Last summer, our intersection only had substantial flooding in the worst rains AFTER the drains had gotten blocked by debris. This spring, the vaults under two drains were collapsing and were rebuilt. The rude surprise we got afterwards was that the city crew had added rain blockers. Now those two drains flood the intersection during every storm that generates significant rain (more than 1/2").
We have one 65-gallon rain barrel in our back yard, which is mostly used for watering gardens. There hasn't been an opportunity to use much of the water between storms, because the gardens haven't needed watering, so it hasn't helped much in reducing the amount of water flow to sewers in the most recent storms.
We've had several storms in the past month that each dropped an inch or more of rain in a very short time. Yesterday morning's storm left 2.5" of rain in our rain gauge in less than 2 hours.
As you can see from the story dates on this item and this one, this problem has been going on for several years now. And after years of using us as guinea pigs, why can't they get it right?
Tell me - do you consider this bit of engineering a success if it slows the flow of a torrential downpour into sewers to the point where all that water backs up over lawns, right up against houses and into window wells or walkout basement stairs? Do you think that having hours of standing water up over the curbs, making streets impassable, is a success? When the ground is as saturated as it's been lately, streets this badly flooded have increased the number of flooded basements.
Some of my neighbors at the low point on our block had everything in their basements ruined by Sunday morning's storm. Many who were not at low spots had a lot of water in their basements. Even with rain blockers, half the block got sewage coming up through their drains. The additional rain blocker-induced flooding at our intersection (high point on the block) ran down to the low point, making things worse for our neighbors in the middle of the block.
I took a bike ride around the neighborhood this afternoon. The high water marks (shown by flood debris) are 2 to 5 feet over the curbs in many places. There are several locations within a mile of our house where the high water marks are anywhere from 10 to 30 feet over the curb. At our intersection, it was 10 feet over the curb. In many places, would have taken very high curbs (1 foot or higher) to hold all of that in the streets.
Since the technology for permeable pavement exists, might it make sense to explore this option more often instead of rain blockers?
In many city neighborhoods and suburbs, the amount of impermeable pavement keeps increasing. People build concrete patios, make small patios bigger, or sometimes cover all of their lot with concrete right up to the house. We have many more big box stores with enormous parking lots, generating huge amounts of runoff. All that water has to go somewhere.
If many of those parking lot and patio areas could be replaced with permeable pavement (in locations where the soil would absorb water), some or all of the water that is currently shed as runoff could be absorbed into the ground, greatly reducing the amount of flooding and the amount of water requiring sewage treatment. Upfront costs would be higher, but the cost of treating all that sewage and dealing with all the property damage would be greatly reduced.
Right now there are way too many mounds of ruined furniture and other items waiting for the garbage men. Some neighbors already have contractors lined up to tear out ruined drywall and rebuild. Many of these homes haven't experienced significant flooding in many years, but now do since rain blockers have been installed. Does it sound like rain blockers are the right answer, unless there are other modifications made to prevent the rain blockers from increasing flood damage? What's your $0.02?