Corps speeds testing of tubes for blocking breaches in levees
Lightweight Universal Gasket, called a PLUG, is a fabric tube that can be floated into place and filled 80 percent with water using an attached pump; the tube is pulled into the breach in the levee by the current, blocking more water from going through the breach; the tube is dropped by helicopter near the breach.
U.S. Army Corps of Engineers researchers think they may have found a better way to plug levee breaches to stop flooding quicker. Engineers have tested several variations of a large fabric tube that could be dropped by helicopter near a breach, where it would fill with water and be pulled into place by the current rushing through the hole. The research — aimed at improving the older method of dumping sandbags into breaches – has so far been done on smaller-scale test levees in Oklahoma.
Amy Wold writes that now the corps hopes to try out the repair techniques on full-size levees by next summer at a test site in Vicksburg, Mississippi. The corps is developing a 40-acre area to allow testing on the types of flood-control structures seen in Plaquemines Parish and New Orleans, said Don Resio, senior technologist with the agency’s Engineer Research and Development Center in Vicksburg.
The corps wants to tackle breaches that are 20 to 40 feet wide with water flows comparable to the levee failures in the New Orleans area during Hurricane Katrina, he said. Resio said the agency looked for sites in Louisiana and elsewhere, but DHS wanted one selected fast. The only area where environmental concerns and other issues could be handled quickly was the Vicksburg property already owned by the Engineer Research and Development Center, he said.
Fully to test breach-repair methods, researchers need a site big enough to handle a huge amount of water — 15 minutes of flow at 1,000 to 2,000 cubic feet per second, or roughly 14 million gallons, he said. “We are hoping this will be a validation of what we did at a smaller scale,” Resio said.
The latest round of small-scale tests looked at a relatively new way to seal breaches. The Portable Lightweight Universal Gasket, called a PLUG, is a fabric tube that can be floated into place and filled 80 percent with water using an attached pump. The tube is pulled into the breach by the current, blocking more water from going through.
A device based on the same concept — but with a curved tube instead of a straight one — has been designed for damaged locks or flood gates.
The group also tested whether the arched tube could be used after a PLUG is in place to create a dry area. Workers could then remove the PLUG and make permanent repairs to the levee while the arched tube holds back the water, Resio said.
Currently a cofferdam must be built to make permanent repairs, which is a slow, expensive process, he said.
The smaller-scale tests held at the Agriculture Research Service Hydrologic Engineering Research Unit in Stillwater, Okla., were promising, he said. “The question is always can you do it at a scale that matters,” Resio said.
Research started in 2007 to find emergency levee-repair methods other than using sandbags. “There hasn’t been a focus on solving this problem,” Resio said. Although sandbags work for slowly rising rivers, they are not effective during flash-flooding or against storm surges along the coast, he said.
The goal for the new effort is to have an emergency-repair technique that can be done in four hours, he said. Windell Curole, general manager of the South Lafourche Levee District, said the trick will be stopping the water as quickly as possible. “That’s really the whole key, if you can deal with the issue before it gets gigantic,” he said. Any research into better ways to deal with levee breaches is welcomed, he said. “I don’t believe we’ve scratched the surface on creativity on dealing with this,” Curole said.
Plaquemines Parish President Billy Nungesser agreed that finding a fast way to stop water from flowing through a breach is important in preventing bigger problems. Some members of the parish’s flood-control department have seen the corps’ demonstration projects, he said. “We’re open to anything that could cut down on flooding in the parish,” Nungesser said.
Carroll Pons, superintendent of flood control for Plaquemines Parish, said he believes the PLUG technique could prove useful — and might have been effective in stopping some flooding during the 2008 hurricane season. “There could be models made that definitely work in our situation,” Pons said.
