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1117 Lone Palm Avenue, Suite B <br /> Modesto, CA 95351 <br /> www atc-enviro com <br /> CVVJkTC F N 1"r, i.,j' c[11 209 579 2221 <br /> T A L 1 f 1 Fax 209 579 2225 <br /> A S S O C I A T E B 1 N C PC--I!, <br /> ti1J1r <br /> November 10, 2003 <br /> 54 14981 0001 <br /> Ms Margaret Lagorio <br /> San Joaquin County, Environmental Health Division <br /> 304 E Weber Street, Third Floor <br /> Stockton, California 95202 <br /> Subject Groundwater Monitoring Report - Third Quarter 2003, N & S Irrigation Property, <br /> 215 West Main Street, Ripon, California <br /> Dear Ms Lagorio <br /> This report presents the results of quarterly groundwater monitoring and sampling performed on <br /> September 10, 2003 by ATC Associates Inc (ATC) at the site located at 215 West Main Street, <br /> Ripon, California (Figure 1) Monitoring was performed to determine groundwater flow direction <br /> and the hydraulic gradient in the uppermost aquifer Sampling was performed to monitor dissolved <br /> petroleum hydrocarbon concentrations in the groundwater at the site <br /> BACKGROUND INFORMATION <br /> In March 1990, one 1,500-gallon unleaded gasoline underground storage tank (UST), one unleaded <br /> gasoline UST of unknown size, and associated piping and dispensing equipment were removed and <br /> transported off-site Laboratory analyses of soil samples collected from beneath the former 1,500- <br /> gallon UST location indicated the presence of detectable concentrations of total petroleum <br /> hydrocarbons Discoloration of the soil and a petroleum hydrocarbon odor were noted in the field <br /> After the tanks were removed,the areas of the former tanks were backfilled <br /> On November 14, 1997, a geologist from ATC supervised the advancement of two soil borings to 30 <br /> feet below ground surface (bgs) Analytical results of soil samples indicated the presence of <br /> petroleum hydrocarbons One groundwater sample was collected from each boring at the depth <br /> groundwater was first encountered, approximately 30 feet bgs Groundwater samples indicated the <br /> presence of petroleum hydrocarbons Results are summarized in ATC's Summary Report of <br /> Subsurface Investigation, dated January 14, 1998 <br /> On July 13, 1998, a geologist from ATC supervised the advancement of four soil borings to 26 to 31 <br /> feet bgs Analytical results of soil samples indicated the presence of petroleum hydrocarbons One <br /> groundwater sample was collected from each boring at the depth groundwater was first encountered <br /> Groundwater samples indicated the presence of petroleum hydrocarbons Results are summarized in <br /> ATC's Summary Report of Additional Subsurface Investigation dated September 9, 1998 _ <br /> On February 18, 1999, a geologist from ATC supervised the installation of three groundwater <br /> monitoring wells from 39 to 41 feet bgs Soil borings MWI, MW2, and MW3 were completed as <br /> two-inch monitoring wells One soil sample from each boring was collected and after the <br /> groundwater monitoring wells were developed one groundwater sample was collected from each <br /> well Soil and groundwater samples contained detectable concentrations of petroleum hydrocarbons <br /> ENVIRONMENTAL, GEOTECHNICAL AND MATERIALS PROFESSIONALS <br /> s lenvlronmentat1149811ReportsOQR 03 doc j <br />