EAA A-2 Reservoir Project – SFWMD S-623 Pump Station Cofferdam

WGI teamed up with Ebsary Foundation Company to provide engineering and design for a temporary cofferdam as part of the Everglades Agricultural Area A-2 Reservoir Project for the South Florida Water Management District. WGI was tasked with the design of the temporary cofferdam for the S-623 Pump Station. As the specialty engineer responsible for the design and detailing of the cofferdam, WGI worked closely with the Contractor to complete the design allowing safe access to the dewatered construction area. Due to the large excavation footprint required for the pump station, WGI utilized a staged five-cell cofferdam design. Each cell incorporated augercast concrete anchors and a tremie slab to resist the buoyant forces throughout construction. The cofferdam design relied on braced walers to resist lateral soil and hydraulic pressures during reinforcement and concrete placement 22 feet below ground level. The design was completed in accordance with the US Army Corps of Engineers (USACE) Engineer Manuals and Engineer Regulations. Design models were developed and construction staging/sequencing detailed for sheet pile installation, staged excavation, waler and bracing installation/removal, sheet pile cutting between cells, augercast concrete and tremie placement, dewatering, permanent construction and backfilling, and final cofferdam removal, with each phase evaluated as successive cells were added throughout the progressive five-cell system.