Dredging v. Diversions

Worth Creech sent around this very well done article last night concerning sediment utilization in coastal Louisiana. We generally try to stay out of this fight — diversion versus dredging — since it seems this truly is an “all of the above” choice. However, I would have to agree that dredging at times seems to be the more practical and tangible approach when compared to its popular and fashionable but largely unproven alternative, engineered diversions. In fact, I would have to agree with this gentleman quoted in the article:

Cooper worries that his 10 grandsons will be senile by the time all the studies are completed. “I know where the sediment is,” he says, lighting a cigar and shouting over the wind and engine noise. “I can show them where it’s at. We’ve got shit-tons of sediment just laying around doing nothing while they study this and study that. They should have 10 dredges out there building land around the clock.”

But the needs are so vast it will surely require a mix of approaches, diffuse and long-term, such as diversions, as well as intense and highly targeted, which is dredging.

 

Baton Rouge, LA - 9/14/2015 - Sediment sprays out from the end of the dredge pipe in the middle of the Mississippi River. The Dredge Jadwin moves sediment from the designated shipping channel into the middle of the Mississippi River, where the natural current will continue to push it downward toward the Gulf of Mexico. The Jadwin, a 1933-vintage dustpan dredge, has seen 75 years of service along the Mississippi River. The boat is an integral part of the US Army Corps of Engineers' Mat Sinking Unit. The Mat Sinking Unit (MSU) is the only one of its kind in the world and performs one of the most important jobs in the Corps’ river stabilization program. The crew places articulated concrete mats along the river banks of the Mississippi River to control erosion. The MSU is responsible for maintaining over 800 miles of navigable channels and harbors to ensure safe, cost-effective, dependable, and environmentally sustainable transportation within the United States’ inland waterways.

Baton Rouge, LA – 9/14/2015 – Sediment sprays out from the end of the dredge pipe in the middle of the Mississippi River.
The Dredge Jadwin moves sediment from the designated shipping channel into the middle of the Mississippi River, where the natural current will continue to push it downward toward the Gulf of Mexico. -Photos by William Widmer for Al Jazeera America

Full Text can found be at Al-Jazeera here

By Richard Grant in Carville, Louisiana, Photos by William Widmer for Al Jazeera America, Published on Sunday, November 1, 2015

A hulking old engineering boat moves slowly up the mile-wide Mississippi River. The Dredge Jadwin operates like a gigantic vacuum cleaner, sucking up sediment from the riverbed and spewing it out to the side through a long pipe. “For us, sediment it’s basically a problem,” says Randy Stockton, master of the Jadwin, built in 1933. “It clogs up the shipping channel. It silts in the river ports. The more of it there is, the harder we work to move it. But down on the coast this stuff is like gold dust.”

These tiny particles of sand and silt, some of which have washed all the way down the river from North Dakota and Minnesota, are at the center of a heated debate in south Louisiana. According to most scientists and environmentalists, sediment from the Mississippi is the best hope of saving Louisiana’s disappearing coast. They support projects, now in the planning stages, that will divert river water into the eroding coastal marshes, in the hope that sediment will settle, accumulate and form land.

The opponents of these proposed diversion projects, many of whom work in Louisiana’s $2.6 billion seafood industry, are also concerned about coastal land loss. But freshwater from the Mississippi, they say, will destroy the shrimp, oysters and commercial fish species that live in the brackish water of the marshland. Instead, they are calling for dredges like the Jadwin to suck up existing underwater sediment and use it to build land. “Dredge don’t divert” is their rallying cry, plastered on bumpers, placards and T-shirts. Indeed, dredging is a proven, if expensive, method that is already taking place in many areas.

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