The manholes and pumping stations of the Island’s sewer network have suffered structural degradation from prolonged exposure to hydrogen sulphide (H2S) attack. When this gas comes into contact with water, sulphuric acid is formed which eats into the concrete and gradually erodes the concrete which ultimately leads to complete failure of the structure. Over the years, several products have been used to attempt to arrest the erosion and restore the strength of the structures. None have been successful until now.
Brenwal provide a solution which completely re-lines the inside surface of manholes and pumping stations and restores their structural integrity. The system involves creating a 3D model of the inside of the structure by means of lidar scanning. Bespoke liners are then fabricated in polyethylene and they are welded in-situ to provide a fully gas tight internal lining which prevents the sulphuric acid from coming into contact with the concrete structure. The annulus between the new lining and the existing concrete structure is injected with a high strength grout to restore the structure to its original proportions.
The Department for Infrastructure engaged Brenwal to reline 11 badly damaged manholes in 2017. Another set are due to be relined in 2018. In addition, we were engaged to carry out the mechanical and structural refurbishment of Greve de Lecq pumping station, which involved complete replacement of the pumps, pipework and valve gear, plus the internal relining of the pumping station with our polyethylene system.