SYMPOSIA PAPER Published: 01 January 1996

In-Situ Stabilization of Mixed Waste Contaminated Soil


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.

Author Information

Siegrist, RL
Oak Ridge National Laboratory, Oak Ridge, TN
Cline, SR
Oak Ridge National Laboratory, Oak Ridge, TN
Gilliam, TM
Oak Ridge National Laboratory, Oak Ridge, TN
Conner, JR
Chemical Waste Management, Clemson Technology Center, Clemson, SC
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Developed by Committee: D34
Pages: 667–684
DOI: 10.1520/STP14144S
ISBN-EB: 978-0-8031-5318-9
ISBN-13: 978-0-8031-1443-2