The wastewater-treatment plant in Merritt was built in the kind of place that almost all such plants in B.C. – indeed, in North America – are: on a flood plain, close to water. In this case, the Coldwater River.
That kind of positioning allows all the water from thousands of toilet flushes, dishwashers, showers and laundry machines, along with storm water, to run to it by gravity, rather than having expensive pumps push the flows to a plant on higher ground. And it means that, once the water is treated, it’s only a short distance to travel to a large body of water that dilutes it even more.
The disadvantages of that location were laid bare earlier this month when the Merritt plant failed during the catastrophic flooding as the river washed over it – “overtopped it,” in engineering wastewater lingo.
That not only made it non-functional, but also produced a situation where sewage mixed with river water and then spilled out over the town. That, in turn, meant surface water made its way to the underground sources of clean drinking water. And that, along with contamination from hydrocarbons, resulted in a do-not-use order for all water in Merritt, on top of all the other flooding problems that required the entire 7,000-person town to be evacuated.
That’s not something that can be easily fixed for Merritt, or for the other 559 wastewater-treatment plants in the province, say engineers, city administrators and wastewater specialists.
“I think we’re going to have to rethink the process and figure out how to adapt. But sewage has to be close to where you’re discharging into a body of water. And it would be an enormous task to change everything. Every home in the province has been built on a gravity system,” says Doug Allin, the chief administrative officer of Spallumcheen township and an advisory committee member with Asset Management BC.
A University of British Columbia engineering professor concurs.
“There’s so much infrastructure built already that it’s difficult to change,” Pierre Bérubé said.
In Spallumcheen, one of the last settlements in the Okanagan to add a wastewater plant, there’s been a chance to try something different.
“It was part of our decision-making criteria to not put it in the flood plain,” Mr. Allin said.
That option isn’t possible for the other existing plants, since all of the entire sewer piping system is geared to their current locations. And it wouldn’t necessarily solve all the problems anyways.
In Princeton, where the wastewater plant came dangerously close to failing, the plant is not in the flood zone. But the three pumps that force the gravity-fed wastewater from all the homes up to the plant ended up being almost non-functional when the river flooded into the area.
For both towns, a little-known network of specialists in wastewater plants has jumped into action to help. Through an already existing Vancouver-based program called Environmental Operators Certification Program, wastewater specialists signed up to a new volunteer effort this year to assist any community with troubles, starting with the forest fires.
City crews from Kelowna and Kamloops have gone in to help Merritt dig the plant out from under silt and mud and get it working again, says the program’s chief executive officer, Kalpna Solanki. Another crew from the Regional District of Okanagan-Similkameen was assigned to Princeton.
The city managed to move the Coldwater River back to its original course Tuesday, using heavy equipment building berms to rechannel it after it had moved over a block toward the plant during the flood. Sewage treatment is again under way.
But that’s a temporary fix, and more permanent solutions must be found once the emergencies are over. Some are suggesting that cities begin slowly adapting their systems to help prevent similar catastrophes, which can and have shut down entire towns. The main alternative is to stop sending all used water to treatment plants, creating what engineers call a decentred system.
“Not everything needs to be pumped away,” Prof. Bérubé said. “It could be treated at smaller facilities. Typically, you would still need to use an engineered system, but then it could be discharged into the local environment. The intent is keeping it local.”
He added that often conservative regional or city governments are reluctant to consider such a move, believing it will be more expensive than having one large plant with economics of scale.
“But that economy of scale isn’t there for a big plant that’s flooded,” he said.
A senior engineer at Aecom Construction says that kind of decentralization is likely a long ways off. It will depend on the creation of new technologies that, for example, allow for the separation of urine – a particularly damaging product because of the hormones and other substances it contains – and accommodate homes where greywater from sinks, washing machines and showers could be recycled almost on site, while actual sewage is pumped away.
“I think maybe in 100 years it might be there with the new technologies,” said Rick Bitcon of Aecom, which is working on upgrades to Metro Vancouver’s Iona treatment plant.
Metro Vancouver did not experience any troubles during the floods, in spite of increased volumes at the five regional plants.
But city engineers are still looking at ways to lighten the flow of water through sewer pipes to the regional plants, in anticipation of more severe weather events.
Vancouver, which along with New Westminster still has some old sewer infrastructure that takes in storm water as well as sewage, has already made some changes in recent years.
The runoff water from the Stanley Park Causeway, for example, is now directed to a retention pond and, once it has cleaned itself through settling and exposure to air, flows into the nearby Lost Lagoon. A similar system is used at Hinge Park, near Olympic Village.
“The more local you can do that, the better,” said Vancouver’s head of engineering, Lon LaClaire.
There are similar efforts elsewhere.
Dockside Green in Victoria has a small treatment system onsite, while both Powell River and Gibsons are using local solutions – lagoons in the forest, existing swamp areas – to treat some water, says Wally Wells, the executive director of Asset Management BC.
“They’re using the natural environment in a very effective way.”
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