Article Sustainability

Brownfield and Biodiversity Net Gain – opportunities and risks

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Biodiversity net gain (BNG) is an approach to development that aims to leave biodiversity in a measurably better state than before. BNG is both an outcome and a process. The approach to BNG consists of ten guiding principles as outlined in the Good Practice Principles for Development[1] and in England, the application of an excel-based tool, the Biodiversity Metric 3.1 Calculation Tool[2] (hereafter ‘the Metric’), as a proxy measure of biodiversity. In this article, we will explore how the Principles for Development are essential to the best practice application of the Metric to avoid biodiversity being considered as a numbers game. We will also discuss the opportunities and risks presented by BNG and its delivery to the development of brownfield land.

Across the UK, the BNG approach is known and associated with policy and legislation to different degrees. In England, the Environment Act 2021 has made the BNG approach a mandatory requirement of planning permission. This primary legislation requires all size developments, excluding permitted development, to achieve a minimum of a 10% net gain in biodiversity for at least 30 years, demonstrated through the Metric. It will come into effect between 2023 and 2025 and tie in with secondary legislation providing further details of how the approach will work in practice. In the meantime, Local Planning Authorities already expect net gain to be achieved in developments, as required by the National Planning Policy Framework (NPPF); the difference being that the NPPF does not define a percentage.

In Scotland, Wales and Northern Ireland, legislation for BNG does not yet exist. Current policy, however, suggests the use of BNG as a valid and robust way to meet policy requirements. For example, in Scotland, the latest National Planning Framework 43 must implement the Planning (Scotland) Act 2019 stipulation for development to secure positive effects for biodiversity[3]. In Wales, under the Planning Policy Edition 11, there is the requirement for development to prevent biodiversity losses or compensate for losses where damage is unavoidable[4] and that any development must provide a net benefit for biodiversity. In Northern Ireland, Planning Policy Statement 2: Natural Heritage 2013 states ‘planning policies of this statement must have regard to any strategy designated for the conservation of biodiversity…’ and ‘protection and/or enhancement’ of ‘natural heritage features and designated sites’ is required[5].

This article will focus on England, where policy and legislation are most developed in BNG, allowing for better exploration of implications for brownfield land. However, many of the principles of how the approach works, as well as drawbacks and opportunities, could apply elsewhere in the UK.

Initially, Natural England, the relevant non-departmental public body, considered whether brownfield land should be excluded from the Metric. However, following a recently completed consultation[6], the government is proposing not to apply exemptions to brownfield sites that meet a set criteria. They state that ‘an exemption based on an appropriate combination of these criteria would deliver little added benefit and would greatly complicate the requirement’s scope for developers and planning authorities alike…. furthermore, many brownfield sites offer significant potential for achieving biodiversity net gain as they often have a low pre-development biodiversity value’[7].  Therefore, brownfield developments are seen to offer significant biodiversity value, especially in urban environments.

The habitats found on brownfield land vary from areas of remaining bare ground or hard standing, to ruderal and ephemeral vegetation, to grassland and scrub. Where a combination of these habitats occurs within a certain continuous area, they can fit the description of Open Mosaic Habitats on Previously Developed Land (OMH). The periodic disturbance and abandonment of the land replicates the ‘disturbance’ process found in natural ecosystems. Disturbance is often essential to ‘restart the clock’ of succession (the process by which the structure and mix of species and habitats in an area change over time). Disturbance supports the creation of a variety of habitats across a landscape, which in turn supports species diversity. This is where brownfield land can be valuable to biodiversity.

Brownfield land often falls into the category of a biodiversity rich habitat or one that is very poor for biodiversity. The type of species and habitats found on brownfield land are often rarer than those found in the countryside, with evidence suggesting between 12% and 15% of all nationally rare and scarce insects are recorded on these sites[8]. Whilst the countryside is often viewed as more biodiverse, many modern farming methods prevent the establishment of diverse habitats and species. Therefore, often brownfield land is more bio-diverse than the farmed countryside.

Where brownfield land does not have OMH and is classified as poor quality, it can offer significant opportunities for habitat banking. Habitat banks are habitats that are created in advance of development i.e., banked for later. When a development goes ahead, and the habitat can’t be saved, the habitat bank can be called upon to offset the habitat lost providing the previous steps of the mitigation hierarchy have been applied[9]. There are various opportunities with brownfield land to provide a bank. Where low scoring brownfield habitats are present, such as with hardstanding, bare ground or certain ruderal, ephemeral, grassland and scrub types, much can be done to improve biodiversity. For example, taking up the hardstanding to plant, planting up bare ground, adding more native species variety to existing grassland or scrubby areas, or adding a range of habitats instead of one.

As habitat banking is in its infancy, expert advice is necessary before setting up a habitat bank to ensure that the correct governance, registration (with the LPA but likely also with NE) and monitoring procedures are in place to meet the Environment Act (2021) requirements. Currently, there is no regulation around habitat banking; regulation is expected between 2023 and 2025 when BNG will become mandatory.

When brownfield land has low scoring habitats of condition and distinctiveness, they can  be used to contribute toward a development project to achieve net gain, as they can be replaced with almost any other habitat and result in significant biodiversity improvements. This is providing that they are not OMH or other priority habitats i.e., some ponds or native woodland. For example, a site consisting of one hectare area of bare ground provides 2 biodiversity units according to the Metric. Should two-thirds be lost to development and the remainder landscaped with native scrub, 2.21 units could be provided, making a 10% net gain.

In the UK, there is a focus on the remediation of brownfield sites. However, remediation can decrease habitat diversity if it involves intense management instead of natural processes. The addition of nutrient rich topsoil and seeding grass species that require intense management regimes homogenises sites, decreasing plant and animal diversity. Where remediation is not considered, brownfield sites are often neglected and result in scrub encroachment, which can in some cases reduce biodiversity.

High quality brownfield sites may be OMH, which must be considered separately. As a mosaic habitat it may include other habitats of principle importance and is not easily defined so its definition depends on meeting a number of quality criteria. It can be made up of a wide range of habitats including grassland, tall ruderal plant species, native and non-native invasive species and early pioneer communities and is particularly valuable to rare and declining invertebrates[10]. They are vital in ensuring high levels of biodiversity in the UK, supporting pioneer species and species that move between habitat patches, and providing refuge for others. OMH is a Habitat of Principle Importance under Section 41 of the Natural Environment and Rural Communities Act 2006 due to its ability to support a rich assemblage of invertebrates. To qualify it needs to be at least 0.25ha, have more than one specified habitat type within the mosaic, and meet other specific criteria including a known history of disturbance at the site[11].

