TRENCHLESS TECHNOLOGY
L to r: the liner was turned inside out and pushed on to the outlet nozzle of the inversion drum and held in place with clamping bands; the inversion drum with liner was positioned close to the pump house entrance; the inversion drum was pressurised with compressed air
A steam pressure hose was then connected from a special boiler to the inversion drum to heat up the liner. At the same time a steam exhaust pipe was also inserted into the exposed section of liner protruding from the outfall. Temperature probes were attached to the liner, which was gradually heated by the steam to 110°C and held for four hours to cure the resin- impregnated, 13mm thick liner. By using steam curing, the required high temperature could be maintained, even though the end of the liner was submerged during high tide. The entire liner inversion and curing process was controlled and monitored by a computer on board a self-contained lorry fitted with highly advanced, purpose built installation equipment, including the boiler and compressors, needed to perform the no-dig, cured- in-place pipe (CIPP) process. After curing and cooling, the ends of the new liner, which formed a self-
supporting pipe within a pipe, were cut off at the next low tide. Aarsleff’s lining crew completed their work in just one and half days and Breheny followed on, restoring the outfall flap valve and returning the pump house to full working order. The repair to the Bawdsey pipeline was completed without any excavation or disturbance of the pipeline and was done in a fraction of the time and at a fraction of the cost it would have taken using conventional, open-cut pipe replacement methods.
Danish expertise
Initial Aarsleff CIPP lining contracts in the UK will be carried out by experienced teams from its parent company Per Aarsleff A/S in Denmark, using their own computer controlled installation equipment and Aarsleff manufactured CIPP liners, but managed and supported from the UK’s Newark headquarters. The company’s Danish parent has considerable resources and pipeline renewal expertise with its long established CIPP restoration technique for the renewal of horizontal and vertical pipelines in the ground or in buildings. The Aarsleff CIPP process is a highly cost effective and environmentally friendly no-dig solution for the repair and renewal of sewers and other damaged and leaking pipes, as it does not require any excavation. The Aarsleff CIPP lining system can be used to renovate pipes from 60mm up to 3m diameter. The self-supporting bespoke linings are available in various thicknesses to cater for different loadings, and lateral connections up to 18m long are also possible. ■■■
www.aarsleff.co.uk
May 2010 Water & Wastewater Treatment 19
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