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J k r 1 <br /> 24 August 1995 <br /> AGE-NC-95-0142 <br /> Page 4 of 6 <br /> 34 COLLECTION OF SOIL VAPOR SAMPLES <br /> On the 14 and 15 June 1995 soil vapor samples were obtained from the site using AGE' <br /> svan- <br /> mounted Geoprobe 5400 Nine probings were advanced to depths of approximately 40 feet Vapor <br />' samples were collected at 10 foot intervals in each probing Each vapor sample was collected by <br /> applying a vacuum potential'to each probe using an electric air pump At each sample point, a PID <br /> is used to screen for organic vapors After field screening, each sample was drawn into a Tedlar bag <br />' via vinyl tubing Because of the clayey soil, samples could not be collected at each depth in each <br /> boring After collection of the vapor samples, each probing was backfilled with bentonite chips and <br /> capped with 6-inches of cement <br />' Each Tedlar bag sample p e was placed in a cool container and transported under chain-of-custody to <br />' MAI A total of nine sod vapor samples were analyzed for TPH-g and BTE&X in accordance with <br /> EPA methods 5030 and 602, respectively' <br />' 4.0. FINDINGS <br /> 4 1 GROUND WATER GRADIENT AND DIRECTION <br /> The depth to ground water at the site ranged from 38 93 feet to 39 61 feet The data indicates an <br /> average increase of ground water elevation of nearly eight feet since November of 1994 The ground <br /> water gradient was calculated to be 0 015 RJR, in a northeasterly direction (N 40°E) The relative <br /> elevation of ground water is illustrated on Figure 3 <br /> 4 2 HYDROCARBON IMPACTED GROUND WATER <br />' TPH- detected$ was ted m each monitoring well, concentrations ranged from 260 µg/L (parts per <br /> million) in,MW-2 to 13,000 ppm in MW-3 BTE&X were detected in each monitoring well at <br /> concentrations from 0 52 ppm (toluene, MW-1) to 5,300 ppm (benzene, MW-3) However, the <br /> reporting limits for sample MW4/5-22-95 were elevated because of matrix interference , The <br /> analytical results of the ground water samples are summarized in Table 1 The laboratory report and <br />' chain-of-custody are included in Appendix C <br />' 4 3 HYDROCARBON IMPACTED SOIL <br /> TPH-g was detected in soil samples from boring ASBA at depths between, 15 and 40 feet at <br />' concentrations up to 13,000 ppm BTE&X were detected in samples from ASB-1 at concentrations <br /> ranging from 0 11 ppm (ethyl benzene, ASB-1/25) to 1,900 ppm(xylenes, ASB-1/15) No TPH-g <br /> L 1 <br />