Costain Limited

M25 Junction 1b to 3 Widening

Cured in Place Lining

Client:	Costain Limited
Employer:	The Secretary of State for Transport
Project Manager:	The Highways Agency
Project :	M25 Junction 1b to 3 Widening

Ferro Monk Systems Limited recently carried out a series of sewer rehabilitations on the M25 south of Dartford, where main contractor Costain, was part way through a multi-million pound upgrade of the motorway to increase capacity by widening two lanes to three and three lanes to four.

New drainage was constructed under the new carriageways and connected to the old pipes under the existing in-use lanes. The old and new pipes were then lined from manholes located in the verge, providing a homogonous relined pipe running underneath both the new and the existing road.

The M25 is used by around 200,000 vehicles per day and closing it to carry out repairs would cause major disruption.

Ferro Monk worked closely with Costain to co-ordinate the works and to fit in with the overall contract programme to install eight liners of between 225mm and 900mm diameter, over two site visits between Junctions 1b and 3.

Investigation and planning were key features of the project and helped to ensure that works were executed without incident. An initial site survey was undertaken by one of the company’s rehabilitation managers. This looked to determine the characteristics of the site and if any special measures or considerations needed to be made. The condition of the pipe was determined using CCTV and accurate measurements were then taken of the host pipes length and diameter, together with details of the depth and any loadings.

Shaun Hazell Drainage Section Engineer Costain, M25 Junctions 1b - 3 widening scheme said, “The Cured in Place Pipe Lining (CIPP) operation has been successful on the M25 Junctions 1b to 3 widening scheme. It has proved a safe, reliable and cost-effective alternative to open trenching, and has provided significant benefits to the travelling public over traditional open trenching methods."

All liners are designed and manufactured to suit each individual pipe to be rehabilitated, with the thickness being determined by the preceding design parameters.

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