An interceptor discharges into a rectangular grit channel. A proportional weir is provided

at the downstream of a grit channel to maintain a constant horizontal velocity. Assuming

that the weir crest is raised by $2$ cm above the channel bottom, and the weir length is less

than the channel width, design a velocity controlled rectangular grit removal facility for

peak design flow. The design average flow, peaking factor, and ratio of minimum to

average flow are $0\mathrm{.}35\frac{m^3}{s},3\mathrm{.}0,$ and $\frac{1}{3},$ respectively. The horizontal and terminal velocity,

and detention time are $0\mathrm{.}30\frac{m}{s},1\mathrm{.}2\frac{m}{m}in,$ and $60$ s $,$ respectively. The grit removal system

consists of a conveyor that raises the grit and washes it to separate the organics. Determine

the followings:

i$)$ Dimension of the grit channel with $25\%$ allowance in the length of the

channel to account for turbulence at the influent and effluent structures.

ii$)$ The opening width of the proportional weir at the maximum weir depth.

iii$)$ The weir length $($assuming the flow as $0\mathrm{.}05\frac{m^3}{s}$ for determination of weir

length$).$

iv$)$ Calculate the head over weir $($m$),$ weir length $($m$)$ depth of the channel $($m$),$

and velocity $(\frac{m}{s})$ at design peak flow, Design average flow, and design

minimum flow.