Isle de Jean Charles project

BioHaven® Floating Breakwater for
Coastal Protection and Restoration
Project Location: Isle de Jean Charles, Point Aux Chene, Louisiana
Overview
On September 22-24, 2011 Martin Ecosystems installed 1560 linear feet of BioHaven® Floating Breakwaters (BFB) near
the Isle de Jean Charles Road in Point Aux Chenes, Louisiana for Terrebonne Parish Coastal Zone Management. Coastal
Conservation Association (CCA) of Louisiana spearheaded the project with the assistance of Terrebonne Parish
Government, Shell Oil Company, Entergy, America’s Wetland Foundation, and many local volunteers. Four sites were
chosen along the Isle de Charles Road. The
vegetation planted was Smooth Cordgrass (Spartina
alterniflora) and Seashore Paspalum (Paspalum
vaginatum).
The Primary goal of this project is to protect
existing sections of marsh from further erosion.
Secondary goals are:
1. Sediment Accretion between Islands and natural
marsh
2. Establishment of new vegetation between Islands
and natural marsh
3. Attachment of roots into the bottom or the
“rooting in” of Islands
Installation Data
Location
Point Aux Chene, Louisiana
System Type
BioHaven® Floating Breakwater
Total FTW Size
1560 Linear Feet
Installation Date
September 22-24, 2011
Water Body Depth
16”-3’ Range of Water Depths
Anchoring
Manta Ray (MR-88) Anchors Driven 20’ Deep
Vegetation
Smooth Cordgrass (Spartina alterniflora) and
Seashore Paspalum (Paspalum vaginatum)
5819 McCann Drive Baton Rouge, LA 70809 (225)292-6750 phone
www.martinecosystems.com
© 2013 Martin Ecosystems, LLC. All rights reserved.
Results
In less than one year the vegetation has completely covered the BFBs with the Smooth Cordgrass measuring between
4’ and 5’ tall. Roots have also begun to grow through the BFBs and are approximately 1’ to 1 1/2’ below.
Wildlife and aquatic life are seen above
and below the BFBs. They are providing
protection and a riparian edge for birds,
fish, crabs, and other forms of waterfowl.
Photo taken July 27, 2012 by Martin Ecosystems
Photo taken July 29, 2012 by Martin Ecosystems
The vegetation is consistently more green than the
natural marsh nearby.
Photo taken July 27, 2012 by Martin Ecosystems
5819 McCann Drive Baton Rouge, LA 70809 (225)292-6750 phone
www.martinecosystems.com
© 2013 Martin Ecosystems, LLC. All rights reserved.
The BFBs are also providing
protection to the Isle de Jean
Charles Road, one of the
Primary Project Goals,
through wave attenuation.
Photo taken January 26, 2012 by Martin Ecosystems
Conclusions
We are extremely pleased with the project to date. The vegetation is healthy and has nearly completely covered the
matrix of the Islands. New shoots and new seeds are abundant signifying further growth. The root mass below is
growing as well. The Islands are now too heavy to lift out of the water due to the biomass accumulating above and
below the Island matrix , so we are unable to take new photos of the roots and must feel for them instead. One can
imagine with the growth on top, that
there is growth underneath. There is
no evidence of disease or insect
damage.
The 4 anchor sites that popped were
repaired and have held without
problem. We believe the cable was
crimped to tight and caused the cable
to pop at these 4 points. All of the
Islands remain in place.
The Islands are beginning to look
more and more like natural marsh
creating a Riparian edge. This has
become attractive to a variety of
species -blue crabs, small fish, and
birds have been seen in and on the
Islands. They can’t tell the
difference---Can you?
Photo taken July 27, 2012 by Martin Ecosystems
5819 McCann Drive Baton Rouge, LA 70809 (225)292-6750 phone
www.martinecosystems.com
© 2013 Martin Ecosystems, LLC. All rights reserved.
Post Hurricane Isaac Update
On September 2, 2012 nearly one year after the installation of this project Martin Ecosystems went to evaluate the
BioHaven® Floating Breakwaters five days after Hurricane Isaac made landfall. Hurricane Isaac sat over South
Terrebonne for nearly 24 hours sometimes with 90 mile per hour winds. Overall, the BFBs remained intact and in place.
There are 16 out of 195 (9%) BFB modules that have not been recovered. Some of the BFBs did flip over and anchors
did pull out of the ground.
Overall we are pleased with how the Islands
performed during and following Hurricane
Isaac. Over 90% of the Islands remain in place.
The Island matrix also remained intact
without showing signs of damage. The
vegetation, although windblown appears to
be healthy and we see no reason for concern
regarding continued growth. Anchoring was
the weak link of the project. Initially, we used
small Manta Ray marine earth anchors, the
MR-88 with a 200 to 800 pound hold strength
in peat and organic soils to secure the BFBs in
place. Some of these anchors were pulled out
of the ground and did not hold against the
pressure of rising water. We also used stainless
steel cable at the anchor points which
popped at the mud line on a few anchors.
Our plan to rectify this issue is to reanchor the BFBs using a Helical anchor.
The anchor has a much greater hold
strength of 3000 to 8000 pounds in
peat and organic soils. We have also
designed the anchor points to include
chain at the anchor points instead of
stainless steel cable to eliminate the
corrosion at the mud line.
5819 McCann Drive Baton Rouge, LA 70809 (225)292-6750 phone
www.martinecosystems.com
© 2013 Martin Ecosystems, LLC. All rights reserved.
5819 McCann Drive Baton Rouge, LA 70809 (225)292-6750 phone
www.martinecosystems.com
© 2013 Martin Ecosystems, LLC. All rights reserved.