Comprehensive Everglades Restoration Program Biscayne Bay Coastal Wetlands - Phase I Project, L-31 Flow-way Pump Station S-709, Miami-Dade County, Florida

The Biscayne Bay Coastal Wetlands Phase 1 project includes construction activities associated with the construction of one electric powered pump station designated as S-709. S-709 is a 40 cfs pump station located north of the C-103 canal on the L-31E canal. S-709 will pump water from the C-103 canal and discharge to the north into the L-31E canal using (2) 20 cfs submersible pumps. Pump station S-709 will also have a sixty inch culvert with a slide gate to pass flows during emergencies when the pump station is not operable. The pump station consist of sheet pile headwalls and wingwalls, with precast concrete intake boxes that are placed in the wet between the sheet pile headwalls. Flowable fill is placed between the precast boxes and sheet pile headwalls. A precast concrete deck is positioned over the precast boxes and concrete cap. In water construction utilizing divers will be necessary, because dewatering is difficult due to the local geology and high conductivity. The pump station has a trash rack on the intake side and flap gates on the discharge side. The culvert consists of a 60 inch HDPE diameter pipe that will be encased by flowable fill placed underwater. The culvert headwalls are precast concrete placed in the wet and grouted between two steel king piles. A stainless steel slide gate is mounted to the headwall and is operated by an electric actuator. Controls will be located in a standalone precast concrete building located adjacent to the pump station structure. Construction activities include installation of precast concrete, H-piles, king piles, sheet piles, concrete piles, precast concrete, cast-in-place concrete, tremie concrete, flowable fill, HDPE culvert, slide gate, precast control building, pumps, pump platform, pump station controls, electrical work, lighting, lightning protection, fencing. Construction activities also include excavation, backfilling, stockpiling, clearing and grubbing, grading, placement of topsoil, sodding, limerock road topping, riprap and bedding stone. Construction activities also includes installation of stilling wells, stilling well platforms, staff gauges and floating barriers. Additional construction activities may include dewatering, and installation of cofferdams.