Low Permeability Cut-Off Walls

Low permeability cut-off walls or diversions are installed below ground. They are used to contain, capture, or redirect groundwater flow in the vicinity of a contaminated site. The types of barriers are soil-bentonite slurry walls, cement-bentonite slurry walls, grouted barriers, and sheet piling cut-offs.

A slurry wall is the most common and least costly technique. The walls are constructed in a vertical trench. Soil bentonite and cement bentonite are amongst the types of materials used to backfill the slurry trench. Grouting occurs when a particular fluid is injected into a soil mass to reduce water flow and strengthen the formation. Sheet piling cut-offs use wood, steel, or precast concrete.

Barrier technologies may be used in advance of other remedial activities. The use of cut-off walls to contain groundwater contamination close to the source, for example, can reduce drastically the pump-and-treat groundwater cleanup time by cutting pumping needs by as much as 90%.


This flowchart illustrates all possible stages of the remediation process and is fully interactive; click on each process box for a detailed description...