Collection System Operation for Class S
The collection system is usually the largest asset a small utility owns and the one that gets the
least attention until it fails. It is also where operators are most often killed.
Components
- Gravity sewers, sized and sloped to carry solids at a self-cleansing velocity. Too flat and
solids deposit; too steep and the pipe scours or the flow outruns the water.
- Manholes for access, direction change, junctions and grade change - and a major route for
inflow when covers and frames leak.
- Service laterals, which are a large share of total pipe length and a large share of
infiltration, often on private property.
- Force mains, which are pressurised, cannot be entered, go septic when detention is long, and
release that sulfide at the discharge point.
- Lift stations, which are the mechanical and the vulnerable pa