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1 <br /> Working To Restore Nature <br /> 7.2.2 Short Term Soil Vapor Tests <br /> ' The vacuums and flowrates achieved during the short term tests on VW-1 and VW-3 were <br /> similar to those achieved during the longterm test High aur flow rates ranging from 105 to 118 <br /> cfm at applied vacuums of 30 inches of water were achieved The induced vacuums in the <br /> observation wells ranged from 0 1 inches of water initially to as much as 1 15 inches of water <br /> ' Again, the induced vacuum responses are considered to be good response levels The achievable <br /> flows in excess of 100 cfm are considered to be high Field monitoring data is presented in <br /> Appendix F <br /> 7.2.3 Estimated Radius of Influence <br /> ' Utilizing induced vacuum and distance measurements obtained during the VET, an effective <br /> radius of influence was estimated for the vapor wells at the site The effective radius of <br /> influence has been defined as the radial distance from a vapor extraction well at which recorded <br /> vacuum levels suggest that subsurface air flow occurs and is presumed to be sufficient for <br /> remediation RESNA assumes that an induced vacuum of 0 25 to 0 5 inches of water should <br /> be sufficient to induce subsurface airflow within the zone of influence <br /> ' The flowrates, induced vacuums, and applied vacuums recorded during each of the three vapor <br /> ' extraction tests suggest that the subsurface conditions are relatively homogeneous and that short <br /> circuiting through the former tank pit is negligible The induced vacuums recorded in the <br /> ' observation wells suggest the effective radius of influence exceeds the distance between the <br /> observation wells (over 30 feet) This is sufficient to cover the area where significant levels of <br /> ' petroleum hydrocarbons remain in the soil <br /> ' 7.2.4 Laboratory Results <br /> The results of laboratory analyses of influent vapor samples indicated that vapor TPHg <br /> concentrations were nondetectable (<5 0 milligrams per cubic meter [mg/m3]) in well VW-1 <br /> and 40 mg/m3 in well VW-3 Concentrations of vapor phase TPHg in well VW-2 increased <br /> ' 1500471x-031594 FNL 11 <br />