This research evaluated a range of sewer sealing systems used to renovate and repair manholes, chambers and pumping stations. The five elements of the work were to:
- Make sealing material / backfill samples with different backfill materials and conduct physical tests after immersion in 3 liquids (high pH, sewage and saline)
- Determine the ability of sealing materials to propagate and sustain plant growth
- Develop an environmental protocol
- Produce sealing repairs in defective pipes within a pressure vessel and subsequently conduct infiltration and exfiltration hydrostatic testing of the repaired pipes
- Use site visits to inspect previously sealed sewers and analyse the CCTV inspection videos
Four UK Water Utilities, WRc, three American manufacturers/contractors and one Japanese contractor collaborated in the research.
The research considered 3 available techniques:
- Structural repair systems (monolithic formed concrete, cementitious sprayed and trowelled liners and CIPP liners)
- Protective coatings (epoxy and polyurethane) and linings (PE)
- Spot repairs (chemical grouting, plugging and patching).
- The manhole/chamber Sewer Sealing Specification and design document produced is used as an standard industry document and referenced in sewerage rehabilitation contracts. The specification outlines the durability of materials used, enabling sewerage operators to have confidence in the expected performance of techniques.
- Information on how these techniques perform in practice enables engineers to plan their use and calculate the real cost/benefits for undertaking repair work. Long term planning and sewerage maintenance expenditure can thereby be supported with reliable information.