When pipelines are renovated, it makes sense to also renovate manholes to render the entire system waterproof. Old concrete manholes may be made watertight in two ways.
1. Building a manhole made of a PEH pipe inside a manhole.
Works are carried out on the spot or by using a welding extruder. The gap between the new and old manhole pipes are filled with either sand or concrete. Using this method, the diameter of a manhole becomes smaller.
2. Gunite technology
Using special mixes, existing manholes can be lined from inside. This method presupposes that the structural part of a manhole has been preserved or requires only minor repairs. Materials used are special mixes and mastics produced in Germany and England.