Heavy weekend rain from a messy tropical disturbance that blossomed into the Atlantic's first tropical storm of the season set a new record in Hollywood and triggered sewage spills that likely flowed into the Miami River, Biscayne Bay and waters off Virginia Key.
The six spills all occurred as heavy rain flooded streets, seeping into the county’s sewer system and at times flowing out of manholes.
“We did not have pipeline equipment or facility failures. It was just the nature and the volume of water that was received,” said Miami-Dade Water and Sewer Deputy Director Jose Cueto. “That was more than what the system is designed for and more than we can handle.”
Each spill, according to reports filed with the Florida Department of Environmental Protection, generated more than a thousand gallons of sewage.
At 2 a.m. Saturday, sewage at the central district plant on Virginia Key overflowed when the plant capacity of 143 million gallons a day more than doubled to 310 million gallons. The spill likely entered waters off Virginia Key just a few hundred feet away, according to the FDEP report.
A second spill at 8 a.m. at Northwest Seventh Street and 10th Avenue from a 60-inch pipe likely sent sewage into the Miami River.
Four other spills occurred: at 7 a.m. at Southwest 17th Avenue and South Dixie Highway; at 10:30 a.m. at 6464 NE Fourth Court; about 6:15 p.m. at 11940 SW 34th St.; and about 1:10 a.m Sunday at 545 NE 55th Terrace.
In some neighborhoods, Cueto said workers found manhole covers removed and flipped over, suggesting residents moved them hoping to lessen flooding.
“We did see quite a bit of that,” he said, allowing debris to get into the system.
“Things like two by fours, you name it. We saw a little bit of everything over the weekend,” he said. “It is something that we'd like to share with the public that the sewer system is not intended for stormwater."
The department is calculating the amount of sewage spilled, he said, and expects it to be thousands of gallons.
“It is a difficult exercise just because roads were also flooded and measuring and estimating that quantity is tough,” Cueto said.
The spills prompted warnings not to swim in waters from just north of the Venetian Causeway to the southern tip of Key Biscayne, both in the bay and on the ocean. The warning remained in place Monday evening, said water and sewer spokesperson Jennifer Messemer.
Miami-Dade is in the midst of a 15-year, $1.5 billion federally ordered improvement plan after the Environmental Protection Agency sued over repeated violations. The work is slated to be completed in 2028 and includes miles of new pipeline and pumps.
Cueto said the absence of line breaks and pump failures showed improvements are helping the sewage system.
“We feel that that really has been one of the key factors as to why there wasn't a pipe failure, there wasn't a pump failure, and there wasn't a facility treatment plant failure either,” he said.
Rainfall totals across Miami amounted to a foot or more, nearly beating the April 1979 record for Miami International Airport of 14.85 inches, said University of Miami Rosenstiel hurricane researcher Brian McNoldy. Hollywood set a new record of 13.5 inches, although he said that record is fairly short since record keeping only started in 2000.
That amount of rain equals to about 20% of what Miami-Dade normally gets in a year, Cueto said.
“Our sewer system is not designed for a 50 or 100-year event. It's designed typically for a two-year event in terms of our collection and transmission system. And our facilities are sized to match,” he said.
While the federally ordered repairs deal with aging infrastructure, Cueto said county officials worry about more intense storms and potentially heavier rain driven by a warming planet. Since building systems to handle such amounts of rain would be hugely expensive, he said planners are looking for other solutions to avoid stormwater overwhelming the sewer system.
“There's always going to be some,” he said. “But it's a matter of limiting it to the point that it doesn't create some of these incidents that we experienced over the weekend.”
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