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I I20 August 2003 AGE-NC Project No 95-0173 ' Page 4of8 3 2 COLLECTION AND ANALYSIS OF VAPOR EXTRACTION AIR FLOW SAMPLES I Between 17 December 2002 and 26 February 2003, a total of three pairs of extracted air flow vapor ' samples were collected from the influent and effluent of the SVE unit to measure concentrations of hydrocarbon vapor Air flow samples were not collected during the 20 March 2003 monthly monitoring event due to SVE operations being temporarily suspended for repairs and maintenance ' The samples were collected in Tedlar bags using a hand air-vacuum pump Following sample collection, the samples were properly labeled,placed in a covered container and transported under chain-of-custody to Castle Analytical Laboratory(CAL) in Atwater, California Each sample was I analyzed within 72 hours of collection for TPH-g, BTEX and MTBE in accordance with EPA Methods 5030/8015M Modified and 8020 I4.0. FINDINGS Ground water elevation, flow direction and gradient were determined from field data collected on 04 April 2003,the contaminant impact to ground water was quantified from the laboratory analysis iFrom field and laboratory data collected at the SVE remediation system between 17 December 2002 and 20 March 2003, AGE determined the average TPH-g concentration, the average flow rate and icalculated the approximate mass and volume of hydrocarbons removed i4 1 GROUND WATER ELEVATION AND GRADIENT During the April 2003 ground water monitoring event,depths to ground water ranged between 27 16 i and 29 80 feet below the tops of well casings,ground water elevations were calculated to be between 18 54 feet(MW-8)and 20 30 feet(MW-4)below mean sea level Ground water elevation at the site increased an average 2 59 feet between the December 2002 and the April 2003 ground water imonitoring events The ground water elevation data for the April 2003 ground water monitoring event is depicted in Figure 3 Ground water flow direction at the site was inferred to be oriented northeast and radially mware towara a ground water depression in the area of well MW-4,the ground wafer gradient at the site was calculated to be 0 003 Rift or less, or approximately 16 feet per mile i i i iAdvanced GeoEnvironmental,Inc i