The challenge is to change that tune: to develop the technology to quickly seal a levee breach and reduce floodwaters through the opening within four to six hours of detection—before the water can do major damage.
Enter Wil Laska of the Science & Technology Directorate (S&T), the research arm of the Department of Homeland Security. Laska has sought out innovative technologies from industry, academia, and government to meet this challenge. Any proposed system, he dictated, had to not only be capable of quickly closing breaches, but also be suitable for scenarios in which the breach may be difficult or impossible to reach with conventional construction equipment.
"The thing is," Laska deadpans, "there's an effective structural material that's readily available during floods…water."
He found four technologies that met his requirements, and on Nov. 9, 2009, all of them passed their second test at the U.S. Department of Agriculture's Agriculture Research Service, Hydraulic Engineering Research Unit in Stillwater, Okla. The facility is used by the Army Corps of Engineers to test hydrology equipment and study water flow, dams and levees.
The PLUG technology is tested on a levee breach in Stillwater, Oklahoma.
(Photo Credit: Paul Wedig, DHS S&T)
The largest technology, proposed by the Army Corps of Engineers Engineering Research and Development Center in Vicksburg, Miss., is a large balloon or tube—light enough to be transported by helicopter and flexible enough to adapt to a wide range of environmental situations. When launched or dropped, the engineers hypothesized, the tube would in quick succession fill with water, float on the flood currents to the breach, and adhere to the breach in the earthen berm or levee that had failed.
It worked.
Dubbed the Portable Lightweight Ubiquitous Gasket (PLUG), the tube of non-stretch fabric is dropped into the floodwaters and an attached pump rapidly fills it to 80 percent capacity—a bubble of air inside keeps the tube from sinking beneath the waters. Positioned upstream, flood currents pull it toward the breach. The incompressible nature of water and the unyielding fabric turn the tube into a rigid plug that conforms to the breach and seals it.
Monday's PLUG demonstration was about 30 per cent larger than the ¼ scale model that was first successfully tested in September 2008. The Stillwater site is currently the only facility that can provide the water flows needed—125 cubic feet per second for several minutes.
While the PLUG system is designed specifically for narrow, deep breaches, several other solutions tailored for other types of levee breaches were also tested on Nov. 9:
*A smaller version of the PLUG–designed to prevent the over-topping flow of a long, shallow breach.
*The Rapidly Emplaced Protection for Earthen Levees (REPEL)—designed to protect against erosion during the intentional overtopping of levees, mitigating erosion from the back slope of a levee which over time could cause a deep breach.
*The Rapidly Emplaced Hydraulic Arch Barrier (REHAB)—an arched tube designed to hold back a surge of water during a levee breach repair, to seal breaches obstructed by debris or other structures, and to be used as a rapidly emplaced surge or flood gate.
>>>>>Oh cryin' won't help you, prayin' won't do no good>>>>>Oh cryin' won't help you, prayin' won't do no good>>>>>When the levee breaks, mama, you got to lose
Engineers could be on their way to writing a less bluesy version of a 90-year-old song:
>>>>>When the levee breaks, mama, you may need a PLUG.
When the levees were breached in New Orleans during Hurricane Katrina, the Ninth Ward was inundated. New technologies such as the PLUG may help when levees are compromised.
(Photo Credit: Paul Wedig, DHS S&T)
When the levees were breached in New Orleans during Hurricane Katrina, the Ninth Ward was inundated. New technologies such as the PLUG may help when levees are compromised.
(Photo Credit: USCG)
Source: US Department of Homeland Security - Science and Technology