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SMT <br /> ENVIRONMENTALTECHNDLOGIES CORPORATION <br /> bbl#t 30 M12* 01 <br /> December 9, 1996 <br /> # 94373 <br /> a • <br /> Ms. Mary Meays <br /> San Joaquin County Public Health Services r <br /> Environmental Health Division <br /> P.O. Box 398 F <br /> Stockton, California 95201-0388 <br /> Subject: Monitoring Report Fourth Quarter 1996, Former Thiemann's Service Station, 106 <br /> West Second Street, Ripon, California <br /> ii Dear Ms. Meays: <br /> i. <br /> This report presents the results of quarterly groundwater monitoring and sampling performed in <br /> October 1996 by Smith Technology Corporation at Former Thiemann's Service. The site is <br /> located .at 106 West Second Street in Ripon, California (Figure 1). Sampling was performed to <br /> monitor the distribution of petroleum hydrocarbons in groundwater at the site. Monitoring was <br /> performed to determine the groundwater flow direction and the hydraulic gradient in the <br /> 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-Jul 1993 a subsurface investigation was conducted.at the site to determine the extent of . <br /> Y g <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 /> y - <br /> w:1443731quarllyl4gr-1996.doc 1 <br /> 1260 Graphics Drive Modesto,CA 95351-1502 (209)579-2221 Fax(209)579-2225 <br /> Engineering Consulting Remediation Construction <br /> i� <br /> I <br />