Why do manhole covers explode during heavy rain?

Thunderstorms in the Montreal area on Thursday evening caused 40mm to 60mm of rain within three hours, thus putting a strain on the metropolitan infrastructure.

Read more: Lightning strikes two families on street: “Big explosion, house on fire”

Read more: In pictures | Geysers and major flooding in Montreal

The blue line of the metro was completely stopped, the other lines were stormed, the streets were flooded, bolted manholes, flooded foundations, the list of effects was long.

According to a Montreal spokesman, yesterday’s situation was exceptional.

“70 and 50 mm in the west of the city. A difficult situation, a very difficult one, ”explains Philip Saborin in an interview with Le Quebec Matin.

“The waterway network in Montreal, especially in the center of the island, is connected. The wastewater and rainwater are sent together to the treatment plant.

While 99% of the city could be evacuated in the usual downpour, yesterday’s network was actually overloaded.

“Yesterday, 50% of the water was overflowing on the shores. It works just like your bathtub. If you forget to turn off the tap the water will overflow. How does it work? ” Saborin explains.

About 40 houses were damaged by the sewer. Owners can file a claim in the city.

Several videos show manhole covers flying in the air under the pressure of water. What is the reason for such an event?

“It pushes the air by the force of the water coming into the sewer. The force is such that, at least in two places yesterday, the sump heads did not resist,” notes Philip Saborin.

He promises a future: the city builds new reservoirs to catch rainwater and store it to avoid such regression episodes.

“Thanks to the existing basins, we have purified the water as much as possible, but there is obviously zero risk. On the contrary, this is not a reason to reduce our efforts.

In addition to the retention beds, natural pits are dug in the streets to control all the water coming in from the rain, which will give a lot of headaches to the citizens.

In addition to the heavy rains, hailstones of 4 to 6 cm fell in Lachute and Deux-Montagnes, adding to the ecosystem of Canada.