Slurry trench cut-off walls provide barriers to the movement of gas and harmful liquids from contaminated sites or refuse dumps. They can also be used to temporarily control groundwater to facilitate excavation and construction.
Slurry walls are usually constructed using tracked hydraulic diggers for depths up to 15 metres, or crane-based rope-operated grabs for greater depths, subject to ground conditions.
The slurry mixing station comprises bulk powder storage silos for the component materials, mixers, wet storage silos, tanks and pumps. The bentonite powder is mixed with water and pumped to storage silos where it is allowed to fully hydrate.
Where a greater resistance to the movement of gas is required, a High Density Polyethylene (HDPE) geomembrane sheet with a proprietary jointing system can be incorporated into the cut-off wall.
The HDPE geomembrane sheets arrive on-site pre-measured, and with interlocking joints welded to the membrane. These sheets are fixed to frames and lowered into the trench through the slurry. The frames are released, and detached from the membrane when a suitable length has been installed.