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f r w ; S , 18 November 1999 - t AGE-NC Project No 95-0184 Page 3 of 4 Y For gradient determination, the wells were divided into two data sets, MW-1, MW-2 and MW-3, with groundwater approximately 24 feet above the screened interval and the remaining wells The inferred ground water flow direction in August 1999 was toward the east with a gradient of approximately 0 003 ft/ft (Figure 3) for both data sets Measurable free product was not detected ' with the interface probe during the August 1999 monitoring event 3 2 ANALYTICAL RESULTS OF GROUND WATER SAMPLES , TPH-g was detected in each well sampled, with concentrations as high as 150,000 parts per billion (ppb, reported as micrograms per liter) Benzene was detected at concentrations as high as 31,000 ppb TPH-d was detected in the sample from MW-4 at a concentration of 3,200 ppb IDIPE and TBA were detected in the sample from MW-3 at concentrations of 2 3 ppb and 6 8 ppb, respectively MTBE was detected in samples collected from VW-2B and VW-4 at concentrations ' of 600 ppb and 930 ppb, respectively 1,2-Dichloroethane (DCA) was detected in four of the ten wells sampled at concentrations as high as 1,600 ppb (VW-2B) Six additional constituents were detected with EPA Method 8260 at concentrations as high as 3,600 ppb (1,2,4-tri methyl benzene, VW-5B) Analytical results are summarized on Tables 2 and 3 The laboratory report (MAI sample Nos 17162-17171) and chain-of-custody forms are included in Appendix B ' Lower hydrocarbon concentrations were detected in MW-7, located between MW-4 and the remaining wells at the site The lower hydrocarbon concentrations detected in samples collected = ' from MW-1, MW-2 and MW-3 are probably due to the deep drowning of these wells(approximately 24 feet) , I 4 0. DISCUSSION AND CONCLUSIONS i Based upon data collected from the site, AGE concludes the following , ' • Petroleum hydrocarbons were detected in each well sampled, at concentrations as high as 150,000 ppb Although not measurable in the wells, free product may remain at the site Additional monitoring wells will be necessary to delineate the horizontal extent of ' hydrocarbon-impacted ground water ' • Concentration of hydrocarbons detected at the site have generally remained stable ' • The inferred ground water flow direction was toward the east during the August 1999 monitoring event The inferred flow direction has generally been toward the east to southeast at the site A&anced CeuEn�ironmental,Inc r 0