wrote in message
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I want to put a drain pipe under a sidewalk for rain drainage. I am
trying to determine the volume of a 6 inch pipe and a 4 inch. I know
that one 4 inch wont be enough, but am wondering if TWO 4 inchers
carry as much or more water than a 6 inch pipe. I have never been any
good at mathematics. I think I have to multiply 4 or 6 by 3.14, but I
am not sure. I will either use a 6 inch or two 4 inchers, which ever
holds more water. Or I may even go to an 8 incher. Alot of water runs
down the hill and keeps putting mud over the sidewalk. I need lots of
drainage volume.
Can anyone help.
Assume similar pipe types such as tile or concrete and a slope that is the
same for both the 4inch and the 6inch pipes.
The maximum (pipe full) flow for the 6inch pipe will be about 15 percent
greater than for the pair of 4inch pipes.
I computed on the basis of Manning's Formula. I'll spare you the details
but you can Google it if you're curious. Been a long time since I did a lot
of that as a young engineer so I checked a nomogram in one of my old
handbooks and got verification. Interesting exercise but I had to scrape
through a lot of mental rust.
SJF
