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' 08 April 2005 AGE-NC Project No 95-0173 ' Page 4 of 10 per liter (µg/1) in the sample from MW-2 Various BTEX compounds were detected in ground water samples MW-1,MW-2,MW-4,MW-13 I (A-C), and AW-2 (A and B) at concentrations as high as 1,160 µg/1 (total xylenes, MW-2) The maximum benzene concentration was detected in sample MW-2 at a concentration of 69 µg/1 1,2-DCA was detected in ground water samples MW-2, and AW-2 (A and B) at concentrations as high as 16µg/l(MW-2) No other fuel components were detected in the samples analyzed Previous and current analytical results of ground water samples are summarized in Tables 3 and 4, respectively The GeoTracker confirmation pages of the submitted laboratory electronic deliverable format(EDF)files are included in Appendix B,the laboratory report(CTEL Laboratory I D 0412- 002),quality assurance/quality control (QA/QC)reports, and chain of custody forms are presented in Appendix C 3.0. SOIL VAPOR EXTRACTION/IN-SITU AIR SPARGE SYSTEM AND RESULTS Between 23 September and 22 December 2004, an SVE remediation system was continuously operated at the site,utilizing a regenerative vacuum blower to selectively apply an induced vacuum to wells VW-1, VW-2 and VW-5,wells VW-3, VW-4, VW-6 and VW-7 were `closed' at the well- heads due to only trace levels of petroleum hydrocarbons previously observed from PID field measurements During this time, IAS remediation was continuously operated on IAS well AW-1B (screened 50 feet to 60 feet bsg)utilizing an air compressor to inject air beneath the water table SVE and IAS procedures for the site were described in the AGE-prepared Remedral Acnon Work Plan, dated 30 December 1998 and approved by the EHD by letter dated 20 April 1999 3 1 REMEDIATION SYSTEM PROCEDURES The SVE system utilized a manifold network of 2-inch diameter, schedule 80 polyvinylchloride (PVC) piping installed underground from SVE wells VW-1 through VW-7 to the inlet of the SVE remediation system The SVE remediation system is comprised of one 41/2-horsepower,regenerative vacuum blower and two 1,000-pound carbon canisters In order to monitor efficiency of the SVE system 1 a Ma nehelic vacuum gauge (Dwyer DS-200 flow sensor was installed prior to the inlet of the SVE unit to monitor air flow,the flow rate was determined from the measured differential pressure and the piping diameter using a nomograph (Appendix D), Advanced GeoEnviranmeatal,Inc