Figure 4. Frozen perched groundwater seeps at Allegan County, MI, on the eastern shore of Lake Michigan. Bluff dewatering
measures will be implemented to reduce coastal bluff instability caused by perched groundwater effects
to bluff movements, and that slumps
hurricanes periodically impact the
and dune grass plantings (Dune
are most prevalent when perched
southern shores of Long Island.
LadderTM, Figure 5). The con-
groundwater levels are high regard-
These storms produce tides and
cave-shaped lattice structure will be
less of wave activity or lake level. In
waves which cause dune erosion.
located in the seaward face of the
partnership with the WMU and the
The only existing form of beach ero-
dune. Vegetation will be planted
State of Michigan, bluff dewatering
sion control at Gilgo Beach is the
between the plank members. The
technology will be evaluated at this
placement of sand material removed
second method of dune stabilization
location to reduce or eliminate
from Fire Island Inlet every 2 to 3
to be investigated will be an expand-
coastal bluff instability. If proven
years. An engineered berm with an
able three-dimensional sand confine-
functional, the dewatering of shore-
elevation of approximately 3.6 m
ment grid system adapted from use
line bluffs will be an inexpensive,
above mean sea level, provides pro-
in inland flood control (Rapidly
noninvasive, and effective method of
tection to a roadway located immedi-
Deployed Flood WallTM (RDFW),
erosion control. District POCs:
ately landward of the beach. Shore
Figure 6). The geosynthetic grid
James P. Selegean (James.P.
protection structures such as timber
cells will provide a protective frame-
Selegean@1re02.usace.army.mil)
groins and bulkheads have been
work for the engineered dune, and
and Scott J. Thieme (Scott.J.
destroyed by wave action.
dune grass will be planted within the
Thieme@1re02.usace.army.mil).
cells of the structure. Dune restora-
At Gilgo Beach, it is anticipated
tion via use of recycled glass com-
U.S. Army Engineer District,
that the State of New York, Depart-
bined with vegetative plantings may
New York, Babylon, NY (optional).
ment of Environmental Conservation,
also be considered for demonstra-
Gilgo Beach, located in the commu-
will serve as a cooperating partner.
tion at this site. District POCs: Odile
nity of Babylon on Jones Island, NY,
Two methods of open-coast dune
Accilien (Odile.Accilien@nan02.
is a 4.8-km-long portion of a barrier
restoration and stabilization are pro-
usace.army.mil) and Lynn M.
beach located on the south shore of
posed for investigation: The first is a
Bocamazo (Lynn.M.Bocamazo@
Long Island between Jones and Fire
combination of a timber or recycled
nan02.usace.army.mil).
Island Inlets. Northeasters and
plastic horizontal lattice structure
5
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