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30 September 1996 <br /> AGE-NC-95-0112 <br /> Page 3 of 6 <br /> 25 SOIL VAPOR EXTRACTIONIIN--SITU AIR SPARGING REMEDIATION SYSTEM <br /> The SVE system has been in operation at the site since 15 August 1995 Between 30 April 1996 and <br /> p g P <br /> 31 July 1996,the SVE system operated a total of 2,207 hours, or about 99 9% of the time, bringing <br />' the total operating time up to 6,503 hours since the system was brought on-line Field data is <br /> summarized on Table 4 <br /> From 30 April to 06 June 1996, the SVE system was extracting an average of 75 cubic feet per <br /> minute(cfm) of vapor from MW-1 On 06 June 1996, the extraction unit was switched back to RW- <br /> I The IAS system, installed concurrently with the SVE system, utilizes a compressor-driven <br /> EnviroSparge system and sparges air through the sparge points at a rate of approximately 7 cfm on <br /> one hour cycles The sparging system was not operational due to mechanical difficulties during most <br /> of June 1996 A new sparging unit has been installed and is currently in operation at the site <br />' 26 COLLECTION OF VAPOR SAMPLES <br /> Vapor samples were collected from the vapor inlet to the extraction unit on 23 May,28 June and 31 <br /> July 1996 Samples were collected in Tedlar bags and transported in a cool container under chain-of- <br /> custody <br /> hain-ofcustody to McCampbell Analytical, Inc (MAI) in Pacheco, California The samples were analyzed <br /> within 48-hours for TPH-g and BTE&X in accordance with EPA methods 5030 and 602, <br /> respectively <br />' 27 MASS CALCULATION OF RECOVERED PRODUCT <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/m3) <br /> Q = extraction flow rate (m3/1u) <br /> t=operational period, in hours <br /> Between 30 April and 23 May 1996,-the vacuum extraction unit operated a total of 507 4 hours, - <br /> between 23 May and 28 June,the extraction unit operated a total of 901 8 hours, between 28 June <br /> and 31 July, the extraction unit operated a total of 797 9 hours This data, the analytical results of <br /> the vapor samples and an average flow rate of 70 cfm were used to calculate the approximate mass <br /> of extracted gasoline during these periods The mass calculations are attached in Appendix F <br /> 1 <br />