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In-Situ Stabilization of Mixed Waste Contaminated Soil Pages: 18 Published: Jan 1996
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View License Agreement A full-scale field demonstration was conducted to evaluate in situ solidification for stabilizing an inactive RCRA land treatment site at a DOE facility in Ohio. Subsurface silt and clay deposits were contaminated principally with up to 500 mg/kg of trichloroethylene and other halocarbons, but also trace to low levels of Pb, Cr, 235U, and 99Tc. In situ solidification was studied in three, 3.1m diameter by 4.6 m deep columns. During mixing, a cement-based grout was injected and any emissions from the mixed region were captured in a shroud and treated by filtration and carbon adsorption. During in situ processing, operation and performance parameters were measured, and soil cores were obtained from a solidified column 15 months later. Despite previous site-specific treatability experience, there were difficulties in selecting a grout with the requisite treatment agents amenable to subsurface injection and at a volume adequate for distribution throughout the mixed region while minimizing volume expansion. Observations during the demonstration revealed that in situ solidification was rapidly accomplished (e.g., >90 m3/d) with limited emissions of volatile organics (i.e., < 1 wt% of initial Soil VOCs). Grout distribution within the mixed region was not uniform, with marked differences in compressive strength and elemental content with depth. Volume expansion was significant (30% v/v) and the hydraulic conductivity of the solidified soil was greater than that of the undisturbed natural deposit (10-6 cm/s vs. 10-8 cm/s) Leaching tests performed on the treated samples revealed non-detectable to acceptably low concentrations of all target contaminants. | ||
