Failure: City takes stock after largest infrastructure malfunction in memory
It seemed harmless enough — water had begun to pool in the parking lot of the Arrow Transportation Systems operation on Mission Flats Road.
City crews were contacted about the water on July 13 and quickly found the source of the problem.
One of the two sewage lines near the Domtar pulp mill, which handles sewage from across South Kamloops, had failed and backed up.
It would turn out to be the origin of the biggest infrastructure failure in the city’s history.
That afternoon, crews attempted to drain the line, which had filled with gravel and sewage. But, each time, the main would fill back up again.
Underneath Mission Flats Road lie two sewage mains — one large line and one small line.
It was the smaller main that failed.
Just before another truck could come in and work on the other side of the sewer main to unplug the problem, the road collapsed.
That failure blocked both sewage lines that lead to a nearby lift station.
Though the city has 50 such lift stations throughout town — depots that help pump the sewage to its final destination, the treatment plant on Mission Flats Road — this specific station by Domtar is one of the two largest in the system.
The city quickly managed to get one of the lines working, while repairs were being done to the problem pipe.
But, the situation was only about to get worse — and what occurred two days later, on July 15, is now part of an investigation by the city into the cause of the entire incident.
The lift station in question is a couple of floors tall and, from the outside, looks about the size of a house.
It’s divided in two — one side filled with wet sewage and another dry area 40-feet in depth, containing four pumps.
Those pumps push the sewage to what is called a force main, which then delivers the waste to the treatment plant.
Each pump has an isolation valve that blocks the sewage from entering the dry area of the station.
At about 3 p.m. on July 15, the dry side of the station started to fill with sewage.
While exact details as to why the dry side of station started to flood remain sketchy, city officials note gravel had made its way into the pumps.
According to David Duckworth, the city’s director of public works and sustainability, maintenance crews were working on one of the pumps at the time.
It appears as though, for whatever reason, the isolation valve may not have been closed.
“There are lots of questions we don’t have answers to yet,” Duckworth noted.
Within 20 minutes, raw sewage filled an entire floor and showed no signs of stopping.
The city was now on the verge of an environmental disaster.
As the torrent of sewage continued to flow, the liquid was backing up along both mains and bubbling up through manholes along Mission Flats Road.
The city typically deals with 30,000 cubic metres of sewage a day, more than half of the volume through the two mains that were now out of commission.
City crews needed a response — and quickly.
The only solution was to divert the waste to a nearby drying bed, belonging to Domtar and located across the road.
That evening, with permission from mill officials, crews built a makeshift trench leading from the lift station to the detention pond.
It was a several-hundred-metre path of pure waste — but had the pond not been there — the sewage would have had nowhere else to go but into the Thompson River.
“We were pretty fortunate. We were very lucky,” Duckworth said, crediting Domtar with helping to save the day.
For the next three days, every vacuum and septic truck in the city was at the site, pumping as much sewage to the treatment plant, while the remaining sludge was funneling into the pond.
The city also brought in expensive pumping machines from Vancouver to help.
On Friday, July 22, Mission Flats Road and the landfill were reopened to the public after a week being closed.
Sewage is moving properly again, but the smell from the waste is still in the air as city crews begin remediation work at the site.
It’s expected to take months to completely clean up the Domtar pond.
Meanwhile, the city is just beginning its investigation into the incident.
Duckworth said the probe will attempt to determine the entire chain of events, from the original break in the main to the time when the lift station had to be shut down.
“We’re looking at all the steps our staff took throughout to try and determine if there are things we can do differently in the future,” he said.
“I think a few small events accumulated to one large event.”
The investigation is expected to take two weeks, with a report to city council to follow.
Duckworth said the report will also address if there is a need to purchase additional equipment, such as backup pumps, to deal with any future situations.
The cost of the entire incident is also unknown, but part of the bill will include remediation work on the Domtar pond.
When asked if the tab could top $1 million, Duckworth said it was unlikely, but he could only offer a guess.
The cost of the entire incident is expected to be covered by a reserve fund meant for these types of infrastructure failures.
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