Treatment plant cleaning up its act

“In the spring, at the end of the day, you should smell like dirt.”

Margaret Atwood wrote that, and many Beachers will agree.

But some who live north of the Ashbridges Bay Wastewater Treatment Plant may have no idea how they smell at the end of a spring day, given how the wind tends to carry odours from the sewage plant into their yards and windows at that time of year.

This spring, however, staff at Toronto Water hope they get fewer odour complaints because a key part of the plant’s $375-million odour control program is nearly done.

“I think there have been some really good improvements made,” says Frank Quarisa, director of wastewater treatment for the City of Toronto.

“The test is always that first part of the spring.”

In September, Quarisa said crews began installing a new system that basically draws odorous air out of the plant’s aeration tanks.

The covers on those tanks are decades old, and were allowing foul air to seep into the neighbourhood.

Even as the new air-drawing system was going in last fall, Quarisa said staff working along the plant’s north service road, a typical problem spot, noticed a marked drop in odours.

The air-drawing system follows odour control work done more than a year ago at the plant’s two pumping stations by the Tubs and Gee Gage rugby field north of Lakeshore Boulevard, which Quarisa said were upgraded first because they are so close to homes.

One of the next steps is an $11-million pilot project to upgrade one of the plant’s 11 aeration tanks, which date back to the 1950s.

“The idea is to do a complete retrofit of what is really the core of the biological process in that facility, really in any wastewater plant,” Quarisa said.

The drum-shaped tanks on the west side of the plant essentially bubble oxygen through partially treated sewage and stormwater to stimulate the microbes that digest organic matter. The upgraded tank will get an airtight cover, new mixers, new controls, and a fine-bubble diffuser.

Karen Buck, a Beach resident and long-time member of the plant’s community liaison committee said the upgrade is welcome news.

“We had asked for fine bubbling in the aeration tanks for years and years and years,” said Buck, noting that the coarse-bubble diffusers the plant uses now are antiquated and have “terribly odorous” results.

Quarisa also said the coarse-bubble diffusers are badly outdated.

“Really, an aeration process shouldn’t be as odorous as at this facility,” he said. “Basically, if you go across Ontario, I don’t think there are too many coarse-bubble aeration systems left.

“Ashbridges Bay, being the largest of our facilities, has been the most costly one for us to tackle,” he said.

Quarisa also noted that when fine-bubble diffusers do go into all the tanks, the plant will need a lot less electric power to run because they are much more energy efficient.

All the odour control projects that are underway or about to be tendered at Ashbridges Bay should be done by 2017.

Quarisa said more odour control could be done at that point, but by then the plant may have already reached its end goal for the program – to have no odours drift beyond the plant’s fence line.

Until then, Buck said residents should not hesitate to phone the city with odour complaints.

“People who are experiencing odour from the plants should call 3-1-1 because mostly, the city works on complaints,” she said.

Located at the foot of Leslie Street, the Ashbridges Bay plant is the largest in Toronto. The plant handles 818,000 cubic metres of wastewater per day, serving a population of about 1.5 million people in the sewershed bordered by the Humber River, Highland Creek, Steeles Avenue and Lake Ontario.

---