Technical Papers

CONTAINMENT, STABILIZATION AND TREATMENT OF CONTAMINATED SOILS USING IN-SITU SOIL MIXING

Steven R. Day
Christopher R. Ryan

Soil Mixing is a technique that has increasinglybeen relied upon for the insitu remediation ofcontaminated soils. Depending on the application, large or small diameter (4 to 0.3 meter) mixing augers can be used to inject cement, bentonite or other reagents to modify soil properties and A major advantage of the method is the capability to treat soils at depth (up to 35 meters deep) without excavation, shoring or dewatering. Recent advances in soil mixing technology include lower permeability additives for groundwater barriers, additives for the fixation of waste-contaminated soils and combination of soil mixing with hot air injection and vapor extraction technology to remove volatile organic chemicals.

Advantages of soil mixing over alternative technologies include lower cost, less exposure of wastes to the surface environment and eliminating off-site disposal. These advantages have made soil mixing the technique of choice on many projects.

The information presented in this paper is intended to provide engineers and owners with the level of understanding necessary to apply soil mixing technology to a specific site. The most important steps in implementing the technology are site investigation, feasibility estimate, selection of performance criteria, selection of appropriate materials bench scale testing, and construction.