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r._. 27 June 1996 <br /> =j AGE-IVC Project No. 95-0118 <br /> t Page 7 of 23 <br /> 1,000 to 1,900 ppm. Induced vacuum measured at the extraction well (VW-1) ranged from 33 to 40 <br /> inches of water. <br /> F.-. As expected, the greatest vacuum was measured in observation points nearest the extraction well <br /> L,. <br /> (MW-3). The lowest vacuum was measured in MW-2, approximately 45 feet northwest of the <br /> extraction point. <br /> F -I <br /> " The maximum vacuum measured at the observation points during the pilot test wasp lotted versus <br /> the distance from the extraction well. Results are depicted in Figure 4 - Effective Radius Qf <br /> Influence. The effective radius of influence can be determined by drawing a best-fit line though these <br /> data points to correlate distance to vacuum data. At a vacuum potential of 0.1 inches of water,the <br /> radius of influence ranges from 27 to 60 feet; at 1.0 inches of water the radius of influence ranges <br /> from 17 to 38 feet. Based upon an effective vacuum potention of 1.0 inches of water, the calculated <br /> effective radius of influence at the site will be approximately 27 feet. However, the actual effective <br /> radius of influence achieved may be somewhat less. <br /> i-<I <br /> �- . ..._.j 5.2.2. ANALYTICAL RESULTS OF VAPOR SAMPLES <br /> TPH-g was detected in the soil gas samples (vapor samples) at concentrations ranging from 46;000 <br /> . _� ppb to 54,000 ppb. BTE&X were detected-in the vapor samples samples at concentrations ranging <br /> from 210 ppb(benzene; VS 1)to 3,200 ppb (toluene; VS3). Analytical results of the vapor samples <br /> are included in Table 5. The laboratory report (MAI Laboratory I. D. Nos. 61542 through 61545) <br /> and chain-of-custody forin are included in Appendix G. <br /> 6.0. IN-SITU AIR SPARGING PILOT TEST <br /> 6.1. PROCEDURES <br /> 6.1.1. SYSTEM INSTALLATION AND SETUP <br /> r1 From 12 March to 17 March 1996, an in-situ airsparging (IAS ilot test.was performed at the site. <br /> This pilot test was conducted to provide data on the feasibility of air sparging as a remediation <br /> method at the site. Two sparging wells were installed at the site on 26 January 1996 (Section 3.1). <br /> PVC piping was installed from a temporary air compressor to sparging well VW-2. Ambient air was <br /> cyclically injected for two hours and then delayed for one hour. On 12 March 1996, compressed air <br /> ?..:-.3 was supplied to the IAS well at a pressure of approximately 12 pounds per square inch(psi). The <br /> pressure was increased to approximately 15 psi, from 15 March to 17 March. Approximately 12 to <br /> 14 psi was required to overcome the water column in the sparging well. <br /> i.� <br />