AGS Annual Conference 2021 – Presentations

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Presentations from the AGS Annual Conference 2021 can be viewed below:

1. The importance of Geo Engineers in the response to the symptoms of a changing climate – Luke Swain

2. Business Practice Working Group Report – Vivien Dent

3. Instrumentation & Monitoring Working Group Report – Jonathan Gammon

4. The UK Specification for Ground Investigation – ‘The Yellow Book’ – Third Edition – Julian Lovell

5. Data Management Working Group Report – Edd Lewis and Roger Chandler

6. Geotechnical Working Group Report – Alex Dent

7. Building Inclusion – Helen Townend

8. Landfill Reclamation – Making Waste Work – Duncan Scott

9. Contaminated Land Working Group Report – Alex Lee

10. Misuse of Monitoring and Testing – Ian Webber

11. Safety Working Group Report – Roseanna Bloxham

12. Laboratories Working Group Report – Will Fardon

13. Loss Prevention Working Group Report – Hugh Mallett

14. Earthworks Asset Management at Network Rail (Eastern Region) – Clare Brint


Thoughts from the Chair: Time

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Article by Sally Hudson, AGS Chair

I have always been in awe of the commitment shown by our AGS committee and Working Group members, or in fact by anyone in industry contributing to any extra-curricular activities over and above the ‘day job’. Ours is an often demanding and fast-paced way of earning a living, requiring an extra level of effort over the norm; to travel, undertake site work and meet deadlines. So this extra-over, as it were, must be recognised and gratitude is extended to practitioners and to Member companies that sanction the considerable amount of non-fee earning contributions made by staff to the AGS and other committees and industry bodies. This is how the AGS remains a not-for-profit Association and can divert resources where needed the most. We strive to provide opportunities to all those in the wider geotechnical and geoenvironmental industry for participation in all our activities. I am also grateful to all of our seminar and conference speakers for their gifts of time and expertise, which enable the AGS to fulfil this commitment to members. I will continue to drive and actively engage in these events.

The time committed to AGS activities is particularly impactful on businesses both this year and last, and our extra-curricular roles are being tested now more than ever, as we recover from the upheavals posed by the Covid-19 pandemic, by Brexit and by the unprecedented demands of HS2 investigations, enabling works and construction. I have spoken to representatives of many companies over the last few weeks and months, from consultants, main and specialist sub-contractors and from client bodies and asset owners, and the situation seems universal in that there is a shortage of quality candidates to recruit to permanent positions. This in turn has led to an increased pressure on the existing labour force. It has been well-reported that there is a national skills shortage in the UK, affecting several sectors and engineering is one of them. This matter has been predicted for some time and I am raising it here as I perceive it as a real risk to one of the core tenets of the AGS, that of a commitment to promote and enhance quality and safe practice. How do we find our way through to ensure a balance between fulfilling our commitments to clients and maintaining a high quality of work and improving on it? As the new AGS Chair, it is my responsibility to support and guide the Association activities to ensure that we provide benefit to all of our participants. I am pleased to report that we are already exploring several routes towards helping address the skills shortage crisis (and it is a crisis). We are working with academic bodies to promote awareness of this rewarding career among students in higher education and to explore potential apprenticeship routes. We are also in the process of consulting with those early in their careers and encouraging representatives into Working Groups to ensure refreshed thinking and to capture input from that group.

There is, for some, still a sense of being under-valued as a profession. Although in the long term this situation in which we find ourselves may improve our standing and recognition in the market place, we are already seeing an increase in remuneration packages required to attract candidates, a cost that will only have to be picked up by our clients. We are seeing costs of certain major infrastructure schemes escalating and although our front-end services are only a part of those costs, it is not hard to see how this could spread across all sectors. One of the powers of the AGS is that it has a voice, along with other collaborative industry organisations within Ground Forum, for Members to lobby Government on issues affecting our members and industry. Those companies that are not Member organisations of the AGS but who are active in the community and who use AGS data, please consider joining to assist in the promotion and enhancement of quality and safe practice within our industry.

Hopefully you have seen an increase in communication on what we do as an organisation to those outside of the AGS Committees during the term of my predecessor’s Chair tenure and I will continue to support this. This is my plea for your suggestions as to how we can improve or how you can assist:


Missing a trick? Is an unnecessarily complex permitting regime for the re-use of materials derived from historical landfill sites stifling their redevelopment?

