Proposed parish pipeline provides promise

Advocate leads area panel for disabled
May 2, 2011
Terrebonne readies for backwater flooding
May 4, 2011
Advocate leads area panel for disabled
May 2, 2011
Terrebonne readies for backwater flooding
May 4, 2011

Most Americans have no idea of what Louisianans know, that the Bayou State is sinking.

Scientists contend it is not global warming that has caused water levels from the Gulf of Mexico to take over coastal real estate during the past century, but a lack of upstream sediment reaching the lowlands, especially after a history of rerouting and blocking the Mississippi River from its natural flow in an effort to reduce severe flooding.

During the past 50 years, Louisiana land loss exceeded a rate of 40 square miles per year, meaning that 80 percent of total coastal erosion in the United States occurred in an area between the states of Texas and Mississippi.

According to the Barataria Terrebonne National Estuary Program, an estimated 163,000 acres of land were lost between 1995 and 2010 alone.

“When I was a little girl there used to be a lily farm over there,” said Chauvin resident Dot-tee Radcliff as she surveyed an area between Dulac and Cocodrie that is now filled with water and to unknowing observers appears to be part of an inlet from Terrebonne Bay.

Terrebonne Levee and Conservation District Executive Director Reggie Dupre has been known for taking newcomers on area tours where land once existed, but had since then been claimed by the sea.

Rebuilding the coast has been an increasing concern in Terrebonne Parish, where as much as 60 percent of the state’s total land loss takes place. Now there might be an answer and opportunity for possible reversal of that pattern.

According to Terrebonne Coastal Restoration and Preservation Director Nicholas Matherne, plans are in the works that could significantly fight off encroaching waters and even rebuild parts of the lost land.

Parish government leaders, state legislators and property owners have been meeting to discuss a project that would bring sediment from the Atchafalaya River, a 170 mile distributary of the Mississippi and Red rivers, to the southern portions of Terrebonne Parish by way of a slurry pipeline.

“We are looking into how we can tap into sediment from the Atchafalaya,” Matherne said. “It could cost $570 million.”

Matherne said that legislators are looking into funding programs that could defer the cost and that landowners have already agreed to provide the needed right of way at no charge.

A preliminary long distance sediment pipeline feasibility study reports the project would involve installation of an approximately 30-inch diameter pipeline specifically designed for sediment transfer at the desired distance of about 30 miles.

The pipeline would be used to transport a mixture of water and sediment and deliver it to needed areas at an estimated land creation rate of 8,500 acres in seven years.

“It’s not a bad idea if it is done on a constant basis,” said Louisiana Universities Marine Consortium professor Paul Sammarco. “It has to be done at a [rate of speed] that the plants and animals can handle. You don’t want to drown them. You can survive me putting a cup of mud on your head, but can you survive 2,000 tons of mud?”

“Fresh water reintroduction is an intricate part of that, but it can take a millennium to get the coast where it needs to be,” said state Sen. Norby Chabert, who is among those involved with the project. “The only way we are going to save the coast immediately is to reintroduce sediment into the marshland and beneficially use dredge material.”

“I have always been a big proponent of slurry pipelines,” said state Rep. Gordon Dove, who is also among the project planners. “They work. The one in Plaquemines Parish [which draws from the Mississippi River] has been successful. It’s too far from the Mississippi River so we got to get it off the Atchafalaya.”

According to the preliminary feasibility study, the Mississippi River is recognized as the state’s single primary renewable sand resource. It delivers sediment to the Gulf of Mexico through its own direct mouth and that of the Atchafalaya. While the Atchafalaya River does traverse a portion of Terrebonne Parish, its mouth and that of the Mississippi leaves a wide area that has not benefited from renewable sediment, resulting in land loss.

“One of the major reasons we are losing coastline is because sediment is not coming in at an equivalent rate that it used to,” Sammarco said. “There is no material being added on top. So what we have is called an apparent sea level rise. It’s not a real sea level rise. It is not water coming up. It is land going down. Adding sediment to a marsh that is already deteriorating? I don’t think we could do much harm unless we do it too quickly.”

Matherne said it is too early to know when construction on a slurry pipeline to restore the coast might begin, but said he is impressed with the level of interest that has been given to the project.

The end of the road seems dangerously close for coastal Louisiana as areas that were once land are overtaken by water levels at the end of Louisiana Highway 55 near Terrebonne Bay and across disappearing marshlands. MIKE NIXON