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Katie Dunn, Environmental Scientist, Atkins
The assessment of contaminated land in the UK has gone through significant change since 2002 when Part IIA of the Environmental Protection Act 1990 came into force in England and Wales. Part IIA introduced a risk based approach to the identification and remediation of land where contamination poses an unacceptable risk to human health or the wider environment. No longer would simply the presence of land contamination automatically mean that a site was “contaminated land” in legal terms.
Under this legislation, all Local Authorities now have a legal responsibility to identify and investigate areas of potentially “contaminated land” i.e. where a significant pollutant linkage between a contaminant source and a sensitive receptor may exist within their jurisdiction. They must also have a structured plan for carrying this identification out and this plan is known as a Contaminated Land Inspection Strategy. It must consider risks to the groundwater, surface water, ecologically vulnerable areas, buildings / property or people living nearby areas of potential land contamination.
Denbighshire County Council commissioned Atkins to design a risk ranking system to assist them in the identification of potentially contaminated land within their area. This exercise would traditionally have been carried out painstakingly ‘on paper’, however using the Council’s own comprehensive spatial database, the multidisciplinary Atkins team developed a GIS-based model that applied a numerical ranking to each of the elements of the pollutant linkage relationship.
Numerical scores were designed and applied to the severity of each potential source hazard identified within the database, the sensitivity of each potential receptor and the viability of each potential pathway. The scores were developed specifically with Denbighshire in mind, and they have been individually adjusted to consider the unique and specific environmental characteristics of the County. By calculating the relationships between each element of the linkage using a series of algorithms, the model provided a mechanism that allowed each source/pathway/receptor linkage to be individually quantified. The result of the model provides a fully prioritised site inspection list for implementation, which allows the Authority to prioritise and target their time and resources towards the real ‘problem sites’.
Furthermore, by developing this system around a database, users are able to interrogate each specific pathway in an interactive fashion, thus providing a quick and efficient tool for use in the Client’s office to take their Contaminated Land Inspection Strategy forward, allowing decisions to be turned around in minutes rather than hours at the touch of a button. Overall, the model has carried out some 600 million calculations using the Council’s data. This is 600 million decisions the Authority would have to have taken to produce their own prioritisation in the traditional way.
In addition to the original contract to purely prioritise the sites within the County, Atkins has also recently been commissioned to build a bespoke ‘relationship database tool’ to assist the Authority in better understanding the relationships between sources, pathways and receptors within each identified linkage. This tool provides a simple and user-friendly query screen which allow the Authority to quickly and easily interrogate each site or group of sites from either a source or receptor perspective, depending on the purpose of the particular query. Due to the level of detail contained within the underlying data, the searches can also be carried out using criteria such as spatial areas, postcode areas, council wards, site types- the possibilities are endless.
For further details please contact Atkins via water@atkinsglobal.com or www.atkinsglobal.com