RSK supports new CL:AIRE guidance

November 16, 2020

CL:AIRE, the independent organisation promoting sustainable land reuse, has published new guidance on applying statistics to land contamination decision making entitled “Professional guidance: comparing soil contamination data with a critical concentration.” RSK is proud to have been represented on the steering group for the new guidance and to have funded the project along with the Soil and Groundwater Technology Association (SAGTA), the Nuclear Decommissioning Authority and the Environment Agency.

CL:AIRE’s original guidance document, published in 2008, was created to help land contamination stakeholders apply statistical methods to their data analysis. This aided decision making that was required under legislative frameworks, including the planning system and Part 2A of the Environmental Protection Act 1990. However, this guidance recommended a single scientific test that gave a definitive yes/no answer, or “bright line”, thereby creating the potential for data to be abused.

“The bright line model recommended in the original guidance could be used inappropriately when it was applied in a black-and-white fashion,” says RSK board member Peter Witherington, who sat on the steering group that shaped the new guidance. Peter was involved in a public inquiry in 2016 that highlighted the failings of the previous guidance and provided the incentive to develop an update. “The new guidance moves to a more holistic assessment in which we look at the distribution of data and make professional judgements,” he continues. “RSK was instrumental in instigating the review and we are passionate about pushing the agenda when things are not right. We are delighted to have been involved in developing guidance that has been well received by contaminated land communities in the UK and as far afield as Australia.”

The guidance, which was four years in the making, was written by statistician Nigel Marriott with support from a steering group that included representatives from RSK, the Environment Agency, the Nuclear Decommissioning Agency, SAGTA, the Society of Brownfield Risk Assessment (SoBRA), and the Yorkshire and Lincolnshire Pollution Advisory Group.

According to the CL:AIRE website: “The guidance updates a 2008 document of a similar name that was published by CL:AIRE and the Chartered Institute of Environmental Health, supported by SAGTA. The guidance adopts an entirely different approach to the previous guidance; it completely supersedes it and the 2008 document has now been withdrawn. The 2020 revision addresses the problem of potentially erroneous conclusions by dropping the reliance on a single scientific test and emphasises the importance of a comprehensive understanding of the data sets in the context of the conceptual site model.”

As the number-one contaminated land consultancy in the UK, as ranked by Environment Analyst in its 2019/20 market assessment report, RSK is committed to leading the way and pushing for the highest standards when dealing with contaminated land in the UK. In addition to its involvement in the new CL:AIRE guidance, RSK is closely involved with using and promoting the National Quality Mark Scheme, and key staff members have senior positions within professional bodies. For example, RSK Geosciences Director Tom Henman is Deputy Chair of the Specialist in Land Condition Register Professional and Technical Panel, and RSK Associate Technical Director Joanna Wilding sits on the SoBRA Executive Committee.

Nigel Marriott will be running training sessions for RSK employees on the new guidance and how to apply it.

The document is available to download free from the CL:AIRE website.