Ground breaking no-dig project keeps Liverpool Street Crossrail station works on track at Moorgate.

UKDN Waterflow

Europe’s biggest construction project calls for Europe’s biggest UV liner.

The biggest UV cured sewer liner ever deployed in Western Europe has been installed near Moorgate station as part of a sewer replacement programme in preparation for construction of Crossrail infrastructure at the site. The record-breaking operation was used to strengthen a section of 1.4 metre-diameter sewer located adjacent to rail tracks.

UV lining has rapidly become the system of choice for lining sewers in the UK due to its high inherent strength and durability however it has never before been installed at this diameter. The liners were so large that the factory had to be upgraded to enable these custom made liners to be fabricated.

UKDN Waterflow was initially contacted to carry out a CCTV survey and this identified two 10-metre-long sections of sewer that needed work, to protect them from any future movements caused by settlement during Crossrail tunnelling. One section was close to a listed building and excavation of the other section would have caused extensive disruption to services passing through Moorgate station.

Working closely with Crossrail contractors BAM Nuttall Kier Joint Venture (BNKJV), and after considering sock and segment no dig methods the team made the radical proposal of using a UV liner, even though no supplier offered a big enough product.

A number of suppliers had already indicated that they could not complete a 1440mm diameter liner, but the UKDN Waterflow Technical Services team have built a solid reputation for innovation and took up the challenge. They worked extensively with a supplier to establish the necessary technical capability to create a custom liner big enough to fit the bill.

At the Moorgate project, installation proved a significant challenge – not only because of the sheer size of the liners being used, but also because the sewer’s position seven metres below ground and within a basement below an LUL ticket Hall, made access extremely awkward.

A team of twelve engineers was deployed to crane the liners into position, suspending them from several different anchor points on their way down so they could be securely positioned in front of the entry points to begin the process.

The works were carried out over two weekends and despite the best efforts of the weather to stop the work the installations were highly successful.

Marcus Smith of BAM Nuttall Kier joint venture, said: “The innovative thinking and proactive approach of UKDN Waterflow allowed this operation to be carried out with a minimum of disruption to the other site activities.

“By working with the liner manufacturer to produce a custom product just for this job we and the UKDN Waterflow team managed to complete a very challenging job in just four days – no mean feat.”