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1 <br /> s •�H <br /> FIRST QUARTER 1995 <br /> ' GROUNDWATER MONITORING REPORT <br /> Former Thiemann's Service <br /> Ripon, California <br /> INTRODUCTION <br /> This report presents the results of quarterly groundwater monitoring and sampling performed <br /> ' <br /> in March 1995 by Canonie/Sm>th Environmental Technologies (SMTH), formerly RESNA <br /> Industries Inc , at Former Thiemann's Service The site is located at 106 West Second Street <br /> in Ripon, California (Figure 1) Sampling was performed to monitor the distribution of <br /> petroleum hydrocarbons in groundwater at the site Monitoring was performed to determine <br /> the groundwater flow direction and the hydraulic gradient in the uppermost aquifer <br /> BACKGROUND <br /> In March 1991, three underground storage tanks (USTs) were removed from the site. <br /> Analysis of soil samples collected from the excavation indicated that high concentrations of <br /> petroleum hydrocarbons were present in soil beneath the tanks Groundwater was not <br /> encountered in the 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 <br /> This included drilling eight soil borings and collecting soil samples Three of these borings <br /> were completed as shallow groundwater monitoring wells (MW-1, MW-2 and MW-3) <br /> Analysis of soil samples indicated that the majority of petroleum hydrocarbons in soil were <br /> present from about 10 feet below ground surface (bgs) to groundwater at a depth of <br /> 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 MW-1 had no measurable concentrations of petroleum hydrocarbons in the i <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 /> ' 1500781QUARTLYUQR-1995 doc <br />