The color of the treated sewage discharged from the Niagara Falls wastewater treatment plant can be "tweaked," but it cannot be made clear, an engineer said Tuesday at an environmental conference in Buffalo.
The only way to produce clear discharges is to convert the plant's treatment system from carbon filtration to a biological process, such as that used in Niagara Falls, Ont., said John Goeddertz.
Goeddertz works for AECOM, a national engineering firm hired by the Niagara Falls Water Board in the wake of last summer's black water discharge into the Niagara River Gorge beside the Maid of the Mist dock.
Video of the July 29 stain quickly went viral and produced a worldwide blow to Niagara Falls and its tourism economy.
There are many ways to improve the sewer plant's operations, and some already have been carried out, Goeddertz said.
But none of them will prevent the discharge from the tunnels in the gorge from containing some colored solids – or "turbidity in your effluent," to use the technical term favored by Goeddertz. He made a 45-minute presentation to an audience of about 280 water and sewer professionals at the Greater Buffalo Environmental Conference in the Adam's Mark Hotel.
The system used at the Niagara Falls plant, built 40 years ago, was chosen because carbon was considered more effective than other means of treating industrial sewage. But Niagara Falls has far fewer of those industries than it did in the 1970s.
Goeddertz said the Niagara Falls facility is the only carbon-based plant from that era that still operates without substantial modification of its original technology.
"Capital upgrades and operational changes at this plant will only get you so far," Goeddertz said.
In an interview after his speech, Goeddertz recommended another approach.
"I believe the best course of action is a biological treatment plant," he said.
The system has been altered somewhat since the black water incident, which resulted in a $50,000 state fine and a 17-point Department of Environmental Conservation consent order governing operational changes at the Water Board.
Different treatment chemicals are being tried to replace the iron-based chemicals that, along with the carbon filters, played the main role in darkening the discharge, which Goeddertz said tends to be most visible in warm water.
Water is being moved through the system faster so it spends less time in contact with the carbon, Goeddertz said, and improvements have been seen in reducing overflows in wet weather. But there are only two choices for eliminating the risk of dark discharges.
"You either relocate the outfall or you pursue an alternative treatment technology," he said.
The tunnels that connect the plant to the gorge are above the surface of the water, meaning the treated wastewater splashes into the river visibly.
Blasting and excavating a new tunnel beneath the surface of the river would cost about $20 million, Goeddertz said in an interview after the speech. The discharge might still be dark, but at least it would be harder to see.
Goeddertz drew some chuckles from the audience when he reported that one of the options in a 2015 study of the plant's discharge was to color it so it wouldn't be as visible. After the speech, he said that could be done with green or blue dye.
He said the 2015 study was begun after observers from the Ontario Ministry of the Environment saw dark discharges from the plant. The discharges are more visible in warm water, Goeddertz said.
Converting the plant's technology, as Goeddertz prefers, would cost more than $100 million. One of his jobs is to come up with a more definite figure.
In December, state officials promised $20 million for upgrades at the plant. Goeddertz said many components would have to be kept in service during or even after the recommended conversion to a biological treatment system.
"We should stabilize the existing plant," he said. "The infrastructure is all 35 to 40 years old now. "We don't think we're going to keep carbon long-term; probably (we will) not spend any more money there. It's not too hard to come up with a list of $20 million worth of improvements at that plant. In fact, it's pretty easy. You can do it without breaking a sweat."
As the Department has said numerous times, the black discharge that occurred last year was a violation of water quality standards, and further violations are unacceptable," DEC spokesman Sean Mahar said late Wednesday. "Consultants of the NFWB should get back to work and focus on meeting New York's strict water quality standards instead of making speeches. Gov. Cuomo has proposed $20 million in funding to take the initial steps toward improving the plant, in addition to directing DEC to issue crystal-clear violations if these requirements are not met."
Under the consent order, the Water Board was given nine months to produce an engineering report on plant upgrades, and 15 months to prepare a report on how to change the treatment process to biological without shutting the plant down.
The Water Board also was ordered to take steps to reduce system overflows in wet weather; eliminate stored sewage solids faster and improve employee training, since the July 29 discharge was blamed in part on employee errors.