Reclaiming contaminated land using domestic waste

A novel technique to combat the UKs looming landfill crisis begins its first field trials in Yorkshire this week.

The technique, known as Biostore, combines stabilised sewage sludge with industrial waste such as coal shale and demolition waste to create solid building foundations. It has been developed by scientists at Imperial College London, and is funded by Yorkshire Water Services, the Institution of Civil Engineers’ R&D Enabling Fund, and a Biffaward.

With England and Wales alone producing 400 million tonnes of waste every year and 0.8% of UK land designated as contaminated, Biostore not only provides a potential alternative to traditional landfill as a method of waste management, but also offers the possibility of reusing brownfield sites rather than developing greenfield land.

Biostore is based on an earlier idea to restore coal tips using artificial soil formulations, but goes a step further by using the space left between particles in compacted rubble.

By filling this 20 to 25% of volume with stabilised sludge and isolating the composite mixture from the outside environment, the researchers expect to demonstrate that it is possible to create stable ground suitable for foundations beneath amenities and light building construction.

“I guess one of the big concerns most people voice when we explain the project is the kind of smells involved and whether the sludge would be safe,” says Dr. Irina Tarasova of Imperial’sDepartment of Earth Sciences and Engineering, a researcher on the project.

“But we’ve shown that by using properly stabilised materials in a clay-lined emplacement with a gravel surround for rainwater bypass, an isolated and largely impermeable composite mass is rapidly formed. The resulting structure is similar to unused land but with the bonus that it has engineered stability and drainage.”

Project leader Dr Bill Dudeney adds: “The idea behind Biostore is relatively simple – but it is only with changes in legislation and public perception that we have had a strong incentive to look for such novel solutions to dealing with waste. For example, just one Biostore emplacement could in principle deal with the annual wastewater sludge output of a large town.”

“However, before any large-scale application can be made, surveys of suitable sites and establishment of an acceptable regulatory framework will be necessary in collaboration with the Environment Agency. Our research partners, the British Geological Survey and the Clean Rivers Trust, are contributing to these tasks.”

“The EU landfill directive means that by 2020 we will have to reduce our use of landfill to 35% of that in 1995. It is timely to consider alternative methods of rubbish disposal such as recycling or incineration and to invest in novel technology to help tackle the growing mountain of waste we produce.”

Having successfully carried out underpinning laboratory studies, the Imperial team is now joining forces with Biffa Waste Services and Yorkshire Water Services to carry out field tests at three sites in Yorkshire, starting at the Yorkshire Water Bradley site on April 26. Further regulated trials will be carried out at sites near Chesterfield and Leeds and will continue for up to five years.

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