Faulty storm sewer gates factored into Brampton flood: report

A pair of malfunctioning storm sewer gates played a part in the flooding of Brampton’s Churchville area last year that saw dozens of homes evacuated or damaged.

That’s one of the findings in a report from the City of Brampton on what led to the rising waters in the Credit River last February that impacted between 50 to 100 households.

Warm weather and rain led to rising waters and flooding across Brampton on Feb. 17, 2022, especially in Brampton’s historic Churchville area. No injuries were reported due to the flood, but many homes and city properties were damaged as rising waters reached up to about six feet deep in some areas.

But a new report from the City has shed light on what caused the waters to rise, finding three factors that were “major causes” of the flood – an ice jam in the Credit River, the floodplain, and the failure of two storm sewer outfalls.

The report found that previous policies allowed development within the Churchville floodplain, where high water from the Credit River will move into the low ground of the neighbourhood. An ice jam also formed at an elbow of the Credit River, causing peak water levels in Churchville to rise from what staff called a “1-in-10-year flood”  to that of a significantly higher 1-in-100-year flood.

But the report also found that two storm sewer outfalls failed to close, which “allowed flooding in the Credit River to back up into the roads and properties behind the berms and floodwalls.”

Staff said the failures occurred “due to jammed flap gates and bolts securing manhole lids being sheared off.”

“These storm sewer outfalls failed because gates installed to prevent water from the Credit River flowing into the storm sewer system when river levels are high did not close properly,” The report reads. “Water flowing into the storm sewer system from the river also caused manhole covers to pop off.”

The City says those flap gates have been replaced with new backflow prevention valves “that are less prone to clogging or jamming,” and staff and contractors have inspected storm sewers, culverts, and flap gates to identify maintenance needs.

Storm sewers and culverts have also been flushed, which the City says will help reduce the risk of clogging the valves.

Staff said last year that damage estimates to City-owned infrastructure due to the flood was approximately $1 million – far below the $15 million threshold for Brampton to qualify for disaster funding from the province.

The report did not give a dollar amount for the overall flood damages to City resources, or the cost of repairing, replacing and maintaining the storm sewer.