During a rainstorm two weeks ago, some Craigleith residents ended up with sewage backing up into their homes.
The Town of The Blue Mountains confirmed the flow of wastewater through a pumping station in Craigleith was excessive, and the two pumps failed temporarily.
Because wastewater was not flowing through the station for a time, it backed up into people’s homes.
The town’s wastewater department received four calls on Sept. 22 about the sewage backups.
According to the town, the rainfall that day was near historic levels for the area.
Though stormwater is not processed through the town’s water treatment plant (it's different drains and pipe infrastructure), storm events can increase the flow through the pumping stations and the treatment plant because of rainwater getting into damaged pipes or through unauthorized connections to the wastewater system.
According to the town, there’s an unknown number of homes where the sump pump, and/or eaves downspout, and/or other stormwater management infrastructure is connected to the town’s wastewater system.
Town data captured during the storm indicated flow rates of 225 litres per second at the Craigleith pumping station, the typical levels at that station are between 10 and 35 litres per second.
According to the town’s director of operations, Shawn Carey, the station is equipped with two 100-horsepower pumps and a backup generator.
“One pump is adequate to handle flow from the station, the second pump provides 100 per cent redundancy,” said Carey in an email to CollingwoodToday.
He said the flow on Sept. 22 exceeded the pump capacity and the first pump failed because of an electrical issue caused by a circuit short. The second pump failed because of a motor overload. The pumps were repaired and restarted the same day.
“In addition to pumping, the town also hauled 500 cubic metres of sewage from the main Craigleith pumping station directly to the town’s wastewater treatment plant,” explained Carey.
This wastewater would normally be sent to the treatment plant via the pumping station.
The treatment plant, according to Carey, is a large-scale plant relative to the service area and operates around 40 per cent capacity on a typical day.
It has a lagoon system where the excess flow can be diverted if the flow rates are excessive.
In Collingwood, when the wastewater treatment plant receives excessive flows that exceed capacity, untreated wastewater overflows to mix with treated water and is sent to Georgian Bay. This overflow measure allows wastewater to bypass the plant and dump into the bay untreated.
Carey said neither the Craigleith Wastewater Treatment Plant, nor the Thornbury Wastewater Treatment Plant is equipped with pipes to bypass the plant into the bay.
“Through the available capacity and the lagoon system, the Craigleith Wastewater Treatment Plant is able to handle heavy rain events,” stated Carey.
The pumping station, however, is not equipped with an overflow safety measure.
Carey said the town is evaluating the status of the pumps and equipment at the main Craigleith pumping station to determine if and when they need to be replaced.
Mayor Alar Soever said the town “should not have seen the volumes” of wastewater that went through its system on Sept. 22, and noted it indicates “excessive inflow and infiltration.”
A statement from the town indicated the cause of the event is being investigated, and the town will be conducting smoke and dye tests in the future to find unauthorized connections to its wastewater system.
Smoke testing involves adding smoke to a specific section of the sanitary sewer system and then watching for the places the smoke seeps out of the ground or out of residential eaves troughs or downspouts.
The former would indicate a leak in the wastewater pipes, the latter would indicate an unauthorized connection of stormwater collection infrastructure to the town’s wastewater system.
“The smoke is odourless and safe for use around people, pets, and personal belongings,” said Carey. “The smoke will dissipate within minutes.”
Dye testing is similar, but involves inserting dye into outdoor drains. If it appears in the sewer, it confirms an unauthorized connection to the sanitary sewer system.
If such a connection is found, a homeowner is told to remove it as per the town’s sewer use bylaw.
“There is the potential for significant fines,” noted Carey. “Every homeowner can help by confirming that their property does not have an authorized connection to the sanitary sewer system.”
The homes affected by the backup were near the main Craigleith pumping station.
The town would not comment on any questions about insurance claims from homeowners related to the sewage backups. But Carey confirmed the town received four phone calls regarding sewage backups, and the town statement indicated staff have been in contact with affected residents.