Report Confirms Corrosion in FL Sewage Spill
In a report issued by the Berkley Research Group in November, experts have both calculated the total amount of sewage leaked and the cause of the breach in Longboat Key’s main sewer line in Manatee County, Florida, that occurred over the summer.
The 20-inch-diameter iron pipeline transports sewage from Longboat Key, Florida, under the bed of Sarasota Bay and along the Florida Gulf Coast, to a wastewater treatment facility in Bradenton.
What Happened
According to the Bradenton Herald, the Longboat Key issued a report to the Florida Department of Environmental Protection indicating that the sewage spill started on June 17 and occurred throughout June 29. The report arrived as a revision to nonprofit organization, Suncoast Waterkeepers’ report, which also alleged Longboat Key of failing to report required information as mandated by law.
However, discrepancies between town officials and the DEP argue over when the reports were received and the time of when the spill occurred. To better represent the incident timeline, Assistant Town Manager Susan Phillips Phillips told reporters that, “The town wastewater staff was reading monitors and they were seeing low flow ratings for a number of days and believed there were meter and equipment issues. That’s what they were looking at and it wasn’t until June 29 that they did a flow and pressure test.”
It was after this that the staff determined that there must have been a leak and fulfilled their obligations to report it to the state.
In affirming Phillips’ claims, Jeff Goodwin, Deputy Director of Manatee County Utilities Department, said that there was no alarm that would have signaled the loss of sewage, but that county staff did notice an early drop in flow.
“The flow from LBK is continuously measured, recorded and delivered to LBK staff on a daily basis,” Goodwin said at the time. “When county staff first noticed a potential abnormal measurement, they contacted LBK staff who indicated the cause was attributable to maintenance activities they were performing on their system.”
While a cause for the break was being investigated, Phillips added that a 2016 study on the mainline indicated it had 20 to 25 years of life remaining and that there had been no issues over its 40-year lifespan until the breach. While there were designs in the works for a new pipeline, the county hadn’t put anything into motion for the $20 million project.
Following the breach, the DEP initiated a formal investigation in which it planned to gather and analyze information about the spill and evaluate if there were any violations that had occurred. Additionally, the DEP also planned to identify any further corrective actions needed, including solutions to avoid future spills, and the potential for enforcement actions.
“The department will hold the facility accountable by identifying necessary restoration and/or remediation actions, with the possibility of enforcement including fines and penalties for associated violations,” said Shannon Hebron, public information manager for DEP at the time.
On the afternoon of June 30, the leak was repaired, and service was restored. The pipeline is reported to transport between 2,500 and 3,000 gallons per minute during peak conditions, but has withstood occasional surges of over 4,000 gallons per minute.
In August, Environmental Science Associates, a third-party contractor, completed its water-sample testing in the Sarasota Bay waters, determining that the environmental effect was low.
As of Dec. 23, 2020, the sewage break cost the area more than $340,000.
The State of Florida Sewage Infrastructure
Just a few months after the incident, The Guardian published a report indicating that more than 230 million gallons had spilled in Fort Lauderdale, Florida, alone, between December 2019 and February 2020 because of the state’s aging wastewater infrastructure.
At the time of the report, the city was facing a $2.1 million fine from the state for the series of spills, a reported worst on record in Florida history. The article further reported that Fort Lauderdale had diverted funds for necessary sewage repairs and maintenance to other city budget projects.
“A lot of the issues in south Florida with sewage spills has to do with the infrastructure getting very old, much of it is beyond its planned life, usually around 50 years, so there are a lot of cracks in the sewage pipes,” said Rachel Silverstein, a marine biologist and Executive Director of Miami Waterkeeper.
According to data obtained from Florida’s DEP, between 2015 and March 2020, there were 13,984 reported sewage spills, which released 1,658,165,304 gallons of sewage, after initial recovery efforts were completed.
In 2019, PaintSquare Daily News reported that Sarasota County, Florida, was still under fire after a 48-inch diameter pipe burst at the Bee Ridge treatment facility on Dec. 20, 2018, releasing an estimated 900,000 gallons of wastewater onsite, some of which flowed into the stormwater system and out into Sarasota Bay.
