An Overview of In Situ Soil Mixing Remediation Technologies(Abstract)

摘要

In Situ Soil Mixing (ISSM) is an emerging alternative for treating subsurface zones containing high concentrations of chlorinated solvents and/or petroleum liquids. The primary benefit of the technology is a large reduction in contaminant discharge from the treated body. This is achieved through contaminant depletion and/or stabilization. This paper provides an overview of methods employed in ISSM remediation efforts. ISSM remediation builds on widely used geotechnical methods employed to improve soil strength. Furthermore, it builds on familiar remediation approaches employing chemical reductants, chemical oxidants, steam stripping, and/or chemical fixation. Mix- ing is commonly achieved using a large diameter auger (typically 3 to 12 ft diameter) with mixing paddles and grout injection ports. In one approach, as the auger is advanced a grout is pumped through the kelly bar to the auger. The grout is the vehicle for delivery of stabilizing agents and/or reactive media. In addition, the grout acts as a drilling fluid. Alternatively, air or steam can be injected while drilling. Multiple vertical passes through the targeted zone produces a uniform column of treated media. Overlapping columns create a continuous body of treated media. Use of large diameter augers is referred to as Shallow Soil Mixing. Other mixing techniques include Deep Soil Mixing involving a bank of multiple augers and In Situ Stabilization involving excavator mounted equipment with a mixing bucket or specialized in situ blending tools.