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23 November 1998 AGE-NC Project No 98-0450 Page 3 of 4 ' Table 1 shows the assumed screen intervals for the monitoring wells at the site, wells BMW-1, BMW-1 and MW-3 area screened within a foot of the ground water table and well MW-5 may be screened approximately 2 2 feet below the ground water table The results obtained are believed to ' be representative of the dissolved hydrocarbon concentrations in the shallow ground water at the site Ground water monitoring data collected at the site indicated a southerly to a south-southeasterly ' ground water flow direction Based on a southerly flow direction within the area contained by four monitoring wells,wells MW-3 and MW-5 remain in down-gradient positions from the former UST system area In August 1998,the gradient was calculated to range from approximately 0 0042 ft/ft on the site to 0 0023 ft/ft south of the site(Figure 3) 3 2 LABORATORY RESULTS OF GROUND WATER SAMPLES ' TPH-g, TPH-d, toluene, xylenes and MTBE were detected in the ground water samples collected from all four wells Benzene was detected in wells BMW-1, BMW-2 and MW-5 TPH-g concentrations ranged from 470 micrograms per liter µg/1 in well BMW-2 to 17,000µg/l(BMW-1) TPH-d concentrations ranged from 220 1.zg/1 (BMW-2) to 1,600 µg/l (BMW-1) Benzene concentrations ranged from 2 1 µg/l (BMW-2) to 940µg/1 (BMW-1) MTBE concentrations ranged from 160 µg11 (MW-3) to 410 µg/1 (MW-5) TBA was detected in wells BMW-2, MW-3 and MW-5 at concentrations of 61 µg/1, 120 µg/l, 320 µg/1, respectively TAME, DIPE and ETBE were not detected by laboratory analyses of any of the ground water samples ' The laboratory report (McCampbell Analytical Inc Laboratory I D. No 93684 to 93687), Quality Assurance and Quality Control Data (QA/QC) and chain-of-custody forms are presented in Appendix B The results of the analyses are contained in Table 3 and Table 4 4.0. DISCUSSION AND CONCLUSIONS Based upon data collected during the August 1998 quarterly monitoring event, AGE concludes • The-ground water was flowing toward the south to the south southeast _ • MTBE was detected at concentrations greater than the State of California Action Limit of ' 4µg/l in ground water samples collected from all four wells The MTBE was encountered in ground water samples at concentrations ranging as high as 410µg/i (BMW-1) • The concentrations of benzene exceeds the state maximum contaminant level (MCL) of 1 Advanced GeoEnvtronmentnl,Inc-