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17 October 2000 . . AGE NC Project No. 98-0468 ' Page 3 of 4 .' decreased an average of 2.37 feet since the previous monitoring event (April 200). A summary of depth to ground water and ground water elevation measurements is presented in Table 1. A ground water elevation contour map for July 2000 is illustrated on Figure 3. Based on ground ' water elevation data, ground water flow direction is inferred to be toward the north. Ground water gradient for July 2000 was calculated to be 0.009. In general, ground water flow direction and ' gradient for July 2000 appear to be consistent with previous monitoring events results. ' 3.2. LABORATORY RESULTS OF GROUND WATER SAMPLES Ground water samples were, collected from MW-3 through MW-5 for laboratory analysis. A ' summary of ground water analytical results are presented in Table 2. The laboratory analytical report is included in Appendix B. ' There were no reported detections of BTEX compounds, TPH-d or TPH-g in any of the ground water samples analyzed during the July 2000 monitoring event (Table 2). MTBE was reported in the ground water sample collected from monitoring well MW-4 at a concentration of 290 ,ugll and ' confirmed by EPA Method 8260 at a concentration of 250µg11. The reported detections of MTBE in.sample MW-4 exceeds the DHS-established secondary maximum contaminant level (MCL) of 5.0µg11 and action level of 13 µg11 far MTBE in ground water. There were no reported detections ' of any other fuel oxygenating compounds. ' 4.0.. SUMMARY/CONCLUSIONS. The following conclusions were drawn from the results of the site investigation: • During the July 2000 monitoring event, the depth'to ground water at the site.ranged from ' 9.31 to 10.01 feet below top of well casings (btoc) (Table 1). Ground water elevation,at the site ranged from 2.42 to 2.93 feet below mean sea level (MSL) in well MW-3 and MW-4, respectively. ' Ground water elevation in the monitoring wells decreased an average of 2.37 feet from the previous monitoring event. • Based on ground water elevation data, ground water flow direction is inferred to be toward the north. Ground water gradient for July 2000 was calculated to be 0.009. • MTBE was reported in the ground water sample collected from MW-4. ' g acted down- The radient extent of MTBE-im round water has not been delineated. . g p _ ' Advanced CeoEnvirnnmental,[nc.