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. QUARTERLY GROUNDWATER MONITORING AND SAMPLING REVIEW 4614 W TURNER RD , LODI PAGE 2 Following the initial excavation, 15 soil borings were drilled, between May 15 and June 2, 1989 Laboratory results of soil analyses determined the presence of petroleum hydrocarbons in concentrations exceeding 100 mglkg in the area surrounding the tank excavation After completion, 10 of the borings were converted to groundwater monitoring wells (Figure 2) Initial sampling of the wells indicated the presence of benzene in concentrations above the DHS Maximum Contaminant Levels (MCL's) for drinking water in three of the wells In the fall of 1992, a groundwater treatment system was installed in MW 1 A report on the installation of this system has been submitted to San Joaquin Public Health Services and to Central Valley Regional Water Quality Control Board In August 1994, the system was turned off Groundwater and Groundwater Treatment System GTS Monitoring Sampling Results from earlier quarterly samplings have been submitted in previous reports The quarterly sampling covered in this report was conducted by Caltest Analytical Laboratories The results of the findings are summarized in the following sections Groundwater levels are presented in Table 1 Analytical results are presented in Table • 2 Copies of the laboratory reports are presented in Attachment I SECOND QUARTER 1995 - Sampled on May 30, 1995 Groundwater levels were obtained from monitoring wells #1, #3, #4 and #5 Samples were obtained from monitoring wells #1 and #3 at the site MW-9 was damaged in 1990 and cannot be sampled The remaining wells (2,4,5,6,7,8, and 10) were not scheduled to be sampled during this round of sampling Groundwater levels at the four points average 10 39 feet below the surface This represents an average rise of 6 02 feet from the First quarter of 1995 This significant rise in the groundwater level can be attributed to the very wet 1994-95 winter Lab analysis shows no contaminants in MW-1 or in MW-3 THIRD QUARTER 1995 - Sampled September 22, 1995 Groundwater levels and water samples were obtained from Monitoring Wells 1, 2, 3, 4, 5, 6, 7, 8, and 10 MW-9 was damaged in 1990 and cannot be sampled Groundwater levels of the 9 monitoring wells averaged 13 01 feet below the surface . This represents an average fall of 2 62 feet from the second quarter of 1995