Within the Metric, OMH is assigned a high ‘distinctiveness’ level. Distinctiveness is a term used in BNG to describe innate qualities of a particular habitat type and can range from very low to very high.  Due to the high distinctiveness of OMH, encountering a site with OMH can be problematic for the developer. Instead of losing and needing to replace 2 units/ha (as would be the case for bare ground), losing OMH habitat would result in the loss of at least 6 units/ha. OMH must also be replaced with the same habitat. Finally, OMH is considered to be of medium difficulty to create in the ‘difficulty to create’ risk factor of the Metric, meaning that it will likely only be successfully created two-thirds of the time. Thus, the Metric requires 1ha of lost OMH to be replaced with 1.9ha of the same habitat of the same quality.

One of the aims of the Metric is to disincentivise development on particularly valuable habitats, which might occur with OMH. However, though it is difficult to create, other habitats in the Metric are considered harder to create. OMH may also be easier to manage: because the habitat is a result of previous disturbance, more disturbance can be used to ‘reset its clock’. This could be as simple as clearing areas rotationally from time to time. Also, this habitat is only considered to require four years to reach moderate condition in the ‘time to target’ risk factor of the Metric, and ten years to reach time to target good condition. However, the site would need to be managed for 30 years under the Environment Act. It should be noted that each site is unique and there is no set time period in which OMH will develop. This period is dependent on various factors like the type of brownfield site, proximity to other landscape features, topology and climate. Furthermore, because the distinctiveness of the habitats is high, they produce high numbers of biodiversity units relative to their area. Finally, these areas punch above their weight in biodiversity terms compared to other habitats and can be particularly valuable in urban areas where other greenspace is lacking.  For these reasons, OMH could be a good habitat to investigate when setting up a habitat bank.

The government has identified that at least 300,000 new homes would need to be built in order to meet the increasing housing supply demands. It recently announced an initiative to promote the development of derelict sites into new homes under a new brownfield fund[12]. Whilst this is viewed as a way to boost local economies and home ownership, there is a significant risk to biodiversity and ensuring climate resilience within cities. Research has shown that ex-landfill sites contain assemblages of rarer birds, which could be lost through new housing developments (Macgregor et al., 2022)[13].

There are several opportunities associated with this type of habitat, including the multi-functionality of these sites and the creation of habitats from the start of the succession, thus supporting more biodiverse pioneer species than had previously occurred.  Additionally, naturally occurring OMHs, which develop as a result, will enhance biodiversity in a fragmented landscape through the creation of habitat corridors, which will have an overall significant beneficial impact on future biodiversity.

In conclusion, brownfield sites, through the presence of OMH, can have greater biodiversity than that of countryside land and other land within the UK, as shown through the Metric. This increased biodiversity uplift in both condition and distinctiveness occurs through the development of OMH on brownfield land that is in a poor condition. However, to realise these benefits, further awareness is required including the correct management regime of these sites and to increase the public and developers’ perception of the benefits of these sites. OMH provides vital successional habitats for a wide variety of species if the natural ecosystem process is allowed to occur. These habitats are Habitats of Principle Importance and are key to enhancing biodiversity, climate resilience and wider natural capital benefits.   These sites have commercial potential through offering habitat credits (i.e., a unit of trade that places monetary value on habitat preservation or restoration[14]) to both developers and Local Planning Authorities via the creation of habitat banks.  However, allowing OMH to occur on these sites is not considered in line with the current government plans to build new homes and boost the local economics.

References:

[1] CIEEM, CIRIA, IEMA (2016) ‘Biodiversity Net Gain: Good practice principles for development

https://cieem.net/resource/biodiversity-net-gain-good-practice-principles-for-development/ Biodiversity-Net-Gain-Principles.pdf (cieem.net)

[2] Natural England (2022), The Biodiversity Metric 3.1. The Biodiversity Metric 3.1 – JP039 (naturalengland.org.uk)

[3] Planning (Scotland) Act 2019 [online]. Available at: https://www.legislation.gov.uk/asp/2019/13/section/2/enacted

[4] Welsh Government. Planning Policy Edition 11 [online]. Available at: https://gov.wales/sites/default/files/publications/2021-02/planning-policy-wales-edition-11_0.pdf

[5] Department of the Environment (2013). Planning Policy Statement 2 Natural Heritage [online].

Available at: https://www.infrastructure-ni.gov.uk/publications/retained-planning-policy

[6] Department for Environment Food & Rural Affairs (2022) ‘Consultation on Biodiversity Net Gain Regulations and Implementations.  https://consult.defra.gov.uk/defra-net-gain-consultation-team/consultation-on-biodiversity-net-gain-regulations/ (accessed 01/08/222). Results expected Autumn 2022.

[7] Department for Environment Food & Rural Affairs (2022) ‘Consultation on Biodiversity Net Gain Regulations and Implementations. https://consult.defra.gov.uk/defra-net-gain-consultation-team/consultation-on-biodiversity-net-gain-regulations/ (accessed 01/08/222). Pg 26.

[8] Lush.M., Kirby.P., & Shepherd.P. (2013) ‘Open Mosaic habitat survey handbook’ Open Mosaic Habitat Survey Handbook (buglife.org.uk) (accessed 29/07/22).

[9] Chartered Institute of Ecology and Environmental Management (2021) ‘Good Practice Requirements for Delivering Biodiversity Net Gain (On-and Off-site)

[10] https://www.nature.scot/sites/default/files/2018-02/Priority%20Habitat%20-%20Open%20Mosaic%20Habitats%20On%20Previously%20Developed%20Land.pdf#:~:text=The%20Open%20mosaic%20habitats%20on%20previously%20developed%20land,sites%20support%20good%20examples%20of%20this%20priority%20habitat. (accessed 01/08/22)

[11] Riding, A., Critchley, N., Wilson, L. and Parker, J. 2010. Definition and mapping of open mosaic habitats on previously developed land: Phase 1. Defra Research Report WC0722. London, Department for Environment Food and Rural Affairs.

