Slurry Trench

Synonyms

Cut-off wall

Definition

A slurry trench is a long narrow vertical excavation, progressively filled with slurry as it is excavated, typically used in the construction of diaphragm walls in civil engineering or cut-off walls (vertical barriers) for the inhibition of groundwater flow or control of contaminant transport.

Construction

Slurry trench construction is often started with a set of guide walls, which are constructed on the ground surface to outline the desired slurry trench and guide the excavation machinery. The slurry, generally a thick colloidal mixture of bentonite (an absorbent aluminum phyllosilicate clay consisting mostly of montmorillonite) and water, typically consisting of 5% solid and 95% water by weight, is mixed for hydration before emplacement. Trenches shallower than 25 m may be excavated using a backhoe whereas deeper trenches are usually excavated by a clamshell or dragline. The typical procedure for excavation of slurry...