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1 <br /> FIRST QUARTER 1996 <br /> GROUNDWATER MONITORING REPORT <br />' Former Thiemann's Service <br /> Ripon, California <br /> I <br />' INTRODUCTION <br /> This report presents the results of quarterly groundwater monitoring and sampling performed in <br />' January 1996 by Snuth Environmental Technologies Corporation at Former Thiemann's Service <br /> The site is located at 106 West Second Street in Ripon, California (Figure 1) Sampling was <br />' performed to monitor the distribution of petroleum hydrocarbons in groundwater at the site <br /> Monitoring was performed to determine the groundwater flow direction and the hydraulic <br /> gradient in the uppermost aquifer <br /> BACKGROUND <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 /> 1 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 This <br />' included drilling eight soil borings and collecting soil samples Three of these borings were <br /> completed as shallow groundwater monitoring wells (MW-1, MW-2 and MW-3) Analysis of soil <br /> samples indicated that the majority of petroleum hydrocarbons in soil were present from about 10 <br /> feet below ground surface (bgs) to groundwater at a depth of approximately 29 feet bgs and <br />' 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 results <br /> showed that MW-1 had no measurable concentrations of petroleum hydrocarbons in the <br /> groundwater Wells MW-2 and MW-3 contained detectable levels of petroleum hydrocarbons <br /> A program of quarterly groundwater monitoring and sampling was begun in March 1994 <br /> 1 <br /> • <br /> 1500781QUARTLYUQR-1996 doc <br /> SMITH <br />