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' 29 September 2000 AGE-NC Project No 96-0254 Page 3 of 4 I3 2 LABORATORY RESULTS OF GROUND WATER SAMPLES TPH-g was detected in samples collected from wells MW-1B, MW-4, and MW-7 at concentrations of 610 micrograms per liter (,ug/1), 2,200 kcg/l, and 260 ,ug/l, respectively TPH-d was detected in the samples collected from wells MW-1 B, MW-4 and MW-7 at concentrations of 66 µg/1, 310 ,ug/l and 290 ,ug/l, respectively TPH-g and TPH-d was not detected in the remaining samples Benzene was detected in samples collected from wells MWA A, MWA B, and MW-7 at concentrations of 12 kzg/l, 110,ug/l, 500 4g/1 and 0 91 jtg/l, respectively Toluene,ethylbenzene and xylenes were detected in these same wells at concentrations ranging from 3 3 ug/l(toluene in MW-7) to 90 Mcg/l (ethylbenzene in MW-4) BTE&X were not detected in the remaining ground water samples No fuel oxygenates were detected in any of the ground water samples analyzed for fuel additives TDS was detected in the ground water samples from MW-5 and MW-6 at concentrations of 1,740 mg/1 and 1,790 mg/l, respectively Chloride, nitrate, phosphate, and sulfate were detected in wells • MW-5 and MW-6 at concentrations as high as 232 mg/l, 47 mg/l, 3 75 mg/l and 317 mg/l, respectively Nitrite was not detected above laboratory reporting limits in either MW-5 or MW-6 The analytical results are summarized in Tables 2 and 3 The laboratory reports (MAI Laboratory ID 43171 to 43177 and 43710 to 43712 and PET Sample ID PE8638-01 and -02), QA/QC reports and chain-of custody forms are included in Appendices B and C, respectively 4.0. SUMMARY AND CONCLUSIONS Based on the data collected during this monitoring period, AGE concludes • The depth to ground water at the site was encountered between 6 92 to 7 78 feet bsg, excluding MW-7 The prevailing ground water flow direction at the site is generally northward with a nearly flat hydraulic gradient of 0 005 to 0 006 feet/feet The depth to ground water in MW-7, which is screened between 37 and 42 feet bsg, was at 23 15 feet bsg • Petroleum hydrocarbon-impacted ground water was encountered in samples from monitoring wells MW-lB, MW-4, and MW-7 with benzene concentrations exceeding the State of California maximum contaminant level (MCL) of 1 ppb in samples MW-1B and MW-4 Figure 4 shows the known distribution of dissolved benzene No fuel oxygenates were detected during this monitoring period Advanced GeoEnviron mental Inc