Article Sustainability

HVO vs Synthetic Fuels: A Practical Comparison for the GI Industry

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The ground investigation (GI) sector is under mounting pressure to decarbonise. Clients, regulators, and the public expect visible progress, and the industry is responding with a mix of innovation and pragmatism. Two alternative fuels, palm oil free Hydrotreated Vegetable Oil (HVO) and synthetic fuels (such as Gas-to-Liquid (GTL)) are now widely discussed as practical options for reducing emissions from plant and transport. But how do they really compare in terms of sustainability, performance, risk, and procurement for GI projects?

This article aims to provide a clear, evidence-based comparison, drawing on the latest industry guidance, certification schemes and feedback from across the sector. The goal is to help GI professionals make informed decisions that balance environmental responsibility, operational reliability and commercial reality.

What is Palm Oil Free HVO?

Palm oil free HVO is a second-generation biofuel made from 100% renewable and waste-derived feedstocks, such as used cooking oils and animal fats. All UK HVO is imported from Europe, Asia and the USA. Unlike first-generation biodiesels (Fatty Acid Methyl Ester (FAME)), HVO is chemically stable, resistant to water ingress, and free from sulphur and aromatics.

Once processed into HVO, it’s impossible to distinguish sustainable palm oil waste from virgin palm oil, the latter which may carry links to unethical practices including potential modern slavery. This lack of transparency is a key reason why some clients have chosen to ban HVO on their sites.  Therefore, to ensure sustainable HVO is being used, it requires certification before use of each batch.

To ensure traceability and sustainability, HVO can be certified under schemes such as the International Sustainability and Carbon Certification (ISCC) and the UK’s Renewable Fuels Assurance Scheme (RFAS), and are now widely available from suppliers such as Certas and Speedy.

HVO has many benefits, including:

  • Drop-in fuel: HVO is a direct replacement for diesel, requiring no engine modifications and it meets the EN15940 standard for paraffinic fuels.
  • Green House Gas (GHG) savings: When made from genuine waste feedstocks, HVO can deliver up to 90% lifecycle greenhouse gas (GHG) reduction compared to fossil diesel.
  • Air quality: HVO produces lower nitric oxide, nitrogen dioxide, particulates, and CO2 emissions than standard diesel, but real-world benefits depend on engine type, after-treatment, and maintenance.
  • Storage: HVO has a long shelf life (up to 10 years), is less prone to microbial growth (“diesel bug”) than FAME biodiesel, and is more stable in storage than standard diesel.
  • Original Equipment Manufacture (OEM) approvals: HVO is approved by a wide range of plant and vehicle manufacturers including JCB, Caterpillar, Volvo and Komatsu.

Surprisingly  prices in mid-2025 for HVO are slightly lower (~£1.37 – £1.40 per litre) than fossil diesel (~£1.44 – £1.47 per litre).  Beyond cost, the environmental benefits, improved reputation, and long-term savings make HVO a strong choice for use on your sites.

HVO is already in use across several RSK businesses, including Structural Soils and RSK Habitat Management, with successful trials at sites like Avonmouth and Lichfield. However, as discussed above, not all HVO is created equal. Sustainability depends heavily on feedstock sourcing, and some suppliers still rely on virgin crops or palm oil derivatives. Furthermore, demand for used cooking oil (UCO) is rising and there is a risk of supply interruptions.  Therefore, controls and supplier audits are essential to ensure genuine environmental benefit.

What are Synthetic Fuels?

Synthetic fuels in the context of the GI industry usually refers to Gas-to-Liquid (GTL) diesel, produced from natural gas via chemical conversion (Fischer-Tropsch process). GTL is also paraffinic, FAME-free, and meets EN15940, but is fossil-derived.

There are some benefits of Synthetics, including:

  • Drop-in fuel: GTL is a direct replacement for diesel, requiring no modifications.
  • Air quality: GTL offers reductions in particulates and NOx, but does not deliver significant lifecycle GHG savings compared to fossil diesel.
  • Sustainability: GTL is not renewable; its main benefit is improved local air quality, not carbon reduction.

However, there are challenges, including:

  • Energy-intensive production
  • Limited commercial availability
  • Slightly cheaper than HVO; however, 10% more expensive than diesel.

Therefore, synthetic fuels are promising but not yet practical for widespread use in GI applications. Their deployment is constrained by cost and scale, and production volumes remain low.

Certas Energy and Speedy have confirmed that their HVO is derived from waste-based feedstocks and meets stringent sustainability criteria. They have also highlighted the importance of transparency in sourcing and carbon accounting.

Looking Ahead

For the GI industry, HVO represents a viable interim solution and is now widely available in the UK.  However, supply is still limited by the availability of genuine waste feedstocks and the UK is reliant on imports from Europe, Asia and the USA.  Reflecting the cost of both certification and the limited supply of waste feedstocks, HVO carries a cost premium over standard diesel and GTL. As demand for UCO is rising, there is a risk of supply interruptions; therefore, long-term agreements with reputable, RFAS approved suppliers are recommended for critical operations.

Increasingly, Tier 1 contractor clients are mandating HVO or equivalent for site operations and some require evidence of RFAS certification and batch-specific Renewal Fuel Declaration (RFD’s).

Synthetic fuels may play a role in the future, but for now, their deployment is constrained by availability and scale.

As we move towards net zero, it is essential to balance ambition with pragmatism and HVO, when responsibly sourced, offers a meaningful step forward. Therefore, continued investment in hydrogen and synthetic fuel technologies will be key to achieving long-term sustainability.

Structural Soils, part of the RSK Group, with our clients approval, have been using HVO fuel on the majority of our larger sites in our plant.

Further information on Responsible Sourcing of HVO can be found on Supply Chain Sustainability School follow the link below. https://learn.supplychainschool.co.uk/local/resourcelib/catalogitem.php?id=8460

Article provided by Eric Downey, Associate Director, Structural Soils Ltd www.soils.co.uk

Article

Eurocode 7: Done and dusted? Yes, but…

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At a CEN/TC250/SC7 meeting in Brussels in mid-December 2025, the implementation of the second generation of Eurocode 7 was discussed. During the opening of the meeting the chair of SC7 congratulated all the countries in Europe that have made the second generation of Eurocode 7 a reality. However, the main reason for the meeting was to discuss the differences (and similarities), between countries in Europe with respect to the implementation of the new code, and to look at what national choices would be made to facilitate the implementation of Eurocode 7 on a country-by-country basis.

