Scottish Water has commissioned its first spray lining project to rehabilitate chambers serving a large wet well.
The innovative project has successfully strengthened the two chambers on the outfall of the wet well at Lower Largo, Fife, preventing the assets from having to be excavated and replaced.
Lanes Group, which is a framework supplier for Scottish Water across the whole of Scotland, suggested the solution after it was found that the chambers needed to be sealed and strengthened.
The company carried out the work for Morrison Construction, a framework contractor delivering design, engineering and construction services for Scottish Water.
Matthew Anderson, Morrison Construction, said: “We’d like to thank Lanes Group for applying the innovative Hermes M-Coating system, in conjunction with ERGELIT dry mortars to these very deep chambers.
“They had been badly affected by hydrogen sulphide corrosion. The spray lining work saved us from having to install temporary works in excess of six metres deep to replace the asset. The carbon savings alone were huge.”
David Beveridge, Regional Sales Manager for Lanes Group, said: “Unless a suitable no-dig rehabilitation solution was found, the only option was to consider replacing the chambers.
“This would have been a major engineering task, carried out over many weeks, with significant mitigation in place to ensure continuity of wastewater services for wastewater customers.
“The solution Lanes provided, instead, was completed over six days, with all required outputs achieved. This was both highly cost-effective and extremely sustainable, with no inconvenience for customers.”
The spray lining was carried out by Lanes Group Sewer Renovation.
One of the chambers was formed from concrete rings and was 6m deep and 1.2m in diameter. The other was a brick-lined square chamber that was 6m deep and 2m wide.
Each chamber was first cleaned by a remotely controlled high pressure water jetting system. Mortar was then injected into the joints of the concrete ring chamber to seal them.
In a final process, another remotely controlled rig was lowered into the chamber to spray-line its walls with a specialist dry mortar.
The computer-controlled system automatically completed 50 coats of each chamber to create a liner 10 millimetres thick, with the coating cured in 24 hours.
In most cases, it is also much quicker, safer and easier to carry out, using less equipment and materials and more limited confined space entry.
Spray lining wastewater assets is much more sustainable than excavation and replacement, providing a solution with a smaller carbon footprint.