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Article provided by Danny Hope SiLC, Hydrock; Eric Cooper SiLC, Hydrock; and Liz Hart SiLC, Lithos

Since the initiative to promote brownfield regeneration through redevelopment and the requirement for local planning authorities to maintain a brownfield register, an increasing number of derelict and contaminated sites have been remediated and safely bought back into beneficial use. Available brownfield regeneration opportunities are now beginning to shift to consider historic landfills, where permits have been surrendered, and areas that were infilled prior to waste management controls.

This interest creates a fantastic opportunity to bring these sites back into beneficial use. It provides a much-needed opportunity to improve and enhance the environment whilst at the same time delivering new homes/places and enhanced employment opportunities for the benefit of the communities in which they are located. However, we are experiencing inconsistency as to how these sites are regulated via the implementation of current waste legislation.

There is an increasing insistence that remediation supporting redevelopment of these sites, reusing site won materials, should be managed under a deposit for recovery permit (Defra, 2009. Environmental Permitting Guidance. The Waste Framework Directive) rather than following well established land regeneration guidance. This approach is causing confusion and significant delays. Ultimately if a practical way forward is not identified, there is real concern that these brownfield sites will be blighted and passed over for development in preference for less challenging greenfield sites, due to the disproportionate regulatory burden.

Anthropogenic material found in historic landfill sites is often similar in composition to ‘Made Ground’ identified on many brownfield sites and can be both chemically and physically suitable for retention and reuse within the development.  Unfortunately, the current approach is that if material is deemed to have been formally disposed of i.e., placed in a landfill (as opposed to made ground that may have been deposited across a site), it must be waste irrespective of its composition; even natural soils that have been placed in a landfill would be described as waste.  Reuse of any waste can only be achieved under an environmental permit.  Once something is classed as a waste, it must be assessed in line with WM3 and allocated a hazardous or non-hazardous waste code.

Remediation carried out under a planning permission embodies a ‘suitable for use’ approach based on generic and/or more detailed quantitative risk assessment – an approach adopted by the industry for many years. However, waste codes are allocated based on absolute concentrations, irrespective of site-specific risks. It follows that because thresholds for hazardous waste allocations are relatively low, material that is deemed suitable for use based on the site-specific risk assessment may be allocated a contradictory and barrier-inducing hazardous waste code

Once material is classified as hazardous waste there are further restrictions on how that material can be used;

  • Hazardous and non-hazardous waste codes cannot be mixed;
  • Different hazardous waste codes cannot be mixed; and
  • Treatment of hazardous waste is restricted to 10 tonnes per day.

It is also an inaccurate assumption that hazardous waste can simply be remediated to non-hazardous thresholds; this is often simply not feasible with time, cost and technical constraints.

The treatment of waste deemed hazardous under WM3 is limited to 10 tonnes per day. The current alternative is the application for and implementation of an Installation Permit. In the context of most remediation schemes, this quantity is miniscule and the upshot is that another layer of bureaucracy is introduced, with contractors having to apply for permits that they have no experience of. The industrial Emissions Directive that drives this requirement was surely never meant to regulate land remediation works?

Once in place, environmental permits are detailed on the Environment Agency public register. Permits (whether live or surrendered) will then be identified during land conveyancing, again this is a deterrent to development with property being ‘blighted’ and final sales hindered. The surrender of an environmental permit can also be a lengthy and costly process, again steering developers towards an easier option.

Within a remediation and earthworks project, limiting the options for re-using physically and chemically suitable site-won material potentially increases off-site disposal which again reduces a site’s commercial viability.

The current approach to historic landfills also undermines the government’s ‘Brownfield First’ policy and could lead to local authorities not achieving their house building targets and / or decreasing the provision of employment opportunities regionally and nationally.

Moreover, the issues raised here may also contradict the government’s ‘levelling up’ agenda. Many of the aforementioned types of site are located in the midlands and the north where land values are such that viability can be a major barrier to regeneration, more so than in the south where land values tend to be higher and development opportunities more prevalent.

Restricting the reclamation of site-won material also directly opposes the drive for sustainable development, which is a core principle in the National Planning Policy Framework and even the Environment Agency has a core principle of improving the environment while promoting economic growth. Sustainability is also important in the wider context, we are a small Island, we must ensure we use available resources wisely.

