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' a 20 April 1995 i AGE-NC-95-0109 Page 5 of 8 4 2 SOIL VAPOR SAMPLING Concentrations of organic vapor (OV) measured in the wells continue the trend observed during the third quarter of 1994, in each well, the OV and to a lesser degree, carbon dioxide readings are negatively correlated with oxygen concentrations The correlation between OV/carbon dioxide and oxygen continues to be predictable However, the degree of correlation was not as pronounced during the last quarter All soil vapor data is summarized in Table 2 4 3 PETROLEUM HYDROCARBON-IMPACTED SOIL TPH-g was detected in all of the 16 soil samples submitted for analysis TPH-g ranged from 5 ppm (P8, 27-foot depth) to 410 ppm (P7, 50-foot depth) Benzene was detected in four of the soil samples analyzed Toluene and ethylbenzene %Neie detected at ti ace concentrations in only two samples Analytical results of soil samples aie surinmanzed in Table 4 Also included in Table 4 are the analytical results of soil samples from the remediation wells, which %vete installed in 1993, and P-1 through P-5 The laboratory report and chain-of-custody aie included in Appendix C 4 4 GROUND WATER GRADIENT AND DIRECTION The depth to ground water ranges from 57 feet at the noith end to nearly 59 feet southwest of the site The data indicates an inciease in elevation of approximately 2 feet since December 1994, contiinunig the trend observed between September and December 1994 The increase in elevation is unifoini throughout the site and is consistent with seasonal fluctuations in giound water elevations Ground water elevations are suminanzed on Table 3 The giound water contour, based upon data collected on 13 March 1995, is depicted in Figure 3 The flow direction is to the south-southwest, and as in previous monitoring events, the gradient steepens towards the south end of the site 4 5 PETROLEUM HYDROCARBON-IMPACTED GROUND WATER Petroleum liydiocaibons were detected in ground water from five of the nine wells sampled TPH-g ranged frons below detectable limits to 2,800 ppb (MW-14/3-14-95) Detectable BTE&X concentrations ranged up to 500 ppb (xylenes, MW-I4) No TPH-g or BTE&X were detected in samples from MW-7, MW-10, MW-11 and MW-12 The analytical results aie stinimai ized in Table 5 The labor atony i epos is aind chain-of-custody forms are included