Manhole rehabilitation

Manhole rehabilitation covers the structural and watertight restoration of an inspection chamber, including benching, channels, walls and cover slab. Techniques include high-pressure cleaning, application of polymer-modified mortars, epoxy linings, mini liners on incoming connections and replacement of corroded ironwork. Many London Victorian manholes have lost mortar pointing and suffered hydrogen sulphide attack, making infiltration and structural deterioration common. Works are typically carried out under the WRc Sewerage Manual and Sewerage Construction Methods, with watertightness verified by visual inspection and infiltration monitoring after rehabilitation. Where a chamber is being adopted by Thames Water, the rehabilitation specification will need to satisfy Sewers for Adoption Edition 7 or the equivalent code of practice in force at the time.