It should be noted that UK industry is at the cutting edge of global remediation innovation, developing products which are exported around the world, a significant contributor to the UK economy. If re-development of brownfield sites becomes less prevalent, this innovation is likely to be stifled and income generated by the export of new technologies overseas will reduce.

Overall, it is unfortunately the case that aspects of the current regulatory regime are creating barriers to sustainable remediation and successful redevelopment of former waste disposal sites rather than facilitating it. No environmental or social benefit is accruing from the position currently being taken and there is no value in it beyond an unimaginative commitment to compliance.

CL:AIRE, with the support of the Environment Agency, has pioneered the sustainable re-use of materials via the Definition of Waste: Development Industry Code of Practice (DoWCoP) which has seen the beneficial re-use of millions of tonnes of earth across England and Wales, when the overarching EU Waste Directive threatened to stifle brownfield regeneration. SiLC and its members have always supported appropriate use of the DoWCoP and would like to ensure its continued and consistent use in line with the guidance and its overarching aim to promote sustainability and protection of human health and the environment.

We hope that a swift resolution can be found to these issues, with a clear and consistent way forward that does not stifle development opportunities, is protective of human health and the environment, encourages industrial entrepreneurship and innovation, but does not contradict government policies and site-specific approach to risk evaluation. Discussions between CL:AIRE, the Environment Agency, government and other experts has commenced and is ongoing. The SiLC PTP will also be adding its support to these discussions.


Q&A with Hugh Mallett

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Full Name: Stephen Hugh Mallett (but known as Hugh since I was 10)

Job Title:  Technical Director

Company:  Buro Happold

I am a Chartered Engineering Geologist and Registered SiLC of forty five years professional experience. The first ten years focussed upon geological and geotechnical investigations in the UK and overseas.  After a particularly rainy day on site in South Wales, I joined the civil service and spent over four years (in the dry) as a geologist in the Minerals Planning Division of the Department of Environment.  In 1990, I joined the contaminated land team of an environmental consultancy (Aspinwall & Company) and have been involved in the investigation and assessment of land affected by contamination ever since (with Buro Happold since 2006).

What or who inspired you to join the geotechnical industry?

Courtesy of a friend in my village football team, I got a summer job as an assistant QS on the M5 construction near Weston Super Mare.  On our stretch of the motorway, there was an impressive limestone cutting which was inspected / mapped by a geologist abseiling down the rock face.  What more incentive does anyone need?  And, many years later, I got to do this myself at Treffgarne Gorge, in Pembrokeshire.  It was heaven.

What does a typical day entail?

The only thing that is typical is that there is no such thing.  It is the variety of projects, the range of tasks to be undertaken and the lovely (and not so nice) people that I work with that makes me keep coming back for more.  Although the majority of my days are spent in the office, I still love site work and get out whenever I can to do some “real work”.  Perhaps the most typical aspect is that every time I think that I know the ground conditions on a site, then the uncertainty principle rears its head and something unexpected / unknown is encountered to make you realise (again) that you know nothing.

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

Jordan Dead Sea Potash investigation.  My first overseas project in 1977 – went for 6 weeks which turned into 9 months (it was called “Wimpey Time”).  Learned to fly a hovercraft. Got rescued by a Jordanian Air Force helicopter on the Jordan / Israel border. Found live land mines (over 1000 eventually cleared from the site).  Channel Tunnel Rail Link (HS1) contaminated land assessment in the early 1990s – really developed our understanding at the time.  Writing R&D 66 and then delivering training on it to over 300 local authority contaminated land officers with some lovely colleagues and the legendary Bill Baker.  The Olympic Stadium – cycling to site, spending the morning with our site engineer Gemma as construction happened and then cycling back to the office along the Grand Union Canal – I could not stop smiling.  Devising and delivering the “Stratigraphic Beer Tour” lecture (on many occasions – invitations welcomed!).

What are the most challenging aspects of your role?

The continual need to keep up to date with the technical aspects of our work on contaminated land is double edged.  It is really hard to do but also always keeps you on your toes, so work never loses its interest.

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

I currently chair the Loss Prevention Working Group.  It is a very active Group and has many very committed members who are always providing really useful advice and guidance through the various Loss Prevention Alerts, articles and the rather wonderful Loss Prevention Guidance, which is worth the membership fee on its own and is due to be reviewed and re-published in 2022.

