Brownfield Ground Risk Calculator

Brownfield Ground Risk Calculator

In a densely populated nation like the UK, identifying suitable land for new homes is a national challenge. The UK Government has a national target of 300 000 new homes each year which it is struggling to achieve. Building on greenfield (undeveloped) areas is often unpopular.

Brownfield sites are defined as having been affected by former land uses. They are often derelict or underused, may have real or perceived contamination problems, are mainly in developed urban areas and require intervention to bring them back to beneficial use. Redeveloping brownfield sites for housing, which are often in prime locations, is strongly preferable and can be acheived once these sites have been remediated ready to be safely re-used.

However, there are many examples where a lack of investigation of brownfield ground conditions has led to redevelopment plans being stalled or delayed, causing considerable overrun and increased development costs. Therefore any additional costs related to risks such as soil and groundwater contamination and natural geohazards, must be considered, planned for and costed-in from the inception of the planning process. The BGS have been working with partners to develop a tool to simplify and speed up this process.

The calculator

Redevelopement of a brownfield site

The Brownfield Ground Risk Calculator is a digital planning tool based in a geographical information system (GIS). The calculator has been developed to help identify the scale of risks and unexpected costs (abnormals) associated with ground conditions such as:

  • soil and groundwater contamination
  • mining hazards (coal and other mining)
  • radon (natural radioactivity)
  • landfill
  • natural hazards, including:
    • landslides
    • shrink–swell clays
    • running sand
    • collapsible ground
    • compressible ground
    • soluble rocks
Summary of the four Brownfield Ground Risk Calculator outputs

The calculator estimates risk and the associated risk mitigation costs derived from a range of environmental data available for the area of interest. The results are presented as digital maps that contain details of the environmental data source used to produce the risk scores and risk mitigation cost estimates.

Risk scores are derived from data on sources of contamination or adverse ground conditions (resulting from previous land uses and natural processes) and the presence of exposure pathways and sensitive receptors (residents, water resources and the buildings).

For there to be a risk, the source, pathway and receptor components of this conceptual model must be connected. Risk mitigation cost estimates represent the added costs that might need to be paid to develop a brownfield site over and above 'normal' development costs.

No allowance is made in the calculator for the financial benefits of pre-existing infrastructure, proximity to services or employment that brownfield land usually have, but these ought to be considered within the overall economic evaluation of individual sites.

Brownfield Ground Risk Calculator examples

Greater Manchester Combined Authority. Copyright Paul Grogan Photography 2019. Greater Manchester Combined Authority

The Brownfield Ground Risk Calculator was originally developed for the Greater Manchester Combined Authority to assess abnormal risk and cost estimates for brownfield redevelopment.

Gateshead waterfrontGateshead Council

Gateshead Council have commissioned the BGS to develop a version of the Brownfield Ground Risk Calculator to conduct an appraisal of their brownfield land.

Wigan and Bolton Housing Growth CorridorWigan and Bolton Housing Growth Corridor

The calculator was used to generate risk and associated risk mitigation costs for eleven sites that form the basis of the Housing Infrastructure Fund bid to Homes England by the Wigan and Bolton Housing Growth Corridor.

Future work Future work

Find out more information about how the Brownfield Ground Risk Calculator can be applied to your area.


GeoBlogyHelping to solve the UK housing crisis with a new tool to understand brownfields

The BGS has developed a new tool to help understand the ground conditions and estimate likely costs of remediating brownfield sites. The tool can be used by councils across the country to help the planning process. It has the potential to save the construction industry millions of pounds and increase buyer confidence for those considering the redevelopment of brownfield sites.


Please contact Darren Beriro for further information.