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13 September 2002 . AGE-NC Project No 97-0290 ' Page 3of6 2 4 SOIL-VAPOR SAMPLING AND ANALYSIS Soil-vapor samples were collected on 15 April, 06 May and 11 June 2002 from the carbon- adsorption soil vapor extraction system The so1I-vapor samples were collected in Tedlar vapor bags using a vacuum pump attached to the influent and effluent stream The samples were labeled,placed in a pre-chilled cooler and transported under chain-of-custodyto McCampbell Analytical,Inc (MAI) and, both California Department of Health Service (DHS) - certified laboratories The samples were analyzed for the following • Total petroleum hydrocarbons as gasoline(TPH-g) in accordance with EPA Methods 8015 Modified and • Benzene,toluene, ethylbenzene and xylene(BTEX)in accordance with EPA Method 8020 25 SPARGE SYSTEM MONITORING I• The effect of the IAS system was monitored utilizing a YSI-55 dissolved oxygen meter on ground water During each monitoring event,the depth to groundwater and percentage of dissolved oxygen I were measured for available monitoring wells General system maintenance and adjustments were performed at this time The sparging flow rate was adjusted to approximately 4 scfm and to a pressure of 6 psi at each well I 3.0. FINDINGS IGround water elevation, flow direction and gradient were determined from field data collected on 24 June 2002, the contaminant impact to ground water was quantified from the ground water I laboratory data From field and laboratory data collected at the SVE remediation system between April and June 2002, AGE determined the average TPH-g concentration, the average flow rate and calculated the approximate mass and volume of hydrocarbons removed 3 1 GROUND WATER GRADIENT AND FLOW DIRECTION The depths to ground water ranged from 45 72 feet to 50 83 feet below the tops of the well casings on 24 June 2002 Ground water elevations calculated from the well monitoring data ranged from 1 18 feet to 1 47 feet below mean sea level(msl) Ground water data is summarized on Table 1 The • depth to ground water decreased an average 0 5 feet since the previous quarter The ground water flow direction was south with a gradient of 0 003 ft/ft Ground water elevation contours based upon Advanced GeoEnvironmental,Inc