FROM New Orleans Advocate, 12/15/13 Share
PORT FOURCHON — A long-coveted deposit of sand from a former Mississippi River delta miles off the Louisiana shoreline is being used to help rebuild part of the state’s eroding coastline.
Known as Ship Shoal, this deposit of good sand is being mined for the first time to help build six miles of beach and dune along the Caminada Headland that fronts an area of Lafourche Parish just south of Port Fourchon.
Ship Shoal has long been recognized as a good source of material for building barrier islands or other beach areas. The problem has been its distance from shore and the associated cost of moving the material. In addition, there has been the issue of getting federal permission to dredge material from the Outer Continental Shelf, which was addressed when the Department of Interior’s Bureau of Ocean Energy and Management agreed to the dredging last year.
As for the cost, Garret Graves, the governor’s executive assistant for coastal activities, said lessons learned from building sand berms after the 2010 Deepwater Horizon disaster helped make the process of transporting the material more efficient. In the 2010 berm work, sediment from the Mississippi River was put on barges and then dumped near the project site to be dredged and pumped into place.
The Caminada Headland project will build about 300 acres of beach and dune along this six-mile stretch of first-line protection for the port and Lafourche Parish. The $70 million project is being paid for with a combination of the state and parish shares of the Coastal Impact Assistance Program and $30 million in 2008 state surplus money.
“A lot of partners worked on this to make the project a reality,” Graves said, citing everyone from private landowners in the area to government agencies.
Windell Curole, director of the Lafourche Levee District, said the Caminada Headland has always been important in slowing down storm surge, not just for the port but also for the levees and communities of Lafourche Parish. All coastal communities need three things, he said: a good economy, infrastructure and environment.
“These types of project help all three,” Curole said.
Weeks Marine is dredging the sediment, loading the material onto barges and then moving it to a site west of the work area. From there, the sediment is pumped into a pipe that takes it to where it is poured onto the beach to make it both higher and wider.
Gary Johnson, project manager with Weeks Marine, said that, weather permitting, about eight or nine of these barges can be unloaded during a 24-hour work cycle. Each of the barges can carry about 3,300 cubic yards of material, that takes about an hour and a half to unload.
“We have put well over a million cubic yards on the beach,” Johnson said.
A total of 3.3 million cubic yards of material is expected to be used for the project, which started in August and is expected to be completed by May or June.
Johnson said the material coming from Ship Shoal is much better quality than the materials used on other projects because it stays put and builds up faster than muddier material, which tends to need more managing with containment levees.
“It’s kind of nice to be working with some good material,” he said with a smile.
Brad Miller, project manager with the state Coastal Protection and Restoration Authority, said that when the distance between the sediment source and where it needs to be placed gets to be 20 miles or more, it’s more cost-efficient to barge it.
“It’s a really good fit for a barrier island because it used to be a barrier island 8,000 years ago,” Miller said about Ship Shoal.
Graves said it’s more cost-effective to use dredges to move the material to shore instead of doing it all by pipeline because the sediment slurry can be moved only so far without the addition of one or more booster pumps. However, he said, as planning continues for other restoration projects, the hope is that the pipeline method will become more efficient and can be used more often. It’s not that pipelines haven’t been used to move sediment to build land in the past, he said, but the volumes of material and the distance they need to be transported are a challenge.
“There is massive volumes of material out there,” Graves said about Ship Shoal.
It’s estimated that there are about one billion cubic yards of material in that area, although only about 20 percent is currently available for restoration purposes because of restrictions on dredging around oil and gas infrastructure like pipelines.
Making pipelines more efficient, and possibly reworking some pipeline routes in the future, will help make more of that material readily available for restoration work.
The work is particularly important in the Barataria-Terrebonne basin, where there isn’t much access to river sediment, Graves said.
“The key to this area being restored and made resilient is long-distance conveyance (of sediment). It just is,” he said.