Note to Reporters: A brief video of the CSU research on levees is available on YouTube at http://youtu.be/5ueSxhP8xJs. Downloadable, broadcast-quality video, including B-Roll, and audio are available with the news release at http://www.news.colostate.edu/Video. Photos are available with the news release at http://www.news.colostate.edu/.
Colorado State University’s Civil and Environmental Engineering department has unique expertise that is assisting the U.S. Army Corps of Engineers with assessing and protecting levees from New Orleans to Jacksonville, Fla.
This summer, the U.S. Army Corps of Engineers in New Orleans accepted applications from companies interested in using engineered erosion-control products to reinforce levees in the wake of Hurricane Katrina. As part of the application process, the Army Corps required any interested companies to seek independent testing of their products at Colorado State.
“The Army Corps of Engineers specified that these companies must use CSU’s wave overtopping facility, which is the largest in the world and the only one in the United States,” said Chris Thornton, director of the university’s Engineering Research Center. “We have assembled the team and have the experience, from working with the Army Corps previously, to test these engineered products, which are designed to protect earthen levees from erosion.”
In 2009, the Army Corps hired Thornton to design and build a levee wave overtopping test facility at CSU that is capable of simulating the enormous waves that likely contributed to Hurricane Katrina’s devastating toll on New Orleans in 2005.
From that project, CSU helped generate preliminary guidelines and methodologies for determining the forces exerted on levees during extreme storm conditions that can be applied to all levee systems, not just the New Orleans area, said Thornton, who is also an associate professor of civil engineering.
Thornton said the project taught him and his team of engineers and students a lot about the importance of failure mechanisms, the importance of engineered products and the effect of vegetation quality on protecting against erosion. Not just any vegetation will work, which is why CSU grows plants native to Gulf Coast areas before testing them in the wave overtopping machine.
These engineered products, called Turf Reinforcement Mats, are designed to supplement a vegetated system and provide significant increases in the level of performance against severe hydraulic forces.
“We want to protect the soil – our goal is to stop erosion and lock everything together so it’s protected from the hydraulic loading of hurricane-strength storms,” Thornton said.
Once the vegetation has grown and is rooted, CSU scientists subject it to multiple tests simulating hurricane-strength waves at the overtopping facility. The specially designed overtopping simulator and control mechanism, about 28-feet-tall by 7-feet-wide, is operated by a computer system that replicates waves larger than the roughly six-foot waves that hit New Orleans during Katrina. Water is sent into 40-foot-long, six-foot-wide “trays” filled with vegetation, and in some cases engineered products, from a particular region. The trays are placed in the facility to replicate the specific levee geometry.
Jacksonville, for example, has sandier soil than New Orleans, so CSU is working with a plant expert, Jeff Beasley at Louisiana State University and Steve Hughes, a coastal engineer and senior research scientist at CSU, to ensure the experiments incorporate the proper locally grown plants and expected storm conditions, Thornton said. The project with Jacksonville is likely to start this all after the vegetation has rooted.
Levees and their supporting infrastructure are susceptible to erosion and, as a result, potential catastrophic breaching with intense hurricanes and the associated storm surge. Scientists and engineers generally agree that there is a need for more information about how levees can be designed to resist wave overtopping and prevent levee failure and widespread flooding.
“A tremendous amount of work has been done across the academic, engineering and manufacturing communities to develop engineered systems that resist the force of flowing water,” Thornton said. “Our job will be to collect state-of-the-art data that will enable us to develop a method that includes the forces generated on levees during wave overtopping so this more accurate guidance can be incorporated into current design methodologies.
“I expect the results of this program to spark innovation and advancement in the engineering community and the erosion control industry.”
About the Engineering Research Center
For the past 63 years, faculty at the Engineering Research Center at Colorado State have used applied research solving site-specific problems for projects located around the world. The lab works with such clients as the Colorado Department of Transportation, the U.S. Bureau of Reclamation, the Federal Highway Administration, the U.S. Army Corps of Engineers, local and national consultants, and organizations throughout the country on performance testing, hydraulic structure modeling and sediment and river modeling. The laboratory is an international leader in conducting model studies and training future engineers in the fields of hydraulics and river mechanics. Colorado State scientists are known for their experience in performing hydraulic studies such as dam overtopping analysis, spillway studies, dam foundation erosion research and erosion control performance testing.