The operators of the nearest sewer treatment plants to Niagara Falls say they would never find themselves in a position to blacken the Niagara River as the Niagara Falls plant did last Saturday.
North Tonawanda’s wastewater treatment plant is almost identical to the Niagara Falls plant, and the city’s mayor asked the plant’s superintendent if that plant would ever be at risk for a similar discharge.
“Never,” William M. Davignon said he told the mayor.
On the other side of the river, in Niagara Falls, Ont., a different method of processing sewage is used. Treated wastewater isn’t discharged directly into the river.
“We would never have a discharge like that,” said Jason Oatley, associate director of wastewater operations for the Niagara Region of Ontario.
The Niagara Falls Water Board issued a statement late Friday, acknowledging that human error caused the black discharge into the Niagara River, which was captured on aerial photos that media outlets published around the world.
The employee monitoring the discharge at the plant left to help with work elsewhere in the plant and returned to find the discharge was dark, according to the statement from Rolfe Porter, executive director of the Niagara Falls Water Board.
“It is our preliminary belief that the submersible pump in sedimentation basin No. 5 was allowed to run longer than was intended, which caused a higher concentration of backwash water to enter the chlorine contact tank than occurs under normal conditions,” the statement said. In water treatment facilities, water is periodically "backwashed" or made to flow in reverse to help maintain filters. That water is supposed to be treated before it's discharged.
North Tonawanda’s treatment plant on River Road does not discharge its backwash water into the Niagara River, said Davignon, superintendent of that city’s water treatment plant.
“We reprocess that wastewater to be cleaned again. We never discharge that to the river, ever, until it’s been cleaned. It goes through all three (treatment) processes and we rechlorinate it after carbon column treatment, and then we discharge that to the river,” Davignon said.
“I was surprised that they would release that out to the river untreated. I’m just saying, we never do. And I just hit my 30th anniversary here,” he said.
An overshadowing event
The discharge drew unwelcome worldwide media attention, with newspapers, TV networks and websites replaying a video shot by a pilot for Rainbow Air of Niagara Falls and tweeted out by the Maid of the Mist. The Maid’s dock was almost the epicenter of the black stain on the river.
“That got a lot of attention over here,” said Oatley, the associate director for water treatment of the Niagara Region of Ontario.
It also drew the attention of the state Department of Environmental Conservation and the Niagara Falls Police Department, and both sent investigators to the plant Friday, looking into why and how the discharge occurred.
The tourist city draws more than 8 million visitors a year.
The sewage incident came six weeks after daredevil Erendira Wallenda hung by her teeth from a helicopter hovering over the Falls, which was supposed to be a catalyst for positive press for the Cataract City.
“This one incident will far overshadow any of the small positive effects from Mrs. Wallenda hanging over the Falls,” said Assemblyman Angelo J. Morinello.
Carbon sewage treatment process
Both the North Tonawanda and Niagara Falls sewer plants use giant beds of carbon fibers in the final sewage cleaning process.
“We’re the world’s biggest Brita filter,” Davignon said. “Seriously, that’s what both plants are designed as.”
North Tonawanda assigns two operators to its backwash process, which takes 15 to 30 minutes, depending on how dirty the carbon beds are.
“They’re to stay there and make sure nothing overflows and to make sure we have the right valves open so when the backwash water reaches that trough and spills over into the area that it does go back to the head of the plant,” Davignon said.
North Tonawanda’s wastewater treatment plant was built at about the same time as Niagara Falls’ plant – in the late 1970s – and Davignon said both cities chose the fairly unusual carbon treatment method because of the challenges they faced in handling industrial sewage.
“We had a lot of chemical plants in Niagara Falls and North Tonawanda,” Davignon said. “They determined it would be a more effective treatment for the potential waste streams that were coming out of those factories.”
He said “99.5 percent” of sewage plants use a biological treatment process, but carbon filters are better at trapping chemicals. The Niagara Falls plant opened in 1978, while the North Tonawanda facility came online in 1980.
Davignon said the carbon filters at North Tonawanda are “regenerated” about twice a year, after a chemist determines that they’re too clogged to work effectively. That was Davignon’s job before he became superintendent in January 2016.
Regeneration “is basically a high-furnace heat that cleans up the carbon,” Davignon said.
The filters are heated to about 1,800 degrees to burn off “any volatile organic compounds or anything hazardous,” Davignon said. The smoke goes through an air scrubber system and a resin cartridge, and the scrubbers are sent to a landfill when they become too dirty.
He said he doesn’t know if Niagara Falls does this, but after regeneration North Tonawanda also applies about 5 feet of “virgin carbon” to the filters, keeping them fresh. The carbon beds are about 28 feet thick, Davignon said.
Carbon fibers that wear off the filters tend to sink to the bottom of a chlorination tank during the backwash process. North Tonawanda tries to vacuum them and reapply them to regenerated carbon beds. If they’re not in good enough shape, the sheddings are landfilled, Davignon said.
Treatment in Canada
Niagara Falls, Ont., doesn’t use carbon beds to handle its sewage. The Canadian plant uses anaerobic digestion by microbes after the heavy grit and large pieces are screened out, Oatley said.
The sludge is then exposed to bacteria that “breaks down any organic matter. It then goes through a clarification process and a chemical is added to reduce the phosphorus,” Oatley said.
The sludge goes through a centrifuge to spin off the water. Lime is added and the sludge is either sold or given away to local farmers as fertilizer.
The material, called biosolids, has been controversial in Western New York, as foes oppose using the remnants of human waste as fertilizer and have persuaded some towns to ban its use. The DEC endorses biosolids as environmentally friendly and safe.
The treated water discharged from the Niagara Region plant on Stanley Avenue in Niagara Falls, Ont., goes into a canal that leads to the Sir Adam Beck hydroelectric plant on the Canadian side of the Falls. After it goes through the power plant to help turn the turbines that produce electricity, it then reaches the river.
Oatley said the Niagara Falls, Ont., plant never would be able to produce black water in the river, as its American counterparts did.
“Our limit for suspended solids is 25 parts per million, so you’d never see what happened over there,” Oatley said.
Carbon can be smelly
The discharge July 29 was remarkably smelly, witnesses said, but Davignon said that doesn’t necessarily mean it contained untreated sewage sludge.
Davignon disagreed with the former Niagara Falls Water Board attorney John J. Ottaviano, who told The News Thursday that he didn’t believe the discharge into the river would have smelled so bad if it was just carbon. He claimed that untreated sewage sludge must have been part of the discharge.
“In my years of service, carbon can get very smelly, because it is absorbing wastewater,” Davignon said. “When you backwash a carbon column, it will give off hydrogen sulfide gas, which is a rotten egg smell. It’s normal. That happens all the time. When we backwash carbon columns, we have to turn on exhaust fans. That does give you a very distinct odor.”
The Niagara Falls Water Board’s explanation of how black water flowed into the lower Niagara River last Saturday is believable, Davignon said.