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' 13 June 2001 AGE-NC Project No. 95-0185 ' Page 3 of 4 ' 3.2. GROUND WATER ANALYTICAL RESULTS TPH-d was detected in ground water samples collected from each monitoring well (MW-1 through ' MW-4)at concentrations of 6,600 micrograms per liter(µg/l),900 gg/l,400 µg/1, and 85,000 µg11, respectively. TPH-g was detected in ground water sample MW-1 and MW-4 at concentrations of 210 µg11 and 590 µg/1, respectively. Ethylbenzene and total xylene were detected in the ground water sample from well MW-4 at concentrations of 1.7 µg/1 and 0.94 µg/1, respectively. MTBE was detected in the ground water ' sample from well MW- 4 at 3.1 µg11 by EPA Method 8260. Current and previous analytical results are summarized in.Table 2. The laboratory report (MAI Laboratory I.D. Nos. 65422 and 65425), quality control and quality assurance data and chain-of- custody form are included in Appendix B. ' 4.0. CONCLUSIONS ' . Based on the data collected during this monitoring period, AGE concludes: ' 0 Ground water flow at the site was toward the south-southwest at hydraulic gradient was determined to be 0.0005, which is nearly flat. The hydraulic gradient suggests that ground water has a very slow flow rate. ' • The concentrations of TPH-•d in samples from well MW-3 and MW-4 has increase since the last monitoring event, yet declined in samples from wells MW-1 and MW-2. ' 0 BTEX compound were generally not detectable, except for trace concentrations of ethylbenzene and total xylene in the sample from well MW-4. ' a MTBE was detected at a low concentration, below the current enforcement maximum concentration level (MCL) set by the State of California. ' 5.0. RECOMMENDATIONS Based-upon:the results-of the-second=quarter-2001-investigation;AGE-recommends:---- =- _- • Continued quarterly ground water monitoring at the site. • Vertical assessment of the dissolved hydrocarbons. Advanced GeoEnvironmental,Inc.