ABSTRACT
The Convoluted Path to Restoration of Whiskey Island, a.k.a. the NRDA Caillou Lake
Headlands Beach and Dune Restoration Project (TE-100)
Session Topic: NRDA Projects, Ecosystem Restoration, Barrier Islands
Michael Poff1, Gregory Grandy1, Jon C. Staiger1, Travis Byland2, and Devyani Kar2
1
Coastal Engineering Consultants, Inc., Baton Rouge, Louisiana and Naples, Florida, USA
2
Louisiana Coastal Protection and Restoration Authority, Baton Rouge, Louisiana, USA
Whiskey Island is the middle island of the three extant remnants of Isle Derniere (Last Island), a
once-inhabited Terrebonne Bay barrier island devastated by an 1856 hurricane. Stabilization and
restoration of Whiskey Island was selected for the Terrebonne Basin Barrier Shoreline
Restoration project (TBBSR), authorized by the Water Resources Development Act of 2007.
The planning and alternatives evaluation described in the TBBSR Feasibility Study laid the
foundation for the current Project.
The Project proposes to restore the beach, construct a dune, and construct a marsh platform. The
beach/dune feature will complement the beach previously constructed in front of the mangrove
wetlands on the eastern half of the island. The marsh feature will complement the marsh
previously constructed between the mangrove wetlands on the eastern half of the island.
Restoration of the geomorphic and ecological form and function of Whiskey Island is considered
a priority because Whiskey Island cannot roll back on itself in response to storm overwash. The
tidal channel behind it has sufficient flow to prevent accumulation of overwashed sediment. As
the island thins, both the two mangrove wetlands and restored marsh between them become more
susceptible to storm damage and loss from erosion. To combat this, and avoid impacting the
wetlands, necessitates a restoration design that enlarges the beach Gulf-ward, rather than over the
existing upland; requiring more sediment, but protecting critical habitats.
A significant challenge during Project design involved cultural resources questions that arose
from analysis of the magnetometer surveys of the Ship Shoal Borrow Area and proposed
conveyance corridor to Whiskey Island. In both cases, avoidance zones were created and
alignments shifted to protect the possible targets from damage. A TBBSR cultural resources
survey found several potential targets at Whiskey Island. A follow-up Phase II investigation
cleared them. Another design challenge arose from the soft nature of the soils behind Whiskey
Island. Failures of in situ sediment marsh containment dikes at similar projects prompted
additional geotechnical investigation and increased safety factor concerns in dike design to
ensure adequate side slope and base dimensions. Further, geotextile mat foundation support was
incorporated in the containment dike design.
Presenting author: Michael T. Poff, P.E., Vice President of Engineering, Coastal Engineering
Consultants, Inc.; 3106 S. Horseshoe Drive, Naples, FL 34104; phone 239.643.2324;
mpoff@cecifl.com. Poff has over 25 years of experience in designing and implementing coastal
protection and restoration projects in Louisiana and Florida. His expertise also extends to coastal
process analyses, model analysis and interpretation, project comparative cost/benefit analyses,
and ecosystem valuation analyses. He has assembled a dedicated team of professionals to
support these efforts.
Corresponding author: Jon C. Staiger, Ph.D., Coastal Engineering Consultants, Inc.; 5745 Essen
Lane, Suite 200, Baton Rouge, LA 70810; phone 225.706.5642; jstaiger@ceci-la.com.