Greening Brownfields: Unlocking the potential for SuDS on brownfield land
This International Women’s Day we are celebrating the inspirational women that contribute to our success. Leading the way are the heads of our Water and Geoenvironmental teams, Jacqueline Diaz-Nieto and Amy Juden, who share their collaborative thoughts on the potential for SuDS to be used on brownfield sites.
With a housing crisis that shows no sign of slowing, coupled with a desire to conserve our dwindling green spaces, there is a renewed push to find development space on brownfield land. The regulative landscape will soon see the introduction of Schedule 3 which means the industry will need to consider using sustainable drainage systems (SuDS) on every development site.
Using sustainable drainage systems on brownfield land brings advantages. Sustainable drainage systems can be designed to complement the ground conditions and constraints and bring multiple additional benefits to a project; greening brownfield sites. The wide-ranging positives of this approach shouldn’t be underestimated.
Schedule 3 requires designers to consider SuDS within a hierarchy that prioritises discharging surface water to ground, and with SuDS also serving a dual purpose of satisfying the Biodiversity Net Gain (BNG) requirements, making SuDS work on brownfield sites makes financial and environmental sense and will ensure compliance with new requirements.
Resistance may exist against infiltration drainage on potentially contaminated sites. It is true that infiltrating water has the potential to mobilise soil contaminants and subsequently pollute rivers and groundwater, however, depending on the contaminants and their leachability (mobility in water), infiltration could be acceptable if properly assessed and designed. This is especially true for diffuse infiltration limited to pre-development rates, which is likely to be suitable on all but the most severely contaminated development sites. Concentrated soak-away drainage might not be suitable through made ground or contaminated materials, but it may still be possible to locate these to discharge at slightly greater depth into natural ground, or on a less contaminated part of the site. Even on development sites where leachable contamination has been identified it may be possible to plan the remediation strategy such that these soils are relocated to less sensitive areas or capped by hard surfacing.
Even on highly contaminated sites, SuDS designed not to infiltrate can bring significant advantages, and shouldn’t be ruled out. Waste disposal costs for contaminated soil, particularly if classed as hazardous can be a significant cost to development. Keeping drainage systems shallow and designing out deep drainage and large attenuation tanks can reduce the associated excavation and removal costs, particularly relevant for contaminated ground. Shallow water storage used in SuDS could include gravel layers or geocellular crates under permeable paving or lined landscaping features. These solutions can come into their own for redevelopment of former landfill sites, where not only is excavation and soil disposal costly, it may also come with specific environmental permitting requirements. With wait times for some bespoke environmental permit decisions extending over 24 months, this is not an appealing option for developers or contractors, and SuDS may provide the solution!
SuDS champions often talk about the four pillars of good SuDS being the design for quantity, quality, amenity and biodiversity. Whilst often overlooked by traditional drainage designers, the potential amenity and biodiversity benefits of SuDS on brownfield land is huge and can strengthen the case for making SuDS work on brownfield land. Well-designed SuDS not only provide the hydraulic attenuation requirements to achieve greenfield runoff rates, reducing the risk of flooding downstream, but vegetated SuDS (with the shallow attenuation below ground) provide much-desired urban greening, they also bring a myriad of other social and environmental benefits.
SuDS sells! SuDS provide multiple landscape and biodiversity benefits, making new developments an attractive place to be as well as providing amenity and social value along with the economic advantages of rejuvenating an area. Together these factors make developments much more desirable. This is particularly pertinent when a site was previously derelict, unused, or unloved. Getting SuDS onto your brownfield sites is literally turning brown to green!
Success in these designs depends on understanding the ground model, specific constraints in the ground from previous uses, levels of contamination and the pathways for contaminant migration. Drainage designs for brownfield sites therefore benefit massively from the input of geoenvironmental professionals from the start. Experts who understand all aspects and can advise SuDS designers on safe working depths for the SuDS attenuation layer and specify from the start whether leaky SuDS can be designed, busting the popular myth that SuDS on brownfield sites must be tanked.
At EPG, our combined skills and experience in drainage design, ground conditions and land contamination allows us to unlock the potential benefits of SuDS on brownfield sites and provide clients with a one-stop shop.
Our dynamic team is changing the narrative around holistic environmental designs for challenging sites. Don’t believe anyone who tells you that you can’t infiltrate on brownfield land. Challenge any design that includes a deep-dig through contaminated ground for a large attenuation tank. Get in touch with EPG to see if we can do better and provide you with a more cost-effective, greener design using our innovative approach.