Sarasota Police reported at the time that the pipe ruptured around 9 a.m. and was isolated and stopped by city crews within the hour. Due to recent heavy rainfall, a significant amount of groundwater infiltrated the sanitary sewer system, diluting the wastewater.
Following the break, the city sent out notifications of the incident to the Florida Department of Environmental Protection and Sarasota County region’s Florida Department of Health. Precautions were also taken to stay away from the infected waterways while initial water quality tests were conducted and affected areas sanitized.
Shortly after, in January, health and safety leaders from the Sarasota Utilities Department released its proactive plans to prevent future wastewater spills. Included in the plans was a creation of a wastewater pump station improvement program, which would fund new pumps and generators $15 million over the next five years.
However, in February, several other sewage spills were linked to broken and aging pipes in Florida. According to WWSB—a local ABC News affiliate—officials had discovered that the cause of the Sarasota spill was a hydrogen sulfite gas that ate away the concrete pipe, causing it to burst. According to those same officials, the pipe should have lasted 75 years but ruptured after 40.
Even though the pipe had since been repaired and running accordingly, several environmental groups began threatening to sue the county for dumping over 800 million of gallons of wastewater into local waterways since 2013.
Since then, even more sewage spills occurred. In March of last year, over 20 million gallons were spilled in Miami-Dade County. Just a few months later in May, 1.8 million gallons spilled in Miami-Dade due to heavy rain and clogged items disrupting flow in the area’s wastewater treatment plant.
Before the July incident in Manatee County, more than 1.2 million gallons were reported to have spilled in Sarasota Bay in June, and in August, an unknown amount of sewage spilled on the streets of Fort Lauderdale due to a pipe break.
“We’re not getting enough funding, so what we’re seeing is this ageing infrastructure collapse and an increase in sewage spills across the state,” said Jenna Stevens, state director of the policy and action group Environment Florida.
The Longboat Key Sewer Main Report
According to a 596-page expert report by the Berkeley Research Group over the Longboat Key sewer pipeline breach, the team calculated that approximately 14.7 million gallons leaked over the course of the leak between June 17 thru June 29, 2020.
As for the cause of the breach, the report was also able to identify that a buried log was the culprit, having rubbed against the underground pipeline since its installation in 1973. The discovered log was found after crews were able to expose the damaged section of pipe, lying perpendicular across the pipeline at a slight angle under the damaged section.
An eyewitness report further indicated that the log was approximately 6 to 8 inches in diameter and stretched beyond the width of the pipe. In light of this discovery, the report concluded that the log was acting as a fulcrum under the pipe, which likely abraded the pipeline’s exterior coating and accelerated corrosion.
“Given the excessively corroded pipe wall condition at the breach location, it is likely that the pipe experienced a force, such as a surge or purge pressure, that instantly caused the weakened pipe section to break. In that instant, the pipe crushed down onto the log, which partially blocked the opening,” the report said, adding the shape of the hole matched the shape of the log.
Additionally, the report found through ultrasonic testing that most of the pipe wall thicknesses measured between .66 inches and .78 inches at 10 underwater excavation sites, with one of the thinnest readings being .63 inches. However, after the sewer pipe emerges from under Sarasota Bay and travels underground, the original pipe wall thickness reduces to .50 inches. At the location of the breach, the pipe wall thickness had corroded to approximately half that thickness.
A corrosion expert working on the report pointed out that one-eighth inch of ductile iron pipe wall thickness loss would be expected if iron were exposed to seawater for 9 years. This information however, only further proves that the pipe had been corroding for at least 18 years, given that it had taken several years for the log to abrade the exterior coating enough to allow for corrosion to start.
Under a proposed consent order, the FDEP is seeking $242,652.50 in civil penalties for the break, though the town also has the option of pursuing an in-kind environmental enhancement project, subject to FDEP approval.
Since the incident, Longboat Key has moved forward with its estimated $16 million redundant pipe project. The project would first duplicate the pipeline on the mainland side and eventually duplicate the underwater portion to the treatment plant.
