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r I I I j s Ij air F „ { I r r t 30 August 1999 I AGE-NC Project No 97-0312 I f r4y1 I Page 6 of 8 I Petroleum hydrocarbons were previously not detected In borings UST-2,UST-3 and UST-4,def ning 4 the northwestern, northeastern and southeastern extent of impacted soil Petroleum hydrocarbons were 'detected at depths as great as 85, 55 and 50 feet bsg in borings UST-1, UST-5 and 50'feet, respectively Petroleum hydrocarbons were not detected at depths greater than 30 feet in'Ithe remaining bonngs a 3 3 GROUND WATER ELEVATION AND GRADIENT Ground water elevation decreased an average of 3 17 feet at the former USTs location since the „ March 1'999 monitoring event Ground water flow direction was inferred to be northeasterly with, , L a gradient of 0 0015 ft/ft The flow direction is similar to previous monitoring events Figure 4 - Ground Water Elevation depicts the contours for June 1999 Static ground water was approximately ,13 to 14,feet above the screened Intenal in UST-2, UST-3 { and UST-4, approximately five feet over the screened interval of UST-5, and approximately 10 feet above the screened Interval in UST-6 A minimum of 80% recharge was measured in each well . immediately following purging , i ' 1 t ' 3 4 ANALYTICAL RESULTS OF GRAB WATER SAMPLES 'TPH-g and TPH-d were detected in each of the grab water samples collected from bonngs B 14, B:5 and B1,7 at concentrations ranging from 450 parts per billion(ppb, reportedras micrograms per liter) to 9,200 ppb Benzene, toluene, ethylbenzene and xylenes were detected :n these samples at concentrations as high as 450 ppb, 27 ppb, 45 ppb and r54'ppb, respectively The highest concentration of each constituent was detected in the sample collected from B 17 MTBE was detected'by EPA Method 8260m in the water samples from B 14, B 15 and'13 17 at concentrations of 6 4 ppb; 8 4 ppb and 9,700 ppb, respectively Tert-butanol was detected in" B 15 at a concentration Sof 14 ppb Other oxygenates were not detected in the'grab water samples The laboratory report for_ the grab water samples (MAI Sample Nos 13202-1,3204) and chain-of-custody forms are included in Appendix B ` I 3 5 ANALYTICAL RESULTS OF'GROUND WATER SAMPLES TPH-g and TPH-d were detected in the water°samples collected from monitoring wells UST-2 ' through UST-6„at'concentratioiis, as high asp 1;900 ppb and 340 ppb, respectively BTEX were ' detected at concentrations as high as 230 ppb „ 'Advanced GeoEnvironmental,Inc ` I I , i I I ' { 11 1 i •, r n ' , '