A sustainable, cost-saving approach to decontaminating land and groundwater

Researchers

Our research into the natural processes that reduce pollutants in groundwater and help protect our environment could save millions of pounds in clean-up costs.

These natural physical, chemical and biological processes - known as natural attenuation - have the potential to manage contamination of land and groundwater. They can be effective in treating a variety of pollutants from different sources in a way which can improves sustainability and reduces negative environmental impacts of engineered clean-up technologies.

Natural attenuation also benefits business, cutting clean-up costs expenses when compared with engineered technologies, which can cost up to £500,000 per site. Also, the engineering processes involved in active clean-ups often require additional measures to manage the problem, which adds further costs.

The research - which was a long-term collaboration led by Professor Steven Thornton and Professor David Lerner from our Department of Civil and Structural Engineering - has enabled the Environment Agency to formally adopt natural attenuation as an acceptable risk management approach for contaminated land and groundwater in the UK. This approach has also been embraced in other European countries.

The benefits of natural attenuation include reduced financial liability for businesses and an increase in land value, which has significant positive implications for the economy. Implementing natural attenuation can also help reduce energy consumption and waste disposal, conserve natural resources and reduce carbon emissions. It can also reduce unnecessary exposure of people to hazardous compounds.

Professor Thornton said: "The groundbreaking research is a result of laboratory studies, numerical modelling and fieldwork across many different sites. The team analysed the processes that occur in groundwater pollution plumes containing multiple pollutants and used their findings to create a new conceptual model of natural attenuation."

He said: "Research showed that biogeochemical gradients at the fringes of pollution plumes provide a unique range of conditions in which rapid biodegradation takes place. This advance led to the development of an assessment framework which enables sites to be screened for their potential to support natural attenuation as a plume management option."

Implementing natural attenuation can help reduce energy consumption and waste disposal, conserve natural resources and reduce carbon emissions

The research was funded by the Engineering and Physical Sciences Research Council (EPSRC), Natural Environmental Research Council (NERC) and the Environment Agency, with support from organisations in industry, such as Shell and Total, among many others.

The research programme was undertaken over a period of 15 years and involved collaborations with many universities and organisations in the public and private sector. The Sheffield team developed innovative lab and field-based methods to investigate, understand and predict the performance and value of natural attenuation as a management approach for contaminated groundwater.

Professor Thornton said: "On a simple level, our team improved the scientific basis for the acceptance and wider use of natural attenuation. The key challenge was to develop the fundamental understanding of the processes in order that stakeholders could then implement the approach. This was further supported with the development of modelling tools which practitioners can use to design natural attenuation schemes."