WORK PLANS - Laserfiche WebLink

Home Browse Search

these zones by: (1) active soil gas sampling as previously described in Section 6 of this workplan and; (2) SVE Pilot testing of the two zones. Because the "A"Clay is presumed to effectively split the LNC site into two subsurface zones the design of the SVE Pilot Test system will account for this condition by focusing vapor capture in each of the multiple wells screened in both the shallow and deep zones. The migration of VOCs within the deep vadose zone at the LNC site is currently unknown. The migration of VOC's both vertically and horizontally in the shallow groundwater surface at the LNC is also unknown. The four deep SVE wells will be completed into the groundwater surface in order to provide some level of understanding of current groundwater conditions in the first water bearing zone immediately underlying the LNC site. Based on previous work conducted by WZI(1996) and the limited work conducted by Geomatrix (2006)we believe that the majority of the VOC contaminant mass in the soil column exists in the deeper vadose zone from 35 to 50 feet bgs and very likely the most significant VOC contaminant mass in soil is contained within the underlying capillary fringe of the first water bearing zone at depths of 50 feet or more. The objectives of SVE pilot testing are to determine: • Subsurface air permeability in shallow and deep zones; • Radius of influence (ROI) in terms of distance in both shallow and deep zones; • Flow rate versus vacuum in both shallow and deep zones; • Influent VOC concentrations; and • Possible effects on the water table and capillary fringe induced by SVE. Vapor capture is planned across the axis of the groundwater contaminant plume as this area will likely yield the highest influent VOC concentrations. M ain\D:AEnvironmenta1\LN CV\10152007.wpd 48