FORT PIERCE — Sewage spills are among the nutrient sources that can fuel harmful algae blooms, according to information shared at the Blue Green Algae Task Force meeting on Aug. 1 at Florida Atlantic University’s Harbor Branch.
John Truitt, Florida Department of Environmental Protection (FDEP) deputy secretary for regulatory programs, said the good news is that roughly two-thirds of sewage spills in the state last year were treated effluent, which did not contain pathogens. The bad news is that the spills contained nutrient load, which can feed cyanobacteria (sometimes called blue green algae) and contribute to algal blooms.
Florida has about 2000 wastewater treatment facilities that treat about 2.5 billion gallons of waste water per day, he said. At any given time, they are roughly at three-fifths of permitted capacity.
The number one cause of spills was rain causing increase in inflows, said Mr. Truitt. “If pipes are not perfectly sealed, and you have high rains, inflow causes more water to get into the treatment plant than would normally occur,” he said. At one facility, one-third of the water treated was inflow.
The second most common cause of sewage spills is a break in the line.
Other spills were from hauling and negligence, he added.
In 2016, some spills were due to loss of power and excess inflow during a hurricane, he said. He said the age of the sewer systems contributes to the problems.
Dr. Valerie Paul, director of the Smithsonian Marine Station at Fort Pierce, noted some of these utility systems were built in the 1950s and 60s.
“The age of facilities and infrastructure with the pipes you can’t see is a nationwide issue,” said Mr. Truitt. “There are still locations in the State of Florida that have wooden sewer pipes.
“As it ages, it leaks more, and a lot of the older systems were in rather large areas, with hundreds of miles of collection lines,” he said. With some of the smaller systems, the problem was availability of power, he said.
Running a smoke test is the best way to find out if the sewer pipes leak, he said, but “if you have hundreds of miles of line, you can’t do that quickly.” He said they might focus on oldest lines or those closest to sensitive bodies of water.
Sewage spills totaled over 300 million gallons in a two-year period, he said.
“Over the grand scheme of things 300 million gallons is not a lot of water,” said Dr. Tom Frazer, Florida’s chief science officer. He said it is important to find out concentrations of nutrient load in the spills, and the proximity to sensitive waterways.
“The human waste stream is around 20 percent of the nutrient entering our waters,” said Dr. Paul Gray of Audubon Florida. As the population grows it is only going to get larger.