In 11 hours, the equivalent of an Olympic-sized swimming pool of waste spilled from the City of Mission’s old sewage pipe before anyone noticed.
The spill began at approximately 10 p.m. on Thursday, May 19, according to Tracy Kyle, director of engineering and public works. By the time public works staff were able to shut off the flow on Friday, approximately 2.5 million litres had escaped.
A valve had been mistakenly left open by a contractor, Kyle said, and no one from city staff had checked. She described it as a “communication failure.”
“During construction activity, there are multiple parties on site, and communication is critical,” Kyle said. “The measures moving forward will be to make sure that when contractors are asked to do something, that we do check to make sure they actually did it.”
Three weeks prior, a 40-year-old valve, attached to the old 750-millimetre line, was used to switch over sewage flow to the new 900-millimetre line.
An emergency switch back to the old line took place on May 19, after storm damage caused an electrical failure at the Harbour pump station, which is still out of commission, according to the city.
While Mission does use a SCADA system to detect pressure drops in its pipes, the electrical issues at Harbour station caused “alarms all over the place,” Kyle said.
She added the forcemain project to twin Mission’s sewage pipe to Abbotsford is still under construction; the city has not taken over operations yet, nor is it tied into the SCADA system.
The city announced news of the spill on May 21, stating cleanup was expected to be completed by the end of the day, with further environmental assessment to follow. The affected area is approximately 1.3 acres, according to the city.
Contractors with hydrovac trucks were mobilized over the weekend to suck up the pooled waste and transport it to the James Water Treatment Plant in Abbotsford.
The 2.5 million litre figure is based on data measurement from missing sewage at the Abbotsford plant.
Kyle said there was a significant amount of standing water at the construction site prior to the spillage, making it hard to determine the amount of waste retrieved by the hydrovac trucks, or the amount which may have seeped into the ground.
But there was no direct spillage into the Fraser River, and the sand and clay surface where the waste pooled is dense and hard to permeate, Kyle said.
City CAO Mike Younie emphasized that the lands will be returned to the pre-spill state.
He said staff are awaiting the results of soil sample tests and a remediation plan over the next few weeks; a debriefing with staff will be held within a week, where liability will be discussed.
There are no estimates on the cost of the cleanup yet, as staff are still waiting on invoices related to the remediation plan, Younie said.
“We just don’t know what (the figure) is at this point,” Younie said, adding the city has reserves in place to handle these types of emergency situations.
Kenny Braich, the property owner, stated he’s had very little communication with city officials since he was informed about the spill through text. The forcemain runs through a portion of the family’s 87-acre property, which is currently for sale.
“We’re stunned and were extremely irritated and agitated about that,” Braich said. “We still don’t understand what’s going on here.”
The property is the largest in Mission’s planned waterfront development area. Braich said these types of events reflect poorly for the development community.
The forcemain infrastructure upgrade, which the city started lobbying for back in 2016, hit a milestone in February when the new one kilometre pipe was finally placed after being dredged underneath the Fraser River.