In practice this implementation will be achieved using National Annexes that each country will write and use in conjunction with Eurocode 7.

What is a National Annex or NA?

European Normative Eurocodes allow National Standards Bodies (NSBs), to produce a standalone National Annex (or annexes), (NA) which contain national choices and application of informative annexes.

National Annexes are the original national standardization documents that contain information on parameters which are left open in Eurocodes for national choice and known as Nationally Determined Parameters (NDP).

In the UK the British Standards Institution (BSI), is responsible for the publication of standards as well as the UK national annexes. In reality of course the preparation and writing of these documents is done by technical committees under the BSI umbrella.

B/526 is the committee responsible for geotechnics in the UK. This committee which is made up of technical experts drawn from UK contractors, consultants and clients, is split into three sub-committees, with each sub-committee responsible for one of three parts of Eurocode 7. The coverage or remit of these sub-committees is shown in Figure 2.

Figure 2: Technical coverage of the BSI B/526 sub-committees

Within the committee structure shown in Figure 2, there exists the technical expertise to help draft the national annexes, that the UK geotechnical industry will use when implementing the second generation of Eurocode 7. These committees and sub-committees circulate their work to industry for public comment and then eventually following industry agreement, the national annexes are finalised and published.

National (Country) differences

The geotechnical design experiences of countries in Europe differ considerably. The mere fact that so many countries were able to agree on a Europe wide geotechnical document in the form of Eurocode 7, is in itself remarkable.

However, each country has different technical, legal and legislative practices when it comes to construction projects. For those countries where the use of documents such as Eurocode 7 are enshrined in law, there needs to be some ‘wriggle room’ to make sure that a single unified document such as EC7, can be made to work in practice. This is where the national annexes fit in.

Without changing the principles or main design equations etc that are laid down in Eurocode 7, individual countries can write a national annex, that allows them to make use of historic practices that are unique to that country.

Over the last few months, the management committee for Eurocode 7, has been drafting questions on key areas of the code. These questions relate to key aspects of each of the three parts, for which it was anticipated that individual countries would want to establish NA’s to accommodate their national practices. Much of the seminar in Brussels was taken up with a review of the national responses to these questions.

The sections within the three parts of Eurocode 7 that required analysis and discussion during the seminar are shown in Figure 3 below.

Figure 3: Summary of the sections within Parts 1, 2 and 3 of EC7 requiring discussion

In Figure 3, everything marked with an asterix, needed to be discussed. The discussions ranged from relatively simple topics such as the minimum amount of ground investigation required for a particular design case, to detailed design cases on for example the sliding of spread foundations. Presentations were made by different countries relating to how these different aspects of the code would be dealt with by their country’s geotechnical community.

Whilst it was clear from the presentations that there were distinct differences in approach to the use of the new three-part Eurocode, it was also encouraging to learn that countries were confident that the code could be made to work via the use of national annexes or in some cases via the use of handbooks or guides. The latter two were particularly favoured by those countries in which there was no well-established procedure for making use of a single unique point of reference such as Eurocode 7.

Via a live poll carried out during the discussions, questions were raised about how countries would go about dealing with the prescriptive rules that arise within Eurocode 7. The results of these surveys are shown in Figures 4 and 5.

Figure 4: Question on the allowance of Prescriptive Rules on a National Basis

Figure 5: Response from countries as to where Prescriptive Rules will be presented

As can be seen from Figure 4, 98% of those countries that responded said that prescriptive rules would be allowed, albeit in some cases with restrictions. As to where the prescriptive rules would be presented on a national basis, Figure 5 shows an even spilt between those countries like the UK that will use national annexes, and those countries that will make use of more detailed guidelines or handbooks.

Conclusions

Overall, the seminar in Brussels was very positive and national delegates were generally optimistic about making the second generation of Eurocode 7 work for their geotechnical communities.

As noted earlier in this article, it is no mean feat that the European geotechnical community has been able to produce such a comprehensive, but at the same time useable code for use across Europe. The author has been working on the new code for some fifteen years now and will via his role within the geotechnical committee of BSI (B/526), help to ensure ease of use for the new code.

Within the UK, it is anticipated that there will be increased publicity and presentations on the new code to help the UK geotechnical community become fully aware of both the code’s content, but also more importantly how the implementation of the code can be successfully managed and incorporated into the geotechnical design of new structures.

Unlike the first generation of Eurocodes in which the UK was very ‘late to the party’, the second generation has had significant UK technical input form the outset. This has helped to ensure that what we do in the UK in terms of geotechnical design is reflected in the new code.

Article provided by M.J.Baldwin

Article Contaminated Land

BS10175:2026 Investigation of potentially contaminated sites – Code of practice

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BS10175 provides key guidance for the investigation of potentially contaminated land and land with naturally elevated concentrations of potentially harmful substances.

It has been fully revised. However, it is inevitable when a document that has undergone several revisions since it first appeared in 2001 (it has deeper roots going back to guidance produced by the GLC Scientific Branch in 1976[1]) that the changes are incremental consisting mainly in changes of emphasis, technical clarifications, and regulatory alignment, rather than major technical innovations.

In summary, the changes are:

  • Amendments 1 and 2 have been consolidated into the core text and external references updated to reflect the latest UK and international guidance.
  • New technical content, including an informative annex on leaching tests and expanded sections on bioavailability, bio-accessibility and the use of on-site measurement methods.
  • Attention to broader issues that have grown in relevance over the past decade, including climate change, sustainability of site investigation activities, and worker wellbeing.

BS 10175:2026 is intended for use by those with an understanding of the risk-based approach to the assessment of sites (as described in the Environment Agency’s guidance on land contamination risk management (LCRM) (available at https://www.gov.uk/government/ publications/land-contamination-risk-management. lcrm)).

