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' 06 December 2000 <br /> AGE-NC Project No 95-0173 <br />' Page 3 of 7 <br />' 1998,prepared by AGE and approved by the PHS-EHD by letter dated 20 April 1999 <br /> 3 1 SOIL VAPOR EXTRACTION/IN-SITU AIR SPARGE SYSTEM PROCEDURES <br /> Between 01 July 2000 and 04 October 2000, the SVE and IAS remediation systems were operational <br /> t at the site The SVE system utilized a Solleco Ecat 250 catalytic converter vapor extraction system <br /> Two-inch diameter, schedule 40 PVC piping was installed underground from each well-head at wells <br /> VW-1, VW-2, VW-3, VW-4, VW-5, VW-6 and VW-7 to the inlet of the vacuum blower, the outlet <br />' from the vacuum blower was routed through the catalytic converter A Magnehelic vacuum gauge <br /> was attached to the inlet of the blower The air flow was monitored using a Dwyer DS-200 flow <br /> sensor The flow rate was determined from the measured differential pressure and the piping <br />' diameter using a nomograph (Appendix B) The vapor stream at the SVE inlet was monitored for <br /> the presence of organic vapor using an organic vapor analyzer (OVA) equipped with a photo- <br /> ionization detector (PID Thermo Environmental 580A, 10 0 eV, calibrated to isobutylene) <br /> 1 Sampling ports were installed upstream of the vacuum blower inlet to recover influent soil-gas vapor <br /> stream samples, and downstream of the catalytic converter to recover effluent stream samples to <br /> monitor the efficiency of hydrocarbon destruction Field measurements were recorded at regular <br /> f• intervals throughout the pilot test and are summarized in Table 4 <br /> 32 COLLECTION AND ANALYSIS OF SOIL GAS SAMPLES <br /> A total of four pairs of extracted soil-gas vapor samples were collected from the inlet and outlet of <br /> the regenerative vacuum blower unit on four occasions to measure concentrations of hydrocarbon <br /> vapor The samples were collected in Tedlar bags using an organic vapor analyzer as an air pump <br />' Following sample collection, the samples were placed in a covered container and transported under <br /> chain-of-custody to McCampbell Analytical Laboratory (MAL)in Pacheco, California Each sample <br />' was analyzed within 72 hours of collection for TPH-g and BTEX in accordance with EPA Methods <br /> 5030/8415 Modified and 8020 <br /> 3.0. FINDINGS <br /> AGE determined from the field data collected on 29 September 2000 that the ground water flow <br /> direction was towards the northeast at an average gradient of 0 003 Laboratory analysis of seventeen <br /> ground water samples detected TPH-g and BTEX in twelve samples and MTBE in one sample <br /> Advanced GeoEnvironmental,Inc <br />