Back from the dead

Mention Ravenscraig and what comes to mind? For many, the former steelworks conjures up images of vast holes ripped out of the earth by years of heavy industry and decaying factories. The steelworks and strip-steel mill, which employed 6,000 workers at its height, dominated the Scottish town of Motherwell since it opened in 1954. When it shut in 1992, it devastated the community.

The plant’s closure left behind chronic unemployment and created one of Europe ‘s largest brownfield sites, measuring more than 1,125 acres, or 13 times the size of Canary Wharf. The site’s ecological legacy was even more challenging. The heavy use had scarred the earth, leaving noxious deposits and deep-set foundations.

A development strategy was published two years after the works closed, outlining a mixed-use development and resulting in a series of masterplans. By 1999, a public-private joint venture between Wilson Bowden Developments, Scottish Enterprise Lanarkshire and Corus (formerly British Steel) had been set up. The plans eventually outlined 3,500 houses, a 100,000m2 business park, a 116,000m2 industrial estate and 84,000m2 of retail premises.

“Motherwell desperately needed an injection that would revitalise the area and replace what had been an important and intensive industrial centre that had provided plenty of work. It was the heart of the community,” says Phil Nokes, a senior project manager with Turner & Townsend. “And Motherwell needed a new one.”

Reusing materials

Turner & Townsend’s involvement in the phase-one works began as masterplanning drew to a close in 2004. It ranges from project and cost management through to managing the reuse of on-site materials. “The driving force behind reusing materials was to minimise the amount taken away and the amount brought on site,” says Nokes. “It’s far better to classify materials and validate their use on site than to take the materials away. It’s expensive and it has environmental consequences. So all materials at Ravenscraig are being validated for reuse on site.”

A significant portion of the phase-one works being carried out by Balfour Beatty involves the formation of stabilised and compacted development platforms. This is being achieved through the grouting of old mineworks, the dynamic compaction of up to 8m-deep loose-filled material and the reorganisation

of existing resources such as steel and blast furnace slag, which along with other man-made soil types is expected to result in the movement of nearly 1,000,000m3 of materials.

Motherwell desperately needed an injection that would revitalise the area

Nokes explains how materials validation evolved: “First a strategy was developed in conjunction with the civil engineering and environmental consultants. We then put in place a testing regime and made sure these elements were put into specifications in the contractual documentation so that the contractor would sample, test and provide all the results. Our environmental consultants would then write a report which would allow the material to be signed off.”

This approach meant concrete structures, such as underground foundations, were broken and crushed for use as granular construction materials. For instance, about 8,000m3 of concrete substructures, foundations and other items were crushed and reused as capping below new roads.

Similarly, large deposits of blast furnace slag were tested, classified and consolidated by dynamic compaction to form the basis of large developable platforms with site-arising clay used to seal the slag and provide a layer in which housing foundations could be formed.

One for the birds

Even the little ringed plover benefited, with steel slag being used to form a replacement habitat for the bird. Although not suitable for development platforms, this material proved an ideal constituent for a replacement top soil.

So pioneering was the approach that WRAP – a not-for-profit company that encourages businesses and consumers to minimise landfill, reduce carbon emissions and improve the environment through recycling and efficiency – provided £70,000 of funding to finance trials.

“Combining on-site mineral resources with quality compost to make topsoil brought environmental benefits as well as saving a lot of money for the clients,” says David Tompkins, project officer for landscape and regeneration at WRAP.