Articles & Case Studies


Posted: Monday 24th March 2014

Saint-Gobain PAM UK has been awarded a major contract to supply more than 70km of its EN545 approved Natural ductile iron pipe range for a flagship project for Wessex Water.

The water company is constructing a number of schemes as part of its water supply grid project to help meet future demand without developing new sources. The project will allow Wessex Water to improve the security of supply for customers – even in the event of a catastrophic failure - and meet reductions in abstraction licences required by the Environment Agency to improve flows in some rivers and protect their ecology. It will also help deal with seasonal or occasional deteriorating raw water quality – particularly increasing concentrations of nitrates at some groundwater sources – as well as meeting future water supply demands. It includes the construction of a new water main to transfer water from the south of Wessex Water’s region, in Dorset, to Salisbury in Wiltshire via Blandford and Shaftesbury.

Due for completion by 2018, much of the pipeline route passes through the Cranborne Chase and West Wiltshire Area of Outstanding Natural Beauty and has been designed to avoid environmentally sensitive areas.

The first order will see around 17km of DN350 pipe supplied for a twin main section between Sturminster Marshall and Snowsdown.

Wessex Water held a number of initial consultations with Saint-Gobain PAM UK to discuss the options for pipe materials. Ductile iron was ultimately selected by Wessex Water for the majority of the project for its strength. The design was able to achieve a bed and haunch to support the pipe, which has reduced the import and export of materials, lowering the impact on the environment. Ductile iron pipes also offer installation flexibility, with multiple pipes in a single trench, as well as a relatively short and discreet installation period, meaning trenches do not need to be left open for extended periods. With the native soils being primarily chalk, the ability to rapidly backfill trenches quickly is key, as chalk left at a trench side for long periods could be exposed to the effects of heavy rainfall, making it more difficult to reinstate.

The Natural range, available in diameters from DN350DN to DN600DN, offers strong corrosion resistance in soils with resistivity as low as 500ohm cm through its 400grm Zinc Aluminium alloy protection. The protective coating also eliminates the need to identify transition points between medium and low resistivity soils, where alternative systems may require a change from standard to supplementary protection.

Simon Cottingham, Director of Key Accounts and Major Projects at Saint-Gobain PAM UK, commented: “We worked closely with the Wessex Water team to define the scope of the project and recommend a solution which would allow the customer to benefit fully from the performance attributes offered by ductile iron pipes. We are very proud of taking part in this project and contributing to its success.”

Davin Eversett, Project Manager at Wessex Water commented: “Wessex Water’s project management team in conjunction with theinternal design and procurement teams have worked with Saint-Gobain PAM UK in the development of this pipeline and concluded that ductile iron pipes will offer the lowest whole life cost as well as the flexibility to deliver what will be a challenging construction programme.”

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