The nature of sewage pipelines is that they often create a chemically-active atmosphere which will contribute to the deterioration of not only the pipe, but also to the manholes which give access to the pipes.
ADPS is often called upon to rehabilitate manholes so that they are safer for workers to use.
The process will normally involve cleaning the inside of the manhole, repairing any damage and leaks and re-sealing the interior with a protective mortar covering.