High Build Spray Lining

High Build Spray Lining


As a part of Wessex Water’s section 19 ‘Undertaking to the Drinking Water Inspectorate’, supplied water quality from the Knowle Hill reservoir required improvement. The original thin bituminous lining of the existing ductile iron pipe supplying water had deteriorated and failed, exposing the underlying iron. This iron had subsequently corroded, causing discolouration and water quality issues, as well as reducing the hydraulic efficiency of the pipe.


As the outlet pipe supplied water from the reservoir to the surrounding networks, any disruptions to service and surrounding communities had to be minimised.

Furthermore, rehabilitation of the pipe demanded that the pipe’s capacity must be retained and the solution implemented was approved for use for potable water.


As pipe integrity was sound and only an improvement to the water quality was required, Radius Subterra chose to rehabilitate the DN 300 unlined ductile iron pipe using high-build spray lining of their Subcote FLP fast setting, polyurethane resin.

Fast drying, SubcoteTM FLP allows for re-commissioning within one hour of spraying to ensure pipes can be returned to service quickly and does not block service outlets, removing the need for reconnections.


The SubcoteTM FLP high build spray lining was applied in 3mm nominal thickness to the lining of the existing unlined ductile iron pipline across a length of 500m using Radius Subterra’s DWI type-approved spray lining rig and an associated team of operatives certificated for the application of the product.

Following curing and recommissioning, water sampling was then undertaken to assure the quality of the water and report documentation was provided in accordance with Wessex Water’s corporate information systems.


Applied in-situ, SubcoteTM FLP removed the need for excavation and its fast drying properties enabled a faster return to operation, minimising disruption to service and the surrounding area. Furthermore, as SubcoteTM FLP forms a smooth internal coating, it significantly improved the outlet’s hydraulic performance.

The lowest cost solution for the rehabilitation of water networks in the UK, Radius Subterra’s SubcoteTM FLP spray lining and expert application provided Wessex Water with a cost effective solution to restore pipeline quality, retain pipe capacity and resolve water quality issues, as well as protect against future deterioration.