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27 October 2000 <br /> • AGE-NC Project No 95-0143 <br /> Page 3 of 6 <br />' Methods 8015m/5030 and 8020/602 by MAI The 26 September 2000 inlet soil vapor sample was <br /> not analyzed, the valve on the Tedlar bag containing the Inlet sample failed during the extraction <br /> process at the lab <br />' The depth to ground water and dissolved oxygen concentrations in ground water were measured on <br /> � �' xY <br /> 21 August and 07 September 2000 Ground water elevation data are summarized on Table 1 <br /> Dissolved oxygen data are summarized on Table 4 <br />' 2 4 HYDROCARBON MASS CALCULATIONS <br />' On 29 August 2000 an hour meter and flow meter were Installed on the SVE unit to record the <br /> operation time and flow rate of the SVE unit Operation time and flow rate were recorded during <br /> weekly monitoring events of the SVE system on field data sheets (Appendix D) The volume of <br /> extracted soil vapor removed was then calculated Analytical results for the two soil vapor samples <br /> collected from the SVE intake while the system was operational were averaged The volume of soil <br /> vapor removed and the average hydrocarbon concentrations were divided into two data sets, based <br />' on the time of collection of the two soil vapor samples The mass of hydrocarbons removed from the <br /> site was then calculated The mass calculations are included in Appendix E <br />' 3.0. FINDINGS <br />' Ground water elevation and flow direction were calculated from field data, the hydrocarbon Impact <br /> to ground water was Inferred from laboratory analysis and field observations The approximate mass <br /> of hydrocarbons removed by soil vapor extraction was calculated <br />' 3 1 GROUND WATER ELEVATION AND GRADIENT <br /> The elevation of ground water in each well was calculated by subtracting the depth to water from the <br />' surveyed casing elevation(Table 1) Between May 2000 and August 2000,ground water elevations <br /> decreased in the nine wells an average 1 59 feet During the August 2000 monitoring event, ground <br /> water ranged from 0 51 feet to 8 19 feet above the screened Interval in the nine monitoring wells <br />' Ground water was within the screened intervals of each vapor well The approximate hydraulic <br /> gradient was calculated to be 0 0020 ft/ft with a northeasterly flow direction on the subject property <br /> Ground water elevation contours for the August 2000 monitoring event are illustrated in Figure 3 <br /> I <br /> • <br /> Advanced GeoEnvironniental,Inc <br /> I <br />