The Central Everglades Planning Project (CEPP) Contract 11B is a cornerstone effort in restoring the natural flow of water through the Everglades ecosystem. As part of the A-2 Reservoir program, Thalle Construction Company is responsible for constructing critical sections of the 17.75-mile D-623 embankment dam and the associated hydraulic structures that will ultimately support improved water storage, flood protection, and long-term environmental recovery across South Florida.

 

Work on the project commences with extensive site preparation across the Everglades Agricultural Area (EAA). This includes clearing, grubbing, and de-mucking operations to remove overburden and expose a stable foundation footprint. Thalle is executing one of the most significant earthwork assignments in the CEPP program: the excavation, placement, and processing of several million cubic yards of material to construct the D-623 embankment. Along its length, the embankment is designed to stand approximately 38 feet above natural grade on the north, east, and west sides, transitioning to 34 feet on the south. Foundation widths reach roughly 260 feet in the northern, eastern, and western reaches, tapering to 235 feet in the southern segment—reflecting the reservoir’s geometry and hydraulic needs.

 

Integral to the reservoir’s operation are multiple water-control structures being delivered under this contract. Thalle is constructing four multi-barrel, gated outlet works (S-624, S-625, S-626, and S-628), an ungated overflow spillway (S-627), and a multi-bay gated inline spillway (S-629). These structures will regulate inflow, outflow, and emergency overflow, enabling precise water management for both ecosystem restoration and flood-control operations throughout the region.

 

Foundation preparation represents another major component of the ongoing work. Thalle is performing rock-foundation preparation and installing a seepage cutoff wall along approximately two miles of the embankment alignment—critical steps to help control groundwater movement and maintain long-term structural stability. Additional canal filling and incidental foundation improvements are being carried out to prepare the full dam footprint, while the remaining 15.75 miles of cutoff-wall installation are coordinated with separate contracts.

 

The project also includes the construction of two parallel open channels: the C-636 Seepage Canal and the C-623 Inflow/Outflow Canal. These channels, ranging from 10 to 55 feet in bottom width and excavated to depths of approximately 16.5 feet, support seepage control and water conveyance for the reservoir system. A raised maintenance road, built between the canals with a minimum crest width of 14 feet, provides year-round access for inspection and operations.

 

Throughout construction, Thalle is implementing continuous surface and subsurface-water-management strategies to maintain dry working conditions—no small task in the hydrologically complex EAA. Delivered in partnership with the U.S. Army Corps of Engineers (USACE) and supported by land from the South Florida Water Management District (SFWMD), this project demonstrates Thalle's ability to perform large-scale, technically demanding civil works that strengthen the resilience and sustainability of vital water resources.