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' 12 June 1996 AGE-NC Project No 95-0112 Page 4 of 7 3 5 SOIL VAPOR EXTRACTIONIIN SITU AIR SPARGING REMEDIATION SYSTEM The SVE system has been in operation at the site since 15 August 1995 Between 29 February and 30 April 1996, the SVE system operated a total of 1,373 hours, or about 94% of the time, bringing the total operating time up to 4,295 hours since the system was brought on-line Field data is summanzed on Table 3 From 29 February to 26 March 1996,the SVE system was extracting an average of 75 cubic feet per 1 minute(cfm) of vapor from RW-I On 26 March 1996, the extraction unit has been extracting from MW-1 The IAS system, installed concurrently with the SVE system, utilizes a compressor-driven EnviroSparge system and sparges air through the sparge points at a rate of approximately 7 cfm on one hour cycles ' 36 COLLECTION OF VAPOR SAMPLES Vapor samples were collected from the vapor inlet to the extraction unit on 22 March and 25 April 1996 Samples were collected in Tedlar bags and transported in a cool container under chain-of- custody to Mc Campbell Analytical, Inc (MAI) in Pacheco, California The samples were analyzed within 48-hours for TPH-g and BTE&X in accordance with EPA methods 5030 and 602, respectively 37 MASS CALCULATION OF RECOVERED PRODUCT The hydrocarbon mass removed during the operating period was calculated using the following equation M= C•Q•t where M = cumulative mass recovered (kg) C = vapor concentration (kg/m') ' Q = extraction flow rate (m3/hr) t = operational penod, in hours Between 29 February and 26 March 1996, the vacuum extraction unit operated a total of 623 2 - hours Between 26 March and 30 April, the extraction unit operated a total of 749 7 hours This data, the analytical results of the vapor samples and an average flow rate of 70 cfm were used to calculate ' the approximate mass of extracted gasoline during these periods The mass calculations are attached in Appendix F S