[12] Department for Levelling Up, Housing and Communities (2022). ‘Derelict sites to be transferred into new homes as new brownfield sites opens’ https://www.gov.uk/government/news/derelict-sites-to-be-transformed-into-new-homes-as-new-brownfield-fund-opens (accessed 29/07/22).

[13] Mcgregor.C., Bunting. M., Deutz.P., Bourn.N., Roy.D., Mayes.W. ‘Brownfield sites promote biodiversity at a landscape scale. Science of the Total Environment, Vol 804, Jan 2022, 150162.

[14] Garnter.T., (2010) ‘Habitat Credit Trading’ PERC Reports, Volume 28, No.1.

Article provided by Hannah Williams (Principal Ecologist, BNG) & Harriett Ricketts (Natural Capital Specialist) – WSP

Image credit to Andy O’Dea, Cognition Land and Water

Article Sustainability

New SoBRA Guidance on the Incorporation of Future Climate Change Effects into Controlled Waters Risk Assessments of Land Contamination

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Overview

In May 2021 a SoBRA sub-committee was established to develop guidance to help practitioners in the land contamination sector to account for climate change effects in controlled water risk assessments (CWRA) in a robust and consistent manner.  The sub-committee has representatives from geo-environmental consultancy and UK regulatory bodies (a full list of contributors is provided at the end of this article).  The full guidance entitled “Guidance on assessing risk to controlled waters from UK land contamination under conditions of future climate change” (V.1.0, dated August 2022), will soon be available for download from the SoBRA website[1].

Context

Climate change is expected to alter the frequency and distribution of rainfall, increase atmospheric temperatures, and increase the frequency and severity of extreme weather events, leading to longer periods of drought and more extreme rainfall events with associated rising groundwater and surface water levels causing flooding and coastal inundation. Furthermore, long-term changes in climate are forecast with the Meteorological Office projecting that by 2070, on average across the UK, summers will be between 0.9 and 5.4 ᵒC warmer, and winters will be between 0.7 and 4.2 ᵒC warmer[2].  Precipitation is also expected to be affected, with a -47% to +2% UK average change during the summer months, and a -1% to +35% change during winter months[3].  The projected pattern of rainfall across the UK is not uniform and will continue to vary on seasonal and regional scales into the future – see information provided by the Met Office[4] for seasonal and regional variations.

Changes in recharge rates, and to a lesser extent atmospheric temperature, can be important factors in determining the outcome of CWRAs[5]  being completed to assess the impacts to receptors from contaminant sources.  Climate change could therefore alter the risk posed to controlled waters (including to groundwater resources, surface water bodies, marine bodies, and groundwater-dependent terrestrial ecosystems), and the required management of these risks.

The need to incorporate the predicted effects of future climate change into qualitative and quantitative risk assessments has been recognised but rarely implemented in practice. This need is set out within the Environment Agency’s 2010 “Managing and reducing land contamination: guiding principles (GPLC2) FAQ 8”, and within the National Planning Policy Framework (NPPF) for England and Wales and LCRM. It is understood that the National Planning Framework 4 and WAT-PS-10 in Scotland will also in future include the need to consider climate change within land contamination risk assessments. Within the recently published BS21365[6] there is a requirement to consider and identify ‘possible foreseeable events’ within CSMs that could affect contaminant impacts or create new exposure pathways, e.g. flooding, rising groundwater or seawater levels and extreme weather which all go hand in hand with climate change. The absence of published UK guidance has resulted in variable ways of inclusion of climate change effects into CWRA, or, more usually, the influence of climate change being ignored entirely.

Effect of Future Climate Change on Controlled Waters Risk Assessments

All CWRA are underpinned by a conceptual site model (CSM), which synthesises the key physical, chemical, and biological processes that characterise the system, and establishes any potential Source-Pathway-Receptor linkages (i.e. no linkage, no risk).

Figure 1: Indicative CSM considerations based on a climatic shift to ‘wetter’ weather.

Future climate change could foreseeably affect any given CSM.  For example, an increase in precipitation could lead to increased recharge resulting in rising groundwater levels; source (e.g. soil) erosion; or overland flow.  It can further be seen how these scenarios could affect the pathways from source to receptors e.g. unsaturated zone thickness, hydraulic gradients and dilution factors, or the introduction of new pathways e.g. from overland flow, or previously unsaturated drains/culverts acting as new preferential pathways (see Figure 1).  As a result of the change in pathway, the number and type of receptors may also be affected, all of which could change the calculated ‘risk’ posed to controlled waters[7].

Figure 2: Indicative CSM considerations based on a climatic shift to ‘drier’ weather.

By way of another example, an increase in extended periods of hot dry weather or drought i.e. as predicted for the summer months, could result in reduced overland flow; falling groundwater levels which could, for example, change the pathway length by increasing the unsaturated zone thickness or increase dependency of baseflow to rivers; source drying increasing the risk of wind erosion/dust generation, and the development of desiccation cracks creating preferential vertical flow paths; changes in water demand e.g. through the installation of new abstraction wells or enhanced drawdown.  All of which could again alter the calculated ‘risk’ posed to controlled waters (see Figure 2).

In line with industry standards (e.g. LCRM[8]), the SoBRA guidance recognises that any change to a CSM (due to future climate change effects) must be determined by a suitably qualified and experienced professional, using evidence-based reasoning, and that the risk assessment process should only progress to higher tiers (i.e. generic quantitative and detailed quantitative) if the risk cannot be determined ‘acceptable’ at the preliminary stage.  The SoBRA guidance supports practitioners in doing this by setting out “What-if” scenarios for source, pathway, receptor CSM components that could be affected by climate change, in order to guide evidence-based reasoning. This is in line with the approach detailed in BS21365.

Adequacy of Available Datasets

The current best source of information for understanding future meteorological (e.g. temperature and precipitation) and sea level rise projections is the Met Office UK Climate Projection (CP) 18[9] dataset. This dataset was primarily developed to inform water resource management and flood risk assessment and as such the data modelled under the worst case high emissions scenario (RCP 8.5) is the most comprehensive, particularly when considering effects at the local scale. Projections are available until the end of the century. The projections consider average effects and do not necessarily include the effects of extreme events.

