Environmental Engineering Reference
In-Depth Information
FIGURE 3.9
Slurry wall construction mixing constituents. (Reproduced with permission from Geo-Con,
Geo-Solutions Inc.)
composite is formed along the sides. Finally soil/bentonite backfill is placed
in the trench (Geo-Solutions Inc.). The slurry wall construction process is
time consuming and is more expensive than sheet piling.
3.3.2 Injection Techniques
Injection methods do not involve excavation and, therefore, have consid-
erable potential to minimize health and safety issues (Geo-Solutions Inc.).
However, the requirement of special equipment incurs higher operating and
maintenance costs than conventional emplacement techniques. They also
require especially skilled personnel to implement this technology on site.
3.3.2.1 Hydraulic Fracturing
With this technology a series of wells are installed along the length of the
proposed barrier. A controlled vertical fracture is created in the wells and an
iron/gel mixture is injected into the well as a reactive barrier. In the case of
an impermeable barrier installation, a soil/bentonite slurry or soil/cement
or composite slurry is injected. The gel is used to suspend and transport
the iron filings into the subsurface. This is a promising technique for the
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