Innovative levee armoring balances flood control and conservation

Overview 

In 2012, Tropical Storm Isaac caused extreme flooding throughout Florida, prompting immediate measures to strengthen the Indian Trail Improvement District levee, which runs alongside the J.W. Corbett Wildlife Management Area. While these actions provided short-term relief, Governor Rick Scott directed a multiagency working group to develop a long-term flood protection solution. 

The working group consisted of the South Florida Water Management District, the Indian Trail Improvement District, Palm Beach County, the Florida Fish & Wildlife Conservation Commission, and the Florida Department of Environmental Protection, and was tasked with replacing a 5.6-mile (9 km) levee segment using the latest technologies and best practices. The levee serves to prevent runoff from the J.W. Corbett Wildlife Management Area from flooding the Indian Trail Improvement District. The goal was twofold; increase flood protection for residents and provide flexibility in operation of water levels within the Corbett Area. 

Challenge 

The levee’s location next to the J.W. Corbett Wildlife Management Area added environmental considerations to the project. The area provides critical habitat for endangered species such as the Bachman’s sparrow, red-cockaded woodpecker, and snail kite. Conservation priorities included restoring natural water flow while maintaining flood protection. 

Installation was also complicated by the inability to control water depth on the canal side of the levee. This prevented the team from digging a trench at the toe of the slope to secure the system. Additionally, the design had to withstand the overtopping and corrosive effects of sand and brackish water, requiring a solution with proven hydraulic resilience and long-term durability. 

Solution 

PROPEX^® Armormax^®, a system combining High Performance Turf Reinforcement Mat (HPTRM) with engineered earth anchors – was selected for armoring and protecting the levee. Tested by the U.S. Army Corps of Engineers, this system increases levee resilience and reduces the risk of breaching from overtopping. It also encourages groundwater recharge and is recognized by the EPA as a Best Management Practice for improving water quality. 

Approximately 66,000 yd² of PROPEX Armormax was installed, with stainless steel anchors providing added protection and corrosion resistance. To address the trenching challenge, the team created burrito-wrap rock structures using MIRAFI^® 160N and PROPEX Pyramat 75 and filled with rock, which were then placed at the toe of the slope with excavators. 

Following installation, soil and sod were applied over the system. PROPEX Armormax promotes rapid root development, creating a reinforced vegetated solution. Colorado State University studies have shown this approach significantly improves hydraulic resistance limits and enhances slope stability both during and after vegetation establishment.