ARCHIVED REPORTS XR0007809 - Laserfiche WebLink

Home Browse Search

I \ lie 10 September 2002 AGE-NC Project No 95-0142 ' Page 3 of 4 water flow direction in the deep monitored water zone(wells MW-6,MW-7 and MW-8)was toward ' the southeast with an average hydraulic gradient of 0 0025 feet/feet The elevation of the ground water table at the site is illustrated on Figure 3 1 32 ANALYTICAL RESULTS OF GROUND WATER SAMPLES ' TPH-g was detected in samples collected from wells MW-6, VW-1, VW-3 and VW-4 at concentrations of 3,800 micrograms per liter (µg/1), 260,000µg/1, 140 gg/l, and 3,200 µg11, ' respectively Benzene was reported in samples collected from wells MW-6, VW-1 and VW-4 at concentrations of 2 8 µg11,32,000µg/1 and 220µg/1,respectively Toluene,ethylbenzene and xylenes were detected in samples at concentrations as high as 50,000 µg/1 (toluene in VW-1) MTBE was detected in wells MW-5,MW-7 and VW-1,VW-2, VW-3 and VW-4 at concentrations of 1 5 µg/1, 6 9 µg/l, 750 µg/1, 11 µg11, 14 µg/l and 160 µg/l,respectively TBA was detected for the first time in the sample collection from well VW-3 at a concentrations of 6 9 µg/l No other oxygenated fuel additive detected in the ground water samples this quarter ' • The analytical results are summarized on Tables 2 and 3 The laboratory report (MAI Laboratory I D Nos 0246431- 01 to 09), quality ualit assurance and quality control (QA/QC) report and chain-of- custody form are included in Appendix B 4.0. CONCLUSIONS Based upon data collected from the site during the current and preceding ground water monitoring events, AGE concludes Ground water flow direction appeared to be toward the northwest in the monitored zone ' defined by the shallow-screened well network and generally northeast and southeast at the intermediate and deep monitored zones, respectively • The highest concentration of dissolved petroleum hydrocarbons continues to be in the area of the former UST TK1-90 (well VW-1) TPH-g and BTEX concentrations have increased in water-table vapor well VW-4 down-gradient of the former USTs, while concentrations ' have declined in the samples collected from vapor well VW-3 up-gradient from the former UST area • TPH-g and BTEX concentrations have steadily declined in the samples collected from the deep screened well MW-6 (screened 70 to 80 feet bsg) Presently, MW-6 is screened approximately 45 feet below the surface of first-encountered ground water