Imagine a simple remortgaging conversation revealing that your house has no financial value. This was the harsh reality for one of thirteen residents in Bradford, who discovered that the developer not adhering to planning conditions had resulted in his home receiving a zero valuation on remortgaging.
The plight of the residents was shared in October 2020, on the BBC programme ‘Rip off Britain’. Details emerged that gas membranes had not been installed and verified as required by the planning conditions, and the developers had since ceased trading, leaving residents stranded and distraught.
With a wealth of experience in risk assessments and land remediation, EPG stepped in to examine the cases in detail. With an offer to investigate, free of charge, our Technical Director Steve Wilson sat down with some of the residents to discuss potential ways to resolve the problem. It became apparent that other planning conditions, relating to soakaways in the back gardens and an access road, had also not been complied with.
The homes are located adjacent to a former landfill site which is also an area of former coal mine workings. However, this does not automatically mean that there is a risk of gas ingress into the buildings. Using existing information, EPG built up a detailed conceptual site model (CSM). The CSM is a vital part of any gas risk assessment and crucially, the part where extra time and effort pays dividends.
It took over a week to drill down into the information and compile the model, which demonstrated that the risk of gas emissions was very low and gas membranes were not required. Furthermore, there was no need for further site investigation or gas monitoring to support this conclusion.
EPG can provide this service for developers, and the cost of the desk study is usually far less than the cost savings achieved by removing the need for gas protection or gas monitoring at the preliminary risk assessment stage. Even where gas monitoring is required, we can often reduce or completely remove the need for gas protection systems.
EPG also provided a revised specification and design for soakaways in the back gardens, with clients Alderburgh and JUTA (UK) kindly supplying the soakaway boxes and geotextile surround at no cost to the residents.
The final piece in the jigsaw was to meet with the Highway Authority and agree that the access road could remain unadopted (private), avoiding the need for remedial works to bring it up to highway standards. There was a small cross over strip at the entrance already owned by the Highway Authority and EPG designed and specified some simple works to resolve the issue.
EPG is part of a wider consultancy – STRI Group, and working alongside one of their senior planners, James Podesta, were able to submit a planning application to remove/vary the planning conditions to formalise amendments, and this was approved last year.
The work put into place will allow the homeowners to proceed as normal and we wish them all the best for the future.
Environmental Monitoring Manager, Leo Phillips, talks us through the work that EPG are carrying out during a ground gas monitoring visit on what will become part of an industrial estate.
As a company we are proud of the fact that we have contributed to much of the guidance on landfill, ground gas and VOC assessment within the UK; including British Standards BS8576, BS8485, CIRIA Reports C665, C735 and C748, Claire Research Bulletin RB17 and Claire Technical Bulletins TB16 and TB17.
The NHBC Foundation’s latest report, Hazardous ground gas – an essential guide for housebuilders, is available to download now. Compiled by experts in the field, this comprehensive report offers guidance and insight for housebuilders covering everything from what constitutes a hazardous ground gas, initial investigations and assessment of ground gas to gas protective measures. EPG’s Steve Wilson and Amy Juden contributed to the guide along with colleagues from Buro Happold, and the guidance will help housebuilders to:
- recognise high risk sites and the appropriate action to take
- avoid unnecessary gas protection on low/minimal risk sites
- appoint appropriate competent professionals at the right stage
- complete the process of assessment, design, implementation and verification
- and implement monitoring strategies suitable for the size, complexity and gas risk of sites.
The report guidance also addresses the current gap between the conclusions and recommendations of ground investigation reports and the structural design of buildings where gas protection measures are not always included.
Hugh Mallett, Director, Ground Engineering, Buro Happold said,
“This new NHBC guide on hazardous ground gas will help housebuilders and their advisors to better assess and manage gas risk and ensure the efficient building of new homes. Buro Happold, EPG and NHBC have worked hard to ensure the guide delivers current good practice and that the advice is practical and relevant to all housebuilders. Following the six-stage process and recognising the importance of competence at each stage will help housebuilders get it right first time and avoid potential pitfalls, saving time and money, whilst delivering homes safe from the potential risks of hazardous ground gas.”
“Adoption of the good practice procedures described in this report will lead to better quality practice, cost savings and a greater understanding of specific issues around detailing, construction and verification,” commented Richard Smith, Head of Standards, Research & Technical Competency at NHBC Foundation. “Early consideration of the risks of hazardous ground gas is essential for all developments and we are pleased to be able to guide housebuilders through this potentially complex process.”
