BGS Brownfield Ground Risk Calculator

Shortlisted for Brownfield Awards Category 2 - Best Scientific/Technical/Digital Advance


The Brownfield Ground Risk Calculator (BGS BGR_calc) is an end-user co-designed digital planning tool presented in a geographical information system (GIS) that is helping public bodies de-risk housing delivery on previously developed land. The BGS BGR_calc has been developed by British Geological Survey (BGS), Greater Manchester Combined Authority (GMCA) and Gateshead Council (GC) to evaluate the scale of risk and risk mitigation costs associated with ground conditions at post-industrial brownfield sites. The tool is designed for use early (pre-desk study) in the planning and development process, not as a substitute for the risk assessments required by the Land Contamination Risk Management guidance.

The ground conditions considered by the BGS BGR_calc include:

  • Soil and groundwater contamination arising from historical land use

  • Land stability and ground gases arising from natural and anthropogenic geology

The BGS BGR_calc uses around 30 publicly available geospatial datasets from British Geological Survey, Environment Agency, The Coal Authority, Ordnance Survey, Groundsure, GMCA and Gateshead Council to derive the following outputs: 

  • Ground risk scores for:

    • Soil and groundwater contamination 

    • Geotechnical (soil, rock and mining) hazards

  • Risk mitigation cost estimates 

    • Soil and groundwater contamination 

    • Geotechnical (soil, rock and mining) hazards

These outputs are derived for individual sites as 50 m grid cells to understand geographical variation in the outputs within and between sites. The BGS BGR_calc has been used to evaluate over 4000 brownfield sites in Greater Manchester and Gateshead. The BGS BGR_calc is innovative and to the best of our knowledge a unique end-user led solution to using publicly available geospatial data based around best practice and guidance on risk-based land management. It provides highly valuable insights into the significance of ground conditions at post-industrial brownfield sites early enough in the planning and development process to shape decisions and investment appraisals – something that has been highlighted as essential in both Manchester and Gateshead by a wide range of stakeholders.

The BGS BGR_calc is important because unforeseen ground conditions are the main cause of cost and time overrun in brownfield development projects. Failure to properly appreciate early enough the scale and cost of ground conditions and the associated engineering solutions to ensure safe and suitable development platforms can derail development. This was recently and rather dramatically demonstrated in the near derailment of the HS2 project. The BGS BGR_calc helps mitigate this situation by building and maintaining confidence through having considered ground risk early in the planning and housing delivery process and avoiding unpleasant surprise down the line.

The four main outputs are ground risk scores and risk mitigation costs estimates for soil and groundwater contamination and geotechnical hazards.

Compliance with legislation, codes and guidance

The NPPF (2019) requires that viability assessments are conducted as part of the plan-making stage of the planning process. A key component of these assessments includes ground conditions – usually referred to as abnormal development costs, but are unfortunately rarely considered in detail. The BGS BGR_calc helps overcome this situation by providing crucial information about ground conditions for viability assessments.

The BGS BGR_calc is underpinned by risk-based appraisals of ground conditions in the context of contamination and ground stability. In each case this approach is underpinned by the conceptual site model. The BGS BGR_calc uses data to characterise and then score each component – source (hazard), pathway and receptor (people, environment and property). This approach to considering ground risks is consistent with Government guidance on risk assessment (Green Leaves III and Land Contamination: Risk Management).

The models used for cost estimates in the BGS BGR_calc are based on existing guidance and expert knowledge from land condition specialists. Risk mitigation cost estimates for contamination are based on the Homes and Communities Agency guidance on estimating remediation costs authored by Arup (2015). Risk mitigation cost estimates for ground stability (soil and rock) hazards is based on an expert elicitation exercise which assigned typical engineered solutions for a range of ‘abnormal’ hazards e.g. grouting shallow coal seams and mine workings. These were costed using industry publications on costs including the SPONS series of price-books.

Effective public/stakeholder engagement

The mandate to develop the BGS BGR_calc came from my Natural Environment Research Council (NERC) Knowledge Exchange Fellowship.  In January 2017, I hosted three workshops in London, Birmingham and Leeds to help participants (including myself!) better understand NERC’s geoscience portfolio and to enable sustainable redevelopment of post-industrial brownfield land in the UK. Over 100 people from the public and private sectors attended these. One crucial insight was that geoscience information that is made available early in the brownfield redevelopment process reduces project risk and can enable the UK Government to achieve its ‘brownfield first’ approach, a key component of current housing policies.

