Soil mixing, originally developed as a means for structural soil improvement, has evolved into a system for effectively treating soil in situ to meet environmental remediation cleanup objectives. Using soil mixing in remedial efforts has significant advantages over alternative methods, specifically in terms of assuring consistent, measureable delivery of reagents to contaminated media without significant lithology or permeability concerns. For specific target clean-up objectives, soil mixing often has a lower cost, requires less time, and is more sustainable than other traditional remedies.
The Evolution of Soil Mixing
Following a U.S. patent issued in 1954, there was little application of soil mixing in the U.S. for the next several decades. The few early applications, in which cement grout was mixed with the soil using small augers 2-3 ft in diameter, were for structural support improvement. Japanese development of the technology saw the advent of multi-shaft rigs in the 1980s, where several columns of similar diameters could be simultaneously mixed. These rigs were used to form containment barriers and structural walls for excavation support.