The material selected for sewer( Malak Water trap) should have:

---

Detailed Solution:

Manning equation V = R^2/3. S^1/2/N, where N is roughness coefficient or manning coefficient

R hydraulic mean depth= A/P, where A cross section area, P is wetted perimeter

S slope of bed

value of N for cement is 0.011, wood planed = 0.015

concrete 0.012