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' 27 February 1997 <br /> • AGE-NC-95-0I12 <br /> ' Page 2 of 5 <br /> 80% recharge Water samples were then collected from each purged well using new disposable <br /> bailers The samples were transferred into 40-m1 EPA-approved VOA vials containing 0 5 ml of <br /> 18%hydrochloric acid as a preservative and were transported in a chilled container, under chain-of- <br /> custody, to Alpha Analytical Laboratories (AAL) All samples were analyzed for total petroleum <br /> hydrocarbons quantified as gasoline (TPH-g), and for volatile organics (benzene, toluene, <br /> ethylbenzene and xylenes, BTE&X) with methyl tertiary-butyl ether (MTBE) in accordance with <br /> ' EPA methods 5030, 602 and 8020, respectively <br /> ' 23 SOIL VAPOR EXTRACTION/IN-SITU AIR SPARGING REMEDIATION SYSTEM <br /> The SVE system has been in opeiation at the site since 15 August 1995 Between 30 October 1996 <br /> ' and 20 December 1996,the SVE system operated a total of 1,218 hours, or neatly 100% of the time, <br /> bringing the total operating time up to 9,124 hours since the system was biought on-line Field data <br /> is summarized on Table 3 <br />' The S V E extract system y s an average of 70 to 75 cubic feet per minute (cfm) of vapor from RW-1 <br /> • during operation The IAS system, installed concurrently with the SVE system, utilizes a <br /> compressor-driven EnviroSparge system and sparges air through two sparge points at a total flow <br /> rate of approximately five standard cubic feet per minute (scfm) on one hour cycles <br /> 24 COLLECTION OF VAPOR SAMPLES <br />' Vapor samples were collected fiom the vapor inlet to the extraction unit on 26 November and 20 <br /> December 1996 Samples were collected in Tedlar bags and were transported in a cool container <br /> under chain-of-custody to McCampbell Analytical, Inc (MAI) in Pacheco, California The samples <br /> were analyzed within 48-hours for TPH-g and BTE&X in accordance with EPA methods 5030 and <br /> 602, respectively <br /> 25 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 T cumulative mass recovered (kg) <br />' C = vapor concentration (kg/rn') <br /> • Q = extraction flow rate (m3/lir) <br /> t= operational period, in hours <br />