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, i t 24 August 1995 AGE-NC-95-0142 ' Page 5 of 6 was detected in soil samples from ASB-2 or ASB-3 However, low concentrations of toluene and ' xylenes were detected in a single sample from ASB-2 at a depth of 20 r Total lead was detected in each soil sample submitted for analysis at concentrations ranging from ' ppm(ASB-1135)to 8 7 ppm (ASB-i/l5) No organic lead was detected in any of the soil samples Analytical results of the soil samples are summanzed in Table 3 The laboratory report and chains-of- custody are included in Appendix D ' 44 ANALYTICAL RESULTS OF SOIL VAPOR SAMPLES Soil vapors from each probing were field screened with a PID Based upon field screening, five soil ' vapor samples were submitted for analysis TPH-g was detected at concentrations ranging from 65900 ppb(AV 1-40)to 52,000 ppb (AV2-30) BTE&X were detected in each soil vapor sample at concentrations ranging to 2,200 ppb(benzene, AV2-30) Analytical results of the soil vapor samples ' are included in Table 4 The laboratory report and chain-of-custody are included in Appendix E 5.0. CONCLUSIONS AND RECOMMENDATIONS 5 1 HYDROCARBON IlvIPACTED GROUND WATER Gr water gradient radient calculations indicate that MW-4 has remained the down-gradient well since January 1995 As in`the two previous sampling events, the highest concentration of dissolved hydrocarbons were detected in MW-3, north of the former UST excavations Low concentrations of TPH-g and BTE&X were detected in both MW-I andMW-2, prior to the May 1995 sampling, hydrocarbons had not been detected in MW-I No hydrocarbons were detected in MW-4, however a matrix interference prevented the samples from being analyzed at full strength Mr Ed Hamilton,Lab Director for MAI, indicates that it is likely that the interferent in MW-4 was caused from acidified ground water in the area of the well It is likely that the acidification is due to elevated concentrations of carbon dioxide Based u on anal ical results of ground water samples from the May 1995 sampling, it appears that ' p Yt - ! MW-1 and MW-2 are located near the: southeast and southwest edges of the dissolved hydrocarbon plume, MW-4 is located down-gradient and outside the dissolved hydrocarbon plume • We do not recommend the installation of additional ground water monitoring wells at this time ' However, additional wells may be required in the future if the dissolved plume migrates down- gradient of MW-4 or if the concentrations of hydrocarbons in MW-1 and MW-2 continue to increase We recommend that all wells be sampled in September 1995 When purging MW-4, dissolved j