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13 February 1998 <br /> AGE-NC Project No 97-0312 <br /> Page 3 of 4 <br /> parts per million (ppm, reported as milligrams per kilogram) and 4,100 ppm, respectively Toluene, <br /> ethylbenzene and xylenes were detected at concentrations up to 0 54 ppm, 2 4 ppm and 44 ppm, <br /> respectively Benzene and MTBE were not detected in the samples analyzed Analytical results are <br /> summarized on Table I The laboratory report (MAI sample Nos 83335 - 83348) and chain-of- <br /> custody form are included in Appendix A <br /> 32 GROUND WATER ELEVATION AND GRADIENT <br /> The elevation of ground water in each well ,xas calculated by subtracting the depth to water from <br /> the surveyed casing elevation (Table 2) The ground water elevation increased an average of 145 <br /> feet since the September 1997 monitoring event The ground water flow direction was northeasterly <br /> with a shallow gradient The flow direction is similar to previous monitoring events Small normal <br /> measurement variations can produce large variations in flow direction at sites with low giadlents <br /> Figure 4 - Ground Water Elei ation depicts the contours for December 1997 <br /> 3 3 ANALYTICAL RESULTS OF GROUND WATER SAMPLES <br /> TPH-g was detected in the sample collected from monitoring well UST-5 at a concentration of 250 <br /> parts per billion (ppb, repotted as micrograms per liter) Benzene was detected in this sample at a <br /> J concentration of 6 9 ppb TPH-d was detected in UST-2,UST-3,UST-4 and UST-5 at concentrations <br /> of 140 ppb, 71 ppb, 59 ppb and 79 ppb, respectively Petroleum hydrocarbons were not detected in <br /> the samples collected from either of the domestic wells Other petroleum hydrocarbons were not <br /> detected in samples collected at the site <br /> 1,2-Dichloroethane (DCA) ,,,as detected in the sample collected from UST-5 at a concentiation of <br /> 360 ppb Other volatile organic compounds including oxygenating compounds were not detected in <br /> ground water samples from the site The anal)tical results are summarized on Tables 3 and 4 The <br /> laboratory report (MAI sample Nos 84216 - 84221) and chain-of-custody form aie included in <br /> Appendix C <br /> 40 DISCUSSION AND CONCLUSIONS <br /> Six USTs were removed in September 1997 Soil excavated during the UST removal is currently <br /> stockpiled on-site and has been characterized A Work Plan for the disposition of the stockpiled soil <br /> has been approved by the PHS-EHD Cost reimbursement preapprovaI is pending from the UST <br /> cleanup fund <br /> Advanced GtoEn%ironmental,Inc <br />�J <br />