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Erosion control, bank stabilization, wetland restoration, water quality improvement,
and habitat enhancement. Serving Brainerd Lakes & Crosslake Areas
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Lakeshore Restoration
 Protect and beautify your
lakeshore. |
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RIPRAP SHORE AND STREAMBANK
PROTECTION Check with local
government to see if a permit is needed.
1. The riprap shall consist of natural rock only,
measuring 12" diameter or larger.
2. The riprap shall conform to the
natural alignment of the shore or streambank.
3. The minimum finished
slope shall be no steeper than 3 feet horizontal to 1 foot vertical (3:1).
4. No materials shall be placed more than 5 feet waterward of the OHW, nor
obstruct the flow of water.
5. The site is not along Lake Superior, on a
designated trout stream, or a posted fish spawning area.
DEFINITION
Riprap is defined as coarse stones, boulders, or
rock, loosely laid against an existing bank or shore for the purpose of
preventing or controlling erosion. Only 12" diameter or larger natural rock
riprap protection may be installed without a permit. The size of natural rock
will reduce movement by natural forces. Riprap is generally placed to prevent
erosion by wave action and currents; it is also useful in preventing burrowing
animals (muskrat, beaver, etc.). Riprap does not prevent ice heaves. |
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LOCATION
The placement of riprap should be limited to the
area subjected to erosion. This information sheet outlines guidelines for the
placement of natural rock riprap without a permit. The installation of other
types of riprap will require a permit.
Riprap shall be attempted only where
site soils are capable of supporting riprap. Such soils may include various
combinations of sand, silt and clay. Soils such as peat and muck are not
capable of supporting riprap.
PLACEMENT
Dumped stone is the most flexible and will adjust
itself to uneven bank settlement. In most cases, dumped stone is also the least
costly. Hand-placed riprap should be roughly square or rectangular to
facilitate placement by hand or derrick. Hand-placed riprap is easily disrupted
by minor settling. |
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CONSTRUCTION
Riprap shall be installed with a minimum finished
slope of 3:1. No riprap or filter materials shall be placed more than 5 feet
waterward of the 0HW. A severely eroding bank may require filling in with a
greater depth of natural rock before a stable slope may be achieved. Gently
sloping banks are more stable for riprap and result in fewer failures. The
extent of riprap into the water should be minimized since flow and wave action
can cause stability problems.
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A transitional layer of gravel, small stone, or fabric shall be placed between the fine
material of an embankment and the riprap materials, The purposes of the filter
are to:
(1) prevent fine embankment material from being pulled through the
riprap materials
(2) distribute the weight of the overlying riprap to prevent settlement, and
(3) to provide relief to hydrostatic pressures inside the embankment.
MAINTENANCE REQUIREMENTS All riprap requires
maintenance. Proper filter blanket thickness, rock size, placement, and slope
will prevent frequent maintenance. All riprap, however, will experience some
displacement. The desired slope, thickness and rock surface should be restored
when needed. All maintenance should be done in conformance with the above
mentioned criteria.
Protect your shoreline using natural materials such
as boulders and plantings. We service lakeshores throughout the Brainerd Lakes
and Crow Wing County areas. |
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©
Copyright 2012
All Rights Reserved
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