A concrete pipe $($Mannings n $=0\mathrm{.}013)$ sewer line has a slope of $0\mathrm{.}006.$ The line carries

$110$ cubic feet per second. If the minimum flow velocity to prevent solids from settling from the

sewage is $2$ ft$/$s$,$ what commercially available size pipe should be used to carry the flow and

maintain greater than $2$ ft$/$s flow velocity? Assume sewage has the same properties as water.

Concrete pipe is available in $8,10,$ and $12$ diameters and then in $3$ increments to $36$

diameter, then in $6$ increments to $144$ diameter.