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09 JJilne 2000 ' AGE-NC'Project No. 98-046$ " - • Page 3 of 4 ' increased an average of 3.77 feet since the previous monitoring event(November 1999). A summary of depth to ground water and groundwater elevation measurements is presented in Table 1'. A ground water elevation contour map for April 2000 is illustrated on Figure 3. Based,on ground water elevation data, ground water flow direction,is,inferred to be toward the north-northeast. Ground water gradient far April 2000 was calculated to be 0.0047. In general, ground water flow ' direction and gradient for April 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 toluene, ethylbenzene,-total xylenes, TPH-d or TPH-g in,any of the ground water samples analyzed during the April 2000 monitoring event (Table'2). Benzene was detected only in well sample MW-4, and was detected at a concentration of 0.72,ug/l (Table 2). MTBE was reported in the ground water samples collected from monitoring wells MW-3 and MW-4' • at concentrations of 1.5 l 200,u .lrespectively. The reported detections of MTBE in sample � and � , MW-4 exceeds the DHS-established secondary maximum contaminant level (MCL) of 5.0�ig/l and action level of 13 µg/1 for MTBE in ground water. There were na 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 April 2000 monitoring event, the depth to ground water at the site ranged from ' -7.04 to 7.53 feet below top of well casings (btoc) (Table 1). Ground water elevation at the site ranged from 0.15 to 0.45 feet below mean sea level (MSL) in well MW-3 and MW-4, respectively. ' Groundwater elevation in the monitoring wells increased an average of 3.77 feet from the previous monitoring event. • Based on ground water elevation data; ground water flow direction is inferred to be toward the north-northeast.-Ground water gradieni for April 2000 was calculated to be 0.0047. .' ' MTBE was reported in the ground water samples collected from MW-3 and MW-4: ; • . ' Benzene was detected in the ground water sample collected from MW-4. : Omneed GeoEnvironmental,Inc.