A major UK Utility company engaged with Primus Line’s local partner, McAllister Group, at an early stage to identify the urgent suitability of a rehabilitation solution for a twin sewer rising mains. From information provided by the client and the portfolio of products available within the McAllister Group, Primus Line® was considered to be the most suitable due to the flexible nature of the material, its capability to withstand the operational conditions together with the speed of installation.
The rising mains identified ran parallel with each other but from different pumping stations, had a number of changes in direction both vertically and horizontally, but more significantly had been overbuilt to extend the original ‘A’ road with a new dual carriageway. The dual carriageway was built on a raised reinforced bank. Each of the rising mains had recent bursts that caused significant local disruption. Traditional open cut methods to replace or repair the mains were considered earlier by the client as a last resort. Excavating near the reinforced bank would add unnecessary risk and considerable cost to the project.
Primus Line® is a flexible slip-lining solution for the trenchless rehabilitation of pressure pipes. The system consists of a flexible aramid-reinforced liner and specially developed end fittings. Primus Line® is not bonded to the host pipe, is self-supporting and allows an annulus to remain between Primus Line® and the host pipe. Two small excavation pits or access points are sufficient for rehabilitating a line section.
Trenchless rehabilitation with Primus Line®
McAllister Group worked diligently with the asset owner, their supply chain and Primus Line to develop a fast track, effective and economic trenchless rehabilitation solution. The asset owner had already committed to set up flow management (tankers at the pumping station) prior to McAllister Group carrying out the initial site survey. This enabled all stakeholders to define the final scope and to develop a seamless programme of works to mitigate unnecessary downtime.
The Primus Line® material was delivered directly to the site as two (DN400 and DN500) jointless lengths of flexible hose on transportation reels. A winch was set up at the receiving pit with the winch wire being installed through the host pipe. The complete 650 metre length was installed for each of the host pipes in a single installation; once installed, the end connectors were attached and a pressure test took place, witnessed by the client. Next, the liner was cut and trimmed at an intermediate air valve chamber, end connectors fitted to facilitate the reinstatement of the air valves.
The rehabilitation of the two rising mains has secured both assets for an extended length of time. The collaborative nature in which all stakeholders approached the project “single organization” helped streamline each stage of the project from concept, through to procurement and to on-site delivery.
Working closely with the client on design, planning and delivery contributed hugely to the project being delivered on time and to budget.