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' 05 May 1997 • AGE-NC Protect No 95-0173 ' Page 9 of 29 ' conflicted with IP observations and distance measurements from MW-2, VW-1 or VW-2 No explanation was evident after reviewing screened intervals,depth to ground water measurements and site lithology The irregular IP observations from MW-1 may be due to channeling of air flow from the sparging points A lower infection pressure and flow rate may help prevent channeling of air flow Surging of the sparging system by starting and stopping the compressor may generate more favorable air flow characteristics IP measurements are summarized in Table 6, plots of IP versus ' time for wells MW-I through MW-4, VW-I and VW-2 are included with Appendix F t4 2 2 Dissolved Oxygen A plot of dissolved oxygen (DO) measurements versus time during the IAS pilot test indicated increasing DO readings from VW-1, VW-2 and MW-3, DO concentrations fluctuated in MW-1, MW-2 and MW-4 during the IAS pilot test with no substantial increases or decreases The overall increase of dissolved oxygen in wells nearest the sparging points indicates circulation of the infected air and augmentation of DO content in the ground water surrounding the sparging points Therefore, IAS should effectively reduce hydrocarbon concentrations in ground water and the saturated portion �. of the vadose zone by stripping out the hydrocarbons (air stripping) and stimulating the low population of hydrocarbon-degrading microorganisms if biotoxic conditions are ameliorated DO measurements are summarized in Table 6,plots of DO versus time for wells MW-1 through MW-4, ' VW-1 and VW-2 are included with Appendix F 4 2 3 Organic Vapor Review of organic vapor(OV) measurements collected during the IAS pilot test indicates increasing OV readings in all observation points (MW-1 through MW-4, VW-1 and VW-2) Generally, substantial OV increases were reported in observation wells between 26 to 28 hours of IAS operation The greatest concentration of OVs were detected in VW-1, ranging from 144 ppm (initial reading) to 2612 ppm after 28 hours The increase in OVs may indicate stripping and volatilization of hydrocarbons from the saturated zone in response to the IAS pilot test OV measurements are summarized in Table 6 4 2 4 Ground Water Depth L-'W ing 1e inS F11VL LesL,&L—,LU—%4 Yvater elevation m4..s�,:rements indicated inrrPagPc of approximately ' 0 18 feet from wells MW-I through MW-3 VW-I and VW-2 Significant increases in ground water elevation during the I t-Se- test is indicative of ground water mounding, no significant ground water elevation changes was observed in well MW-4 The tendency for ground water mounding AdvaitcedGeoEmironmental,Inc