Soil-Bentonite Cutoff Walls
Soil-Bentonite Cutoff Walls |
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| Soil-Bentonite Cutoff walls are a
productive way to keep pond and lake dams from seeping. The cutoff
wall is excavated in a continuous manner under bentonite slurry.
The cutoff is keyed in most cases into an impervious stratum or bedrock.
Bentonite "filler cake" is developed on each wall of the trench, and
slurry enters any formational voids adjacent to the trench.
Impervious backfill is placed into the trench, displacing slurry to form
the completed cutoff. Backfill includes soil excavated from the
trench and/or from borrowed materials which are blended with slurry to
yield a homogeneous mixture with a consistency corresponding to a 3-6
inch clump. Native clay in the backfilled mixture increases its
density, but if not enough clay is present, Bentonite is added to the
mix.
Soil-Bentonite cutoff walls have been used for many years as permanent cutoffs through and below dams and as temporary cutoffs to minimize the flow of groundwater into large excavations. As containment protocol at hazardous and toxic waste sites, when leachate collection or extraction systems are provided as part of the remediation program, Soil-Bentonite Cutoff walls minimize both the inflow of groundwater into the leachate and the outward migration of leachate groundwater. Click on the images below to see a larger image.
Just a word about Bentonite. Not all bentonite is created equal. Usually, when buying over the counter, you will encounter a product which is actually sodium based bentonite. This product, although still bentonite, is usually used in salty or saline conditions. Although it is less expensive, it is not a good product to use when repairing lakes and ponds. Here at Farm and Ranch Construction, we use a calcium based product which chemists say is the product that was intended to do this type of work. This is the same product used in the oil drilling business. |
