U.S. Army Corps of Engineers Uses Turf Reinforcement Mat to Rebuild New Orleans Levees
The U.S. Army Corps of Engineers (USACE) embarked on one of the largest and most comprehensive public works projects in American history following the catastrophic damage caused by Hurricane Katrina in 2005. USACE established Hurricane Storm Damage Risk Reduction System (HSDRRS) to provide the greater New Orleans Area a 100-year level of risk reduction, meaning that infrastructure would be established to defend against a storm surge that has a 1% chance of occurring in any given year.
One of the most critical measures of HSDRRS was protecting refurbished earthen levees against the erosion-causing hydraulic forces of storm surge overtopping. Without protection, overtopping can lead to significant landside erosion and potentially a breach of the levee. During Hurricane Katrina, most levee failures were due to water overtopping. The specifications of the project were to supply a high-performance turf reinforcement mat (HPTRM) in combination with engineered earth anchors to provide improved erosion control stabilization to the top and side slopes of levees. USACE stipulated use of HPTRMs that meet the standards outlined by the U.S. Environmental Protection Agency (EPA) Storm Water Technology Fact Sheet as a best management practice (BMP) for compliance to the NPDES storm water regulations. In addition to providing superior protection against hydraulic forces, the customer needed a solution that would be resistant to non-hydraulic stresses such as heavy mowing equipment and construction traffic.
To ensure the effectiveness of the project design, USACE required rigorous testing before the project was installed. USACE partnered with Colorado State University to build a full-scale wave-overtopping simulator. The simulator tested erosion resistance of armoring materials for a 500-year resiliency HSDRRS overtopping conditions.
Additionally, the Louisiana State University AgCenter performed multiple non-hydraulic tests on the armoring system to evaluate the ability of vegetation to establish within the HPTRM and to test how the material would hold-up against heavy mowing equipment.
Testing showed that ArmorMax engineered earth armoring system by Propex GeoSolutions provided levee resilience and durability while handling maintenance operations smoothly. Additional testing showed that using the system, which consists of HPTRM with Engineered Earth Anchors, reinforces vegetation on the earthen levees, which reduces the risk of breaching caused by overtopping waves and non-hydraulic stresses.
This armoring system has been recognized by the by EPA and the Federal Highway Administration as a BMP to improve water quality. Additionally, the patented technology used in the system helps lock in seeds and promotes rapid root mass development to enhance the development of a fully vegetated solution. One million sq yd of ArmorMax 75 engineered earth armoring system has been installed in the New Orleans area to date, with plans to install another 3 million sq yd in the near future.
