Munyon Island, Florida
Coastal Systems International Inc. designed the
docking facility planned for the John D.
MacArthur Beach State Park on Munyon Island
in Palm Beach County. A preliminary design
report was prepared for Palm Beach County based on
hydrographic and marine resource surveys conducted by
Coastal Systems. Three alternatives including different
dock layouts and wave attenuation structures were
evaluated based on construction budgets. Coastal Systems
was then retained by DEP (Department of Environmental
Protection) Parks to complete the final engineering design
and prepare construction documents for the selected option.
The final design consisted of a pile-crib breakwater for
wave attenuation attached to the shore on the west side of
the island with a 20-slip floating dock facility. The pile crib
breakwater serves three purposes; 1) approach pier for
public access to the floating docks, and 2) wave attenuation
for boat wakes and 3) habitat for marine resources.
A statistical analysis was conducted to provide wave
characteristics (height, period) for the design of breakwater
with respect to the selected 25-year coastal storm return
period. Wave forces were calculated for the structural
design of the piles, caps, and slabs that support the pier
structure. Wave transmission studies were also conducted to
specify characteristics and geometry of the rock to be
placed in the crib for optimum wave attenuation for the
docking facility. A geotechnical investigation was
conducted for the design of the pile-supported structures.
Designs and details for structural precast pile, caps, and
slabs were developed due to the remote island construction.
Fiberglass grating was specified to span concrete slabs
along the pile-crib structure to provide a composite design,
to relieve uplift pressures from wave action during coastal
storms, and to provide light penetration for sea grass. The
design provided ADA structures, as well as a slip for
landing craft to transport maintenance vehicles on and off
of the island.
Coastal Systems has been retained by the Florida DEP to
perform pre-construction seagrass surveys and to perform
monitoring and reporting of the adjacent seagrass beds for
five years as required by the environmental permits issued
by the South Florida Water Management District and the
U.S. Army Corps of Engineers.