After more than ten years of intricate interventions, Scottish Water has successfully completed a major project to safeguard wastewater services for customers in Renfrew.

The initiative addressed severely challenging ground conditions beneath the King George V Memorial playing fields, which had led to a significant sewer collapse.

Since 2013, Scottish Water has been working to manage the unstable Clyde Alluvium – a mixture of clay, silt, and sand deposited by the river – which is prone to compression. Brian Campbell, Delivery Manager with Scottish Water, explained: "Unfortunately, over the years this has caused a range of problems culminating in a sewer collapse, eight metres underneath the King George V Memorial playing fields. The scale of the challenge has been matched by the scale of the solution and completion of this project marks a significant milestone for the community and our customers."

The extensive efforts included a substantial package of ground investigation and monitoring, regular tankering to clear sewer back-ups, and the installation of temporary pumps while a permanent solution was developed.

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Works on the permanent repair, carried out by delivery partner George Leslie and specialist sub-contractors, began in November 2023. The complex operation involved driving metal sheets into the ground to create a cofferdam, followed by extracting groundwater to allow for the safe excavation of the eight-metre-deep sewer. The damaged pipe and associated manholes were then replaced, and the site was backfilled using more suitable materials to mitigate the risk of future subsidence or collapses.

Ian Jardine, Contract Manager at George Leslie, highlighted the collaborative success: "The technical collaboration exhibited by our entire project team including our designer, Cowi and specialist contracting partners including WJ Dewatering and Mabey Hire were critical in resolving the challenges we faced. We are proud to have delivered for Scottish Water. The innovative engineering solutions we found to tackle the complex ground conditions will be a valuable case study for future civil engineering projects."

Brian Campbell acknowledged the difficulties: "To say this has been a challenging project is an understatement, and we are extremely grateful to the local community for their patience and understanding over the years. Their co-operation has been just as important as the engineering excellence shown by the project team." He added that the work reflects the difficult ground conditions prevalent in Renfrew generally, noting Scottish Water's heavy investment in the area, including the playing fields and King's Inch Road, to protect customers and the environment.

Scottish Water is now in discussions with the local authority to ensure the playing fields are reinstated to meet the community's needs and expectations for many years to come.