The Enhanced Future Flows and Groundwater[10] (eFLaG) Project, which is based on UKCP18 meteorological data, is the most up to date source of information detailing projections to recharge and river flows. This may be a more useful data source in relation to understanding changes to the hydrogeological CSM in relation to future climate change.

The choice of data set used to understand future climate change influences on the CSM is ultimately the responsibility of the risk assessor and should be suitably justified with uncertainties and limitations clearly stated. As the effects of climate change vary seasonally and spatially across the UK, careful consideration should be given to the site setting when choosing the appropriate climate model output for use in risk assessment.

Adequacy of Available Modelling Tools

Commercial modelling tools used in the higher tiers of risk assessment e.g. the Remedial Targets Methodology worksheet (‘P20’)[11], and ConSim[12], currently assume environmental conditions remain constant, however, the effects of future climate change are projected to vary over time, and so therefore will the established pollutant linkages.

This poses a challenge for practitioners with tools ill-equipped to model changes to the values of parameters over time.  Although distributed flow models exist (e.g. MODFLOW and FEFLOW), in addition to compartmental modelling environments (e.g. ConSim), the data requirements, time, and computational and staff resources required to develop and run these models is unlikely to be proportionate to most routine land contamination risk assessments.

It is therefore evident that further tools need to be developed (or current tools adapted) to model the transient effects of future climate change.  However, until such time, the SoBRA guidance recommends that existing tools are employed, except where risks are borderline acceptable (in which case an existing transient modelling approach may be most appropriate).  The SoBRA guidance sets out recommendations for how this can be achieved using commercially available tools.

SoBRA Sub-Committee Members

David Drury (Golder Associates / WSP); Emma Evans (Arcadis); Emma Hipkins (Golder Associates / WSP); Emma Khadun (The LK Group); Helen McMillan (RSK Geosciences); Isla Smail (The Scottish Environment Protection Agency); James Wilson (Atkins); Jesse Davies (Ramboll); Jonathon Atkinson (The Environment Agency); Katie Gamlin (WSP); Leon Warrington (Hydrock); Roisin Lindsay (WSP); Sarah Poulton (Natural Resources Wales); and Suzanne Blackman (Mott MacDonald).

We would also like to thank Simon Cole (SoBRA chair) and the wider SoBRA Executive Committee for their support and contributions in making this guidance possible.

[1] https://sobra.org.uk/

[2] UK Climate Projections: Headline Findings.  July 2021 (available at https://www.metoffice.gov.uk).  Values presented are based on Met Office high emissions projections (RCP8.5) for 10% and 90% probability levels.

[3] Where a negative value denotes a reduction in precipitation.

[4] UKCP18 Climate Change Over Land (available at https://www.metoffice.gov.uk).

[5] Controlled waters is a term used in legislation in England and Wales. Its equivalent in Scotland is the water environment. It is understood that Northern Ireland use both terms. Throughout this article the term ‘controlled waters’ is used to refer to regulated groundwater and surface water throughout the UK.

[6] BS EN ISO 21365:2020 Soil quality – conceptual site models for potentially contaminated sites

[7] Changes to a Conceptual Site Model can also be envisaged because of increases in the frequency and duration of extreme cold weather events, changes to wind intensity and duration, pluvial or groundwater flooding, marine inundation, and river or coastal erosion.

[8] Land Contamination Risk Management Guidance.  Available at https://www.gov.uk/government/publications/land-contamination-risk-management-lcrm

[9] https://www.metoffice.gov.uk/research/approach/collaboration/ukcp

[10] https://www.ceh.ac.uk/our-science/projects/eflag-enhanced-future-flows-and-groundwater

[11] https://www.gov.uk/government/publications/remedial-targets-worksheet-v22a-user-manual

[12] http://www.consim.co.uk/

Article provided by Dr. Emma Hipkins, Helen McMillan, and Isla Smail on behalf of the wider SoBRA Climate Change and Controlled Waters sub-group.

Article

Q&A with Alex Dent

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Full Name: Alex Dent
Job Title: Associate Director
Company: WSP UK Ltd

I have 25years experience in ground engineering, covering a wide variety of ground conditions, market sectors, geotechnical structures and deliverables. I have worked on UK and international projects. I have extensive experience in the design of foundations, basements and earthworks and in the assessment of ground movements and slopes. I am WSP’s Geotechncial Net 0 lead and mentor a number of junior team members on their route to chartership. I believe that the best way to deliver cost effective ‘joined up’ design solutions is through close collaboration with our structural, civil engineering and geo-environmental colleagues.

What or who inspired you to join the geotechnical industry?

Desperation! I graduated from a B.Sc in Geology and Geophysics (University of Durham) in the mid 90s recession and jobs in the oil and gas sector were hard to come by. Out of desperation I researched other geological opportunities and Engineering Geology came up as an option. It sounded like and interesting technical challenge involving geology, physics and maths. I also liked the idea of an industry that that provides direct benefit to society.

What does a typical day entail?

There is no such thing a typical day! But broadly speaking this week; Providing technical advice for the ground investigation on part of HS2, reviewing settlement monitoring data on another project, resolving contactor queries on a slope stabilisation project, line management duties, progressing WSPs Net 0 priorities and duties as an AGS Committee member.

Are there any projects which you’re particularly proud to have been a part of?

Geotechnical design for the award winning Proton Beam Therapy Centre for UCL Hospitals – at 24m, then London’s deepest basement with nearby tube tunnels, Thames Water assets and surrounding buildings all requiring consideration.

Freetown, Sierra Leone. A lovely locally based client team and a project with great vision and the potential to raise people out of poverty.

What are the most challenging aspects of your role?

Clients, or perhaps more correctly, their Project Managers and QSs, nearly all mistaking cost for value. Clients should be educated to ‘invest’ in ground investigation and ‘invest’ in design – this could pay substantial dividends over the project lifecycle. But no: they would sooner quibble over a handful boreholes or ‘brow beat’ over design fees etc.

The industry wide lack of qualified and suitably experienced engineers/geologist, with resultant resourcing issues is a challenge. This challenge is only going to get harder if the numbers taking up geology degrees continues to decrease.

