It didn’t just rain, it poured for 24 hours Wednesday to Thursday in Barrie.
The remnants of Hurricane Beryl dumped 68-82 millimetres of rain on the city, depending on location, between July 10 at 5 a.m. and July 11 at 5 a.m., said a city official.
“Based on historical averages, we would only expect to see this magnitude of storm about once every five years,” said Tom Reeve, the city's senior project manager, engineering. “This is a fairly significant amount of rain for 24 hours.”
A network of five rain gauges are maintained across the city and data is collected in five-minute intervals. It’s used to support planning, design and operation of city infrastructure.
There was slightly higher rainfall recorded at city gauges in the south of Barrie, but overall the rain was fairly consistent across Barrie.
Given Barrie’s size, it isn’t unusual to have variance in the rainfall across the city, Reeve said.
He said the rainfall came in two back-to-back events.
The first one started near 5 a.m. Wednesday, lasting until 1 p.m., with approximately 33 mm of rain during that time. There was virtually no rain from 1 p.m. until 7 p.m., less than two millimetres.
The second rainfall started at 7 p.m. Wednesday and ended near 3 a.m. Thursday morning. Barrie received as much as 47 mm during that time, with the two hours from 7 p.m. to 9 p.m. seeing 25 mm alone.
“The city’s storm infrastructure is designed to handle storms like this,” Reeve said. “Rainfall events are collected in catch basins and storm sewers and conveyed to stormwater ponds and creeks and Lake Simcoe.
“During the most extreme events, we expect to have some water flowing on the road, in the gutter, which is part of the stormwater infrastructure too,” he said.
Reeve said Wednesday and Thursday morning, the city’s stormwater system performed well, with no reports of major flooding. He said city operations staff watch weather forecasts and proactively maintain key infrastructure to be ready for these events.
“Roads are also patrolled during and after events to make sure the system continues to function well,” Reeve said.
Barrie has 440 kilometres of storm sewers which collect rainwater and surface water runoff, mostly from roads and parking lots, into natural channels and catch basins or storm grates, transporting it to various points in Kempenfelt Bay.
The system also includes 1,082 culverts, 129 km of ditches, 103 km of watercourses, 93 stormwater ponds and 100 manufactured treatment devices - prefabricated structures that use technology to help remove pollutants from stormwater runoff.
Stormwater infrastructure is required to protect people and property from flooding and bodies of water - such as Kempenfelt Bay - from any harmful stormwater runoff.
The city’s stormwater assets include infrastructure that can be seen — ponds, ditches, the water courses — and those unseen, such as storm sewers and manufactured treatment devices.
