Rapidly Deployable Repair System for Levee Breaches
Thousands of miles of levees and floodwalls protect critical infrastructure in highly populated areas throughout the United States. Of these structures, many are aging, have not been properly maintained and have been compromised by natural occurrences. Since traditional levee breach repair work can take days, the key element in all response systems designed to counteract the devastating effects of broken levees should be mobility and fast deployment.
Seals Levee Breaches Quickly, Minimizing Damages
Levee breaches during Hurricane Katrina in August 2005 raised national awareness for the potentially dangerous condition of levees across the country. Soon after, with funding from the US Department of Homeland Security, ERDC Coastal and Hydraulics Laboratory (CHL) researchers investigated innovative ways to stop a levee breach within the first 4 to 6 hours, before it grew too big to contain.
Researchers developed a rapid repair response system to quickly close breaches in areas difficult to access. This technology, dubbed the Portable Lightweight Ubiquitous Gasket (PLUG), is a large tube of non-stretch fabric that is dropped into floodwaters where it fills rapidly to 60-70 percent capacity assisted by 4-inch trash pumps. The water transforms the unyielding fabric into a rigid plug that conforms to the levee breach and seals it.
Light enough to be transported by helicopter and flexible enough to adapt to a wide range of environmental situations and adverse weather conditions, PLUG uses a primary structural element readily available during flood events: water. PLUG could be used at a primary breach on a levee and at a secondary location within an area undergoing flooding to accomplish the following:
- Reduce water flows rapidly
- Minimize the possibility of additional "raveling" along the levee
- Repair breaches difficult or impossible to reach with conventional construction equipment
- Provide faster, more resilient response to flooding situations
- Protect people and infrastructure from the destructive effects of floods due to levee breach
PLUG seals a levee breach and reduces floodwaters through the opening within 4 to 6 hours of detection—before the water can do major damage.
The US Army Corps of Engineers (USACE) Jacksonville District requested a method to prevent the rapid increase of a levee breach at Lake Okeechobee, Fla. Lake Okeechobee is a prime example of how soil conditions play a large role in rapid breach expansion. To stop the expanding of the breach it will be necessary to prevent the sides from continuing to erode.
CHL researchers and engineers deployed PLUG to prevent the widening of potential levee breaches at Lake Okeechobee. This will limit the outflow of water and reduce the level of necessary repair once a flood event has ended. This system can be rapidly deployed and will either help stop the outflow of water from the lake or limit the flow while other methods are used to fix the levee breach. The system also helped the USACE Jacksonville district develop procedures and deployment options for a wide range of potential flood control and levee breach scenarios.
- 104 feet in length and can hold 400 tons of water
- Tube-shaped balloon made of polyester and PVC
- Automatic motorized water pumps
- First tool designed to repair a levee breach while powerful floodwaters are still coursing through it
- Lightweight design can be transported by helicopter to reach remote and/or difficult levee breach areas
Tailored Variations for Different Breach Types
While the PLUG system is designed specifically for narrow, deep breaches, CHL researchers have developed and tested several other solutions tailored for other types of levee breaches, including the following:
- Rapidly Emplaced Hydraulic Arch Barrier (REHAB)—Arched tube designed to hold back a surge of water during a levee breach repair, seal breaches obstructed by debris or other structures, and function as a temporary surge or flood gate to help engineers make permanent repairs.
- Rapidly Emplaced Protection for Earthen Levees (REPEL)—Structure positioned prior to a flood to provide protection to a levee/dam section from overtopping in extreme flood events. REPEL also protects against erosion during the intentional overtopping of levees.
- Repair of Long Shallow Breaches—Modified version of PLUG is used to repair long shallow breaches which typically are storm induced. This includes breaching of navigation and drainage channel floodwalls in coastal areas and overtopping long stretches of levees along rivers during floods.
- Variation on PLUG Deployment—PLUG can be used to seal the sides of a breach to inhibit further breach widening. The importance of this capability is critical in situations where the breach is very rapidly growing through erodible material. Such a capability could save many millions of dollars per breach over the present alternatives which allow breaches to grow until the water levels equilibrate or flooding subsides. See Success Stories and Future Work.
CHL researchers demonstrated that innovative lightweight fabric structures like the PLUG can play an important role in revolutionizing the way engineers repair levee breaches. Throughout 3 years of incremental testing, the CHL research team successfully completed the following:
- Conceptual investigation and theoretical design of breach mitigation alternatives, including fabric structures
- Demonstration of systems for protecting exposed levees during overtopping and closing very long breaches
- Demonstration of the PLUG’s capability to seal a 7-ft wide breach
- Conceptual framework for PLUG deployment and transition to permanent repairs
- Design of a full-scale facility for testing the PLUG and demonstrating its capability to seal a 40-ft wide breach
The PLUG work unit was completed in 2012. The research showed the PLUG has high potential for rapidly plugging a breach in a levee early in the breach development, preventing millions of dollars in flood damages and loss of life.