I’m awake at three in the morning, and listening to a thunderstorm that clearly wanted to be an alarm clock, when it grew up. Thunder, lightning, and just a teenie-weenie bit of hail. My town **used** to have an above-ground storm sewer system, so rain always looks worse than it actually is.
The above ground system is basically a series of deep ditches through which the water flows (downhill) across town and into the river. Simple enough.
Except, of course, that the water has to get across the main streets, too. That means that the main streets should have dips for water running across them at the intersections. Some of those dips were still there, when I was a kid.
Legal Speed Limit: 35 mph.
But don’t worry. The laws of physics brought that right down around 15, unless you wanted to scrape the bottom out of your car.
As sewer systems go, it’s inexpensive, and effective.
It had to go.
So, the main streets have now been leveled for the convenience of motor cars, ’cause we’re all about the modern, here in Small Town Nebraska. (Unless the tourists ask, in which case we’re historical. Very, very historical.)
Yup. You can now drive the length and width of town at a consistent 35 miles per hour, with nary a dip in sight.
Only… they didn’t remove the rest of the above ground sewer system. They just plugged up the drain holes, drove over it a couple times, and called it good.
In a solid rain storm, the below ground system (which likely didn’t take the above ground system into account) isn’t enough to keep up with the runoff from all over town, and it backs up across the main streets. And there goes the nice, modern street, under water again.
Technically, it’s probably not flooding. But you’d still hesitate to drive a motor-car through the pools of water.
So much for flow system design.