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16 April 1997 <br />AGE -NC Project No 95-0121 <br />Page 5 of 9 <br />destruction Optimal destruction will depend on four operational parameters combustion <br />temperature, volume of processed vapor, oxygen level and the lower explosive limits (%LEL) <br />Vapor samples will be collected on a monthly basis The samples will be collected in Tedlar bags and <br />transported to a state certified laboratory for analysis of total petroleum hydrocarbons quantified as <br />gasoline (TPH-g) and volatile aromatics (benzene, toluene, ethyl benzene and xylenes BTE&X) <br />Selected vapor samples may also be analyzed for TPH as diesel (TPH-d) and methyl tert butyl ether <br />(MTBE) All analysis will be performed in accordance with the appropriate EPA and/or DHS <br />methods <br />Dunng the "start-up" period for the SVE system, organic vapor monitoring will performed on a daily <br />basis The anticipated start-up period will be approximately one to two weeks <br />3 2 PROPOSED IN-SITU AIR SPARGING SYSTEM <br />IAS is proposed in conjunction with SVE concurrently at the site The proposed IAS system would <br />consist of a compressor to inject air beneath the water table using air sparging points Approximate <br />air sparging point locations are depicted in Figure 7 - Proposed Air Sparging Point Locations <br />The compressor will provide between 3 and 10 pounds per square inch (psi) of air to each sparge <br />point The injected air will volatilize dissolved hydrocarbons in ground water, and force hydrocarbon <br />vapors into the vadose zone, where they can be withdrawn by the SVE system <br />3 2 1 PROPOSED IN-SITU AIR SPARGING INJECTION POINTS <br />Installation of seven IAS injection points are proposed utilizing direct push technology (DPT) Each <br />IAS injection point will be installed using AGEs van -mounted Geoprobe probing unit equipped with <br />1 125 -inch diameter probe rods Probing rods will be cleaned prior to advancement in each borehole <br />Sparging points will be advanced to depths of approximately 30 feet bsg Soil probe borings will be <br />completed as IAS injection points using 318 -inch diameter teflon tubing and 31/2 -feet of 3/8 -inch <br />diameter stainless steel screen Glass beads (50-100 mesh) will be used as a filter pack around the <br />injection point An five foot interval of bentonite will be placed above the filter pack and will serve <br />as an annular seal Portland Type II cement will be utilized to grout from the annular seal to surface <br />grade Proposed IAS injection point construction diagrams are included as Figures 8 - Proposed Air <br />Sparging Point Design <br />• <br />