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08 June 2003 <br /> • AGE-NC Project No 98-0448 <br /> Page 4 of 9 <br /> I blower and analyzed Field measurements were recorded at regular intervals and are summarized In <br /> Table 6 <br /> I32 COLLECTION AND ANALYSIS OF VAPOR EXTRACTION AIR FLOW SAMPLES <br />' A total of eight extracted air flow vapor samples were collected on 17 December 2002 and 27 <br /> January, 26 February and 20 March 2003 from the influent and effluent streams of the regenerative <br /> vacuum blower unit to measure concentrations of hydrocarbon vapor The samples were collected <br /> Iin Tedlar bags using a hand 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 BTE&X in accordance with EPA Methods <br /> 8015C Modified and 8021B <br /> • 4.0 FINDINGS <br /> AGE determined ground water flow direction and gradient from the field data collected on 20 March <br /> 2003 The hydrocarbon and oxygenate impacts to ground water was assessed from the laboratory <br /> data <br /> From field data collected at the SVE remediation system between 17 December 2002 and 20 March <br /> 2003, AGE determined the average TPH-g concentration and the average flow rate and calculated <br /> the approximate mass and volume of hydrocarbons removed <br /> I <br /> 4 1 GROUND WATER ELEVATION AND GRADIENT <br /> The depths to ground water were measured at between 15 OS and 2133 feet below the tops of the <br /> well casings (Table 2) Ground water elevations at the site were calculated to be between 5 56 feet <br /> (MW-4A) and 11 92 feet (MW-4B) below mean sea level (Table 2) The ground water elevation <br /> contours are depicted in Figure 3 Ground water elevation at the site increased an average 106 feet <br /> between the December 2002 and the March 2003 ground water monitonng events <br /> IThe ground water flow direction at the site was inferred to be southwest, ata gradient of <br /> approximately 0 02 feet/feet ,or approximately 105 feet per mile Ground water elevation recorded <br /> Iat well MW-4A was not utilized to contour ground water elevations at the site due to the possibility <br /> IAdvanced Gco En viron mental,Inc <br /> I <br />