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r - 14 May 1998 [ AGE-NC Project No. 95-0185 ' Page 3 of 4 3.2. LABORATORY RESULTS OF GROUND WATER SAMPLES TPH-d was detected in ground water samples collected from monitoring wells MW-1,MW-2,MW-3 ' and MW-4 at concentrations of 7,800 parts per billion (ppb, reported as micrograms per liter), 75 ppb,200 ppb and 13,000 ppb, respectively. TPH-g was detected in the ground water samples from well MW-I and well MW-4 at concentrations of 130 ppb and 190 ppb, respectively. BTE&X compounds were detected in samples collected from wells MW-1 and MW-4 at concentrations as high as 1.1 ppb(benzene, MW-4), and 0.67 ppb (toluene and total xylenes, MW- 1). MTBE was not detected by EPA method 8260m in the samples collected from the monitoring wells. Tert butanol was detected in the sample collected from wells MW-1 at a concentration of 24 ppb. Analytical results of monitoring well ground water samples are summarized in Table 2 for analyses ' by EPA Methods 8015M and 8020, and in Table 3 for analyses by EPA Method 8260. The laboratory report (MAI Laboratory I.D. Nos. 82612 to 82615), and chain-of-custody form are included in Appendix B. ' 4.0. SUMMARY AND CONCLUSIONS The following conclusions were drawn from the results of this investigation: ' Ground water elevations have increased an average of approximately 3.06 feet In all wells since the last quarterly monitoring event. ' Concentrations of TPH-g and BTE&X hydrocarbons have fluctuated over a wide range in MW-I and MW-4, and have increased slightly in MW-2 and MW-3. t0 Free-phase floating product was not encountered in well MW-4. • Well MW-2 appears'to be located at the'southem edge of the dissolved TPH-d plume and ' monitoring well MW-3 lies near the western margin of the plume. • The northernand eastern margins of the dissolved phase plume have not been fully ' delineated. 1 Advanced GmEm9ronmental,Inc.