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y ,e 4 . was placed between the well casing and the boring from the bottom of the boiing to 1-foot above the ,cieened interval A 0 5-toot thick bentonite layer was placed between the ,andpack and the overlying cement sanitary seal A Portland cement sanitary seal was placed above the bentonite layer to prevent surface watei tiom infiltrating into the well The wellheads are piped directly into an air-sparging manifold, which is piped directly to the air source (Figure 2) See Appendix C for well completion logs 3 -2 Vapor-Extraction WoaL The remediation system incoiporates the use of seven (7) vapor- extraction (VE) wells During the dual-phase test conducted in August 2000, the VE radius of influence was shown to be at least 45-feet based o n measurements collected during the dual-phase test To be conservative, ASE assumed a VE influence of 20-feet and thus a spacing of 40-feet foi VE wells across areas of the site with elevated hydrocarbon concentrations Based on this spacing, ASE installed seven (7) VE wells (Figure 2) The VE wells were drilled with a drill rig equipped with S-inch diameter hollow-stem augers by West Hazmat Drilling Corp of Rancho Cordova, California between November 27 and 29, 2001 The wells were constructed with 2-inch diameter, flush threaded schedule 40, 0 020-inch factory slotted PVC well screen and blank casing The VE wells were screened between 4 and 12-feet bgs The depth of 12-feet was chosen because that depth is dust above the shallowest depth of groundwater measured historically in on-site monitoring wells Blank casing was installed above this screened interval Lonestar #2112 sand was placed between the well casing and the boring from the bottom of the boring to 05-feet above the screened interval A 0 5-foot thick bentonite layer was placed between the sandpack and the overlying cement sanitary seal A Portland cement sanitary seal was placed above the bentonite layer to prevent surface water from infiltrating into the well The wellheads were piped individually into a vapor-extraction piping manifold, which is piped to the abatement device (Figure 2) See Appendix C for the well completion logs 3 . 3 Groundwater RecQyery Wells Two additional groundwater-recovery wells were installed west of RW-1 to • enhance the recovery of groundwater in areas containing elevated hydrocarbon concentrations west of the current capture zone (Figure 3 ) These two additional wells have a spacing of 30-feet, which is consistent Frank's One Stop ASNE Remediation System Installation Report — February 2002 -2-