Amy Juden, Associate at EPG added
“We are delighted to see this report published, and the guidance out there to enhance best practice in the industry. We’re looking forward to continuing to work alongside colleagues to increase awareness of these important and complex issues, and use our expertise to help mitigate against risks.”
Written specifically for housebuilders wanting to get up to date and widen their knowledge on this important subject, Hazardous ground gas – an essential guide for housebuilders is available to download here.
Imagine a simple remortgaging conversation revealing that your house has no financial value. This was the harsh reality for one of thirteen residents in Bradford, who discovered that the developer not adhering to planning conditions had resulted in his home receiving a zero valuation on remortgaging.
The plight of the residents was shared in October 2020, on the BBC programme ‘Rip off Britain’. Details emerged that gas membranes had not been installed and verified as required by the planning conditions, and the developers had since ceased trading, leaving residents stranded and distraught.
With a wealth of experience in risk assessments and land remediation, EPG stepped in to examine the cases in detail. With an offer to investigate, free of charge, our Technical Director Steve Wilson sat down with some of the residents to discuss potential ways to resolve the problem. It became apparent that other planning conditions, relating to soakaways in the back gardens and an access road, had also not been complied with.
The homes are located adjacent to a former landfill site which is also an area of former coal mine workings. However, this does not automatically mean that there is a risk of gas ingress into the buildings. Using existing information, EPG built up a detailed conceptual site model (CSM). The CSM is a vital part of any gas risk assessment and crucially, the part where extra time and effort pays dividends.
It took over a week to drill down into the information and compile the model, which demonstrated that the risk of gas emissions was very low and gas membranes were not required. Furthermore, there was no need for further site investigation or gas monitoring to support this conclusion.
EPG can provide this service for developers, and the cost of the desk study is usually far less than the cost savings achieved by removing the need for gas protection or gas monitoring at the preliminary risk assessment stage. Even where gas monitoring is required, we can often reduce or completely remove the need for gas protection systems.
EPG also provided a revised specification and design for soakaways in the back gardens, with clients Alderburgh and JUTA (UK) kindly supplying the soakaway boxes and geotextile surround at no cost to the residents.
The final piece in the jigsaw was to meet with the Highway Authority and agree that the access road could remain unadopted (private), avoiding the need for remedial works to bring it up to highway standards. There was a small cross over strip at the entrance already owned by the Highway Authority and EPG designed and specified some simple works to resolve the issue.
EPG is part of a wider consultancy – STRI Group, and working alongside one of their senior planners, James Podesta, were able to submit a planning application to remove/vary the planning conditions to formalise amendments, and this was approved last year.
The work put into place will allow the homeowners to proceed as normal and we wish them all the best for the future.
As contaminated land risk assessors and designers, we have the greatest opportunity to minimise the carbon impact of developments on brownfield land. Similar to the waste hierarchy we learned at primary school, where the first priority is to Reduce, then Reuse, then Recycle, when it comes to remediation, the most sustainable option is often to do nothing. Better conceptualisation of a site and using detailed quantitative risk assessment (DQRA) can make this possible, but these tools are underutilised. Over-conservative assessments lead to over-engineered designs and unnecessary remediation works, contributing to the significant embodied carbon in the construction industry.
It should be considered environmentally irresponsible to specify remediation on the basis of a generic screening approach alone, without considering further assessment that could lead to a reduction in remediation. Remediation should not be used as a substitute for adequate investigation and assessment.
Most of the rhetoric and guidance/publications on sustainability in contaminated land to date (i.e. that produced by the CL:AIRE Sustainable Remediation Forum SuRF-UK) focuses on methods to minimise operational carbon emissions during remediation works. However, I argue that we could have a more significant impact on the carbon budget of a project if we consider the carbon impact earlier in the process and eliminate unnecessary remediation at the risk assessment stage.
As risk assessors and designers, we have a responsibility to design out carbon from our development projects wherever possible, in the same way that we have a duty to design out health and safety risks under CDM.
If climate change is causing deaths now at a rate of a few hundred tonnes of carbon dioxide per death, are our frameworks for assessing risk from contaminated land fit for purpose? Do we need to rethink the precautionary principles on which we operate? It also depends on people’s attitudes to risk. Perhaps climate change is so well-known and accepted in society now that we accept the fact that people all over the world are dying in climate related natural disasters. Our appetite for health risks associated with ground contamination (i.e. toxins in our garden soils, or carcinogenic vapours in our homes or workplaces) may be different.