During the BGS BGR_calc project, BGS, GMCA and GC collaborated with a range of key stakeholders including the Environment Agency, The Coal Authority, Local Authorities, strategic planners and small and medium housing developers to answer the following question: ‘What is the most meaningful way to quantify the scale of risk and indicative costs to mitigate contamination and geotechnical hazards present on brownfield land?’

Working with GMCA involved many discussions with senior officers in housing and strategic planning teams. This led to workshops with the Environment Agency, the GM Archaeological Advisory Service and Tameside Council to scope out and develop a minimum viable product (MVP). The MVP was presented to relevant GMCA committees and led to buy-in eventually to funding from the GMCA Chief Executive to further develop the BGS BGR_calc.  The tool development process included expert elicitation workshops with planners, environmental protection officers, housing and place managers and BGS staff to co-design the scope and specification of the final tool.

The work with Gateshead Council built on a significant amount of participatory work that GC and the Future Cities Catapult had already completed with local housing developers. They found that ground conditions were the greatest barrier and risk to buying and developing brownfield land for SME house builders.  The BGS BGR_calc team built on this momentum by hosting workshops with developers, planners and land owners to co-design the tool. We continue to work closely with a range of local stakeholders to ensure the tool meets the end-user need including planners, environmental protection officers, IT, The Coal Authority and local developers. We are sharing our understanding and knowledge about what is needed for the ground conditions component of the imminent Gateshead Site Information Tool – an innovative web-based planning platform for local developers which embeds the Brownfield Ground Risk BGS BGR_calc.

Real environmental/economic/social benefit

The BGS BGR_calc is resulting in policy and economic impact at the local and regional scale within England. Measured economic impact will take longer to quantify but the benefits so far realised are significant and include:

  • GMCA are currently using the BGS BGR_calc cost estimates in their Viability Assessment of the 2019 Greater Manchester Spatial Framework as required under the NPPF. The GMSF is underpinned by a ‘brownfield preference’ policy and forms the region’s development plan for the next 20 years. To the best of our knowledge this is the first time such a tool has been used for this purpose. The GMSF is due to be tested in an examination in public in the future, the BGS BGR_calc will form part of the evidence base for this.

  • The Environment Agency is using the BGS BGR_calc outputs to assess and quantify the scale of regulatory effort required by its officers for land contamination risk management in the Manchester region over the next 5 years.

  • The BGS BGR_calc has been used to define an evidence base in housing and infrastructure funding applications to central Government by GM Local Authorities worth over £10m and over 10,000 potential new homes.

  • Gateshead Council are using the BGS BGR_calc to de-risk housing delivery by reducing uncertainties in deliverability testing. It is also speeding up planning consultation responses on land contamination risk management by its environmental protection officers. The BGS BGR_calc is also contributing to digital transformation within its planning department by making data and ground risk scores available in the Cloud.

These benefits are supported by testimonials from both GMCA and Gateshead Council below.

A robust, sustainable and defensible solution.

The BGS BGR_calc is a transparent shared venture that can be repeated for other areas but also be used by GMCA and Gateshead Council, either with BGS or alone. The methods and models used are dynamic and open to change and improvement over time and rely on publicly available datasets. We designed the tool to be consistent with risk-based land management and ground engineering – putting the conceptual site model at the centre of all thinking. Cost estimates are based on published guidance and expert judgement by experienced land condition specialists. Being transparent, reproducible and repeatable using openly available data and methods, we believe the tool is a defensible solution to providing initial knowledge on ground conditions at brownfield sites early in the planning process.

The following testimonials demonstrate the BGS BGR_calc is robust and fit-for-purpose as a valuable digital planning tool. We strongly believe that it is sustainable and are currently in talks with a range of potential end users which in time will provide evidence to show it is a sustainable solution.

"BGS has worked with GMCA to develop the Brownfield Ground Risk Calculator. The project has proved to be very useful and is contributing to the place-based work to support delivery of housing and growth across Greater Manchester with its partners. The working relationship has been very good and BGS have worked hard to deliver a tool that helps GM partners make decisions on the development of brownfield land and sites across Greater Manchester." Murray Carr, Director of Land and Property, GMCA 

"Working with BGS to develop a digital brownfield risk calculator will not only free up officer time for value adding activity a distilled version of the data will be made available through our open access Gateshead Site Information tool specifically for brownfield sites. The innovative approach of BGS together with the extensive local knowledge of our officers has produced a very robust a credible digital tool to support housing delivery." Neil Wilkinson, Spatial Planning and Environment Manager, Gateshead Council.