River maintenance necessary, hard work

The mat sections are comprised of squares – 100-square-foot sections -- made of concrete and connected by stainless steel wiring. “We try to offset them when they’re placed,” says Raimondo.

"Those levees have to be watched closely and mats have to be placed farther out. In other areas, the levees aren’t close and concerns are different.”

Is the plan to do a certain amount of mat-laying a year? “The Number One thing is funding. This is expensive to run. It takes about 300 folks in mat-sinking unit: ground crews, guys with typing tools, the people that take care of the quarter’s barge, all of it.

“Every outside bend of the Mississippi River from Cairo, Ill., to the Gulf of Mexico has revetment. We do underwater surveys of the revetment as see if there’s been any damage.” The strength of the river is hard to overstate. “Floods and currents can do crazy things, push up under mats and flip them over. We find those spots and repair them.”

One of the reasons “we armor the banks is to keep the Congressionally-authorized channel (at 300-feet wide and 12-feet deep) in place,” says Raimondo. “If the river meandered all over like it used to, all the work on channel improvements – dikes, revetment, dredging – would be for naught.”

A second reason to armor banks: “if the river scours away the bank, that eating-away will quickly reach the levee. Obviously, that wouldn’t be good for all the people behind the levee.”

A winch barge holds the main mat-laying operation – the matboat --upstream. Further anchoring is provided by additional cables attached to, and pulled taut by, riverside bulldozers.

“The dozers act as mobile anchors. They use winches to control the angle from the bank, control how far the mat-laying section can push out.

“We’re having a particularly tough time with the current in this section,” says Raimondo. Indeed, a tugboat is holding the main boat in place. “A tugboat is not normally necessary. They had to bring that in to prevent downward drift. Getting a mat to lay down perfectly in these conditions is kind of like keeping a long ribbon straight when it’s being tossed around by the wind. The mat is concrete and steel but the current is just that strong.”

“This is the spar barge,” says Raimondo. The main mat-laying section “slides along the spar barge. Depending on how much mat they need to lay, they can go out hundreds of feet. It’s kind of like moving along a ladder set on its side. They start close to the bank and work out, always moving north – the mats are laid like shingles.”

Once a mat is in place “They’ll cut it and drop it to the bottom. Then, they’ll take the whole operation and slide it upstream about 140 feet and start over from the bank.”

There used to be two matboats. “Those boats used to work two shifts a day – 24/7 – for years. They began with two normal cranes on each end. Can you imagine how unstable that would be? It must have been scary having two cranes swinging around on a boat in such a current.”

Now, gantry cranes are used. “They slide out back over the top of the mat supply boat, two squares at a time, and slides them back on the deck. It’s much more efficient.”

Once the job was completed along the full stretch of the river, the focus shifted to maintenance and repair. “Now, we do repairs on about 1 to 2 percent of the mats per year.

This matboat, its homeport in Vicksburg, is the last of its kind. Built in 1948 “it’s an amazing piece of technology,” says Raimondo. “Surveyers guide the boat to proper position.” In current dollars, it cost well over $100 million to build.

The matboat also costs some $6 million a year to maintain. That’s one of the reasons the Corps wants to build a new version that incorporates current technologies like GPS and robotics. “It would be really nice to be able to (use robotics) to help pull the mat off the supply barge.”

If funding, research and development lines up, the Corps would to have a new matboat in a decade, or so.

As the mat-laying continues, commercial barge traffic with an occasional smaller vessel mixed in keeps passing. Pushing 40-plus barges, a boat passes close to the Corps operation.

“Moving downstream is much harder to control that passing upstream,” says Raimondo. “Downstream boats have the right of way if they choose to take it. In order to steer well coming downstream you have to be moving faster than the current. With this river, in places like this bend, that can be a little tricky.”

“I really like being outside with this job, at least when it isn’t raining” says Raimondo.

“You never know what you’re going to see out here,” says a worker listening in. “You won’t believe this but yesterday, we had Chris Columbus’ ships float by. I’m not kidding.”

The claim seems dubious but later the sighting is confirmed. It turns out replicas of the Pinta and Nina have been moving on the river in the last few days.