Never-the-less there is far more that can be done within the existing frameworks and acceptable minimal risk levels. Remediation is being over specified on the basis of theoretical risks that are poorly determined.
In summary, as contaminated land risk assessors and designers, we have the power to minimise the carbon impact of developments on brownfield land. The most efficient way to do this is by intervening early. This means that before considering remediation, we should better conceptualise a site and use DQRA to determine if no action is the most sustainable option.
This is the approach that is always taken at EPG. We pride ourselves on delivering the most sustainable solution for a site, and are never afraid of offering an innovative assessment or bespoke approach to get there. This can have the added benefit of saving our clients significant sums of money in the construction phase.
But what will the future of contaminated land assessment look like in the context of climate destruction and the race to net zero? Should we incorporate the carbon cost of a human life into a new holistic framework for construction and remediation on brownfield land that considers the need for development and remedial intervention against the actual human cost? By changing the narrative and talking about carbon footprints in terms of death rates, we can increase awareness of the urgency of the climate crisis and the need to transition to net zero as quickly as possible.
Improving standards in contaminated land risk assessment through increased use of DQRA, education and training, and new targeted research, will allow for a reduction in the carbon footprint of our industry. As well as saving money on development projects. Development of standardised tools for measuring the carbon impact of remediation works, will allow us to manage this effectively. And incorporation of the concept of the “carbon cost of a life” would allow for comparison of carbon budgets, with human health risks.
Better risk assessment is integral to reducing carbon emissions in remediation of brownfield land. Let us work together to create a more sustainable and resilient future for all.
The Environmental Protection Group (EPG) is delighted to welcome their new Head of Water, Jacqueline Diaz-Nieto.
Jacqueline joins EPG to lead the water department and brings with her a wealth of experience in the industry. EPG has an established water team and is committed to ensuring innovative, sustainable solutions become a fundamental part of urban and sports designs. Jacqueline will use her extensive expertise in sustainable drainage (SuDS) to address flooding issues and deliver the multiple benefits of SuDS for communities.
A chartered water and environmental manager with CIWEM, she has over ten years’ experience in the water industry and is currently working towards Chartered Engineer status with the Institute of Civil Engineers.
Jacqueline has a BSc in Geography from UCL, which she followed with a MSc in Environmental Monitoring, Modelling and Management. Following time in a research role in South America, she then studied for a PhD in urban flooding and sustainable drainage at the University of Sheffield.
Jacqueline then worked for over 10 years in the water industry, first at Yorkshire Water and most recently at Severn Trent, as a technical specialist promoting and championing SuDS and then a senior design engineer.
The Environmental Protection Group (EPG) is now a registered Urban Design Practitioner with the Urban Design Group.
Founded in 1978, the Urban Design Group (UDG) is a campaigning membership organisation dedicated to raising the standards of urban design to improve the quality of life in our cities, towns and villages.
Through its work as a geo-environmental engineering design consultancy, EPG is well-placed to positively influence the built environment, and is committed to providing clients with futureproof solutions that help to protect and enhance our precious environments.
Phil Williams, EPG’s Technical Director, commented:
“Designing solutions that protect the environment is at the core of what we do, and being part of organisations which enable us to join forces with like-minded companies and individuals is key to making this a fundamental principle of urban design.
“The recent government decision to implement schedule 3 of The Flood and Water Management Act 2010 which will mandate sustainable drainage (SuDS) in new developments is an very positive step forward, but there is so much more we can do. I’m looking forward to working alongside others in the Urban Design Group to educate and influence decision makers.”
We are delighted to share the recently published CIRIA guidance, detailing the use of sustainable drainage systems (SuDS) and how they can be utilised in order to reduce phosphorus in surface water runoff. Finding effective ways to reduce phosphorus is important in improving quality of our water, and limiting the damaging impacts on local ecology. Over 100,000 homes are now being delayed across 74 local authorities as a direct result of potential excess nutrient pollution, of which phosphorus is a key contributor.
This document is co-authored by Phil Williams and Karolina Stachyra of the Environmental Protection Group, and provides good practice guidance on the use of SuDS for the reduction of phosphorus in runoff from new development to help developments become nutrient neutral. It sets out the necessary SuDS, deployed in ‘treatment trains’ to achieve phosphorus removal, particularly for sensitive receiving waters and nationally important nature conservation sites. It represents good practice surface water management through the use of SuDS and can be applied anywhere.
We currently have a vacancy for a motivated graduate to join a growing team at our office in Bingley, West Yorkshire.
