If a sewer X is to be designed to generate equivalent self-cleansing action as in sewer Y, then
1
velocity in sewer X must be equal to velocity in sewer Y
2
slope of sewer X must be equal to slope of sewer Y
3
tractive force intensity generated in sewer X must be same as that in sewer Y
4
the roughness coefficient of X sewer material should be same as that of Y sewer material