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r I <br /> A copy of the chromatogram has been included in Appendix C. It is likely that the <br /> difference in chromatograms represents degradation and selective adsorption of gasoline <br /> constituents during migration from the source since the peaks fall within the retention <br /> window for gasoline. <br /> i' The remaining four monitoring wells, MW-2, MW-3, MW-4 and MW-S all indicated non <br /> detectable levels for gasoline and gasoline constituents during this <br /> quarter. These data are <br /> consistent with data from previous sampling events. <br /> 6.0 CONCLUSIONS <br /> The following conclusions and recommendations are based on the observations and <br /> analytical data collected to date. Site, soil and ground water conditions not discovered or <br /> currently known may cause a change in the opinions presented in this report. <br /> Laboratory analysis of ground water samples indicates the presence of significant levels of <br /> gasoline and gasoline constituents in water cM <br /> ollected from monitoring well W-1 and <br /> minor concentrations in MW-G. All other monitoring well samples indicated non <br /> detectable levels for analyzed constituents. These data are consistent with previous <br /> sampling event data. <br /> 7.0 RECOMMENDATIONS <br /> 1 The lateral and vertical extent of gasoline contaminated soil and ground water have not <br /> been defined to date. Additional soil and ground water investigation is required at this site <br /> to fully define the limits of contamination. A work plan was prepared and submitted to the <br /> San Joaquin County Public Health Services to address the definition of the contaminant <br /> boundaries, and to investigate possible remediation alternatives. <br /> L Water samples were not collected from the two supply wells located on the site. Samples <br /> were previously collected from the supply well pressure tank and indicated non detectable <br /> levels of BTEX. Sample taps have not been installed near the well heads to allow for <br /> more representative sampling. AGS recommends that spigots be installed near each well <br /> head prior to the collection of new samples from these wells. <br /> American Geological.Services, Inc. <br /> CA95D&029 <br /> 11 <br />