JACKSONVILLE — The U.S. Army Corps of Engineers (USACE), Jacksonville District awarded a $136,637,750 construction contract for the Indian River Lagoon-South (IRL-S), C-23/C-24 STA part of the Comprehensive Everglades Restoration Plan (CERP) to Kiewit Infrastructure South Co., of Sunrise, Florida.

“The C-23/C-24 STA is the first major construction feature of the IRL-S project to address the C-23 and C-24 basins in St Lucie County,” said Michael Drog, project manager with the Army Corps of Engineers.

“When completed, this STA will provide an estimated 4,800 ac-ft of new storage and act to treat water from the future C-23/C-24 North and South Reservoirs,” he said.

The Indian River Lagoon, home to more than 3,000 species of plants and animals, is considered the most biologically diverse estuarine system in the continental United States.

The purpose of the STA is to reduce sediment, phosphorus, and nitrogen going to the St. Lucie River Estuary and the southern portion of the Indian River Lagoon. Redirection of water from the C-23/24 basin to the north fork of the St. Lucie River, will attenuate freshwater flows to the estuary.

Ultimately, the stored water will be released into the C-23/24 STA to sequester nutrients from water conveyed from the North and South Reservoirs. The C-23/24 STA is designed to remove phosphorus from stormwater entering the C-23/24 Reservoirs.

The multi-cell STA will be located both east and west of County Road (CR) 613, and consist of 1,970 acres of effective treatment area spread among five cells within the approximately 10-mile perimeter: two cells of roughly 200 acres each and three cells at roughly 500 acres each, and will have a normal operating depth of about 1 to 2- feet, 260 cubic feet per second (cfs) inflow, and 200 cfs outflow. Inflowing water will be treated by filtering through emergent wetland vegetation.