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BENTONITE
J. P. Self and Associates only sells granular bentonite by the tractor trailer load, 45,000
lbs. minimum,unless local pick-up.
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Sodium bentonite
clay swells up to eighteen times its dry size when it becomes wet.
Expanded bentonite forms an impermeable gel seal which makes an
excellent pond sealant. Bentonite is environmentally safe and does
not affect the water, livestock, or wildlife. When properly
applied, it will not harm fish. For these qualities, bentonite also
makes an excellent liner for new pond construction.
When sealing a leaking pond to prevent water loss through seepage,
sodium bentonite can be applied directly to the soil in the pond
bottom or it can be sprinkled on the surface of the water and
allowed to settle to the bottom. There are three basic methods: the
blanket method, the mixed blanket method and the sprinkle method.
Sodium bentonite is easily applied. In the case of small ponds, it
can be applied with simple hand tools and for larger ponds, with
ordinary farm equipment.
INDEX
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The Blanket Method
The blanket method
is usually the most effective method for sealing leaking ponds with
bentonite. However, more care is required during it's
application. Pond Sealer, a mixture of powder and granular sodium
bentonite, is best suited for this method unless working in an
extremely windy area, in which case, we would recommended Granular
Seal.
The first step is to prepare the surface to be sealed. Remove all
rocks, trash, and vegetation, including trees and roots. Roots left
in the ground will decay over time, leaving the potential for future
leakage problems. Remove the top 4" - 6" of the soil from the pond
bottom. Fill any deep holes or crevices with a uniform mixture of
one part bentonite to five parts soil. Then smooth the area by
roller or drag.
Cover the area with the prescribed amount of sodium bentonite. It
is very important that the bentonite layer is even and that there
are no bare or thin spots. This will ensure complete coverage and a
water tight seal. After the bentonite has been spread as evenly as
possible, carefully replace the 4 to 6 inches of soil that was
removed earlier. While spreading the soil, be certain not to
disturb the bentonite layer, as this could leave bare spots which
could allow water loss to continue. If livestock will have access
to the pond, the cover coat must be thicker than 4 inches. In this
case, a top layer of gravel would be best to protect against
puncture by cattle hooves.
Finally, compact the pond bottom by rolling or tamping. Use care
when filling the pond. A gentle water flow is recommended to
prevent erosion of the soil and bentonite layers during this final
phase. It may take several days for the bentonite to reach the
point of full saturation and fill the voids in the underlying soil. |
Mixed
Blanket Method
Begin by preparing
the surface to be sealed. Remove all rocks, trash, and vegetation,
including trees and roots. Roots left in the ground will decay over
time, which leaves the potential for future leakage problems. If
the soil is dry, lightly moisten it, then plow, disc or till the
bottom of the pond 4" - 12" deep, then roll or drag the surface
until it is smooth. This initial plowing and blending of the soil
will assure consistency of the soil throughout the bottom of the
pond before the bentonite is mixed into it. When this is complete,
apply the prescribed amount of sodium bentonite. We recommend Pond
Sealer, a mixture of powder and granular sodium bentonite for this
application.
The bentonite can be spread by several different methods, however,
we recommend a fertilizer or seed spreader to ensure even
spreading. Mix the bentonite with the top 4" - 12" of soil by
discing, tilling, or by hand raking. It is extremely important for
the bentonite to be mixed uniformly with the soil. To ensure that
no bare or thin spots will be left, we recommend multiple passes
over the area. If livestock will have access to the pond, the cover
coat must be thicker than 4 inches.
Finally, compact the pond bottom by rolling or tamping. Use care
when filling the pond. A gentle water flow is recommended to
prevent erosion of the soil/bentonite layer during this final
phase. It may take several days for the bentonite to reach the
point of full saturation and fill the voids in the soil. |
The
Sprinkle Method
The sprinkle method
is recommended only when it is not feasible to drain the existing
pond or in cases of isolated leaks when a spot treatment may be a
possible alternative. This method is less effective than the other
two methods for several reasons: Uniform and accurate placement of
the bentonite is difficult; the pond bottom may include debris such
as trash, vegetation, logs, rocks, etc., which may prevent
sufficient coverage. If the bottom of the pond can be cleared, this
method has greater chances of providing a good seal.
The granular
grade of bentonite, “Granular Seal," is best suited for this method
of sealing leaking ponds. The granular bentonite should be used
when using the sprinkle method because the particles are large
enough to sink to the bottom, while finer particles cloud the water
and stay in suspension. Begin by simply sprinkling the prescribed
amount of granular bentonite (Granular Seal) on the water surface
and allow it to fall into place. The granular bentonite particles
will sink to the bottom of the pond or be drawn into porous areas
where they will swell and reduce the seepage rate. |
Testing
Your Soil
The purpose of this test is to find out the type of soil at the
bottom the pond, and thus, to determine the amount of sodium
bentonite needed to seal the pond.
Perforate the bottom of a can, a pail, or a drum and put two inches
of gravel in the bottom. Take a sample of soil from the area to be
treated. Be sure that the sample used is representative of the
entire pond bottom. Cover the gravel with 6" of the sampled soil.
Tamp the soil, then elevate the container so that the bottom is open
to drain before filling the container with water. Once the
container is filled with water, observe the results. Based on the
result, repeat the procedure using the chosen application method and
the recommended bentonite dosage to seal the pond. If the test
doesn't seal off the leak as desired, repeat the procedure with a
slight increase of bentonite dosage on each test until the leak
stops.
Keep in mind that an additional 25% to 50% more bentonite could be
needed on large scale projects to allow for greater water depths
(water pressure) in the pond. |
Application
Rate
Soil type and
pond size are the key factors in determining the amount of sodium
bentonite required to seal ponds. Normally, coarse soils require
more bentonite.
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Soil Type |
Application Rate
(Pounds per square foot) |
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Clay |
1.0 -
1.5 |
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Sandy
Silt |
2.0 -
2.5 |
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Silty
Sand |
2.5 -
3.0 |
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Clean
Sand |
3.5 -
4.0 |
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Rock
or Gravel |
4.0 -
5.0 |
If the size
of pond is known and the type of soil is available, the chart above
gives a good estimate on the amount of bentonite needed to seal
pond. Performing a soil test is another good way to estimate. You can perform the
soil test yourself or contact your local conservation service for a
free test. |
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Also see
our Drilling Fluids
webpage |
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J. P. Self and Associates only sells granular bentonite by the tractor trailer load, 45,000
lbs. minimum ,unless local pick-up.
VISA and MASTERCARD accepted |
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Visits
since March 18, 2006
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