The Everglades' original plumbing worked just fine. But as the marshland was cleared away and its natural flow was redirected to accommodate exponential growth, its natural filtration capabilities were ruined. The South Florida Water Management District is undertaking a massive fast-track effort to reverse water pollution in the sub-tropical wilderness. Photo: Virginia McKain
An inside look at Acceler8
The Everglades Agricultural Area project is moving right along.
In southern Palm Beach County resides a 6430-acre constructed wetland treatment system called Stormwater Treatment Area No. 2 (STA-2).
Divided into three cells that operate in parallel, this wetland reduces stormwater runoff pollution levels flowing in from the Everglades Agricultural Area. It receives agricultural runoff waters containing an estimated total phosphate concentration of more than 50 ppb, and through a natural filtration flow process reduces this phosphorus to no more than 20 ppb. As part of the Acceler8 expansion project, a fourth cell will be added to bring phosphorus levels down to no more than 10 ppb.
The project also includes the construction of two levees. They are about 12,500 feet long, and then they turn north for about another 5000 feet where they tie into another supply canal levee. These new levees will be built wide enough to be used as roadways with occasional safe passing zones.
The first step in building the levees is to clear vegetation and muck from the underlying limestone with a large tracked dozer. The lime rock is then drilled and blasted on a 15x16-foot square pattern.
“The rock being excavated and compacted out here is really tough,” says Don Stetter, project manager and superintendent with Bergeron Land Development Inc., a Ft. Lauderdale-based earthwork subcontractor with the project. “It's almost like flint in some places, which is rough on excavator bucket teeth.”
According to construction manager Ed Bashman of subcontractor Brown and Caldwell Engineering, contractors saved time with a Bomag BW225D-3 compactor, which helped them put down the rocky levee building material in 36-inch-thick lifts. “With the levees averaging between 9 and 10 feet tall, this equates to making only three lifts instead of five,” says Bashman.
Brown and Caldwell is responsible for the project's engineering and geotechnical investigations.
Geotechnical testing engineers NODARSE International are performing nuclear density tests on the 36-inch-thick course of material. So far, the results have been very good, says Bashman.