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1 TABLE 2 Groundwater Analytical Results San ,Joaquin County Human Services Building Site Fourth Quarter 1993 Sample Date: October 7, 1993 I Method Monitoring EPA 602 EPA 8015M Notes ' WeIl Benzene Toluene Ethylbenzene Xylene TPH-G ' Detection 0 5 ug/L 0 5 µg/L 0 5 Ig/L 0 5 µg/L 50 µgIL Lint MW-4 ND' ND ND ND 140 ' MW-5 ND ND ND ND ND MW-6 ND ND ND ND ND ' MW-7 ND ND ND ND ND MW-8 ND ND ND ND 3,l00 MW-103 NA= NA NA NA 3,500 Duplicate of MW-8 ' MW-114 NA NA NA NA ND Decon Rinsate Sample (atter sampling MW-8) 1 ND = Non-detectable at detection limit shown at top of column 2 NA = Not analyzed 3 MW-10 = Duplicate of MW-8 I4 MW-11 = Equipment decontamination sample collected atter sampling MW-8 As shown on Table 2, no BTEX compounds were detected in any samples collected The only analytical parameter quantified was TPH-G in only two wells, MW-4 at a concentration of 140 pg/L and MW-8 at a concentration of 3, 100 µg/L With regard to the quality control samples, good analytical reproducibility was achieved The primary well sample MW-8 and the blind duplicate (labeled MW-10) had analytical results for TPH-G of 3,100 Mcg/L and 3,500 µg/L respectively Analysis of the field decontamination sample, which was collected after sampling MW-8, showed no detectable compounds remained in the field equipment after completion of standard ' field decontamination procedures 2.3 Chemical Concentration Tt ends ' To assist in reviewing trends in the hydrocarbon concentrations found in the various wells at the site, Table 3 presents a chronological summary of the TPH-G concentration data from the ' beginning of the Phase II Groundwater Investigation project in 1991 through the current date No BTEX concentrations have been quantified in any monitor well since monitoring began in 1991 ' VrKNRPTS1.VC 4T)i WP 5 OZOV96