The leading water treatment company in the UK, Siltbuster, has created and installed a processing plant in just seven days to help remove dissolved iron from groundwater as part of the £1 billion project commissioned by the National Grid and Scottish Power Transmission.

The scheme to build the Western Link is bringing renewable energy from Scotland to businesses and homes in England and Wales, and will be delivered by a Consortium of Prysmian Group (which is responsible for cable manufacture and installation) and Siemens (responsible for converter stations).

The dissolved, iron contamination arose when below ground, high voltage, power cables were being installed. The complex cable routes, spanning a distance of 420 Km, pass within TATA Steel’s works at Shotton.

When installing the 400kV A.C cables on this land it was found that the groundwater generated was in parts heavily contaminated with dissolved iron. Such contaminated water would pose significant risk to aquatic life if discharged without treatment.

The removal of the groundwater was crucial as the cables were being installed using the open cut trench method with well pointing used to dewater the trenches and joint bays. All this had to stay dry 24 hours a day during the cable installation and jointing works.

Tankering the groundwater offsite for treatment would have required an articulated tanker (50m3) every hour, 24 hours a day, at huge costs both financially (cost £150-£250 per cubic meter) and to the environment, in terms of carbon footprint.

The Consortium’s subcontractor Balfour Beatty’s environmental team contacted Siltbuster to find out the best way of dealing with the iron contaminated water.

Experts at Siltbuster got to work on designing the best practical solution, while the system had to be strong enough to cope with the flow rates between 15 and 50 m3/hr, ensure compliance by reducing the iron concentration within the water to below 10 mg/l and be easy enough for site personnel to operate.