What do you enjoy most about being an AGS Member?

Being part of an organisation that is concerned about raising the standards in our industry and which does something about it by the provision of useful (and used) guidance and advice.

What do you find beneficial about being an AGS Member?

I have been an active member of the AGS since the early 1990s (being a founder member of the Contaminated Land Working Group) and can honestly say that I have learned so much from that involvement – getting out far more than I put in.

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

I shudder to think where the industry would be without it.  Think of the AGS Data Format, all of the technical and commercial advice and guidance, the support provided to all of the membership, the unselfish and collaborative behaviour of so many people.

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

At my first AGS meeting people talked about the need to raise the status of ground engineers.  Sadly, despite initiatives such as SiLC and RoGEP, we are still often perceived as people grubbing around in mud who need little, if any, consideration and deserve little if any respect.

I have a dream:  To see ground engineers knighted for their professional services, receiving the salaries of lawyers and obtaining the respect currently attributed to health professionals.


Taking soil samples for determination of volatile organic compounds (VOCs)

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Article provided by Judith Nathanail (LQM), Geraint Williams (ALS), Mike Smith, Paul Nathanail (GHD)

“It’s not there!” 

“You haven’t looked hard enough”.

Once the preliminary risk assessment is done, and volatile organic compounds (VOC) are contaminants of concern the sampling and analytical strategies need to reflect the ease with which VOCs can be lost from a sample resulting in a false negative analytical result.

In case you are wondering, a VOC is “any organic compound having an initial boiling point less than or equal to 250 °C (482 °F) measured at a standard atmospheric pressure of 101.3 kPa.”

Volatiles are lost rapidly if soil samples are left exposed.  Losses of 25 – 50% have been recorded within 30 seconds of exposure.  Sampling method has an even bigger effect – with losses of up to 99.9% recorded from bulk sampling.  Where in situ VOC concentrations exceed an assessment criterion, such losses can result in false negatives, leaving behind unremediated soils or prematurely ending remediation.

BS 10175 recommends that samples intended for the determination of VOCs should be taken in a way that minimizes the loss of volatiles.  The primary purpose of BS 10176 is to specify procedures that can be followed in the field to minimize loss of volatile organic compounds (VOCs) during sampling.  These procedures need to be strictly adhered to in order to provide reliable and repeatable results.

The procedures described in BS 10176 are similar to those described in long standing guidance and standards across the world.  The immersion methods require considerable time, resources, safe work practices, competent oversight and quality control.

The procedures involve taking a small sample of known weight and volume is taken using a coring device followed by either sealing the intact core or immersing the sample in a liquid to prevent losses through volatilisation in a subsequently sealed vial.   BS 10176 describes procedures based on immersion in methanol, in sodium hydrogen sulfate (sodium bisulfate) (only for low VOC concentrations) or in de-ionized water.  The core is then used directly in the laboratory without sub-sampling.

BS 10176 requires duplicate samples are taken from the same soil stratum and as close as possible to the location of the first sample to provide the laboratory with an additional sample in case re-analysis is required.

Soils up to coarse sand can be sampled.  It is unlikely that samples representative of the in-situ VOC concentration can be obtained or tested from coarser soil fractions. For coarse gravel, cobbles, etc. alternative methods such as PID headspace screening or soil vapour sampling need to be adopted.

Standards like BS 10176 are drafted by working groups appointed by BSI’s Soil Quality Committee EH/4. EH/4 is responsible for developing British Standards in the fields of soil quality, soil pollution and contaminated soil. The committee contributes to European (CEN) and International (ISO) Standards. The EH/4 committee comprises representatives of relevant industry and academic bodies, learned and professional organisations and/or individual experts. Committee members volunteer their time and expertise to the development of standards.  You can find out more at:

The authors presented an introduction to BS 10176:2020 in a webinar in April – a link to the recording is at:

Article Loss Prevention

Revised AGS Client Guide to Domestic Basement Construction

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Construction of basements beneath houses in central London remains a buoyant market, which is good news for the sector.  Not so great, is the sad fact that building collapses still happen during basement works.  The AGS Client Guide to Domestic Basement Construction has therefore been updated (to version 3) in order to emphasise more prominently the fundamental importance of adequate temporary works.