The successful candidate will help us to deliver effective and professional services for a range of varied and high-profile clients. While you’ll be given appropriate responsibilities from day one, we’ll give you the chance to take on more as you progress and broaden your skills through training from our team of industry experts
Your work would include, among other things:
- Working with EPG’s colleagues in specialisms such as contaminated land investigation, ground gas risk assessment, vapour intrusion risk assessment, mitigation design and design of remediation strategies.
- Site work including ground gas, groundwater and vapour monitoring and sampling.
- Working with and meeting clients and collaborators such as contractors, consultants, architects, landscape architects, manufacturers, local authorities and others.
- Specifying and analysing relevant information to enable design e.g. ground investigation data, survey information, ground gas monitoring data, geological data etc.
- Undertaking feasibility studies and preparing technical reports.
- Producing conceptual site models and cross-sections.
- Using software packages such as GIS, Scalgo, Grapher, GasSim, CAD and CorelDRAW.
- Managing your own time and deadlines to meet project commitments.
- Undertaking regular training to further enhance your career development.
The role will include some travel throughout the UK to undertake site work.
If you have a degree in a relevant subject and are enthusiastic about a career in contaminated land, engineering and environmental science and want to work as part of a dynamic and forward-looking organisation, then we would like to hear from you.
About you
Essential
- Degree in Civil Engineering, Geology, Environmental Science or other related field.
- Highly motivated individual with good organisational and analytical skills.
- Initiative to work individually or as part of a wider team.
- Strong written and oral communication skills.
- Ability to show initiative and creativity in problem solving.
- An interest in the environment and sustainable development.
- A keen eye for detail.
- Excellent word processing and excel skills, along with general IT proficiency.
- Full UK driving licence.
Desirable
- Basic GIS skills.
- Report writing experience.
- Experience working outdoors in adverse weather conditions.
How to apply
Please send a CV (two A4 pages maximum) and covering letter (500 words maximum) to recruitment@epg-ltd.co.uk.
About EPG
The Environmental Protection Group (EPG), established in 1998, is a leading independent Geo-Environmental Engineering Design Consultancy delivering cost-effective, sustainable designs; focused in the areas of contaminated land remediation and gas protection, sustainable water management, flood risk assessment and structural waterproofing.
We provide a professional, comprehensive design service offering uncompromising design excellence. Our core values include combining regulatory compliance with complimentary innovative ideas and technologies to ensure we deliver robust, leading edge, cost-effective design solutions. Our client base ranges from government agencies, major developers and contractors to small individual private clients and our service offering encompasses the complete cross-section of the construction sector.
About STRI
EPG is part of the STRI Group focused on sport and outdoor recreation, sustainable development, green infrastructure, and water management sectors with its head office in Bingley, West Yorkshire. STRI is a world leading sports surface solutions, environment and green infrastructure development business. With research and innovation at its heart STRI is an exciting environment to work, where new ideas are always welcomed.
We are delighted to see the news that the government has accepted a review to implement Schedule 3 to the Flood and Water Management Act 2010, which will mandate sustainable drainage (SuDS) in new developments.
The review recommends that the government must act and implement Schedule 3 to the Flood and Water Management Act 2010 as written, with the unitary authority or, if there is not one for the area, then the county council as approving bodies.
This follows the letter sent to Rishi Sunak encouraging him to implement schedule three of the 2012 Flood and Water Management Act as a matter of urgency. Phil Williams, who heads up EPG, was pleased to be one of the forty signatories on the letter, alongside other leading figures from engineering and environmental groups.
The review recommends implementation subject to final decisions on scope, threshold and process once a full regulatory impact assessment has been completed. The assessment will look at different options and the expected costs and benefits. This will ensure a consistent and more effective approach in using SuDS to help address the impacts of climate change, urbanisation and increasing population while achieving multiple benefits such as reducing surface water flood risk, improving water quality, and harvesting rainwater to meet current and future needs.
However, these benefits can only be realised if SuDS are designed, constructed, adopted, and maintained to national standards for the lifetime of the development.
Implementing Schedule 3 will guarantee this is achieved. The review recommends that successful implementation of Schedule 3 will require professionals with the skills and knowledge to design, construct, assess and maintain SuDS. It also recommends that actions are developed to ensure there is sufficient access to the right skills and capabilities to deliver and maintain SuDS
Defra will carry out a consultation in order to collect views on the impact assessment, national standards and statutory instruments in 2023.
https://www.gov.uk/government/publications/sustainable-drainage-systems-review