The theories behind our designs assume that soils are homogenous and isotropic. They aren’t. We only sample (let alone test) as small fraction of the ground we are modelling. There also a number of factors that may influence a given soil parameter, e.g. strain magnitude. Modelling of the ground is therefore a perpetual joy and challenge.

What AGS Working Group(s) are you a Member of and what are your current focuses?

I am the leader of the AGS Geotechnical Working Group (GWG). My focus is to ensure that our meetings are stimulating and provide tangible results for the benefit of the AGS membership. The GWG are looking at a number of matters relation to Net 0 in geotechnical design, the next generation of Eurocodes and a number of other interesting topics.

What do you enjoy most about being an AGS Member?

Sharing knowledge.

What do you find beneficial about being an AGS Member?

A sense of community; we are all in this together. We are facing the same challenges and generating guidance to benefit of each other.

Why do you feel the AGS is important to the industry?

It provides some great resources which are really helpful for briefing and guiding more junior team members. It helps ensure that the quality of work produced by its members is of a suitable standard, and hence drives up standards for the industry as a whole. Through the Ground Forum, its gives us a collective voice.

What changes would you like to see implemented in the geotechnical industry?

A change in Client’s/QS’s/Project Manager’s attitude to geotechnical engineering – Geotechnical engineering is not a bolt on to a Geoenvironmental investigation required to discharge a planning application. When we write a report it is meant to be read, understood and its advice considered – not ‘ticked’ as done and then filed.

A chance to be ‘on the top table’ and present the findings of our reports and our design solutions directly to clients. This might help them better understand the issues that their projects face, the key role we play in helping them manage their risks, the value geotechnical engineers can bring to a project and ultimately help them to ‘invest’ in what we do.

Some better quality logging (and checking of logs prior to issue) would be nice too – how is it 25years in and I still see logs with ‘stiff SAND’, ‘dense CLAY’, ‘very sandy very gravelly CLAY/SILT with many cobbles and boulders’ and the like in factual reports?

Article

AGS Awards 2022

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This year’s AGS Awards took place during the AGS Annual Conference at the Warwickshire Event Centre on 6th July 2022. A select number of AGS Working Group Members, who were nominated by their Working Group Leaders, were awarded to thank them for their contribution and dedication to the AGS over the past year.
AGS Business Practice Working Group
David Hutchinson (award)

AGS Safety Working Group
Jon Rayner (award)
Julian Lovell (award)

AGS Instrumentation & Monitoring Working Group
Katharine Barker (award)
Steve Walthall (award)
Andrew Ridley (commendation)

AGS Geotechnical Working Group Award 2022
Peter Reading (award)
Stephen West (commendation)

Services to the Association
Jackie Bland (award)

AGS Data Management Working Group
Asitha Senanayake (award)

AGS Contaminated Land Working Group
Geraint Williams (award)
Andy O’Dea (award)

Article

PFAS – Nomenclature

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Per- and Poly-Fluoro Alkyl Substances (PFAS) are a universe of several thousand manufactured fluorinated organic chemicals with very varying chemical and physical properties (Figure 1).  Some are still in use, some are present in legacy fire fighting systems and some have been banned.

This short article was initially intended as an overview of the land contamination risk management aspects of PFAS but ended up using all the words AGS Magazine articles run to in exploring definitions and naming conventions for PFAS.

Figure 1 PFAS hierarchy (only terms used in this article are shown) (After colour conventions of ITRC[1] and OECD Level numbering)

Definitions

Definitions matter[2] especially when regulations apply to named substances.  The OECD and the Environment Agency[3] consider almost any chemical with at least one fully (per-) fluorinated methyl (–CF3) or methylene (–CF2–) group as a PFAS (OECD, 2021)[4].  Under this definition, the simplest PFAS is tetrafluoromethane (CF4), also known as carbon tetrafluoride or R-14 (a low temperature refrigerant).

Figure 2 Fully fluorinated methyl and methylene groups. Black = carbon; green = fluorine; grey = covalent bond with the rest of the (unshown) alkyl chain

The US EPA’s Office of Pollution Prevention and Toxics definition is narrower: PFAS have at least two adjacent carbon atoms, where one carbon is fully and the other at least partially fluorinated.  This would exclude CF4 and about 40% of the substances that would meet the OECD definition.

The US Congress[5] definition sat in between the OECD and US EPA definitions: “perfluoroalkyl and polyfluoroalkyl substances that are man-made chemicals with at least one fully fluorinated carbon atom.”

OECD recognised that organisations may develop their own working definition of PFAS to meet specific needs. OECD even provided an approach based on molecular structural traits to organisations to make their own categorization in a coherent and consistent manner. The OECD highly recommends the context and rationale for such definitions be transparent to avoid confusion.

Table 1 PFAS related acronyms used in this article

Acronym Meaning
PFAS Per- and PolyFluoroalkyl Substances
AFFF aqueous film forming foams
PFOA Perfluoro octanoic acid
PFOS Perfluorooctane sulfonic acid
PFNA Perfluorononanoic acid
PFCA Perfluoro carboxylates
PFSA Perfluoroalkane sulfonates
PFAA Perfluoroalkyl acid
PFHxS Perfluorohexanesulfonic acid
PASF Perfluoroalkane sulfonyl fluoride

 

What’s in a name?

There are three parts to the name of individual PFAS: the first tells you whether it is Poly- or Per-Fluorinated, the second tells you how many carbons in the alkyl chain (Hx = 6; Hp = 7; O = 8; N = 9)  and the third what the functional group at the end of the molecule away from the fluorinated chain is (sulfonic acid = SA; octanoic acid = OA).

Long and short chain PFAS have significantly different properties – affecting the risks they pose and their amenity to different remediation strategies.  According to the OECD (2013), “long-chain PFAS” are:

(i) Perfluoro carboxylates (PFCAs) with 7 and more fully fluorinated carbons, such as PFOA (8 carbons) and PFNA (9 carbons);

(ii) perfluoroalkyl sulfonic acids (PFSAs) with 6 and more fully fluorinated carbons, such as PFHxS (6 carbons) and PFOS (8 carbons); and

(iii) precursors such as PASF- and fluorotelomer-based compounds that can degrade to long-chain PFCAs or PFSAs.

Human health, ecological and controlled waters risk assessments reflect the fate, transport and for the first two the toxicity of the hazard.

