When the massive wall is completed, passers-by won’t see it.
The wall under construction is about 3 feet below the top of the Herbert Hoover Dike, and extends through the dike and into the earth. When construction is done, the disturbed areas will be sodded and the Lake Okeechobee Scenic Trail repaved.
The wall is designed to prevent water from the big lake from seeping through the earthen berm that encircles it.
When the Herbert Hoover Dike repairs are complete, cutoff walls within the dike will be completed from Belle Glade to Moore Haven, with one section near Lakeport, explained Ingrid Bon, project manager with the U.S. Army Corps of Engineer.
Rehabilitation work on the dike started in 2007. Federal funding for the project is $1,499,500. The dike work is not part of the Comprehensive Everglades Restoration Plan (CERP), which requires a federal-state match, but the State of Florida put $100 million into the project to help speed up completion. The original completion date was estimated for 2025. Thanks to the additional state funding, along with expedited federal funding, the project will be finished next year.
Bon said the contractor, Bauer Foundation Corp., has three of the six contracts for seepage walls within the dike.
“When we award a cutoff wall contract, we tell the contractor what the finished project is,” Bon explained. “There are different ways to build cutoff walls.”
For the South Bay project, the first step was to remove the organic peat and replace it with sand.
Later, a Concrete Slurry Machine (CSM) injects grout into the predrilled area and mixes it with the soil. A compressor pumps compressed air into the mixture, helping it to mix more smoothly. The CSM operator monitors the progress of the process on a computer, which also uploads data for monitoring by the Corps of Engineers.
See a more detailed description of the cutoff wall construction process here.
Cutoff walls around the dike will range from 55 feet to 75 feet in height depending on the soil and geology of the area.
Col. Andrew Kelly, commander of the U.S. Army Corps of Engineers Jacksonville District, explained the dike was built in two phases, with a smaller dike built in the 1930s in response to the devastation of the 1926 and 1928 hurricanes. This embankment, constructed along 67.8 miles of the lake’s south shore and 15.7 miles along the north shore, was completed in 1938. A major hurricane combined with storms that created the “Great Flood of 1947” prompted the need for additional flood and storm damage reduction work. As a result, Congress passed the Flood Control Act of 1948 authorizing the first phase of the Central and South Florida (C&SF) Project, a comprehensive plan to provide flood and storm damage reduction and other water control benefits in central & south Florida. The taller, 143-mile Herbert Hoover Dike was completed in the late 1960’s.
Construction methods available in the 1930s and the 1960s were not the same as those used today, Kelly explained. They dug available materials from the area next to the lake to build an earthen berm. After the hurricanes of 2004 and 2005, the federal government put more focus on the need to address dike safety issues. The Herbert Hoover Dike ranked high on a list of safety concerns.
South of the lake, when the level of Lake Okeechobee is higher than the elevation of the ground on the other side of the dike, water pressure builds up on the south end. (Okeechobee is 26 feet above sea level. Moore Haven and Pahokee are just 13 feet above sea level.) The higher the lake level goes, the more pressure the water exerts on the earthen dike. This can result in seepage of water through the dike or “piping” which creates tiny holes in the dike, with the water eroding soil from within the dike. The cutoff walls are designed to stop this movement of water through the dike.
The corps is in the “home stretch” of a 15-year project, said Bon.
“I know the public is very interested in the completion of our work in regard to the FEMA flood zones,” she explained. Once the dike work is complete next year, the corps should be able to report to FEMA the accreditation of the Herbert Hoover Dike.