[A] faulty valve in Burlington’s wastewater treatment plant this week led to the release of more than 7 million gallons of partially treated wastewater into Lake Champlain. Operators say the discharge also included some partially treated sewage.
The release poses little risk of harming human health, officials say, and it is not expected to appreciably contribute to other pollution problems Lake Champlain currently faces.
Bacterial samples taken during the April 16 incident showed E. coli concentrations of more than four times allowable levels where the plant discharges effluent.
No other meaningful quantities of pollutants escaped the plant, said Jessica Bulova, section supervisor for the Vermont Department of Environmental Conservation’s Watershed Management Division.
The portion of Burlington’s wastewater treatment facility that removes solids, sediments and nutrients such as phosphorus operated properly throughout the incident, Bulova said, and sent no unusual amounts of those pollutants into the lake.
The failure occurred with a valve that releases a disinfectant called hypochlorite into the filtered wastewater, she said. The faulty valve directed some hypochlorite into the water but sent a portion of the chemical back to the plant’s headworks, where it takes in wastewater needing treatment, she said.
As a result, the primary issue with the effluent was the level of bacteria it included, said Chapin Spencer, Burlington’s public works director.
The partially treated wastewater flowed into Lake Champlain through the plant’s normal discharge point located underwater half a mile into Lake Champlain.
Burlington officials placed signs on beaches within a mile of the discharge, and nearby municipalities were alerted as well, Spencer said.
Because there are few swimmers at this time of year in Lake Champlain, the risk the incident posed to human health was relatively minimal, Spencer said.
Nevertheless, he said, this was “a significant incident.”
“We take these situations very seriously,” Spencer said. “Situations like this keep me focused and up at night, because I live next to the lake, in Burlington, and I recreate in the lake … and we all want to be good stewards of the lake.”
Both Burlington and the Department of Environmental Conservation are conducting investigations into the incident.
Plant personnel appear to have responded appropriately and rapidly, Spencer said, an assessment shared by Bulova.
“The Burlington team went right into action to try to solve this as soon as they noticed it, which was right away,” Bulova said.
The valve failure occurred during a storm that brought almost an inch of rain, according to documents about the incident that the Public Works Department placed online.
The storm and related snowmelt sent 7.1 million gallons of stormwater and other wastewater through the plant between 2 p.m. and 9:30 p.m. on April 16. Plant operators noticed during that time that hypochlorite levels in the plant’s effluent were lower than they should be. They confirmed the following day that a broken valve was the cause.
The broken valve was installed as part of a plant upgrade performed in the 1990s, Spencer said. Following the April 16 release, workers replaced the broken valve and other similar remaining valves within the plant, Spencer said.
The faulty valve worked properly as recently as April 13, when Burlington experienced a storm of similar size to the one three days later, according to Public Works Department records.
