detectable concentrations of TPHg, total petroleum <br /> s 12687C3QR-2004 doe ENVIRONMENTAL, GEOTECHNICAL AND MATERIALS PROFESSIONALS <br />