Analysis of CFD Simulations of Structures in Support of the EAA A-2 STA Project

The Central Everglades Planning Project (CEPP) New Water Everglades Agricultural Area Stormwater Treatment Area (EAA-STA-A-2), herein after referred to as A-2 STA, consists of approximately 7,000 acres of land and is a principal component of the EAA Storage Reservoir and Treatment Wetland Project. The purpose of the project is to further reduce the number, return frequency, and severity of undesirable, damaging high-volume discharges from Lake Okechobee, thereby improving salinity and water quality conditions in the St. Lucie and Caloosahatchee Estuaries. Hydraulics near the proposed structures of the A-2 STA Project could be challenging when considering combinations of low/high flow-stage conditions. Velocities could be excessively high, and depths could create undesirable conditions to the operation of such structures that could not be properly identified with the use of one-dimensional (1D) or two-dimensional (2D) modeling. This paper discusses modeling results associated with the design of two critical project features: (1) the S-619 Discharge Structure, a triple barrel, 10-ft x 10-ft box culvert, to be constructed under the STA 3/4 Inflow Canal to allow treated water from the A-2 STA to flow south in the Miami Canal; and (2) the S-640 Pump Station, a temporary pump station that will deliver water to the A-2 STA during an interim period while the A-2 Reservoir is being constructed. Simulation results showed that the original design could lead to undesirable hydraulic conditions, such as eddies. This prompted modifications to the original design by the Design Team to improve the hydraulics near these structures. The results of the CFD analysis provided detailed predictions of hydraulic parameters in and around the structures, offering additional insight to the Design Team and the South Florida Water Management District regarding their capacity and performance under different hydraulic and hydrologic conditions. As such, the modeling results were key input in the decision-making process involving stakeholders regarding how the various conveyance channels and structures would be operated and maintained during the project's lifespan.