Laserfiche WebLink
unsaturated zone. Ground water and lysimeter sampling to be conducted <br /> during the pilot study are described in Section 3.2. <br /> The pilot study data will be used to evaluate the probable utility of the <br /> full-scale subsurface soil flushing system. The pilot study evaluation <br /> will involve the following activities: <br /> • Unsaturated and saturated ground water contaminant modeling that <br /> is performed and calibrated based on the pilot study results. <br /> • Comparison of injection water flow rates to pilot study design <br /> calculations. <br /> • Comparison of extracted pore water and ground water contaminant <br /> concentrations to concentrations detected in monitoring well , <br /> lysimeter, piezometer, and monitoring tube samples. <br /> • Measurements of moisture content changes at pilot study <br /> monitoring tube locations. <br /> • Effects of multiple wells on rate of moisture content change. <br /> An evaluation of the pilot study results may warrant modifications to the <br /> full-scale design prior to Phase III construction. The subsurface soil <br /> flushing system modifications may include the following: <br /> • Addition, deletion, or relocation of injection wells, extraction <br /> wells, monitoring tubes, or lysimeter nests. <br /> • Installation of nested, angled, or horizontal injection wells. <br /> • Changes in injection or extraction well diameters, screen sizes, <br /> intervals, and or filter pack materials and dimensions. <br /> • Implementation of pulsed or pressurized flushing conditions. <br /> 2.2.2 Phase IV Full-Scale Flushina System Operation <br /> Based on an evaluation performed during the development of the RI/FS, the <br /> anticipated duration of the full-scale operation is five years. As <br /> discussed in Section 3.4, monitoring activities will be on-going at the <br /> site until the subsurface soil flushing is discontinued. Because the deep <br /> soil lithology is not homogeneous, an unknown number of pore volumes will <br /> be required to remediate the deep zone. Pore water contaminated with <br /> chromium exists in both fine-grained and coarse-grained soils. Pore water <br /> trapped in the fine-grained soils will take longer to remove (if possible <br /> to remove at all) . In addition, as lower concentrations of hexavalent <br /> 11654.652 2-4 <br />