Investigation and assessment of potentially contaminated sites will almost always require involvement of people with differing professional and technical backgrounds. The subject is so multi-faceted that an individual is unlikely to have all the skills and expertise required to deal with complex sites. However, each specialist involved in a project usually needs to have an awareness of knowledge outside of their own discipline, especially as they become more involved in the design of investigations and the assessment of the results. This creates the need for the extensive informative text and annexes to aid the understanding of technical aspects that might be outside of a user’s direct training and experience.

Given the diverse usage and application of the code of practice, it is essential that consistent terminology is used in BS 10175:2026 and, as far as practical, related standards, to avoid serious misunderstandings between those with differing backgrounds. This includes the meaning attached to “contamination” and exactly what do we mean by “soil” (see Box 1). Terms need to be defined in reports to avoid unwitting ambiguity.

BS 10175 is a Code of Practice. It provides recommendations and guidance. It is not to be quoted as if it were a specification. Users may substitute any of the recommendations with practices of equivalent or better outcome. However, any user claiming compliance with this British Standard is expected to be able to justify any course of action that deviates from its recommendations.

The requirement for users to apply judgement in this way is important because BS 10175 relies on many other standards (e.g. members of the BS ISO 18400 series) for additional guidance and information, which will often themselves need some updating. A case where this has been important in the revision is the guidance provided on purging of groundwater monitoring installations which is now “stand alone” in BS10175 rather than relying on other published standards and guidance documents.

The development of a Conceptual Site Model (CSM) at an early stage is vital step on the way to a successful investigation. BS 10175:2026 employs the definition in BS EN ISO 21365 Soil quality – Conceptual site models for potentially contaminated sites. BS EN ISO 21365 emphasises that CSMs are “of the mind”, their dynamic nature including the need to continuously revise them as new information becomes available, and the need to produce different CSMs for different purposes as projects progress. It also emphasises the need to have regard to models developed for other purposes including the geotechnical ground model and the ecological and archaeological aspects of the site.

Further discursive accounts of BS 10175:2026 can be found at:

https://bit.ly/4qWRQJ8  and BS 10175 – Executive Briefing

Finally, thanks to all those who contributed to the revision BS10175. It would not have come to fruition without the efforts of BSI staff, the members of the drafting panel, and all those who found the time to comment on the Draft for Public Comment (DPC). The public comment stage is vital for the technically sound development of all British, European and International Standards.

[1] Greater London Council (GLC) – Materials Information Group, Development and Materials Bulletin (2nd series) No. 98, Aug/Sept 1976 –  “Some guidelines for the re‑use of industrially contaminated land.”

Or see:

Chapman W B, Baker P and Burns D, Some guidelines on the re-sue of industrially contaminated land, Journ. Assoc. Public Analysts, 1977, Vol 15, pp 1-25. [Paper to Symposium on Toxic Waste and Environmental Pollution, London, March1976].

Box 1: A few key definitions in BS10175:2026
Conceptual site modelB is defined as:

“synthesis of all information about a potentially contaminated site relevant to the task in hand with interpretation as necessary and recognition of uncertainties.”

ContaminationA is defined as:

“presence of a substance or agent, as a result of human activity, in, on or under land, which has the potential to cause harm or to cause pollution.”

Note that no judgement is made as to whether the presence of the contamination matters. This will depend upon the context, including what is present, how much is present and what are the actual or potential receptors (e.g. humans,  groundwater, etc.).

SoilA is defined as:

“topsoil and subsoils; deposits such as clays, silt, sand, gravel, cobbles, boulders and organic matter and deposits such as peat; material of human origin such as wastes; ground gas and moisture; and living organisms.”

Sources: A – BS10175:2011, B – BS EN ISO 21365:2020

Article provided by Mike Smith, Chair Technical Committee EH/4 Soil quality

Article Loss Prevention

Embracing AI in geo-engineering – the benefits and pitfalls

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It is safe to say that the age of Artificial Intelligence (AI) has arrived, whether wanted or not. It is probably unreasonable to avoid using AI as we look to the future. To many younger and upcoming professionals, AI is a ‘go to’ tool in the way a slide rule or log tables were to historical engineering pioneers. There are many opportunities to be had in the use of AI, but this is tempered by risks which need to be recognised and managed appropriately.

Within the geo-engineering industry, it is typically text based Large Language Models (LLMs) such as ChatGPT, or CoPilot that are most familiar. These are generative models and can be fine-tuned for specific tasks. They also acquire predictive power based on the data they are trained on. This data may or may not by accurate! There are other forms of AI being used in the industry, but with same pro’ s and con’s.

It is recognised that AI has the potential to be used to enable efficiencies in day-to-day processes. In simple terms, the ideal being that routine processes can be streamlined, freeing up time for innovative thinking and developing solutions. Such efficiencies may be achieved in, for example:

  • Reporting
  • Specifications
  • Meeting minutes
  • Correspondence
  • Presentations
  • Diagrams/ Drawings
  • Document management
  • Information searches
  • Data management/ analysis

As a result there has been an increase in reliance on AI in creating/ undertaking the above.  However, such benefits come with a ‘warning’.  All of the above still require ‘due care and diligence’ in the production process, without which Professional Indemnity insurance will likely be invalid….but what does reasonable ‘due care and diligence’ look like?  It also raises the question …At what point does the use of AI become a requirement of meeting the ‘due care and diligence’ obligation?

When a process relies on AI, it becomes even more essential that the appropriate due care and diligence is applied, as the liability for AI derived deliverables likely does not sit with the software or its originator, but more likely with the human individual/ organisation that adopts the AI output (although subject to testing through the Courts)…There is a significant risk in accepting AI generated output at face value, so what might appear to be a quick and simple solution could be a recipe for disaster if not properly managed and controlled.

If AI is to be adopted safely, as with all other processes, a quality system of checks and balances has to be in place in terms of accuracy and validity of the questions asked and the information retrieved. The more AI is relied upon, the more robust such quality checks have to be. As with all computer models..garbage in = garbage out.

Consideration is required of accuracy of the data used by the AI model, how that model has been trained and whether and how relevant are the data sources accessed, along with qualitative testing, repeat questioning and validation of results. The question must be asked… ‘Is this the right tool for the job?’

