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S.dF. RepW . I SW L 9.Fe-"W Comp.,y.I— I K 1800 6 Fisnwa 9,9adeu4 CA Props Na IMM.00 P.F 4 Analytical Results No petroleum hydrocarbon analytes were detected in the sidewall and bottom samples collected from the excavation. Additionally, chromatogram peaks did not indicate the presence of longer chain hydrocarbons, therefore none of the samples were analyzed for total petroleum hydrocarbons as diesel (TPHD) (Table 2). Attachment 2 contains the sample analytical data and chain-of-custody documentation. CONCLUSI ONS(RECOMMENDATIONS Soils Previously collected analytical data indicate that the main areas of concern were the soils in the center of the former 500 gallon fuel tank (sample #11 03113191), and near the former gasoline dispenser (samples #2, 6, and 7, 03113191). These areas were addressed during Kleinfelder's investigation in January of 1992 (Soil and Groundwater Assessment, dated April 10, 1992) with the j installation of one vertical soil boring in the center of the former 500 gallon unleaded tank area (B2) and one westerly 20 degree angled soil boring in the vicinity of the former dispenser (B1). Petroleum hydrocarbon analytes were not detected in either boring at depths of 20 to 40 feet except a minor impact in the 25 foot sample from boring B2 at 0.0072 parts per million of xylenes and in the 40 foot sample from B2 at 1.5 ppm of TPHD. Due to the minor concentrations detected in both samples and due to the analytical results collected of the current soil sampling, RESNA believes the detected contamination was most likely introduced during drilling through the impacted residual soils. The analytical data indicated that vertical migration had not occurred below 40 feet below surface grade in either area and that lateral migration was not extensive in the area of the former pump island. Due to the potential for degradation of groundwater through migration, however slight, RESNA supervised (after removal of the clean fill gravel) further excavation of residual soil contamination in the former 500 and 10,000 gallon tank areas and the former dispenser area. Visual, olfactory and Photoionization Detector (PID) readings were used to determine the extent of excavation of residual impacted soils. Confirmation soil samples were collected when field evidence indicated that all residual soil contamination had been removed. No petroleum hydrocarbons were detected in the confirmation soil samples collected from the areas of concern. Based upon the current analytical results and previous investigations RESNA believes that all impacted soil has been removed from the site and does not recommend further soil investigation. Groundwater Analytical data for groundwater samples collected since monitoring well MW 1 was installed have been inconsistent. Petroleum hydrocarbons were present above method detection limits (MDL's) in the first sampling round (May 31, 1991), but given the analytical data collected since well PAR-0593.FNL