The most studied PFAAs to date are PFOA and PFOS – the primary PFAS focus of many site investigations. However they are not the only PFAS and they cannot be used as surrogates for all PFAS.

Long and short chain PFAS behave in different ways. Short chain PFAS are very mobile, soluble and have low adsorption potential. It has also been recognised that PFAS have broad toxicity[6].

The C8 Science Panel[7], that featured in the legal case depicted in the Dark Waters film, determined that a “probable link” exists between C8 (PFOA) and the following 6 diseases:

  • Kidney Cancer.
  • Testicular Cancer.
  • Ulcerative Colitis.
  • Thyroid Disease.
  • Pregnancy Induced Hypertension (including preeclampsia)
  • Hypercholesterolemia

Discussion

We have been here before. About 30 years ago the dawning realisation that petroleum hydrocarbons were too broad a universe to have their varied fate, transport and toxicity represented by a single “total petroleum hydrocarbon” analysis led to the “TPHCWG” working group that gave us the Equivalent Carbon hydrocarbon fraction method of assessing the risks to human health from petroleum hydrocarbons.

The current body of scientific evidence clearly indicates that there are real, present, and significant hazards associated with specific PFAS – not least PFOS and PFOA – but significant gaps remain related to the impacts of other PFAS on human health and in the environment[8].

The time has now come for us to realise that PFAS may be a universe of substances but they are too diverse to be considered together or to consider individual substances – such as PFOS or PFOA – as surrogates in the way that we have been able to use benzo(a)pyrene as a surrogate for polyaromatic hydrocarbons (PAH).

Understanding and dealing with the societal challenge that is PFAS will involve a multi-disciplinary approach: chemists to resolve behaviour and develop analytical methods, toxicologists to establish dose-response relationships, geologists to predict subsurface fate and transport, engineers to implement remediation.

[1] https://pfas-1.itrcweb.org/2-pfas-chemistry-and-naming-conventions-history-and-use-of-pfas-and-sources-of-pfas-releases-to-the-environment-overview/

[2] https://www.sciencepolicyjournal.org/uploads/5/4/3/4/5434385/dean_adejumo_caiati_etal_jspg_v16.pdf

[3] https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/1012230/Poly-_and_perfluoroalkyl_substances_-sources_pathways_and_environmental_data_-_report.pdf

[4] https://www.oecd.org/officialdocuments/publicdisplaydocumentpdf/?cote=ENV/CBC/MONO(2021)25&docLanguage=En

[5] https://www.congress.gov/116/bills/s1790/BILLS-116s1790enr.pdf

[6] https://www.sciencepolicyjournal.org/uploads/5/4/3/4/5434385/dean_adejumo_caiati_etal_jspg_v16.pdf

[7] http://www.c8sciencepanel.org/

[8] https://www.epa.gov/system/files/documents/2021-10/pfas-roadmap_final-508.pdf

Article provided by Paul Nathanail, Director, LQM

Article

Granular working platforms for construction plant: An overview on guidance documents available

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Temporary granular platforms for construction plant (including haul roads, working platforms and general hard standings) are a necessary feature of almost all construction sites but the need to ensure that they are adequate for the intended use is often overlooked. Inadequate design would most likely lead to significant incidents of overturning plant that would result in, at best, cost and delay or, at worst, injury and/or death. A major cause of plant instability is a poor site surface or working platform. This may be due to a lack of design, poor quality installation, or a lack of maintenance or inspection. Given the consequences of a rig falling over, most would agree that each of these aspects should be carried out thoroughly and by competent people.

While current methods for the technical design of granular working platforms have proved generally reliable, it is recognised that there is a lack of consistency on how and when they are applied, resulting in varying degrees of economy (and possibly un-economic design in certain instances). In addition, the introduction of the ‘Eurocodes’ (although not entirely applicable) has brought about an increased expectation that temporary structures should be designed in line with current national standards.

In 2019, ‘a Guide to good practice’ document was published by the Temporary Works forum (TWf), that summarises all existing rigorous and empirical design methods and good practices available in UK industry. The Guide is not intended to replace current guidance, but it is hoped that it will supplement current guidance and provide an overall approach that addresses the aforementioned issues.

This guide is, therefore, aimed at:

  • providing recommendations for the overall design of working platforms;
  • improving the application of current structural design methods;
  • suggesting a suitable method for the application of Eurocodes;
  • considering ways of achieving greater economy while maintaining a suitable level of reliability with regard to the particular risks under consideration;
  • providing an introduction to related health and safety and sustainability issues

The guidance offered is intended primarily for temporary works designers, in particular less experienced engineers. It is also, however, intended to act as an aid to others involved in the procurement and use of granular working platforms.

The link to the TWf Guide is below:

https://www.twforum.org.uk/viewdocument/working-platforms-design-of-granu

Another useful document that summarises good practice and guidance from around Europe and beyond, is the ‘Guide to Working Platforms’ that was published by the European Federation of Foundation Contractors (EFFC) in January 2020 and the link is below:

EFFC-DFI_Guide_For_Working_Platforms_Edition_1_LowRes-1.pdf

 

Article provided by Chaido Doulala-Rigby, member of the Association of Geotechnical and Geoenvironmental Specialists (AGS), Geotechnical Working Group.

Article Sustainability

The impact of ‘Net Carbon Zero’ on the Geo-Engineering Industry

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The UK Government has committed to Net Carbon Zero by 2050 Net Zero Strategy: Build Back Greener – GOV.UK (www.gov.uk).  Underpinning this goal is a 10 point plan encompassing the following areas:

  • advancing offshore wind
  • driving the growth of low carbon hydrogen
  • delivering new and advanced nuclear power
  • accelerating the shift to zero emission vehicles
  • green public transport, cycling and walking
  • ‘jet zero’ and green ships
  • greener buildings
  • investing in carbon capture, usage and storage
  • protecting our natural environment
  • green finance and innovation

Whilst this puts a focus on the energy industries, this does not mean that the construction industry and associated industries are exempted. Indeed, according to the UK Green Building Council, around 10% of the country’s carbon dioxide emissions are directly associated with construction activities. The number rises to 45% when taking into account the whole of the built environment sector.