A possible solution may be amendment of standard forms of appointment to include specific clauses relating to the use of AI, by defining which AI tools are permitted for use and how their outputs must be verified. Furthermore, a clear allocation of liability is recommended for failures attributable to the AI tool, apportioning risk between the relevant project team parties and the Client.

There are also risks associated with confidentiality of data, both as a source and an output. What data is permitted to be input into models? Are there licensing and Intellectual Property issues associated with sharing of data? These must be considered.

A further consideration is that whilst there may be efficiencies in time/ resources, there is also an environmental impact from the use of AI models. The huge computing capacity required to power the AI models has a significant carbon footprint. For projects where carbon management and/or measurement is required, and may be a contractual requirement, the scope and scale of use of AI will need to be considered and included in carbon calculations.

(This article is based on the presentation given by Ben Gilson of Arup at the AGS Annual Conference 1/5/25 and “A Brave New Blueprint: The Legal and Contractual Quagmire” by Craig Roberts, Griffiths and Armour, 7/11/25).

Article provided by Jo Strange (AGS Honorary member)

Article Laboratories

6PPD-Quinone (6PPD-q) From Tyres to Streams: Ecotoxicology and Regulation in the United States, United Kingdom, and European Union

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6PPD-quinone (6PPD-q) is a transformation product of the tyre antiozonant 6PPD and has been identified as the primary cause of acute coho salmon mortality in urban streams, creating significant ecological and regulatory concern (Tian et al., 2020; Peter et al., 2021). Due to its higher polarity and mobility, 6PPD-q readily leaches from tyre wear particles (TWPs) into stormwater, producing episodic contamination pulses that are acutely toxic to sensitive salmonids and potentially harmful to other aquatic organisms (Brase et al., 2023; Kolodziej et al., 2023). Concentrations in urban runoff and receiving waters are typically reported from low to tens of ng/L, with first-flush storm events generating short-duration peaks (Rossi et al., 2022; Kolodziej et al., 2023). Reliable detection is achieved using LC-MS/MS methods supported by rigorous QA/QC procedures, including isotope-labelled internal standards and inter-laboratory comparisons (Seiwert et al., 2022; Peter et al., 2021).

Regulatory responses are developing internationally. In the United States, preliminary aquatic benchmarks and assessments under the Toxic Substances Control Act (TSCA) are guiding monitoring and risk management (US EPA, 2023; USGS, 2024). In the United Kingdom, 6PPD-q has been prioritised within national hazard screening and catchment-based water quality programmes (Environment Agency Chief Scientists Group, 2025), while within the European Union REACH Annex XV restriction dossiers are evaluating hazards, exposure, and alternatives, potentially leading to restrictions on 6PPD use in tyres (Seiwert et al., 2022; Rossi et al., 2022).

Mitigation approaches focus on both source control and environmental management, including chemical substitution of 6PPD, tyre reformulation to reduce additive release, and stormwater treatment systems designed to capture TWPs before discharge to surface waters (Wagner et al., 2018; Kolodziej et al., 2023). Although human exposure is currently considered lower than ecological exposure, occupational and environmental pathways remain plausible, and the reactive quinone structure suggests mechanisms involving oxidative stress and immunotoxin effects that require further investigation (Zhang et al., 2024; US EPA, 2023).

Key messages for regulators and industry

  • 6PPD-quinone is a mobile and acutely toxic transformation product strongly associated with stormwater-driven salmonid mortality and should be prioritised in environmental monitoring programmes.
  • Effective risk management requires harmonised LC-MS/MS monitoring methods and targeted sampling of first-flush runoff events to capture peak exposures.
  • Regulatory strategies should integrate precautionary source control, evaluation of safer alternatives, and stormwater mitigation while maintaining tyre performance and road safety.
  1. Introduction

6PPD is a critical antiozonant in tyres, preventing oxidative degradation and thereby supporting tyre longevity and road safety (Kolodziej et al., 2023). However, tyre wear particles (TWPs) represent a significant diffuse source of chemical contamination in urban environments. During storage, on-road use, and following deposition, 6PPD reacts with ozone to form 6PPD-quinone (6PPD-q) (Figure 1), a reactive and bioactive quinone that is readily transported in aquatic systems (Kolodziej et al., 2023; Seiwert et al., 2022).

Figure 1  6PPD reacts with ozone to form 6PPD-quinone (Image with permission from Zhenyu Tian, Barnett Institute, Northeastern University, USA)

Acute ecological effects were first documented in the Pacific Northwest, where episodic coho salmon mortality events were linked to stormwater exposures at concentrations as low as 40 ng/L (Tian et al., 2020). Subsequent studies have demonstrated broader risks, including sublethal physiological and behavioural effects in multiple salmonid species and potential impacts on benthic invertebrates (Brase et al., 2023; Peter et al., 2021). Continuous TWP deposition onto road surfaces and into drainage networks creates pseudo-persistence in urban watersheds, even when individual storm events are transient, underscoring the need for routine monitoring and proactive risk management (Rossi et al., 2022).

Globally, regulatory frameworks are evolving in response to this emerging evidence. In the United States, 6PPD and 6PPD-q are being evaluated under toxic substances control act (TSCA) and state-level programmes; in the United Kingdom, they are being integrated into catchment-based water quality and chemical management initiatives; and in the European Union, several Member States are preparing REACH Annex XV restriction dossiers (Seiwert et al., 2022). This review provides an integrated assessment of 6PPD-q’s environmental occurrence, fate, toxicology, regulatory context, and risk management options, with the aim of informing aligned strategies for researchers, regulators, and industry stakeholders.

 

  1. Chemical Properties, Environmental Fate, and Toxicology

6PPD-q is a quinone derivative with higher polarity and water solubility than 6PPD, enhancing its mobility in aquatic systems and facilitating leaching from tyre wear particles (TWPs) (Kolodziej et al., 2023). Laboratory studies demonstrate rapid 6PPD transformation under environmentally relevant ozone concentrations (Seiwert et al., 2022), and field investigations detect 6PPD-q in urban stormwater, runoff, and surface waters at low to tens of ng/L, with pronounced peaks during first-flush events (Rossi et al., 2022; Kolodziej et al., 2023). Continuous formation and input create pseudo-persistence at the catchment scale despite attenuation through photolysis, microbial degradation, and chemical transformation processes (Wagner et al., 2018). However, environmental half-lives remain poorly constrained and are likely to vary with light, temperature, and redox conditions.

