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27 November 1996 AGE-NC-95-0112 ' Page 4 of 5 ' 3 3 LABORATORY ANALYSIS OF VAPOR SAMPLES TPH-g was detected in the vapor samples collected on 29 August, 30 September and 30 October ' 1996 at concentrations of 1,400 ppmv, 1,300 ppmv and 520 ppmv, respectively All three samples were collected during extraction from RW-1 Concentrations of extracted hydrocarbons has generally decreased since the previous quarter Field data is included on Table 3 Analytical results of vapor samples aie summarized in Table 4 The laboratory reports (MAI, sample ID Nos 68483, 69641 and 70713) and chain-of-custody forms are included in Appendix C ' 34 HYDROCARBON-IMPACTED SOIL REMEDIATION ' The mass of hydrocarbons extracted from MW-1 and RW-1 between 31 July and 30 October 1996 was calculated to be approximately 152 kg or 335 lbs A gallon of gasoline weighs approximately 6 25 lbs The approximate volume of hydrocarbons as gasoline removed during this operational period is 53 6 gallons This br]ngs the total volume of liydiocarbons removed from the soil since initiation of the SVE system up to approximately 1,560 gallons The mass calculations for the current quaiter are attached in Appendix D ' 4 0. CONCLUSIONS & RECOMMENDATIONS 41 CONCLUSIONS ' Based upon data collected from the site, AGE has the following conclusions ' • The concentration of TPH-g in MW-1 was slightly higher in the October sample than in the July 1996 monrtoiing sample However, concentrations were below those detected during the April 1996 and all previous momtoiing events Benzene and toluene have not been detected in the sample collected from MW-1 for tAo monitoring periods • Petroleum hydrocarbons have not been detected in any of the remaining monitoring wells ' during the last three monitoring events • Concentrations of extracted hydrocarbon vapor continued to show a slight decrease from ' previous monitoring quarters rip