PLASTIC CUT-OFF WALLS / UNDERGROUND DAMS

Plastic Cut-Off Wall

by   Foundation Specialists, Inc. 

Definition of  “Plastic Cut-Off Wall.” 

A  ”Plastic cut-off wall”  is a deep-foundation technology, employed to form impervious, permanent, underground “diaphragm” (or  barrier), to “seal off” certain underground areas and prevent passage of fluids [generally water],through it. 

The use of the word “Plastic” is  to describe the very nature of the diaphragm, barrier or membrane created  with  this technology, in fact the “Plastic Cut-Off wall” is made of a mix of bentonite,  cement,  water and other components, proportioned in such a way to remain indefinitely plastic (and impervious) with time. 

The word “Cut-Off” is meant to define the specific purposes of this technology, i.e. to either stop the flow,  to “Dam”  the underground stream, or to surround   and seal-off  an area, to prevent  water inflow  and  water outflow from the encircled area.    For this technology, the medium employed to “Cut-Off”  is  the Plastic Wall, or  Plastic Diaphragm  that  has the effect of completely stopping the water flow at a chosen section of a river bed  underlaid  by [deep] alluvium, or sealing-off an area[tipically underlaid by alluvium], surrounding  it, with a cut-off wall along the entire perimeter.  

Applications of “plastic cut-off wall” 

Plastic Cut-off Walls are used to provide a totally impervious underground diaphragm from the base of cofferdams to the lower end of the alluvium strata. Plastic Cut-off Walls  are usually installed from the top of cofferdam, thus providing also an impervious core  to the cofferdam, in addition to sealing the areas below it. 

Plastic Cut-Off Walls are a very important medium for the protection of the environment, insofar as the bentonite-cement mix  also called  self-hardening mud, or cement stabilized bentonite mud,  is an extremely stable material, unaffected  by  the  leachates and  contaminants produced by landfills.and by Mines' tailings 

Plastic Cut-Off walls are used to construct  impervious barriers around old and new landfills to prevent leachates from contaminating the water table and the water streams  around the landfill locations and mine tailings.. For the purpose, the cut-off walls are installed to depths sufficient to eliminate the possibility of polluting streams and water table by escaping landfill leachates. 

UNDERGROUND DAMS

A very important application of Plastic Cut-Off Walls in areas with scarce rainfalls, shrinking water reservoirs, dwindling water tables, deep alluvium and large rivers’ catching basins, is to close the underground outflow of water within the alluvial river bed, by forming an underground continuous “dam” perpendicular to the river longitudinal axis, resembling a vertical gate inserted through the river bed to close the underground water outflow. 

Advantages of using  Plastic Cut-Off Walls. 

The advantages of using plastic cut-off walls as described above, are several,   self hardening Bentonite-Cement mud are extremely stable  chemically,  are not affected by polluted and aggressive underground water. 

By remaining indefinitely plastic in time, Plastic Cut-Off Walls can deform without cracks and fissures in response to the surrounding ground’s settlements, thus remaining as impervious as it was built, throughout time. 

Experienced Specialized Contractors can install Plastic Cut-Off Walls , totally impervious in any kind of alluvial formation, at a relatively fast pace. 

Foundation Specialists, Inc. [FS] has expertly and successfully designed and installed  Plastic Cut-Off Walls for  fortysix  years in the most diverse soil and hydro-geological conditions.