Helping to solve the UK Housing Crisis with a new tool to understand Brownfields // by Catherine Pennington
BGS has developed a new tool to help understand the ground conditions and estimate likely costs of remediating brownfield sites. The tool can be adapted for use by councils across the country to help the planning process when considering development. It has the potential to save the construction industry millions and increase buyer confidence for those investing in the redevelopment of brownfield sites. Catherine Pennington finds out more.
‘The UK Housing Crisis’ is something we’re all used to hearing in the news. The government and housing charities say the lack of affordable homes is to blame. Others say our housing problems are not a simple feature of supply and demand, rather speculation in the property market and planning system. Whatever the reasons, house prices and rents have risen, and continue to rise, to such an extent that first time buyers can’t get their foot in the door and those renting are swiftly being priced over the mat and into the street.
Back in October 2018, the government announced plans to speed up the planning system so they can meet their commitment to build 300,000 new homes every year by the mid-2020s. But where these homes go is a delicate matter. Building on greenfield areas (sites that have not been built on before) is highly contentious and largely unwanted by those that enjoy living next to them. With this in mind, the government is also encouraging the redevelopment of brownfield sites.
In the UK, ‘brownfield sites’ are thought of 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 post-industrial brownfields can be expensive, mostly due to dealing with ground-related unknowns. Historic site contamination as well as soil and rock hazards, if not identified and allowed for early in the planning process, can affect the viability of constructing new homes on post-industrial land.
We are hoping we can help prevent this kind of calamity with a new tool:
Project manager Dr Darren Beriro explains: “We wanted to bring together all the data we knew would help us get the best possible picture of the ground conditions as well as the likely costs to remediate the brownfield site early in the process”.
Gateshead Council have also commissioned the BGS to develop a version of the calculator aimed at encouraging local developers to build homes on brownfield land. Gateshead has a number of small brownfield sites with significant risks from coal mining and industry that, in turn, affect whether a site is a viable option in terms of development.
Back to Darren Beriro: “We’re hoping that this will be of interest to other councils and developers in the UK. Developers can be risk-averse when it comes to brownfield sites, understandably because of the uncertainties and potential unforeseen costs. The calculator will help by giving developers a bit more confidence to investigate brownfields further.
"We believe that the calculator can change the way brownfield ground conditions are understood very early in planning and viability studies and we're keen to demonstrate this is the case with forward-thinking individuals and organisations. We envisage working collaboratively with new partners where co-design, co-development and co-delivery form the basis of the working relationship".
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| An example of a brownfield site in Greater Manchester |
Back in October 2018, the government announced plans to speed up the planning system so they can meet their commitment to build 300,000 new homes every year by the mid-2020s. But where these homes go is a delicate matter. Building on greenfield areas (sites that have not been built on before) is highly contentious and largely unwanted by those that enjoy living next to them. With this in mind, the government is also encouraging the redevelopment of brownfield sites.
When things go wrong
There have been many occasions throughout history when unexpected ground conditions have cause major problems for developers, some of which have been devastating. Understandably, this is not something widely advertised so finding details of such events is not easy. One example, however, involved the development of several hundred homes in former greenbelt land. For legal reasons, the details cannot be revealed but, in summary, weak ground conditions caused by historic and unidentified mining resulted in delays and additional costs to the project. More expensive deep pile foundations were needed that led to interruptions in housing delivery that, in turn, impacted the council’s five-year housing supply.The good news
Project manager Dr Darren Beriro explains: “We wanted to bring together all the data we knew would help us get the best possible picture of the ground conditions as well as the likely costs to remediate the brownfield site early in the process”.
How does the calculator work?
The calculator helps to identify the scale of risk and abnormal (not anticipated or routinely encountered) costs associated with ground conditions such as:
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| Summary of the four brownfield ground risk calculator outputs. |
- Soil and groundwater contamination
- Natural hazards
- landslides
- shrink-swell clay
- running sand
- collapsible ground
- compressible ground
- soluble rocks - Mining hazards (coal and other mining)
- Radon (natural radioactivity)
- Landfill
It uses environmental data to produce ground risk and mitigation cost estimates. Data sources include those from the British Geological Survey, Coal Authority, Environment Agency, Ordnance Survey and individual Local Authorities as well as local documents.
Brownfield sites are analysed and the results are presented in a geographical information system (GIS) in 50 x 50 m grid cells. Each cell contains information about the site. The ground-risk score and associated risk-mitigation-costs-estimate data are presented as two layers: detailed site overview and generalised site summary. They reflect the risk that contamination might pose to human health and controlled waters as well as the potential effect of adverse ground conditions on the structural integrity of newly built homes.
Where has it been used?
The calculator has been used most extensively for the Greater Manchester Combined Authority Council (GCMA) area. 4,770 brownfield sites were analysed and have been applied by the GMCA to generate risk and associated risk mitigation costs for eleven sites that form the basis of their Housing Infrastructure Fund bid. This £132 million bid was submitted by Wigan and Bolton Housing Growth Corridor to Homes England. The funds are required to deliver infrastructure and overcome ground related Abnormals in the proposed development area. Plans are regionally significant and include nearly 13,000 houses along a new growth corridor, meeting 6% of the housing need across Greater Manchester to the year 2037. In addition, nearly 50 hectares of employment land will also be delivered creating over 180,000 square metres of new employment floor space.
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| Brownfield ground risk calculator conceptual model for risks to human health and controlled waters from soil and groundwater contamination |
Gateshead Council have also commissioned the BGS to develop a version of the calculator aimed at encouraging local developers to build homes on brownfield land. Gateshead has a number of small brownfield sites with significant risks from coal mining and industry that, in turn, affect whether a site is a viable option in terms of development.
Future work
"We believe that the calculator can change the way brownfield ground conditions are understood very early in planning and viability studies and we're keen to demonstrate this is the case with forward-thinking individuals and organisations. We envisage working collaboratively with new partners where co-design, co-development and co-delivery form the basis of the working relationship".
If you would like to find out more about the BGS Brownfield Ground Risk Calculator, please contact Darren Beriro or see www.bgs.ac.uk/brownfield. You can also follow our progress @BGSBrownfields
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