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QUARTERLY GROUNDWATER MONITORING AND SAMPLING REVIEW <br /> ( QUARTERLY GTS MONITORING AND SAMPLING REVIEW <br /> 4614 W . TURNER RD. , LODI <br /> PAGE 2 <br /> Following the initial excavation, 15 soil borings were drilled, <br /> between May 15 and June 2 , 1989 . Laboratory results of soil <br /> analyses determined the presence of petroleum hydrocarbons in <br /> concentrations exceeding 100 mg/kg in the area surrounding the <br /> tank excavation. After completion, 10 of the borings were <br /> converted to groundwater monitoring wells (Figure 2 ) Initial <br /> sampling of the wells indicated the presence of benzene in <br /> concentrations above the DHS Maximum Contaminant Levels (MCL 's ) <br /> for drinking water in three of the wells <br /> In the fall of 1992 , a groundwater treatment system was installed <br /> in MW 1 A report on the installation of this system has been <br /> submitted to San Joaquin Public Health Services and to Central <br /> Valley Regional Water Quality Control Board <br /> Groundwater and Groundwater Treatment System (GTS) Monitoring_-and <br /> Sampling . -- <br /> Results from earlier quarterly samplings have been submitted in <br /> previous reports The quarterly sampling covered in this report <br /> was conducted by Caltest Analytical Laboratories The results of <br /> the findings are summarized in the following sections - <br /> Groundwater levels are presented in Table 1 . Analytical results <br /> are presented in Table 2 Copies of the laboratory reports are <br /> presented in Attachment I . <br /> FIRST QUARTER 1994 - Sampled on February 1 , 1994 <br /> Groundwater levels and samples were obtained from monitoring well <br /> #3 at the site Monitoring Well 1 has been converted into an <br /> extraction well MW-9 was damaged in 1990 and cannot be sampled <br /> The remaining wells were not scheduled to be sampled during this <br /> round of sampling. The influent and effluent to the GTS were <br /> also sampled <br /> Groundwater level at MW 3 was 15 . 20 feet below the surface. <br /> These levels represent a drop of . 75 feet from the fourth quarter <br /> of 1993 . <br /> Laboratory analyses indicate 96 ppb Total Petroleum Hydrocarbons <br /> (Gasoline) . No other contaminants were detected. <br /> In the Groundwater Treatment System (GTS) , 7 ppb Benzene and . 8 <br /> ppb Toluene were detected in the influent ( formerly MW 1) No <br /> contaminants were detected in the effluent from the GTS <br />