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1117 Lone Palm Avenue, Suite B <br /> 4: ;+ Modesto, Cafforn'ia 95351 <br /> www.atc-enviro.com <br /> 209.579.2221 <br /> o Fax 209.579.2225 <br /> A S S O C I A T E .S I N C <br /> a � <br /> September 7, 2001 <br /> 54.14981.0001 <br /> Ms. Margaret Lagorio <br /> San Joaquin County Public Health Services <br /> Environmental Health Division <br /> 304 E. Weber Street, Third Floor <br /> Stockton, California 95202 <br /> Subject: Monitoring Report Second Quarter 2001, N & S Irrigation Property, 215 West <br /> Main Street, Ripon, California <br /> Dear Ms, Lagorio: <br /> This report presents the results of quarterly groundwater monitoring and sampling performed on <br /> June b, 2001 by ATC Associates Inc. at the site. located at 215 West Main Street, Ripon, <br /> California (Figure 1). Monitoring was performed to determine groundwater flow direction and <br /> the hydraulic gradient in the uppermost ,aquifer. Sampling was performed to monitor the <br /> i <br /> petroleum hydrocarbons in the groundwater at the site. <br /> BACKGROUND <br /> In March 1990, one 1,500-gallon unleaded gasoline underground storage tank (UST), one <br /> unleaded gasoline UST of unknown size, and all associated piping and dispensing equipment <br /> were removed and transported off-site. Laboratory analysis of soil samples collected from <br /> beneath the former. 1,500-gallon UST .location indicated the presence of detectable <br /> concentrations of total petroleum hydrocarbons. Discoloration of the. soil and a petroleum <br /> hydrocarbon odor were noted in the field. After the tanks were removed, the areas of the former <br /> tanks were backfilled. <br /> On November 14, 1997, a geologist from ATC Associates supervised the advancement of two <br /> soil borings to 30 feet below"ground surface,(bgs): .Analytical results of soil samples indicated <br /> the presence of petroleum hydrocarbons. One groundwater sample was collected from each <br /> boring at the depth groundwater was first encountered,' approximately 30 feet bgs. Groundwater <br /> samples indicated the presence of petroleum hydrocarbons. Results are summarized in ATC's <br /> Summary Report of Subsurface Investigation, dated January 14, 1998. <br /> On July 13; 1998, a geologist from ATC Associates supervised the advancement of four soil <br /> borings to 26 to 31 feet 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, Groundwater samples indicated the.presence of petroleum ' <br /> hydrocarbons. Results are summarized in ATC's Summary Report of Additional Subsurface <br /> Investigation, dated September 9, 1998. <br /> w:lwordpro1149811Reportsl2QR-Ol.doc ] r <br />