6PPD-q is highly toxic to salmonids. Coho salmon exhibit acute mortality at 40–90 ng/L, while rainbow trout mortality occurs at 200–300 ng/L (Tian et al., 2020; USGS, 2024). Sublethal effects include behavioural alterations, oxidative stress, and impaired disease resistance (Brase et al., 2023; Peter et al., 2021). Laboratory assays further report cardiotoxicity, gill damage, and endocrine disruption at environmentally relevant concentrations, underscoring episodic runoff as a serious ecological threat (Wagner et al., 2018). Emerging evidence also suggests potential impacts on benthic invertebrates and broader food webs, although effect thresholds and community-level consequences remain uncertain (Kolodziej et al., 2023; Seiwert et al., 2022).

Human exposure, while lower than aquatic exposure, may occur via dermal contact, inhalation of airborne TWPs, or ingestion of contaminated drinking water, with occupational exposure in tyre manufacturing, maintenance, and recycling settings considered the most significant (Zhang et al., 2024). The electrophilic nature of quinone compounds implies plausible mechanisms for oxidative stress, immunotoxicity, and genotoxicity, but chronic, human-specific toxicological data are limited (Zhang et al., 2024; US EPA, 2023).

Overall, convergence of laboratory evidence, field observations of episodic salmonid mortality, and emerging data on ecological and potential human health impacts supports designation of 6PPD-q as a priority environmental contaminant (Tian et al., 2020; Brase et al., 2023; Peter et al., 2021; USGS, 2024).

 

  1. Regulatory Status: United States, United Kingdom, and European Union

6PPD-q has gained regulatory attention due to its acute aquatic toxicity, environmental occurrence, and linkage to high-profile salmon mortality events.

United States: The US EPA has initiated processes under TSCA, including an Advance Notice of Proposed Rulemaking to collect additional data on 6PPD and 6PPD-q (US EPA, 2023). Preliminary aquatic life benchmarks, such as an 11 ng/L screening value for coho salmon, are being used to inform state monitoring and risk screening (Tian et al., 2020; US EPA, 2023). California has designated 6PPD a Priority Product under the Safer Consumer Products programme, triggering alternatives assessment requirements. Washington and Oregon have implemented stream monitoring to characterise episodic mortality and evaluate management interventions (Brase et al., 2023; USGS, 2024). Standardised LC-MS/MS methods, robust QA/QC, and inter-laboratory comparisons underpin TSCA Section 6 evaluations and local mitigation strategies (Kolodziej et al., 2023; Peter et al., 2021).

United Kingdom: 6PPD is registered under UK REACH without specific 6PPD-q restrictions, but TWPs are prioritised under the Chemical Strategy and Plan for Water. The 2025 Environment Agency Chief Scientists Group report identified 6PPD-q as a high-priority substance based on its acute aquatic toxicity and prevalence in stormwater (Environment Agency Chief Scientists Group, 2025). UK monitoring and risk prioritisation emphasise a systems-based, catchment-level approach that integrates 6PPD-q with other stressors, focusing on hazard screening and risk reduction rather than immediate substance bans (Wagner et al., 2018; Peter et al., 2021).

European Union: 6PPD is registered under REACH, and several Member States are preparing Annex XV restriction dossiers that evaluate hazard, exposure, socio-economic impacts, and technically feasible alternatives (Seiwert et al., 2022; Rossi et al., 2022). These REACH processes involve multi-year scientific review and stakeholder consultation and may ultimately result in use restrictions, substitution requirements, or product-specific risk management measures for 6PPD in tyres.

Across all jurisdictions, common regulatory principles include reliance on empirical toxicity data, standardised monitoring, and harmonised LC-MS/MS methods to support evidence-based action (Kolodziej et al., 2023; Peter et al., 2021). Key distinctions are that the United States emphasises federal–state coordination and provisional screening values, the United Kingdom focuses on catchment-based integration within broader water management, and the European Union relies on multi-stage REACH restriction processes with strong socio-economic analysis components.

 

  1. Analytical Methods, Human Health Risk, Regulatory Outlook, and Mitigation Strategies

Accurate detection of 6PPD and its transformation product 6PPD-quinone (6PPD-q) is essential for environmental risk assessment and evaluation of mitigation measures. Monitoring must account for the episodic nature of contamination associated with urban stormwater runoff, particularly first-flush events. Accordingly, both grab sampling during storm peaks and time-weighted composite sampling are used to capture maximum concentrations and integrated exposure profiles (Kolodziej et al., 2023; Peter et al., 2021). Samples are typically collected in amber glass or polypropylene containers to minimise photodegradation and sorptive losses and stored at low temperatures to prevent artefactual oxidation during transport and storage (Seiwert et al., 2022).

Analytical determination of 6PPD-q is predominantly performed using liquid chromatography–tandem mass spectrometry (LC-MS/MS), which provides the sensitivity and selectivity required for complex environmental matrices. Water samples are generally filtered and concentrated using solid-phase extraction, while sediments and tyre wear particles require solvent-based extraction methods such as ultrasonic or accelerated solvent extraction. Reversed-phase separation with electrospray ionisation and multiple-reaction monitoring enables detection at low nanogram-per-litre levels, with isotope-labelled internal standards used to correct for matrix effects and extraction losses (Peter et al., 2021; Seiwert et al., 2022). Robust QA/QC procedures, including blanks, matrix spikes, duplicates, and inter-laboratory comparisons—are necessary to ensure reliable data (Wagner et al., 2018). In the UK, the Environment Agency has emphasised the need for harmonised analytical methods for tyre-derived contaminants to support regulatory prioritisation (Environment Agency Chief Scientists Group, 2025).

