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• reported TPH-Extractable as Diesel in MW-1 at a concentration slightly above the laboratory reporting limit. i The EPA Method 8260 analysis for oxygenates indicated that MTBE was not present above the laboratory reporting limit of 2.0 Etgll, even though the Method 8020 analysis reported this compound at 159 µg/l. This discrepancy appears to be attributed to the fact that MTBE may have co-eluted at the same chromatograph peak as another similar compound, thus producing a false-positive for MTBE according to the EPA Method 8020 analysis. The GC/MS analysis (by EPA Method 8260) is generally considered much more accurate for identifying compounds than the GC analysis (EPA Method 8020). Based on these results, the results of the previous Department of Water Resources Water Supply Well Search, and previous monitoring events, Kleinfelder does not recommend additional site investigation or monitoring be conducted at this site and that the San Joaquin County Environmental Health Division approve this site for closure. 4 LIMITATIONS Kleinfelder has prepared this report in accordance with the generally accepted standards of care which exist in southern California at the time of writing. It should be recognized that definition and evaluation of geologic and chemical subsurface conditions are difficult. Judgments leading to conclusions and recommendations are generally made with an incomplete knowledge of the subsurface and/or historic conditions applicable to the site. The conclusions of this assessment are based on site conditions and design guidelines described by others. More extensive studies may further reduce the uncertainties associated with this assessment. Kleinfelder should be notified for additional consultation if the client wishes to reduce the uncertainties beyond the level associated with this report. No warranty, expressed or implied, is made. Kleinfelder offers various levels of investigative and engineering services to suit the varying needs of different clients. Although risk can never be eliminated, more detailed and extensive investigations yield more information, which may help understand and manage the level of risk. Since detailed investigation and analysis involves greater expense, our clients participate in determining levels of service which provide adequate information for their purposes at acceptable levels of risk. Regulations and professional standards applicable to Kleinfelder's services are continually evolving. Techniques are, by necessity, often new and relatively untried. Different professionals may reasonably adopt different approaches to similar problems. Therefore, no warranty or guarantee, expressed or implied, will be included in Kleinfelder's scope of service. This document may be used only by the client and only for the purposes stated, within a reasonable time from its issuance. Land use, site conditions (both on site and off site) or other factors may change over time, and additional work may be required with the passage of time. 40-327301/4018RO51 5 Copyright 1998 Kleinfelder. Inc. KLEINFELDER 780 Chadhaurne Road, Suite D, Fairfield CA 94585-964.3 (707)429-4070 (707)4Z9-4162 fax