Small dredges for shallow water work smarter. Down in South LaFourche, Windell Curole, takes his levees seriously. Terrebonne and Barataria basins experience the highest land loss rates of the coast, and are ground zero for historic oil and gas damages. Even before we consider the subsidence that the receding delta is experiencing, the LaRose to Golden Meadow ring levee has become more and more exposed to the Gulf of Mexico over time. Windell Curole, General Manager of hte South LaFourche Levee Dist right, looks at the newest land in LaFourche Parish. by Jimmy Delery “marsh apron” created to protect the levee. Bing Maps Imagery A son of fishermen and a biologist, Windell knows how wetlands can protect from storm surges, and particularly protect levees. As a manager, he is ever looking for ways to work smarter, and do more with less. To protect the levee from wear and tear of the tide, Windell needs to build a “marsh apron” around the edge, or toe of the levee. Newer tools are allowing marshes to be built faster for less money, with small dredges that cost less to mobilize and to operate. Consider that1) a lot of the cost of marsh restoration is paying for mobilization and de-mobilization of machinery that was never designed to work in shallow water. Existing dredges are usually designed for the deep draft of rivers, and so getting them into shallow water and marsh environments requires wheelwashing to (at least) an 8 foot draft, and hiring cranes to move heavy machinery into place.(photo: large dredge in Empire ship channel moving sand from the Mississippi River to Scofield Island, GRN)Large dredges for moving sand from the river to barrier islands (like the ones we saw with SCB) have to operate in large channels like the Empire Waterway, and require multiple additional vehicles to get them where they need to be.Large dredges also cost more to fuel and to staff. Small dredges would have less operational overhead, critical for parish budgets and parish finances. This particular dredge, called an “amphibex”, lowers the cost again–not only is it able to motor about in 16 inches of draft, but it can also “walk” using it’s jack-up legs and crane arm. Small Dredge moving itself from water to land by Jimmy Delery2) Another chunk of the cost spent making the containment berm for sediment slurry. Windell has repeatedly advocated that the Department of Natural Resources and Army Corps of Engineers look at beneficial use marsh creation without creating containment berms, to save cost. And to make marsh without containment, Windell is targeting “broken marsh” that acts as its own containment, and not in open water, where tidal energies keep the sediment from settling. broken marshes outside of the South LaFourche ring levee. Karen Westphal at Audubon has a super-small dredge (“John James”) for working at Rainey Refuge. They made containment from binding felled tallow trees into 5-gallon buckets and anchoring them in the marsh –like the christmas tree project. The christmas tree project has been less exciting than people think, but it’s interesting to think of it as containment without a source of sediment. Marrying the benefits of Windells’ small dredges to a christmas tree project would be matching a containment project without sediment with a sediment delivery project without containment.cutterhead –the business end of the dredge, attached to two pump lines (GRN) The outfall pipe by Jimmy Delery But the real lesson is that every coastal situation is different, and every place on the Louisiana coast should be restored in the most efficient and effective manner possible. The only way Louisiana is going to get close to $50 billion for restoration is to show that we can spend the dirt with some intelligence. Marsh, months after sediment is placed. Scott Eustis is GRN’s Coastal Wetland Specialist
