They may rip during application.
l
Some materials are degraded by sunlight.
l
The successful use of sediment covers to
rooted aquatic
tion is directly related to the technique of application, as well as to the
Mater-ials that
used as sediment covers in
selection of materials.
reservoirs and lakes include polyethylene, polyvinyl chloride, polypropylene,
Some of these materials are
nylon, fiberglass, synthetic rubber, and burlap.
highly unsuitable; some are very effective.
The cover should be applied directly on the sediment surface without
"ballooning" or bare spots.
In many cases, especially with soft, muck sedi-
ments, this will be very difficult' since stakes may not hold, and bricks or
other weights will anchor only the site at which they are placed.
When covers
are installed over heavy vegetation, as is often the case, there will be great
difficulty in getting the material flush with the sediment surface.
Several steps, if included, can help ensure a successful installation.
Use SCUBA to survey the reservoir sediments.
Locate and mark obstructions
such as stumps or boulders.
Test the sediments for their ability to hold a
If the sediments are highly fluid or muck-like, then either very long
stake.
Stakes
If the sediments are unsat-
cannot be used in hard sediments such as gravel.
isfactory for steel stakes, examine the possibility of sewing link chain into
Obviously, some sediment covering materials cannot be
the edge of the fabric.
used for this type of holdfast.
The most commonly used stake has been made of
or
steel
Sharpen the other end to
wire.
Bend the stake so that one end is L-shaped.
The length of the stake
ease the penetration of the fabric and the mud.
needed will vary directly with the degree of softness of the mud.
In nearly every situation, SCUBA will be needed for an effective appli-
cation.
A successful procedure in many applications has been to build a reel
in the stern of a boat.
Most of the materials are sold in rolls of
to
Two applicators, one on each side of the boat,
width and
length.
unroll the screen from the reel.
The screen is pressed and smoothed to the
Stakes, bricks, or other fasteners will be
sediment surface and fastened.
needed every 1 to 2 m, depending upon the density of the vegetation. In
deeper waters, divers will be needed to apply the covers.
Be certain that a
backup, fully suited diver is prepared to assist the applicators.
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