This was the first paragraph of my first post about the parking lot that
"How much water can a drain beside the road that is 4 inches high by 6
feet long, that feeds a 22 to 24" diameter pipe that is 50 feet long
remove from the parking lot? It used to be as much as could rain on
109 townhouses, plus their yards and streets, but now it doesn't seem to
be that much. Or it rains move than it did before. "
A couple days ago it occured to me. Arithmetic!!
The drain opening is 4" x 6' = 4 x 72 sq.in. = 288 sq. in.
The pipe is at least 22" in diameter, = pi x 11^2 = pi x 121 = 380
sq.in, in cross section.
So of course the drain opening limits what the pipe can carry.
288/380 = 0.76. The area of the drain opening is only 3/4s the
cross-section of the pipe.
This would all be different if the drain opening were 8" high like it
was 35 years ago when the n'hood was built. But two paving contractors
putting down asphalt have laid the asphalt right up to the drain, taking
off about 3 or 4 inches
Is there any reason the length of the pipe, 120 feet (not what I said
before), could provide resistance**
to water flow, so that the ratio
right above would not be correct. After all the narrow part of the
drain opening is only an inch long, and the pipe is 120 feet. If these
were two wires of different diameter, the unequal lengths would make a
big difference. OTOH, does it matter
I can't google because I don't know what resistance (in electrical
circuits) is called when dealing with water in pipes. ??????
The 2nd repaving was not the whole n'hood, just 2000 square feet that
needed repair. Still it was a real paving company. Shouldn't they
have known better than to pave riight up to a rain water drain?
Doesn't that mean they should come out and cut out the drain obstruction
for free? That's 5" horizontal (towards the roadway) x 4" vertical x
6 feet wide, the width of the drain. (only half of the thickness did
they do.) How long could that take, an hour?
Then how long would it take to resurface what's left behind where they
cut stuff out? That is, what about resurfacing the blacktop that is
left, the bottom of the hole and especially the sides of the hole they
cut. Won't they crumble if something is not done? Is it necessary?
The equivanlent of rolling over the flat part of the road with a steam
roller, or whatever they are called now.
That was not done before so of course we never paid for it. How long
would that take them?