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V � 5 1117 Lone Palm Avenue, Suite B <br /> { <br /> Modesto, CA 95351 <br /> a° www atc-enviro coin <br /> yin + 209 579 2221 <br /> Fax 209 579 2225 <br /> A 5 6 0 C I A T E S 1 k C <br /> June 3, 2003 RDEUMMED <br /> 54 62605 0001 <br /> AUG 15 2003 <br /> ENVIRONMENT HEALTH <br /> PERMIT/SERVICES , 10 <br /> Ms Vicky McCartney ` <br /> San Joaquin County <br /> Environmental Health Department r 1' <br /> 304 E Weber Avenue, Third Floor <br /> Stockton, California 95202 R e ,0 ' t <br /> Subject Monitoring Report - First Quarter 2003, Former Thiemann's Service Station, 106 <br /> West Second Street, Ripon, California <br /> Dear Ms McCartney <br /> This report presents the results of quarterly groundwater monitoring and sampling performed in <br /> January 2003 by ATC Associates Inc at Former Thiemann's Service Station The site is located <br /> at 106 West Second Street in Ripon, California (Figure 1) Sampling was performed to monitor <br /> the distribution of petroleum hydrocarbons in groundwater at the site and to determine the <br /> groundwater flow direction and magnitude of the hydraulic gradient in the uppermost aquifer <br /> SITE HISTORY <br /> In March 1991, three underground storage tanks (USTs) were removed from the site Analysis of <br /> soil samples collected from the excavation indicated that high concentrations of petroleum <br /> hydrocarbons were present in soil beneath the tanks Groundwater was not encountered in the <br /> excavation The location of the former USTs is shown on Figure 2 <br /> In July 1993, a subsurface investigation was conducted at the site to determine the extent of <br /> petroleum hydrocarbons present in soil and to determine if groundwater had been impacted The <br /> investigation included drilling eight soil borings and collection of soil samples Three of the <br /> borings were completed as shallow groundwater monitoring wells (MW-1, MW-2 and MW-3) <br /> Analysis of soil samples indicated that the main concentration of petroleum hydrocarbons in soil <br /> occurred from approximately 10 feet below ground surface (bgs) to the groundwater surface at a <br /> depth of approximately 29 feet bgs and within a radius of 35 feet from the former UST pit <br /> In August 1993, wells MW-1, MW-2, and MW-3 were monitored and sampled Analytical <br /> results showed that wells MW-2 and MW-3 contained detectable levels of petroleum <br /> hydrocarbons in the groundwater MW-1 had no measurable concentrations of petroleum <br /> w lwordpro1626051quartlyll QR-2003 doc 1 <br /> ENVIRONMENTAL, GEOTECHNICAL AND MATERIALS PROFESSIONALS <br />