Therefore, members of the AGS and their clients have an obligation to change behaviours, practices and methodologies to meet the challenge of net carbon zero. The clock is already ticking and changes need to be made sooner rather than later if the 2050 deadline is to be achieved.

There are a number of instigators and drivers which trigger a starting point on this journey. This could be an internal commitment from senior management or funders requiring businesses to meet a standard or set commitment, such as ‘Pledge to Net Zero’ Home | Pledge to Net Zero or ‘SME Climate Commitment’ Commitment – SME Climate hub. These schemes trigger baseline carbon footprinting and structured planning towards  the 2050 (or earlier) target.  Alternatively, the trigger could be external through commercial 3rd party requirements. The whole supply chain is affected by the Government Pledge and therefore public client bodies will be requesting evidence from suppliers of they will meet the current targets. We can expect that these requirements will also be seen from private clients, especially as they develop their carbon reduction requirements beyond Scopes 1 and 2 and into Scope 3[1], which requires assessment of the supply chain.

Having established a driver and committed to reducing carbon, the next step is to measure the business’s carbon footprint and establish a comparable metric. This will vary between business types, but there is much guidance and support available from organisations such as the Carbon Trust. The process can be started small with simple assessments related to energy usage and develop complexity with time , especially as the ‘wins’ and reductions become harder to achieve.

Beyond business carbon footprints sits project carbon footprints.  PAS 2080:2016 “Carbon Management in Infrastructure ” is already 6 years old and was designed to help organisations in the construction industry move to a sustainable future by identifying areas for improvement and utilising sector best practice. The PAS2080 framework looks at the whole life cycle carbon management when delivering infrastructure assets, aiming to reduce carbon and reduce cost through more intelligent design, construction and use. There are also multiple tools to assist in assessing carbon footprints and opportunities for carbon reduction through good design and construction practice. The EFFC/DFI’s Carbon Calculator for foundations allows contractors to establish their carbon footprint on site and determine a benchmark against which reduction can be assessed and where the carbon intensity is within a project. The Federation of Piling Specialists (FPS) plans to mandate that all projects over £1m in value require EFFC/DFI Carbon Calculator calculations to be submitted. For projects less than this, the FPS is considering a simple ‘rule of thumb’ calculation that can be applied to give an approximate carbon value. This process can be adapted to some site investigation driller techniques.   Similarly, structural engineers Elliott Wood have developed ‘The Structural Carbon Tool’ in conjunction with the Institution of Structural Engineers to enable assessment of embodied carbon in structures. This includes geotechnical structures such as basements, retaining walls etc.  On the contaminated land side of geo-engineering, SURF-UK has developed guidance towards Sustainable Remediation which includes a number of Environmental Indicators such as ‘Emissions to Air’ and ‘Natural Resources’ and will expand to carbon measurement. Use of such tools is increasing and we can expect it to become a normal part of ‘value engineering’ or ‘options appraisals’.

What could reduced carbon methods may look like?  Each business will have different effective solutions. A big part is having the relevant technology available commercially, which is a work in progress for plant and commercial vehicles where battery power is currently limited in scope and range. In the meantime, sustainable fleet management and driving is already established as good practice .eg FORS, which provides a measurable starting point.   Electric drilling rigs have been available for some time, but often require a commercial electricity supply which is problematical, especially whilst the electricity supply infrastructure is not in place to support demand.  Technology is continually developing and changes to support carbon reduction can be expected to become more frequent and more available.

Also think about office related improvements. Switching energy suppliers to green non-carbon based suppliers where possible, committing to zero waste to landfill/ recycling and resourcing eco-friendly supplies from re-cycled/recyclable materials will provide first steps to carbon reduction.

For businesses who believe they can carry on as always and simply off set their carbon without fundamental changes to processes, this is the equivalent of putting a plaster on a wound that needs surgery.

The drive to reduce carbon is no longer a ‘wish-list‘ item.  Being able to demonstrate how your business and designs or procedures contribute to carbon reduction is becoming both a technical and commercial requirement.  It will soon be a ’must have’ and geo-engineers need to be thinking ahead to meet the needs of both Clients and Government drivers. If everyone starts to think about what they could do to manage their carbon footprint and plan towards it and put relevant demands on their supply chain, the goals will be achieved sooner.

[1]  Scope 1: Direct emissions that result from activities within your organisation’s control. This might include on-site fuel combustion, manufacturing and process emissions, refrigerant losses and company vehicles. • Scope 2: Indirect emissions from any electricity, heat or steam you purchase and use. Although you’re not directly in control of the emissions, by using the energy you are indirectly responsible for the release of CO2. • Scope 3: Any other indirect emissions from sources outside your direct control. Examples of Scope 3 emissions include purchased goods and services, use of sold goods, employee commuting and business travel, outsourced transportation, waste disposal and water consumption (Ref. www.carbontrust.com)

Article provided by Jo Strange, Technical Director at CGL

Article

Use of DoWCoP for Landfill Developments

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There have been a number of incidences of the Environment Agency (EA) objecting to the use of the ‘Definition of Waste: Development Industry Code of Practice (DoWCoP) published by Contaminated Land: Applications in Real Environments (CL:AIRE), V2, 2011, for re-use of soil on developments on both permitted and un-permitted landfills. There has also been inconsistency in their interpretation of the Waste Regulations in relation to applying DoWCoP on such sites.  Whilst it may be possible in specific cases to negotiate a solution with the EA to re-use soils under DoWCoP on such sites, in general terms, this apparent change in EA policy effectively removes the option for re-use of soils on such sites without implementing an Environmental Permit. This has implications on sustainability, costs, programme, and ultimately viability of development projects on landfill.

This situation prompted a letter from the Specialist in Land Condition Professional & Technical Panel, (SiLC PTP) to Department of  Environment, Food & Rural Affairs (DEFRA)/EA, The Ministry of Housing, Communities and Local Government (MHLGC) and Department for Business, Energy and Industrial Strategy (DBEIS). This requested:

EITHER: Amend the guidance within the DoWCoP, to include the re-use of site won materials from within historic landfills without the need for Environmental Permitting;

OR: Produce new guidance which streamlines the waste recovery and surrender process for the re-use of materials from within historic landfills.

