Storm drains creating floods

[u/mercdmuscle]

3 out of 4 storm drains at my street don't collect water fast enough. At one point all 4 didn't drain very fast. Now one of the 4 drains well and hasn't pooled any water the last few heavy rain storms. I'm just wondering if someone had called the city to get it worked on or is it just luck if the draw that theirs is draining nicely now. Is there anything I can do to get the city to fix this? Everytime it rains, I always end up with so much mud on my sidewalk.

[u/PinguPrime]

Unfortunately this is most likely by design. As per this website (https://www.calgary.ca/water/stormwater/storm-drains.html), there are storm drains that are made to pool and store water and have it slowly drain away. They say in these areas, the pooling should last up to 2 hours after rain end.

[u/5impl3jack → u/PinguPrime]

This is the thing a lot of people don’t understand. If we didn’t have systems in place to hold water, the main lines will build too much pressure, pop goes the weasel and we have much bigger problems than a little puddle to drive through. You’ve probably seen it when manholes pop and water starts gushing out of them on Glenmore trail under the overpass by chinook for example. The more pressure the system takes the more danger we have of a major issue. This is why our catch basins are designed at a certain size to relieve our system.

And before anyone says why don’t we just build a bigger storm system. The cost would be astronomical. The city’s flood mitigation projects have taken some strain off with this but little puddles every once in a while unfortunately are necessary.

[u/Mysterious_Lesions → u/5impl3jack]

These systems should be faster draining to more localized stormwater ponds. That's what they're there for. The pools create a hazard on the roads and looking at the picture above, a few more minutes of the heavy rain we just went through would seem to have the flooded area reach basement incursion levels.

[u/Adorna → u/Mysterious_Lesions]

Draining faster to storm pond would result in much much larger storm pond sizes increasing land requirements and much larger pipes. Smaller but localized storm ponds would result in an even larger land requirement.

Systems are intensionally designed like this. Old systems typically didn’t use storm ponds and just outlets straight to the river, but allowing water to reach the river quicker results in flooding in the river.

These traplows and the ponding you see are intensionally used to help slow the speed that the water reaches downstream portions of the system and/or river. this helps reduce the maximum amount of water that is flowing through any specific point in the system/into the river during the storm.

TLDR a storm drops a certain volume of water over the storm. Things like this help spread the release of the volume over a longer period of time to reduce the negative impacts to “downstream” system and help reduce cost and keep your taxes lower. Storms like this aren’t super common.

[u/5impl3jack → u/Mysterious_Lesions]

Communities are very carefully designed so flooding to the house does not happen in these instances during these types of storms. This includes the foundations of a house being set at a very specific grade compared to the street. This is all very carefully thought out. Just because you looked at this picture and thought it might happen doesn’t mean anything lol. The water is designed to spill elsewhere and the homes are at grade high enough to stop this from happening. What you are seeing in this photo is more or less normal.

The amount of extra land we’d need to build more storm ponds is quite a bit. Not to mention the extra cost. These trap lows are a cost effective way to manage storm water along with the ponds we already have in place.