Design Of Sewers And Sewerage System – GATE CE Environmental EngineeringPractice Questions & PYQs

A system of seven river segments is shown in the schematic diagram. The $\mathrm{R}_{1}{ }^{\prime} \mathrm{s}, \mathrm{Q}_{1}{ }^{\prime} \mathrm{s}$ , and $\mathrm{C}_{\mathrm{i}}$ 's ( $\mathrm{i}=1$ to 7 ) are the river segments, their corresponding flow rates, and concentrations of a conservative pollutant, respectively. Assume complete mixing at the intersections, no additional water loss or gain in the system and steady state condition. Given : $\mathrm{Q}_{1}=5 \mathrm{~m}^{3} / \mathrm{s} ; \mathrm{Q}_{2}=15 \mathrm{~m}^{3} / \mathrm{s} ; \mathrm{Q}_{4}=3 \mathrm{~m}^{3} / \mathrm{s} ; \mathrm{Q}_{6}=8 \mathrm{~m}^{3} / \mathrm{s} ; C_{1}=8 \mathrm{~kg} / \mathrm{m}^{3} ; C_{2}=12 \mathrm{~kg} / \mathrm{m}^{3} ; C_{6}=10 \mathrm{~kg} / \mathrm{m}^{3}$ . What is the steady state concentration in $\mathrm{kg} / \mathrm{m}^{3}$ , rounded off to two decimal place) of the pollutant in the river segment 7 ? ____

Crown corrosion in a reinforced concrete sewer is caused by:

Assertion [a]: At a manhole, the crown of the outgoing sewer should not be higher than the crown of the incoming sewer. Reason [r]: Transition from a larger diameter incoming sewer to a smaller diameter outgoing sewer at a manhole should not be made. The CORRECT option evaluating the above statements is :

Determine the correctness or otherwise of the following Assertion [A] and the Reason [R] : Assertion :The crown of the outgoing larger diameter sewer is always matched with the crown of incoming smaller diameter Reason : It eliminates backing up of sewage in the incoming smaller diameter sewer.

An existing 300 mm diameter circular sewer is laid at a slope of 1:28 and carries a peak discharge of 1728 $m^{3}$ /d. Use the partial flow diagram shown in the given figure and assume Manning's n = 0.015 At the peak discharge, the depth of flow and the velocity are, respectively