Responses have been received from the EA and DEFRA which clearly indicate that the EA and DEFRA currently consider re-use of materials on landfill sites falls outside the scope of DoWCoP.  It is also noted that the EA is undertaking a review of DoWCoP as they now ‘have concerns that elements of the framework are not legally robust’. In terms of alternative approaches, the EA is producing internal guidance on permitting options to ensure consistency in EA opinion.

This current interpretation appears to represent a volte-face, given that the original application of DoWCoP was clearly intended to include materials contained in/derived from historical landfill sites, as evidenced by the published CL:AIRE case studies.

However, on the basis of recent correspondence, the AGS recommends that members advising clients with respect to redevelopment of land containing historical landfills take account of the current EA Regulatory opinion regarding DoWCoP to avoid the risk of involvement in material handling which could potentially be interpreted as being illegal waste activities.

Article provided by Jo Strange, Technical Director at CGL

Article

Sustainability in the Delivery of Brownfield Regeneration Webinar Series Summary

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On 17th May and 26th May 2022, the AGS Contaminated Land Working Group hosted their first webinar series entitled Sustainability in the Delivery of Brownfield Regeneration.

The first webinar was on the topic of Sustainable Remediation Solutions, which was chaired by Alex Lee (Technical Director, Environment, WSP) and featured three speakers; Jill Crawford (Senior Associate Solicitor in the Planning and Environment Team, Irwin Mitchell), Jon Davies (Director, RSK Biocensus / RSK Wilding) and Nicola Harries (Technical Director, CL:AIRE).

The second webinar looked at Sustainable Management of Soils, which was chaired by Ian Bishop (Managing Director, One Touch Data) and featured four speakers; Nicholas Willenbrock (Manager – Definition of Waste: Development Industry Code of Practice, CL:AIRE), Anna Willets (Partner, Gunnercooke LLP), Will Fardon (Technical Director, Chemtech Environmental) and Chris Swainston (Principal Environmental Consultant, Soils Limited)

205 delegates registered for the webinars, which looked at topics including; The Environment Act, BNG and ENG for Remediation Sites, the concept of Sustainable Management Practices, Sustainable Soils Management, Legal Responsibilities and the implications of getting it wrong, and standards and best practice related to sustainability.

If you missed this webinar series, the recordings is now live and can be purchased from £25 per webinar via the AGS website by clicking HERE or HERE.

Article

AGS Annual Conference 2022 – An inspiring event all round

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On the 6th July, we were delighted to hold the AGS Annual Conference 2022, on the first day of Geotechnica. Over 86 industry professionals from across the UK attended the Annual Conference and were welcomed to the Warwickshire Event Centre near Leamington Spa for a full day of networking and expert presentations.

The conference saw Dave Petley discuss landscapes and climate change, Steve Wilson explore good practice for risk assessment for coal mine gas emissions, and Dr Basil Ogunmakin speak on ground improvement.

An important presentation from Vicky Gutteridge from The Ollie Foundation reminded attendees of the importance of checking in on the mental health of yourself and your colleagues, with those in the construction sector particularly at risk.

We were also joined by Paul Roberts, who discussed UK initiatives to arrest the decline in students taking on Geoscience degrees, and Paul Eaves, who spoke through the application of ALARP principals to the management of Geotechnical assets.

It was an inspiring day all round and a great opportunity for people to get together, learn, and enjoy the exhibition space. We can’t wait to do it again next year!

If you missed the AGS Annual Conference 2022, you can download the speaker presentations here.

Article Data Management

AGS publish roadmap for AGSi

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AGSi is a transfer format for ground model and interpreted data, created and maintained by the Association of Geotechnical and Geoenvironmental Specialists (AGS). It was launched, as a beta version, in November 2020 with a further update issued in November 2021.  Documentation for AGSi can be found here.

AGS have now issued a roadmap for the future of AGSi. This identifies the processes and actions required to get AGSi ready for its first formal release (version 1.0), before going on to look at what needs to happen to achieve the ultimate goal of establishing the use of AGSi in our industry, for the benefit of the industry.

The roadmap identifies a steering group that has already been formed and the plan is for an early adopter user group to develop out of this. If you are interested in joining the steering group or getting involved as an early adopter, then please get in touch with us.

AGS is aware of other international initiatives relating to geotechnical data and models. In particular, AGS is an active participant in the OGC Geotech Interoperability Experiment project that was launched in early 2022.

The current intent, reflected on the roadmap, is for AGSi version 1.0 to be formally launched at the The Geotechnical Data Conference, hosted by AGS and to be held on 1 December 2022 at The Burlington Hotel in Birmingham.  Hope to see you there!

Article Business Practice Contaminated Land Data Management Executive Geotechnical Instrumentation & Monitoring Laboratories Loss Prevention Safety

UK Specification for Ground Investigation (third edition) – Now Available for Purchase

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Tags: Featured ICE publishing third edition UK Specification for Ground Investigation yellow book

We’re pleased to announce the launch of the third edition of the UK Specification for Ground Investigation – also known as ‘Yellow Book.’

This latest edition of Yellow Book has been revised by an industry working group led by the AGS, and provides best practice guidance for designing and executing good-quality ground investigations that will allow clients and land developers to manage the risks and help to reduce project time and costs.

Ground investigations are an essential part of the design process for any structure and land condition assessment. They are used to validate the ground model, assess ground risk, obtain geotechnical data for design and geoenvironmental data for the assessment of the risk to human health. Yellow Book will help to protect construction professionals and clients, from unexpected ground conditions during construction. Updates in this edition take account of changes to health, safety and environmental legislation, numerous new British Standards and industry guidance.

The UK Specification for Ground Investigation is essential for all ground practitioners involved in ground investigation, including geotechnical engineers, engineering geologists, environmental scientists, instrumentation and monitoring specialists, hydrogeologists and geophysicists, as well as specialists in other disciplines involved in specific investigations.

To purchase Yellow Book, click HERE

Want to know more about the new edition? Then join Julian Lovell, Mathew Baldwin and Stewart Jarvis, three of the main authors of the third edition, for a free webinar on 23rd June 2022 at 11am. The trio will set the context for the revision, explain the changes made and reasons behind them and provide details of how the new Specification document should be used and the major areas of change required by industry to conform to current good practice.

To register for the webinar, or to watch the replay (post-event) click HERE.