On Wed, 21 Dec 2005 22:42:25 GMT, Speedy Jim wrote:

j probose wrote:

I am planning the installation of a waste pipe (either 3" or 4") over a
distance of 46 feet. The drop in elevation over that distance is 30",
which I calculate to be aprx .65 inches per foot (instead of the nominal
.25 inches per foot). Is .65 inches per foot too much? I COULD
excavate more at the high end, and come closer to the .25 inche per
foot, but is it worth the extra effort? Also, does the pipe size make a
difference?

The only problem with too much slope is that
velocity will be higher and solids *may*
tend to settle out.


Jim


I've heard this all my life. Not wanting to start a war but can
someone prove it is true?

I just don't buy it; for a couple of reasons. Sediment doesn't settle
out in a flowing stream. It only settles in eddies or broad flat
stretches with slow flow.

Even if it is true, the second flush liquid will push the first flush
solids.

And the ultimate slope, a vertical drop, doesn't seem to be a clog
problem due to settling.