Problem $6$

Inlet and Outlets

A rectangular settling basin is $70ft(21\mathrm{.}33m)$ wide by $140ft(42\mathrm{.}67m)$ long and has a flow of $4\mathrm{.}90MGD$ or $7\mathrm{.}58cfs(0\mathrm{.}2146\frac{m^3}{s}).$ The inlet flume is an orifice channel with eight orifices that are $8\frac{1}{2}in.(216mm)$ in diameter, each with an area of $0\mathrm{.}394f{t}^2(0\mathrm{.}0366m^2).$ The difference in the elevations of the water surface at the influent pipe $($that is$,$ the center of the flume$)$ and at the last orifice in the flume is $0\mathrm{.}02ft(0\mathrm{.}0061m).$ This loss in head is due to the friction and form losses in the flume. The effluent weir plate consists of $90V-$notch weirs spaced at $8-$in$.(203-mm)$ centers. The effluent channel is $160ft(48\mathrm{.}77m)$ in length and extends across the downstream end of the basin, which is $70ft(21\mathrm{.}33m),$ and $45ft(13\mathrm{.}72m)$ upstream along each side. The effluent channel is rectangular in cross section and is $1\mathrm{.}75ft(0\mathrm{.}533m)$ in width. There is a $4-$in$.(102-$mm$)$ freefall between the crests of the V$-$notch weirs and the maximum water depth. The Manning friction coefficient is $0\mathrm{.}032,$ and there is a freefall at the effluent box. Determine: