The mixing auger is moved up and down to assist in removal of contaminated vapors. The soils are mixed with a single-blade auger or with a combination of augers ranging in diameter from 3 to 12 feet. Mixing is likely to be effectively applied to depths of 40 feet, although commercial vendors have worked at depths as great as 100 feet with the smaller diameter augers. Enhancements such as injection of heated air in combination with vapor extraction, injection of oxidants, or injection of grout are utilized based on the specific system selected for a particular site. Illustration of the continuously mixed subsurface soil reactor concept.
Rigs can have single or multiple shafts.
In situ soil mixing, also known as deep soil mixing, shallow soil mixing, soil mixing wall, auger mixing, etc., has been used for a number of years in the construction industry. Cement grout is typically mixed with soil to create a foundation system or barrier wall. The field demonstration was conducted at the X-231B Unit in June 1992. Replicated tests of in situ vapor stripping, peroxidation, and solidification were made in soil columns measuring 10 ft in diameter and 15-22 ft deep. The X-231B Unit was used from 1976 to 1983 as a land disposal site for waste oils and solvents.