Every district has at least one - a nightmare of a pumping station.
A pumping station that is always subject to clogging. A pumping station that requires more time and attention than all the other stations in the district put together. Places that demand all too frequent emergency calls. It could be the remains of a plastic bag, rags, or a pair of nylon tights. If you are unlucky, the material will rap itself around the impeller of a centrifugal pump, putting it out of action.