Septic Tanks Not Sole Nutrient Culprit, New Report Will Show
By Jesse Schneckner
Ten months after an alarming report hit Miami-Dade lawmakers’ desks outlining how rising sea levels could wreak havoc on septic tanks county-wide, a second report will reel in prior projections and recommend an action plan.
But while the possible damages may be less than previously expected, the county is still at risk of health perils unless it takes broad preventative steps, said attorney Wayne Pathman, chairman of the Miami Sea Level Rise Committee and Miami Beach Chamber of Commerce.
“As waters rise and impact the drain fields, salt water may corrode the tanks… pushing bacteria and solid waste to the surface or spreading it out over an area, and people are going to be exposed to it,” he said. “It could fall into [Biscayne Bay] and other areas, depending on the proximity of the tanks to other bodies of water, and become a significant health risk.”
The question of how malfunctioning septic tanks could affect the bay will factor heavily in the follow-up report Water and Sewer Director Kevin Lynskey said he plans to bring to county commissioners next month – four months later than he’d originally estimated.
The extra time, he said, was used to explore “opportunities that emerged” during the report’s production.
One opportunity, he said, was a chance to “correct the first report,” which said that up to 64% of all septic tanks in the county – more than 67,000 – would malfunction periodically every year by 2040 due to rising sea levels unless expensive countermeasures are taken.
Those staggering figures were overblown, he said, because they depended on a rainfall event prediction estimate known as the “100-year storm.”
“But the problems we have with our bay water are day-to-day and aren’t related to 100-year storms,” he said. “[This new report] has a much higher focus on the number of tanks that are most problematic.” That’s about 2,000 septic tanks now, plus up to 10,000 more over the next 20 years – markedly fewer than the alarming figure Mr. Lynskey’s own department listed in the November 2018 report it published with the county’s Regulatory and Economic Resources Department and the Florida Department of Health.
In total, the report placed a more than $3.5 billion price tag on connecting residential and commercial septic tanks to the county sewer line.
The new report, he said, will “broaden the conversation” beyond looking solely at preventing future septic system failures and how to pay for it – with one option discussed in January being an up to $220 increase to some residents’ water and sewer bills – to how two categories of contaminants now affect the bay.
One category is pathogens – bacteria, viruses and microorganisms – which “can be significant after rains and failures of[septic]systems…but don’t build up [and] tend to diminish immediately,” he said.
The other, which should be of most concern, he said, are nutrient pollutants: nitrogen and phosphorus, which cause seabed die-offs and are long-lasting to the point that they “could stain the system.”
If half of the county’s nearly 105,000 septic tanks failed today, he said, it would only contribute a quarter of the nutrient pollution already in the bay.
“To us, what’s important is to transmit to the [county commission], as opposed to just an update on the septic tank report, a report that conceptually lays out four or five separate contributors to the nutrient problem and then use that as a matrix to help us understand where we should invest and what our policy should be,” he said.
Those contributors, he said, include canal water flowing in from outside the county that brings roughly 25% of the nutrient pollutants detected in the bay, as well as agricultural runoff in the south, urban runoff in the north during heavy rainfall and “what comes out of the septic systems and potentially the wastewater management systems.” The report will recommend two courses of action. One would be “substantially more testing” to “fingerprint” pollutants in the bay and link them to their sources for a comprehensive picture of what’s there.
The second, which should come in that order, Mr. Lynskey said, would be to design “a broad-based policy and investment approach to curtailing the pollutant sources.”
“The challenge is, if the board believes that by spending $4 billion [to connect the septic tanks to the county sewer system] that we solve an issue for the bay, we will have used up probably all of the money and more than the county will spend on this,” he said. “But the bay issue may not be solved.”
Samir Elmir of the Florida Department of Health wrote in the initial report that groundwater contamination by failed septic systems could, if undetected, migrate to private and public wells, lakes, canals and coastal and bay water ecosystems, leading to illnesses including shigellosis, salmonella, hepatitis A and gastroenteritis.
“Bacteria and viruses from wastewater treatment by septic systems travel considerable distances in saturated soil and cause groundwater pollution, ”Dr. Elmir wrote. “A compromised treatment function may result in the relatively unimpeded movement of wastewater contaminants to ground and surface waters.”
But Mr. Lynskey said that the county’s drinking water supplies are “surprisingly independent” of any nutrient and pathogen issues affecting the bay, as it’s “primarily fed from the north, underground,” and urban pollutants don’t migrate northward.
“However, those pollutants are obviously a problem for the recreational waters and the environmental health of the bay,” he added, possibly alluding to recent spills like the ruptured pipe in Northeast Dade that leaked sewage into the Oleta River this month.
“If the septic system is a large contributor to the problem and the septic system becomes less functional,” he said, “then the pollutants to the bay would increase.”