Question $3.(25$ pts$)$The sewerage system of a city has already been designed and the wastewater treatment plant has

been constructed. Calculate the total flow rate to the treatment plant and design the discharge pipe

from the wastewater treatment plant to the river.

$(q=0\mathrm{.}01\frac{L}{s}\frac{?}{m},k=2,$hdmin$=1\mathrm{.}5,$hdmax$=4m,$Vmin$=0\mathrm{.}5\frac{m}{s},$Vmax$=2\mathrm{.}5\frac{m}{s},\frac{h}{D}$min$=10\%,\frac{h}{D}$max$=65\%,$

Jmin $=0\mathrm{.}003,n=0\mathrm{.}013.)$

Note: The discharge to the river should be made such that the discharge pipe's top elevation coincides

with the ground surface.

In a $1500mm$ diameter sewer system with $0\mathrm{.}0008$ slope, an overflow structure is going to be built as shown in the figure below. The wastewater treatment plant is in the downstream of this pipe and has a capacity of $145000\frac{m^3}{d}.$ To prevent any flooding at the treatment plant, the overflow structure shown in the figure below is constructed to divert the excess flow into underground storage tanks where it will be pumped to treatment plant later during dry weather conditions. Calculate the height of the weir so that the flow over $145000\frac{m^3}{?}$ day can be diverted into storage tanks. The Manning's roughness coefficient of the pipe is $n=0\mathrm{.}013.$