X 231b Technology Demonstration For In Situ Treatment Of Contaminated Soil PDF Download

The goal of the study described in this report was to determine the efficiency of vapor stripping coupled with soil mixing for removing volatile organic compounds (VOCs) from clay soils such as those that underlie the PORTS X-231B Solid Waste Management Unit. This was accomplished by conducting experiments wherein contaminated soil cores were treated in the laboratory using a system that simulated a field-scale vapor stripping/soil mixing treatment process. Treatment efficiencies obtained using several sets of process conditions, such as air temperature and flow rate, were determined through subsampling of the soil cores to establish pre- and posttreatment levels of VOCs in the soil. Two series of experiments were conducted under this study. In the first series, laboratory treatment was performed on intact soil cores that were taken from contaminated zones within the PORTS X-231B Unit using sampler liners that could be adapted as reaction lysimeters. Since soil core disturbance was minimized using this approach, the treatability experiments were conducted on soil that was fairly close to in situ conditions in terms of both soil structure and contaminant levels. The second series of experiments were performed on cores that were packed using X-231B soil and spiked with known amounts of trichloroethylene (TCE). This approach was taken for the second series because the VOC levels in the intact cores were found to be much lower than field values. In addition, the packed cores were smaller than the intact soil cores, with treatment volumes that were about a fifth of the treatment volumes in the intact soil cores. The smaller packed cores were not only easier to handle but were also more reliably characterized due to smaller treatment volumes from which samples were taken.