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30 September 1996 <br /> AGE-NC-95-0112 <br /> Page 5 of 6 <br /> Thirteen soil samples were analyzed for TPH-g, BTE&X and MTBE TPH-g was detected in 11 <br /> 1 samples at concentrations as high as 2,900 ppm (reported as micrograms per gram) Toluene, <br /> ethylbenzene and xylenes were detected at concentrations as high as 690 ppm Benzene and MTBE <br /> were not detected in any samples analyzed Petroleum hydrocarbons were not detected in samples <br />' PI-30 and P3-55 Analytical results are summarized on Table 3 The laboratory report(AAL Batch <br /> No 96-0806-006) and chain-of-custody forms are included in Appendix D <br /> 35 LABORATORY ANALYSIS OF VAPOR SAMPLES <br /> TPH-g was detected in the vapor samples collected on 23 May, 28 June and 31 July 1996 at <br /> concentrations of 1,800 ppmv, 1,900 ppmv and 130 ppmv, respectively The May sample was <br /> collected during extraction from MW-1,the June and July samples were collected during extraction <br /> from RW-1 Concentrations of extracted hydrocarbons continue to show a decrease over time Field <br /> data is included on Table 4 Analytical results of vapor samples are summarized in Table 5 The <br />' laboratory reports (MAI, sample ID Nos 65385, 66447 and 67448) and chain-of-custody forms are <br /> included in Appendix E <br /> 3 6 HYDROCARBON-IMPACTED SOIL REMEDIATION <br />' The mass of hydrocarbons extracted from MW-I and RW-1 between 30 April and 31 July 1996 was <br /> calculated to be approximately 411 kg or 906 lbs A gallon of gasoline weighs approximately 6 25 <br />' lbs The approximate volume of hydrocarbons as gasoline removed during this operational period <br /> is 145 gallons This brings the total volume of hydrocarbons removed from the soil since initiation <br /> of the SVE system up to approximately 1,506 gallons The mass calculations for the current quarter <br /> are attached in Appendix F <br />' 4.0. CONCLUSIONS & RECOMMENDATIONS <br /> Petroleum hydrocarbons were encountered over the entire depth of probing P1,which was advanced <br /> over the center of the former UST location Low concentrations of hydrocarbons were encountered <br /> in probing P2 from depths of 15 to 25 feet, north of P 1, while higher concentrations were detected <br /> from 40 feet to 55 feet bsg, corresponding to a smear zone from historic ground water fluctuations <br /> 1 _ _ Silt,encountered at these lower depths, slows the rate of remediation by vapor extraction Petroleum- <br /> hydrocarbons were encountered in probing P3, west of P1, only at depths from 45 to 55 feet bsg <br /> confirming the limited lateral extent of impacted soil above the smear zone Concentrations of <br /> organic vapor detected in soil samples have decreased since the installation of vapor well RW-1 Soil <br /> vapor samples will continue to be collected monthly to monitor the mass of hydrocarbons removed <br />