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7 <br /> 18 August 2004 <br /> 'AGE-NC Project'No 95-0142 ` <br /> tPage 3 of 4 r <br /> � r <br />' Ground water on the west side of the ridge flows towards the northwest at an average hydraulic <br /> gradient of 0 03 ft/ft, the ground water on the east side of the ridge flows southeast at a hydraulic <br /> gradient of 0 01 ft/ft The elevation of the ground water table at the site is Illustrated on Figure 3 <br /> 32 ANALYTICAL RESULTS OF GROUND WATER SAMPLES <br /> 1 TPH-g and BTEX compounds was not detected in samples collected from wells The fuel additive <br /> MTBE was detected In wells MW-5 and MW-7,at concentrations of 12 microgram per liter(�tg/1) <br />' and 22 pg/l, respectively The analytical results are summarized in Tables 2 and 3 The laboratory <br /> report(MAI Work Order 0405480),quality assurance/quality control(QA/QC)report and chain of <br /> custody forms are Included` in Appendix C GeoTracker confirmation pages of the submitted <br />' laboratory electronic deliverable format (EDF) files are Included in Appendix D <br />' 4.0 CONCLUSIONS <br /> Based upon data collected from the site during the current and preceding ground water monitoring <br /> events, AGE concludes <br />' During Second Quarter 2004, the ground water `potentiometnc surface appears as a <br /> southwesterly-plunging ridge, flowing southwest at a hydraulic 'gradient of 0 007 ft/ft <br /> However, there is the possibility that the ground-water flow pattern may be influenced by <br /> difference in hydraulic heads from wells screened at two different depth Intervals (between <br />' 25 feet and 60 feet bsg, and between-70 feet and 80 feet bsg) Compared to the fine-grained r <br /> soils between 25 and 60 feet bsg, the interval between 70 and 80 feet bsg appeared more <br />' sand-prone, and may be associated with a different hydrogeologic unit <br /> • Only the fuel additive MTBE was detected during Second Quarter 2004, however, all <br /> monitoring wells are ,"drowned" acid analytical data from these wells may not be <br />' representative of shallow ground water conditions <br /> • Histoincally,the highest concentrations of dissolved petroleum hydrocarbons were detected <br />' in shallow well VW-1, located in the area of former UST TK1-90, however, TPH-g and <br /> BTEX concentrations in the deep-screened well (MW-6) at TK1-90 have steadily declined <br /> to non-detectable levels <br />' MTBE has been detected in ground water samples collected from well MW-7 for six <br /> consecutive quarters, and sporadically from well MW-5,the distribution of MTBE suggests <br />' that the MTBE plume has migrated laterally and vertically from the former UST location to <br /> wells MW-5 and MW-7 , <br /> Y <br /> Advanced CeoEnviran mental,Inc <br />