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07 December 2004 <br /> -AGE-NC Project No 98-0448 <br /> Page 5 of 9 <br />' 33 COLLECTION AND ANALYSIS OF VAPOR EXTRACTION AIR FLOW SAMPLES <br /> A total of three extracted air flow vapor samples were collected on 22 July, 31 August and 23 <br />' September 2004 from the influent stream of the regenerative vacuum blower unit to measure <br /> concentrations of hydrocarbon vapor The samples were collected in Tedlar bags utilizing an electric <br /> air-vacuum pump <br /> Following sample collection,the samples were properly labeled, placed in a covered container and <br /> transported under chain of custody to a DHS-certified laboratory for analysis Each sample was <br />' analyzed within 72 hours of collection for TPH-g and BTEX/MTBE in accordance with EPA <br /> Methods 8015M Modified and 8021, respectively <br /> 4.0. FINDINGS <br />' AGE determined ground water flow direction and gradient from the field data collected on <br /> 03 September 2004,the contaminant impact to ground water was assessed from the laboratory data <br /> • From field data collected at the SVE remediation system between 22 June 2004 and 23 September <br /> 2004, AGE determined the average TPH-g concentration and the average flow rate and calculated <br /> ithe approximate mass and volume of hydrocarbons removed <br /> 4 1 GROUND WATER ELEVATION AND GRADIENT <br /> On 03 September 2004, the depths to ground water were measured at between 19 83 feet and 22 47 <br /> feet below the tops of the well casings (Table 2) The September 2004 ground water elevations at <br /> the site were calculated to be between 11 11 feet (MW-7) and 13 46 feet (MW-8)below mean sea <br /> level(Table 2),groundwater elevations are depleted on Figure 3 Generally,ground water elevation <br />' at the site decreased an average of 1 foot between,the July 2004 and the September 2004 ground <br /> water monitoring events <br /> lx <br /> I The September 2004 ground water flow direction at the site was inferred to be southwest, at an <br /> approximate gradient of 0 013 ft/ft (Figure 3) The flow direction this quarter was consistent with <br /> historical flow directions <br /> , <br /> IAdvanced GeoEnvironmental,Inc <br /> r <br />