Staff at greater Moncton's wastewater utility had to move fast last week to clean up oil and chemicals that someone apparently dumped down the drain.
Oil could be seen on the surface of the primary clarifier and in one of the bioreactor cells on Aug. 17, and a strong acetone-type smell was in the air, TransAqua manager Kevin Rice said.
Rice suspects the substances may have included parts-washer solution from an automotive shop or other industrial facility.
"It's a large quantity," he said. "It's not your neighbour next door dumping things down the drain in the middle of the night."
A vacuum truck had to be brought in to skim the surface, and an extra blower had to be turned on to pump more air into the bioreactor to force the volatile organic compounds to the surface to evaporate, Rice said.
He estimated the total cost, including emptying the scum tank and disposing of the hazardous waste, to be $15,000 to $16,000.
Similar incidents every 2 or 3 months
This kind of thing has been happening every two or three months, but not on as large a scale as was seen Aug 17.
It could be deliberate or accidental, said Rice.
He noted that businesses such as machine shops and other industrial equipment operators are required to have systems in place to prevent hazardous waste from going into city drains.
But "if they had a real busy week and weren't keeping an eye on the water separator, it's possible they might have missed a maintenance check," he suggested.
Rice said there are ways to track down the source of the dumped substances, such as asking shops that do auto body work or change oil to provide records for their oil/water interceptors and hazardous chemical disposal.
Another option, he said, is to "pop manholes" at potential contamination sites and look for stains on the pipes.
If a particular location is suspected, a device can be placed inside a line to collect samples of what's being released there.
And it's not just industries and businesses that should take note. Individual homeowners should also avoid dumping oil and chemicals down the drain, said Rice.
Those substances should be disposed of through the city's waste management facility.
Rice said the ongoing incidents are a real cause for concern. In the past two years, he said, $90 million has been spent on system upgrades to switch to more biological treatment and away from chemical treatment.
This time, by the time the problem was discovered the pollution had almost killed off the bioreactor's good bacteria, which is used to treat effluent before it's released into the Petitcodiac.
But the work that's been done over the last week has been effective, he said, and the bacteria are starting to recover.
Oil and chemicals aren't the only thing people shouldn't be dumping down the drain.
Food waste is also a concern, said Rice, who urged people to stop putting food down garburators.
Food waste degrades in the sewer system and sucks out oxygen, which is important to bioreactor bacteria.
More oxygen then has to be pumped in, at a cost.
They also see a lot of grease, which can feed "bad bacteria" to the point that it outnumbers the "good bacteria."
And people continue to flush sanitary wipes, which aren't really flushable regardless of what it says on the packaging.
"Changing some behaviour would be very helpful," Rice said. "We wish for the public to be reminded of the three Ps: Pee, poo and toilet paper should be the only things that go down the drain."