To stop Baton Rouge flooding, they dig a 12-mile river | Louisiana News

By DAVID J. MITCHELL, Attorney

ZACHARY, La. (AP) — You can’t see it yet from Plank Road or La. 19 near Zachary, but work crews are building a lazy river from scratch.

Inside a huge wide “V” dug into the earth, the concrete pillars of a bridge have been poured and smoothed by workers. Nearby, long-reach excavators placed large boulders along the sides of a canal, while other digging machines scooped up the earth and dumped it into trucks which transported it.

After decades of delays, political wrangling and roughly $580 million tinkering, the long-awaited Comite River Floodway is finally becoming a reality.

The U.S. Army Corps of Engineers and the State Department of Transportation and Development have divided construction of the Comite River Floodway into a series of phases, or segments, which can be constructed somewhat independently of each other at if an area experiences delays. Some of these areas, including Segment 3, have encountered problems due to delays in the negotiation of interstate gas pipelines owned by Florida Gas.

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Critics of the 40-year-old construction work of the flood control project have derisively called it a “mess up” and simply a “drainage ditch”. But the contractors working for the Corps of Engineers are clearly building something much bigger than a ditch.

It’s a whole new body of water.

When the canal opens – in 2024 or 2025, officials hope – a diversion structure will continually redirect the Comite River once it exceeds a certain height. Experts say these higher water levels often contribute to flooding downstream, where hundreds of thousands of people live.

Excess water will be diverted west of the Amite River, where it normally flows, and down the new channel to the Mississippi River north of Baton Rouge.

The new waterway is carved into what was once solid earth. It will be able to channel the equivalent of the Arkansas River, reducing flooding in the middle Amite basin, according to Corps of Engineers estimates.

To achieve this goal, this straight, rock-lined waterway will need anything in its 12-mile path to swerve out of its way, over its banks or slide under its bottom. This includes roads, railroads, pipelines, wetlands and private property, according to Corps of Engineers plans.

The landscape will change so much that seven new bridges will be needed. They include the one that contractors are building near McHugh Road and farther west at US 61 and the Kansas City Southern Railroad.

Patrice Maguire, 53, lives just north of the McHugh Road Bridge construction area with her husband, Chris, 55. They heard the dirt material in the distance from the woods behind their house, and they saw the trucks driving past. from their home.

At present, only mounds of fresh earth and the tops of cranes and construction equipment are visible from Plank Road. But Maguire said she knew all that work would eventually come to pass, should the canal reach the River Comite east of her home.

“Every time I pass there and see what they’re doing, I’m like, ‘Are they going under that road? What will happen to Plank Road? “, Did she say.

Maguire had heard of the project. But failed to realize that extending the canal to the Committee meant that a new long bridge had to be built for Plank Road across what is now solid ground.

“Wow, that’s a lot of money,” Maguire said.

Plank Road and La. 19, which contractors from the State Department of Transportation and Development will manage, are the next digging and bridge projects slated for construction later this year, Corps and Department officials said. DOTD.

A short stretch of unexcavated canal near McHugh’s site shows how much earthworks are underway. It is almost as long as a football field on top and drops below the surface about 42 feet.

Corps officials estimate that the entire project will require the removal of nearly 9.2 million cubic meters of earth, enough to fill New Orleans’ Caesars Superdome roughly twice. A chorus of dump trucks piles this material into large spoil banks lining each side of the canal; they have removed 1.68 million cubic meters so far.

One of the most spectacular landscape alternations for the diversion is yet to come: three local bayous will be entirely redirected towards the canal.

Although the Comite River Diversion provides about 70% of the flood reduction benefits of the Comite Diversion, Bobby Duplantier, the Corps’ senior project manager, said shifting bayou flow would also make a big difference.

“It’s really going to bring…a lot of benefit to those neighborhoods in smaller events, you know, those events when you have a lot of untimely flooding,” Duplantier said.

Estimates from at least two decades ago – the latest available, although new estimates are forthcoming – suggest that the greatest benefit from the diversion will be in the Zachary and Baker areas, where more than a 6 feet of water levels during a 100-year flood are projected. The bayous will also retain some water in the diversion channel when the Committee is too low to divert. But the public interest has a permanent price.

The channel will bisect the bayous Blanc, Bâton Rouge and Cyprès. Their water north of the canal will be permanently diverted, according to Corps plans.

Artificial electric pumps will draw water from the future diversion channel and discharge it into the bayous so that the water continues to flow there under the channel. However, the diversion will remain a permanent barrier for aquatic fauna.

East Baton Rouge Parish, under prior agreement with the Corps, will have to keep these pumps running for wildlife, as well as most other long-term maintenance costs like debris removal, said Corps officials. Parish officials said they and Corps are still working out the total costs for the canal.

Corps plans originally called for expensive concrete structures that would have sent bayou waters spraying more than 25 feet of waterfalls into the channel, Duplantier explained.

But Corps officials met with their counterparts in Mississippi, where a less dramatic and less expensive option was already being used.

The so-called “rock falls” will slow the waters of the bayou 1,200 to 1,500 feet upstream, gradually easing the transition and channeling the water to the bottom of the floodway. The chutes widen as the bayous approach the channel.

In addition to cutting costs by about $25 million, Duplantier said the falls eliminated a safety concern: Spectacular waterfalls would likely have attracted curious onlookers. The diversion will not be a public access waterway, including for anglers and boaters.

“It’s a much less intrusive type of flow in our channel compared to a large waterfall, I call it, in the channel,” Duplantier said.

The Corps of Engineers has already awarded construction contracts for two of these falls, at White and Cypress bayous, but work is only just getting ready.

Copyright 2022 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

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