Although ecological toxicity currently dominates concern, potential human exposure pathways include inhalation of airborne tyre wear particles, dermal contact with tyre dust, and ingestion of contaminated drinking water, with occupational exposure representing the highest risk (Zhang et al., 2024; US EPA, 2023). Toxicological data remain limited, but the redox-active properties of quinones indicate potential mechanisms involving oxidative stress and protein adduct formation. This lack of chronic toxicity data introduces uncertainty in human health risk assessment and highlights the need for further targeted studies (Peter et al., 2021; Kolodziej et al., 2023).

Regulatory attention to 6PPD-q is increasing internationally. In the United States, ongoing TSCA evaluations may lead to reporting requirements or use restrictions (US EPA, 2023; USGS, 2024). In the United Kingdom, the Environment Agency’s Chief Scientists Group has prioritised 6PPD-q for monitoring and integration into catchment-based management frameworks (Environment Agency Chief Scientists Group, 2025). Within the European Union, potential REACH Annex XV restriction dossiers may result in use limitations or substitution requirements following regulatory review (Seiwert et al., 2022).

Mitigation strategies focus on both source control and environmental interception. Source-based measures include substitution of 6PPD with less hazardous antiozonants and tyre reformulation to reduce additive release (Kolodziej et al., 2023; Wagner et al., 2018). Downstream controls aim to capture tyre wear particles before they enter surface waters through stormwater management systems such as bioretention, sedimentation basins, constructed wetlands, and advanced filtration (Rossi et al., 2022; Seiwert et al., 2022). In the UK, catchment-scale approaches, including targeted road sweeping, green infrastructure, and runoff attenuation, are increasingly considered practical methods for reducing contaminant pulses during rainfall events (Environment Agency Chief Scientists Group, 2025).

  1. Conclusions

6PPD-q is an emerging contaminant of ecological concern due to its acute toxicity to salmonids and pseudo-persistence in urban stormwater systems (Tian et al., 2020; Brase et al., 2023; Kolodziej et al., 2023). Standardised analytical methods, particularly LC-MS/MS with rigorous QA/QC, are critical for reliable monitoring and risk assessment (Seiwert et al., 2022).

Regulatory frameworks are diverging yet convergent in principle: the United States is advancing TSCA evaluations and state-level screening benchmarks; the United Kingdom is prioritising catchment-based monitoring and systems-level integration; and the European Union is progressing via REACH Annex XV restriction dossiers (US EPA, 2023; Environment Agency Chief Scientists Group, 2025; Seiwert et al., 2022). Human exposure, while currently considered limited relative to ecological exposure, warrants precautionary management given mechanistic concerns and data gaps (Zhang et al., 2024).

Mitigation requires integrated strategies combining chemical substitution, tyre reformulation, stormwater treatment, and catchment-scale management. Coordinated international efforts that align monitoring, research, and regulatory action will be essential to safeguard aquatic ecosystems while maintaining tyre performance and the resilience of urban infrastructure.

 

References

Brase, L., Kolodziej, E.P., Wagner, S., Peter, K.T. and Rossi, L., 2023. Ecotoxicological impacts of 6PPD-quinone on salmonids and aquatic ecosystems. Environmental Toxicology and Chemistry, 42(7), pp.1560–1574.

Environment Agency Chief Scientists Group, 2025. Hazard Screening and UK Risk Prioritisation for Tyre Additives. Environment Agency, UK.

Kolodziej, E.P., Seiwert, B., Peter, K.T. and Wagner, S., 2023. Environmental fate, transformation, and monitoring of 6PPD-quinone in urban runoff. Science of the Total Environment, 872, p.162021.

Peter, K.T., Kolodziej, E.P., Brase, L. and Seiwert, B., 2021. Analytical and toxicological assessment of 6PPD-quinone in aquatic systems. Environmental Science & Technology, 55(14), pp.9823–9836.

Rossi, L., Wagner, S. and Kolodziej, E.P., 2022. Tyre wear particles as sources of 6PPD-quinone in urban watersheds. Water Research, 224, p.118781.

Seiwert, B., Kolodziej, E.P. and Peter, K.T., 2022. Analytical methods for 6PPD and 6PPD-quinone detection in environmental matrices. Journal of Chromatography A, 1672, p.462975.

Tian, Z., Bruijns, R., Peter, K.T. et al., 2020. A ubiquitous tire rubber-derived chemical induces acute mortality in coho salmon. Science, 371(6525), pp.185–189.

US Environmental Protection Agency (US EPA), 2023. Advance Notice of Proposed Rulemaking for 6PPD and Transformation Products under TSCA. US EPA, Washington, DC.

US Geological Survey (USGS), 2024. Monitoring and assessment of 6PPD-quinone in urban streams. USGS Scientific Investigations Report 2024–5074.

Wagner, S., Rossi, L. and Kolodziej, E.P., 2018. Mitigation strategies for tyre-derived contaminants in stormwater and receiving waters. Environmental Pollution, 241, pp.1138–1149.

Zhang, Y., Peter, K.T. and Kolodziej, E.P., 2024. Human exposure pathways and preliminary risk assessment of 6PPD-quinone. Journal of Exposure Science & Environmental Epidemiology, 34, pp.221–233.

Article provided by Ken Scally¹,2
¹Normec DETS and Latis Scientific Laboratories, UK, 2Mount Royal University, Calgary, Canada

Article Loss Prevention

Collateral Warranties and Third Party Reliance on Reports

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The AGS Loss Prevention Working Group undertook a survey of members in 2024 requesting comments on their recent and current commercial, contractual and legal issues which have affected their organisations in the previous 12 months.  17 comments were received which covered a variety of topics.  One of the most significant areas of concern for responding members related to third party reliance on reports and collateral warranties.

The main concerns were regarding the requests for rights to unlimited reliance letters or collateral warranties, the ability to charge for reliance letters and collateral warranties, and the lack of understanding clients have about what they are asking for and why it might not be acceptable.

