Working in partnership with contractor CPC Civils and Amey, Radius Subterra have rehabilitated a section of a 12” cast iron water main ahead of schedule, helping Severn Trent Water keep the water on.
When a section of a 12” cast iron main running under the main West Coast railway line on Holdiford road, Milford near Stafford needed replacing, sub-contractor CPC Civils and tier one contractor Amey appointed Radius Subterra to carry out the operation using their innovative Subline DR trenchless pipe lining technology.
One of the main challenges facing CPC Civils was to satisfy Network Rail that the works would not affect rail traffic and the technique used to install the new pipe would not create any damage to the railway line. Besides, it was vital for Severn Trent Water that the new pipe was kept as close as possible to the existing 12” main size for capacity requirements. Using traditional no-dig techniques such as directional drilling under the railway line to install the pipe, or slip-lining the main with a 250 mm polyethylene pipe were evaluated, but were deemed either too risky and technically too challenging as ground conditions were unknown, or unworkable, as using a 250 mm pipe (9” equivalent) would have considerably reduced the main carrying capacity.
Subline DR is a revolutionary close-fit pipe rehabilitation technology where the polyethylene (PE) pipe’s diameter is concentrically reduced through a set of specially designed profiled rollers. The PE pipe is selected to be slightly greater in diameter than the internal diameter of the existing main, butt-fusion welded into long strings before being processed through the SublineTM machine and inserted into the prepared host main. Once inserted, the pipe is pressurised using cold water to revert it back to its original diameter and form a close-fit against the bore of the original mains pipe providing maximum flow capacity within the pipeline.
Amey were familiar with the Radius SublineTM technologies and engaged Radius Subterra to determine the benefits of using their unique technique as a solution to this particularly challenging project. Radius Subterra established that their Subline DR pipe lining system using a 315 mm PE100 SDR21 polyethylene pipe, would offer a reliable option for the 12” pipe rehabilitation and would be the ideal solution to deliver the required flow carrying capacity and the reassurance of a low-risk installation technique that would safeguard the railway line’s integrity.
John Williams, Radius Subterra’s engineering projects manager (water) explained: “We have worked closely with CPC Civils and Amey to provide an engineered solution that would meet Severn Trent Water and Network Rail’s objectives and our Subline DR pipe lining technology was ideal for this job. The project has gone really well and we are very pleased that the commissioning of this section and connection to the existing main is now completed.”
Carl Hobbs, Construction Manager for Amey said: “I would like to personally thank the CPC Civils and Radius Subterra teams who have gone the extra mile to accelerate the completion of the programme in challenging conditions. They made sure that 6500 customers had continuity of water supply, during one the hottest weeks on record.”
This project is part of the ambitious Stafford East trunk main replacement and upsizing scheme, which will see 20km of pipe being replaced by Severn Trent Water to future proof their water supply network.
For more information on our SublineTM close-fit PE pipe lining technologies, please contact Radius Subterra on t: 01773 582317 or e: firstname.lastname@example.org.