The creation of a muck management area on Pineda Causeway marks the start of a significant step in improving water quality in the Indian River Lagoon, but tight quarters and manatees will add months to the $26.4 million project.
The goal is to remove, dry and truck away 479,000 cubic yards of muck from the Grand Canal, three entrance canals and 16 residential finger canals. Dredging the muck will remove thousands of pounds of nitrogen and phosphorus linked to algae blooms in the Indian River Lagoon, including the Banana River and its canals.
The small seven-acre site will be used starting Oct. 1 to stage and dry the muck before trucking it to fertilize pastures at Platt Ranch on the south side of U.S. 192 west of Interstate 95.
Fencing and a vegetation buffer was left at the muck management site to address concerns of residents in nearby South Patrick Shores. They worry about noise from the work and, with less vegetation, more road noise from Pineda Causeway.
The main challenge for the project is manatees, which gather in the canals from Nov. 1 to May 31 to keep warm. Under state and federal permits, manatee sightings will prompt dredge shutdowns from Nov. 1 to May 31 with the entire operation to be shut down from Dec. 1 to March 15.
The project is something that could have been done in about 18 months under the best circumstances but having to work around manatee habitat, especially with such a small staging area, nearly doubles the time needed, said county project manager Walker Dawson.
“It’s a very small footprint to work in but we want to make every effort (to buffer sound and work efficiently) because we’re going to be working near people’s back yards for about three years. We’re going above and beyond,’’ he said.
The possibility of odors from the site drifting into the neighborhoods should be minimal, said Austin Fox, Ph.D., an assistant professor in the Department of Ocean Engineering and Sciences at Florida Tech in Melbourne. Fox studies the causes of excess nutrients which contribute to algal blooms and reduced water quality that can lead to losses of seagrass, reduced biodiversity, hypoxia and fish kills.
FIT research identified fine-grained, organic-rich sediments – known as “muck” – as a major source of nutrients to the Indian River Lagoon, contributing more than 40 of the total nutrient loads to this system, according to the FIT website.
While the canals were considered Ground Zero for more than 22 million gallons of county sewage releases during and after Hurricane Irma, the residual effect of the spills do not impact the composition of the muck, Fox said.
The releases “(even big ones) make up only a small fraction of the annual nutrient loading to the lagoon. They can be important locally as a sudden pulse of nutrients plus they are gross. So yes, spills/releases are not good, but the waste is relatively quickly processed into other forms of organic matter,’’ he said.
“Legacy” muck refers to the fact that the organic fraction of the muck entered the lagoon sometime in the past and creates nutrients through decomposition, he said.
As for the future, Fox said small changes now can make difference.
“The individual must take responsibility! I have talked to homeowners that agree this is a problem, then the next day I see their landscapers blowing grass into the lagoon. If we don’t change our behavior, we will see the same problems coming back,” he said.
Sticking with the plan to dredge and remove the muck, rather than considering diverting the funding elsewhere as has been discussed, will yield significant reductions in nitrogen and phosphorus for a healthier lagoon, said Leesa Souto, executive director of the Marine Resources Council.
“The plan is science-driven and has a method and is cost-effect. If you value the process, you stick with the process,’’ she said.