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r <br /> 17 August 1998 <br /> AGE-NC Project No 95-0103 <br /> ' Page 5 of 7 <br /> induced vacuum(negative pressure)of approximately 30 Inches of water was measured in the piping <br /> between the blower and extraction wells The radius of a measurable vacuum at the outlying <br /> wellheads was noted to extend 90 feet from VW-1 to MW-3, with a transmitted vacuum force <br /> (potential) of 0 16 inches of water <br /> TPH-g was detected in the 04 June 1998 sample collected from the influent vapor stream at a <br /> concentration of 52 parts per billion (ppb, reported as micrograms per liter) BTE&X were not <br /> detected The analytical results of soil vapor samples are summarized on Table 5 The laboratory <br /> report(MAI Lab No 90055), Quality Assurance and Quality Control (QA/QC)reports and chain- <br /> of-custody forms are Included in Appendix C <br /> t3 b MASS OF RECOVERED HYDROCARBONS <br /> The hydrocarbon mass removed during the operating period was calculated using the following <br /> equation M= C•Q•t <br /> where M =cumulative mass recovered (kg) <br /> C =vapor concentration (kg/m}) <br /> Q= extraction flow rate (m3/hr) <br /> t=operational period, in hours <br /> The operational time over the last quarter was estimated to be 34 5 days The mass of hydrocarbons <br /> ' removed was based on laboratory analysis of one soil gas sample collected and analyzed The mass <br /> of extracted hydrocarbons was calculated for the period using the hydrocarbon concentrations <br /> ' determined from the influent vapor samples collected and the average air flow rate <br /> An estimated total of 13 gallons of hydrocarbons quantified as gasoline were removed from the site <br /> ' The mass calculations are attached in Appendix D <br /> ' 4.0. DISCUSSION/CONCLUSIONS <br /> Based upon data collected from the site and the ongoing monitoring during site remediation, AGE <br /> ' concludes the following <br /> • The relative ground water elevations at the site have remained similar to the previous quarter <br /> ' The profile of the ground water contours have indicated a depression in the area of the active <br /> SVE network, near the area of highest detected dissolved hydrocarbons <br /> Advanced GeoEn%ironmental,Inc <br />