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I' 19 July 1996 AGE-NC-95-0109 ' Page 3 of 6 ' 2.3.2. COLLECTION OF GROUND WATER SAMPLES Water samples were collected from each purged well using disposable plastic bailers. Immediately ' upon retrieval, the samples were transferred into 40-m1 EPA vials containing hydrochloric acid as a preservative and transported in a chilled container to McCampbell Analytical, Inc. (MAI). Samples were analyzed for TPH-g and BTE&X in accordance with EPA methods 5030/8015m, and 602, ' respectively. Samples from MW-7, MW-8, MW-9, MW-13, MW-14 and EW-1 were also analyzed for volatile halocarbons in accordance with EPA method 601. The sample from MW-14 was also analyzed for ethylene dibrornide (EDB) in accordance with EPA method 601. 3.0. FINDINGS 3.1. MICROBIOLOGICAL ACTIVITY IN GROUND WATER Microbiological plate counts from ground water samples collected during the second quarter of 1996 showed a general decrease. Nutrient concentrations have also shown a general decrease at the site during the past quarter. Microbiological data for ground water is summarized on Table 1 and Table 2. The laboratory reports (A. Keith Kaufinan - May 14, 1996 June 1, 1996 and June 28 1996) and chain-of custody forms are included in Appendix B. 3.2. SOIL VAPOR SAMPLING Concentrations of organic vapors (OV) measured in the wells remained low during the second quarter of 1996. In each well, carbon dioxide readings are negatively correlated with oxygen concentrations.The correlation between carbon dioxide and oxygen continues to be predictable. OV measurements tend to correspond with carbon dioxide readings. Concentrations of carbon dioxide were generally low over the southern half of the site, moderate over the northern half of the site, and increased off-site. All soil vapor field data is sununarized in Table 3. Charts 1 - 7 (Appendix E) show concentrations of CO2, Oz and organic vapors versus time for wells VW-1, VW-3, VW-4, VW-5, MSV-5, MW-11 and MW-14. Nitrogen was detected in soil gas samples from MW-3, MW-4 and MW-14 at concentration of 78% to 79%. Oxygen was detected at concentrations ranging from 19% to 22%. Carbon dioxide was detected at concentrations ranging from 0.2% to 1.0%. Methane and carbon monoxide were not detected in the three soil gas samples analyzed. Analytical results are summarized on Table 4. The laboratory report and chain-of-custody form are included in Appendix C. I