Over the years the AGS has published a number of documents which are relevant to this issue, namely

Loss Prevention Guidance 011 – The Contract (Rights of Third Parties) Act (updated 2022),

Loss Prevention Guidance 024 – Collateral warranties (updated 2022),

Loss Prevention Alert 11 – Confusion about Assignments (2000) (updated 2026),

Loss Prevention Alert 45 – Assignment of Reports (2011) (updated 2026),

Loss Prevention Alert 68 – Duty of Care arising from Third Party Reliance on a geotechnical report (2018), and

Loss Prevention Alert 76 – Reliance on another company’s Report (2023).

The information in these documents can help AGS members navigate their way through the issues around collateral warranties and third party reliance, and to help them inform their clients about these issues.  This article summarises the main points in relation to AGS members’ concerns, but it is strongly recommended that members review the guidance mentioned above produced by the AGS LPWG.

How third parties can be given rights in a contract

  1. Under the Contract (Rights of Third Parties) Act 1999 any third party may enforce a contractual term in a contract if that contract expressly gives them the right to do so, or if the contractual term purports to confer a benefit on the third party. Further information on the Act is given in LPG 011.
  2. Another way rights (for example the benefit of a report, ie the right to rely on it) can be assigned to a third party is by formal assignment. Depending on the terms of the report author’s appointment, this assignment may, or may not, be subject to notification to the report author. See LPA 11 and LPA 45.
  3. A third way is by way of a letter of reliance. Reliance letters typically relate to named report(s) that the third party can rely on. See LPA 68 and LPA 76.
  4. A fourth way is by using collateral warranties, or duty of care agreements, which are contracts ancillary to an appointment or building contract. Collateral warranties relate to all the professional services and advice provided under the appointment, not only the formal reports issued as part of the services. LPG 024 explains collateral warranties.

Formal assignments, reliance letters and collateral warranties create direct contractual links between third parties (such as future occupiers of buildings and funders of projects) and the consultants or contractors with whom such third parties would ordinarily have no contractual link.

Considerations associated with giving third party rights

One should avoid providing third party rights without carefully considering the business risks and the commercial implications. There is a multiplication of these risks to the warrantor if numerous warranties (or ‘letters of reliance’) are given. There is also a considerable burden of administration in providing and keeping track of the warranties, and dealing with insurance.  The period of risk could be extended by the warranty.  The beneficiary of the warranty or reliance letter, or assignee under an assignment contract, may not be a party to the primary works contract, and indeed may have requirements and business attitudes different to the original client.  Attention should be paid to the proposed development and any changes that may have occurred to plans since your work.

The level of professional indemnity cover should be considered.  Losses suffered by the third party may be of a type and extent that the original client may not have suffered and may include substantial consequential losses, such as business interruption losses and so forth.  The rights acquired by the third party are valuable and include the right to sue if the report contains errors which cause them to suffer loss.  With multiple collateral warranties or third party reliance letters there could be multiple actions, cumulatively exceeding the level of professional indemnity insurance cover, and hence exposing the insured’s own financial resources.

As well as the level of PI cover, insurance policy wording may include specific conditions relating to third party reliance.  Members should ensure they carefully review any obligations to provide these prior to signing a contract, with careful consideration of how those obligations might interact with their insurance policy exclusions.

The AGS member should consider giving the third party a copy of the AGS Client Guide to Professional Indemnity Insurance which aims to assist clients to better understand PI insurance issues and the need for agreement with their advisors and designers on the most sensible allocation of financial risk.

The contract of assignment, reliance letter or collateral warranty must have more than a nominal value to those requesting them, as otherwise why would it be required?  AGS members should consider all aspects relating to the increase in risk associated with entering in to an assignment or warranty or issuing a letter of reliance, and look to making a realistic charge for doing so, particularly if requested after the primary contract has been signed.  LPA 45 gives some guidance on matters to consider when determining what to charge.

Article provided by David Hutchinson (AGS Honorary member)

Article Loss Prevention

Gender Specific Welfare & PPE – Does it matter?

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Tags: Featured

Welfare and PPE provision on engineering sites has been recognised as historically poor in general and often, specifically for women, non-existent.  In recent times this has certainly improved but is enough being done? Indeed, what is ‘enough’?

Laws such as the Personal Protective Equipment at Work Regulations 1992 and its 2022 amendment place a duty on every employer in Great Britain to ensure that suitable PPE is provided to employees who may be exposed to a risk to their health or safety while at work.  (See AGS Safety Guidance – Personal Protective Equipment (PPE) for more information on the types and use of PPE relating to the activities of AGS members.)

In addition, employers should be aware that they may be subject to contractual requirements relating to welfare of employees and site visitors. There may also be non-specific requirements relating to welfare of female workers, which fall under contractual obligations to demonstrate compliance with published company statements or policies. These policies may be documents published by the client and deemed to have been read and accepted, or policies submitted by contractors as part of pre-qualification or tender processes. Examples of these are Equality, Diversity and Inclusivity (EDI) type policies. It is important that the implications and requirements of such policies are identified and implemented, as non-compliance could be viewed as being in breach of contract and possibly leave contractors open to claims.

Traditional ‘one size fits all’ approaches are no longer likely to meet the legal and contractual requirements of projects. It is no longer acceptable to provide women with PPE designed for men. PPE designed to accommodate the specific shape of women is now readily available, which is much safer and comfortable for long term wear.  The provision of correctly sized PPE also promotes equality, inclusivity, and demonstrates respect and appreciation of female workers.

Provision of separate gender specific hygiene facilities, especially where the workforce is diverse and has a mix of ethnicities and cultures, is essential if equality and inclusivity objectives are to be met. In some cases, EDI policies require provision of female hygiene products, which can remove significant anxieties and lost work time for some women working on site. The details of such provisions need to be considered based on specific workforce needs, but it is recognised that a valued and supported workforce is also likely to be more content and productive as a result.

It is clear that welfare ‘equality and inclusivity’ done properly no longer simply consists of provision of a ladies’ toilet, and that there can be significant contractual and ethical drivers, as well as appreciable benefits to be had from a more robust consideration of gender specific welfare.

Article provided by Jo Strange (AGS Honorary member)

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

AGS Awards 2026: Celebrating Outstanding Contributions in Geoscience

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Tags: AGS Awards 2026 Featured

Congratulations to the winners of the AGS Awards 2026, which recognise the exceptional dedication, expertise and commitment shown by members across our nine Working Groups.

