Program Aims To Use Dredged Material To Fight Erosion
NEW ORLEANS (AP) — River sediment is a nuisance and a need in Louisiana.
On one hand, the U.S. Army Corps of Engineers dredges tens of millions of cubic yards of the stuff out of local waterways every year in its effort to keep those waterways clear for ship traffic, a lifeblood of the state's and nation's economy.
Most of that sediment then gets dumped right back in the water: either in the Gulf of Mexico or in deeper parts of the same waterway, where the current is expected to carry it downstream and away from the dredged area. By law, the Corps is required to do the most cost-effective thing with the dredged material, which limits the options on its use.
On the other hand, sediment is serving a valuable purpose: helping to rebuild and reinforce Louisiana's retreating coastline and wetlands.
A centerpiece of the state's plan to fight coastal loss is the construction of two large sediment diversions, which, it is hoped, will help rebuild land in areas that have received too little sediment since the federal levee system was constructed and flooding eliminated.
In several smaller projects, dredges are being used to pull sediment from places like Lake Pontchartrain and pump it into the marsh, where it is used to create new land that will reduce the risk of storm surge and restore ecosystems.
A new pilot program is attempting to bring the two activities together. The Corps is soliciting projects aimed at using dredged material for "beneficial use," which is defined as a use that reduces storm damage, promotes public safety or recreation, bolsters aquatic ecosystems or reduces cost.
At present, only about 42 percent of dredged material is used for beneficial projects, said Sarah Bradley, of the Corps of Engineers. The rest is disposed of in the most cost-efficient way possible, she said.
Nationwide, 94 projects have been proposed for the pilot program, 13 of them in Louisiana. Florida submitted nine and Washington eight, according to information from the Corps. Ten projects from around the country will be selected in June and — once funding is allotted — executed, Bradley said.
"It's a classic win-win," said Bren Haase, head of planning and research for the state's Coastal Protection and Restoration Authority, which has partnered with local agencies on five of Louisiana's 13 proposals. "We have to get this stuff out of the navigation channels, and we have a tremendous need for this sediment."
The CPRA's five projects are along the Mississippi, Atchafalaya and Calcasieu rivers, all of which are among Louisiana's most heavily dredged waterways, Haase said. The projected costs for the five projects range between $24 million and $52 million, according to CPRA estimates.
Other programs in Louisiana have shown that using dredged material can be helpful, Haase said.
"We have demonstrated that it's a viable technique, that it's something that's needed," he said. "We would love to see this develop into a long-funded program."
Building land is a focus of the state's coastal restoration program because it is estimated that the state lost an area nearly the size of Delaware between 1932 and 2010. Marsh creation, often with dredged material, is a centerpiece of the state's plan to at least slow the rate of that loss over the next 50 years.
Using more of the sediment that's taken out of the water to facilitate navigation could provide a boost to the state's efforts in that regard, Haase said.
"It's got the potential to be a big deal," he said.
- by AP reporter, Faimon A. Roberts III