The major E. coli leak that has kept 11 miles of the Chattahoochee River closed for two weeks resulted from a die-off of the “good bacteria” that help clean wastewater at the county’s Big Creek Water Reclamation Facility, Public Works Director David Clark told Fulton County commissioners this week.
“Something entered the plant that was toxic to those good bugs,” he said.
It might have been from someone dumping chlorinated swimming pool water into the sewer system, Clark said. The contaminant, whatever the source, killed about 80% of the microorganisms that help treat the water, he said.
A new supply of “good bugs” was brought in from the Johns Creek Environmental Campus, and those have begun to grow and work, Clark said. He expected the plant would be back in compliance with environmental regulations soon.
When the river will reopen for recreation is up to the National Park Service, Clark said. On Friday, a park service alert said the river was still closed from the Chattahoochee Nature Center to Powers Island.
The danger from E. coli, found in fecal matter, didn’t stem from an actual sewage spill. Rather, it came from inadequately treated wastewater.
Chattahoochee Riverkeepers discovered the discharge at Morgan Falls near Sandy Springs. Clark said Riverkeepers and the park service contacted treatment plant staff June 28.
At first a broken pipe or overflowing manhole was thought to be the problem, he said. It took several days to figure out the real issue.
On July 2, workers began diverting 5-7 million gallons of wastewater a day to DeKalb’s water treatment plant, and increased other methods of disinfection, Clark said.
The Big Creek plant serves Alpharetta, Roswell, part of Milton and parts of Cobb and DeKalb counties. It opened in 1971 and has expanded several times.
The plant, owned by the county but operated by a third-party contractor, is in the midst of a $300 million expansion, taking capacity from 24 million gallons a day to 32 million. Work is expected to be finished in 2024.
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