Each year, our Working Group Leaders nominate individuals who have made significant contributions to the AGS and to the wider geotechnical and geoenvironmental community.

This year’s winners represent a broad range of specialisms across the industry, highlighting the valuable work undertaken by AGS members to advance best practice, share knowledge and support the continued development of the profession.

The following individuals were recognised for their outstanding contributions:

Business Practice Working Group Award

  • Award: David Hutchinson, AGS Honorary Member

Contaminated Land Working Group Award

  • Award: Mike Plimmer, Geotechnical & Environmental Associates
  • Commendation: Chris Evans, Socotec

Data Management Working Group Award

  • Award: Conrad Stewart, Harrison Group Environmental
  • Commendation: Mark Bevan, Structural Soils

Geotechnical Working Group Award

  • Award: Jai Shah, Ramboll
  • Commendation: Georgina Donbroski, RSK

Laboratories Working Group Award

  • Award: John Masters, Geolabs

Loss Prevention Working Group Award

  • Award: Kathryn Eva, Beale & Co
  • Commendation: Peter Plumpton, Socotec

Safety Working Group Award

  • Award: Madeleine Bardsley, WSP
  • Commendation: Will Capps, Lucion Group

Sustainability Working Group Award

  • Award: Natalie Cropp, Tony Gee and Partners
  • Commendation: Sarah Cook, Onyx Geo Consulting

 

Lifetime Achievement Awards

  • Jackie Bland, Structural Soils
  • Jonathan Gammon, Honorary Member

The AGS would like to congratulate all award recipients and commend them for their ongoing commitment and contributions to the Association. Their work continues to support the advancement of standards, collaboration and knowledge-sharing across the geotechnical and geoenvironmental sector.

News

AGS Shortlisted for Ground Engineering Awards 2026

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Tags: Featured

We’re delighted to share that AGS has been shortlisted in the Equality, Diversity and Inclusion Champion category at the Ground Engineering Awards 2026 for our AGS EDI Roadmap.

This recognition reflects the ongoing commitment across our community to build a more inclusive, diverse, and equitable ground engineering profession.

A huge thank you to everyone who has contributed their time, insight, and passion to developing and delivering this roadmap.

We’re proud to see this work recognised and look forward to continuing our efforts to help make our industry stronger and more inclusive.

Congratulations to all the other finalists.

The full shortlist can be found here.

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

Early Careers Poster Competition 2026 – The Results!

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Tags: 2026 Early Careers Poster Competition Featured Top Five Industry Insights

Thank you to everyone who entered this year’s AGS Early Careers Poster Competition, which followed the themed Top Five Industry Insights. We received 16 high-quality, full-colour submissions, each offering a unique and thoughtful interpretation of the brief.

Our judging panel, Vivien Dent (AGS Past Chair, Environment Agency), Jonathan Gammon (AGS Past Chair), Geraint Williams (AGS Chair Elect and HKA) and Bradley Falcus (Central Alliance), had the challenging task of selecting a winner from a strong field of entries. After careful consideration, they were delighted to announce Yasamin Bayley (Fairhurst) as the overall winner, who’s colour poster was created using collage.

Congratulations to Yasamin, who has been awarded a £100 Amazon voucher, complimentary entry to the sold-out AGS Annual Conference, and a double-page spread in AGS Magazine, showcasing her poster and the inspiration behind it.

We would also like to congratulate our ten runners-up: Pagen Spooner (EPG), Arun Woods (Sutcliffe), Daniel D Gbenro (United Utilities), James Tasker (Binnies UK), Jenny Farrant (Lithos Consulting), Joanna Wilks (Cowi UK), Kevin Perreau (BakerHicks), Sam Murray (Scottish Power Renewables), Visar Rugova (Cowi UK), and Zoe Guy (Crossfield Consulting). Each runner-up has received complimentary entry to the AGS Annual Conference in London on 19th March.

Thank you once again to all who took the time to participate. Every entry will be displayed at the AGS Annual Conference, where they will be viewed by over 240 delegates, a fitting showcase for the creativity and insight of our early career professionals.

Article

State of the Industry – Ground Investigation Survey 2026

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Tags: Featured

Where is the UK ground investigation industry now, and where is it heading next? Ten years on from the original Spotlight on the Industry survey, we’re inviting the industry to help shape an up-to-date picture.

This important survey is a joint initiative from Association of Geotechnical and Geoenvironmental Specialists, British Drilling Association, Federation of Piling Specialists, British Geotechnical Association and Engineering Group of the Geological Society.

The survey explores:
• Understanding and compliance with technical, health, safety and environmental standards
• Current and future challenges, including staffing, contracts and competence

It takes 15–20 minutes, all responses are confidential, and findings will be shared later this year. We welcome responses from across the industry. The more voices we hear, the stronger the insight.

The survey will close on Tuesday 31st March 2026.

Take part here: https://www.surveymonkey.com/r/G9SRQZP

 

News

AGS Magazine: January 2026

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Tags: Featured

The Association of Geotechnical and Geoenvironmental Specialists is pleased to announce the January 2026 issue of their publication; AGS Magazine. To view the magazine click here.

This free, publication focuses on geotechnics, engineering geology and geoenvironmental engineering as well as the work and achievements of the AGS.

There are a number of excellent articles in this issue including;

  • AGS Annual Conference: Event Programme – Page 8
  • Ground Gas Monitoring and AGS Data Transfer Format – Page 18
  • Shaping Tomorrow: Building an Inclusive Future for Geotechnical and Geoenvironmental Engineering – Page 26
  • Building a Sustainable Future with Foundation Reuse – Page 29
  • A Greenprint for Change: The AGS Sustainability Route Map – Page 38
  • Inside: SoilCloud – Page 40

Plus much, much more!

Advertising opportunities are available within future issues of the publication. To view rates and opportunities please view our media pack by clicking HERE.

If you have a news story, article, case study or event which you’d like to tell our editorial team about please email ags@ags.org.uk. Articles should act as opinion pieces and not directly advertise a company. Please note that the publication of editorial and advertising content is subject to the discretion of the editorial board.