Rising and Gravity Mains at Forton WwTW

The scheme upgraded the existing drainage network around Forton, Lancashire. Working for Advance Plus on behalf of United Utilities, SGC supplied and installed gravity sewer pipework of various diameters and a new rising main, online, at depths of up to 6 m, connecting to Forton Wastewater Treatment Works.

The pipeline route crossed agricultural land and the public highway, including the A6. Our scope included:

• Supply and online installation of gravity sewer pipework and rising main
• Deep excavations to 6 m, including construction of chambers
• Auger boring and directional drilling beneath the A6
• Temporary overpumping of the live sewer network
• Design and operation of groundwater dewatering

Because the works were carried out online, substantial overpumping systems kept the live sewer in service throughout. Our review of the ground investigation reports identified groundwater as a considerable risk, so a dewatering method was established in advance, with particular care taken over environmentally sensitive discharge points.

Open-cut works across the A6 would have needed temporary traffic regulation orders and placed operatives next to a live, high-speed road. We chose to auger bore and directionally drill these sections instead, removing the programme risk of waiting for TTROs, reducing disruption to residents and the road network, and keeping operatives away from live traffic.

Working jointly with Advance Plus, we upgraded the Forton network while keeping the live sewer in service and minimising disruption to the local community.