The company successfully relined 2.8 km of wastewater networks as part of Anglian Water’s Basildon and Billericay Sewer Rehabilitation scheme.

The sewers were renewed with Per Aarsleff’s cured-in-place pipe (CIPP), with resin-impregnated polyester felt liners, which formed internal joint-free, leak-proof smooth bore pipes. Per Aarsleff (UK) worked with framework contractor Barhale Construction plc as part of the One Alliance delivery partnership for Anglian Water.

One of Aarsleff’s installation teams came from Denmark for the Basildon project and averaged 2.75 liners a day, beating the client’s production requirements of two liners a day by 40 per cent, and on one day installed four liners.

The required 46 liners ranged from 150 mm to 450 mm in diameter and from 15 m to 136 m in length.

Article continues below…

Per Aarsleff completed the lining in two visits with an interval of two weeks.

Before any lining took place, JK Environmental was employed to perform detailed inspections using CCTV and initial cleaning to determine a program of renovation. In addition its purpose built installation and steam curing equipment was tested and approved for working to UK health and safety requirements.

Barhale Contracts Manger Richard Beecroft said, “Aarsleff is a very experienced outfit and has worked extensively throughout Europe, but had to adapt to UK requirements and legislation, which they did quite well.”

Typically at each installation, a thin plastic pre-liner, with a blanked end, was first inserted into the damaged pipeline using compressed air to protect the main resin-impregnated polyester liner during installation.

The main liner, manufactured by Aarsleff was made inside out from special resin-impregnated needle felt, so that the outside surface eventually became the inner smooth bore surface when the liner was inverted into the damaged pipeline.

The main liner was packed in flake ice during delivery from the factory to site to prevent premature curing.

The liner was wound into the special inversion drum, inside a purpose-built lorry incorporating all the necessary equipment for the lining installation process. A length of liner was pulled out of the drum and turned back on itself so the inside of the liner was now on the outside.

The liner was pushed onto the outlet nozzle of the inversion drum and held in place with special clamping bands. It was then lowered down into the manhole and guided by hand a short distance into the pre-liner and into the entrance of the pipeline.

The inversion drum was then pressurised with compressed air, which forced the liner, with its closed end, to unwind from the drum and unfold and invert itself through and out of the open end of the damaged pipeline. The inversion process forced the liner through the pre-lined damaged pipe and against the wall, which effectively acted as a former for the new lining.

A steam pressure hose was then connected from a special boiler inside the lorry 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 exit manhole. Temperature probes were attached to the liner, which was gradually heated by the steam to 110°C, and depending on the pipe diameter, held for specific periods to cure the resin-impregnated liner.

The entire liner inversion and curing process was controlled and monitored by a computer on board the self-contained lorry.

The lorry is fitted with highly advanced, purpose-built installation equipment, including the boiler and compressors, needed to perform the No-Dig, CIPP process.

After curing and cooling, the ends of the new liner, which formed a self-supporting pipe within a pipe, were cut off.