RELINING OF concrete outfall pipes at Longniddry Water Waste Treatment Works ground to a halt when the new plastic liner stuck to the pipe. Scottish Water had awarded ABV East the contract to upgrade and convert the Longniddry works in southern Scotland into a new transfer pumping station.
The project entails the complete reconstruction and refurbishment of the treatment works.
The contract also involved relining the 375mm concrete storm water outfall pipe which was laid during the 1960s. Trenchless technology was chosen for the job because the treatment works lies in a site of special scientific interest and care had to be taken not to interfere with a nearby salt marsh.
About 365m of concrete pipe was relined.
However, during work on a 140m long section towards the end of the task, the liner stuck to the wall of the pipe. In places the liner collapsed and became detached from the pipe wall.
One option was to remove the failed section of liner. This would have been expensive and time consuming, so ABV East and Scottish Water chose pipe bursting to burst out the lined concrete pipe and install replacement 450mm MDPE pipe.
The project was a challenge for the Tracto Technik UK engineers: the concrete pipe had been laid in rock, excavated material was used as backfill and bursting had to be carried out between neap tides.
Because of the severe ground conditions and the fact that the liner had collapsed in a number of places, TT UK used its Grundoburst 1000G hydraulic mains replacing system with patented QuickLock rods.