The temporary works play a crucial role in minimising potential damage to adjoining and adjacent properties, as well as the host building.  Forward movement of the basement’s perimeter retaining walls must be resisted with high stiffness temporary and permanent props in order to minimise ground movements alongside the basement.  The revised Guide notes that as the contractor is responsible for the design as well as the implementation of temporary works, clients must ensure that the appointed contractor has adequate in-house design expertise or that they employ a professionally qualified temporary works engineer.  In both cases the temporary works designer should be able to demonstrate successful completion of other basement projects similar to the one being planned.

The revised guide can be downloaded from:

Article Report Contaminated Land

AGS Contaminated Land Working Group – Update

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Alex Lee, AGS Contaminated Land Working Group Leader, has provided an update on the top issues the Contaminated Land Working Group discussed at their last meeting which took place virtually in July 2021.

Client’s Guides

The AGS CLWG are currently in the process of revising A Client’s Guide to Desk Studies and Reference List. The CLWG are also in the final stages of producing A Client’s Guide to Geoenvironmental Reports, which is being reviewed by the group ahead of publishing.


At the last meeting, the CLWG discussed sustainability, which may lead to a sub-group to work collaboratively on looking at sustainable site investigations and providing advice to AGS members on this.


The CLWG have provided feedback on HSG248 and concerns from both CLWG and the AGS Labs WG were considered at the meeting. Representatives from the CLWG and Labs WG will continue to be involved with further discussions within the wider industry regarding this document.

ERES Codes

Members of the CLWG are involved with a sub-group which is assisting with the review of ERES codes.

Working Outside Of The AGS

The AGS Contaminated Land Working Group have many members who are involved in a range of different projects and working groups; SAGTA C4SL project, the National Brownfield Forum, SiLC, SoBRA and more. This enables us to share new information within the Group but also relay the position of the AGS CLWG outside of the organisation.

If you interested in joining the AGS Contaminated Land Working Group, please contact the AGS Secretariat at

Article Laboratories

Laboratory Assessment and Sampling Practice Webinar Summary

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On 30th June, the AGS held their first webinar on the subject of laboratories, focusing on laboratory assessment and sampling practice. The event was sponsored by ALS Environmental and Geotechnical Engineering.

This webinar saw Will Fardon (AGS Laboratories WG Leader), Geraint Williams (ALS) and John Powell (Geolabs) investigate various aspects of sample submission, discussing best practice and guidance for how to get the most from the laboratory, the testing and some pitfalls to avoid. The event also covered different methods for assessing vapour intrusion and issues related to the quality and quantities required of laboratory samples for geotechnical testing to ensure representative Soil Parameters

This paid for event was rated 4.6 stars out of 5, by our 100 registered delegates.

If you missed this webinar, the replay is now live and available for view on the AGS website. The webinar costs £25 for AGS Members and £30 for non-Members (prices exclude VAT). Click HERE to view the replay and download the speaker presentations and file handouts.


prEN 1997 Parts 1, 2 and 3 – Latest versions

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Free download of the latest [April 2021] versions of the prENV Eurocode 7 for review and information. Any queries or comments should be addressed to the AGS representatives currently serving on the BSI B/526 Committee [Gary Evans] or [Chris Raison] or direct to BSI.




Article Geotechnical

Digital transformation in ground engineering – hopes and fears?

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Article provided by Neil Chadwick, Director, Digital Geotechnical and Stephen Lawrence West, Director, Ground Engineering, Ramboll

Digital transformation is a term that, within the ground engineering sector, can engender feelings of hope or fear or possibly both at the same time. The hope is for a future where we have tools that can help us all to do a better job for society’s benefit. The fear is of being left behind, individually or corporately, or concern about potential undesirable consequences if we allow the machines to take over. In this article we will explore some of these fears, a few of which are well founded, but our main goal is to accentuate the positives that digital transformation can bring and encourage creative thought and debate about this issue by the AGS members.

It starts with the data

The digital revolution is also a data revolution. The good news is that our industry is already pretty good at handling data. At the heart of this is our own AGS data transfer format for factual GI data. We take it for granted but it is probably the world’s most successful ground data transfer format. Other countries, and other parts of the construction industry, look at us with envy.

Despite this success we should not rest on our laurels – and we are not. The AGS format is adapting and expanding. We have introduced AGSi, for ground models and interpreted data, and a draft for AGS piling is now starting to gather some real interest. The AGS Instrumentation and Monitoring Working Group is also on the case, currently studying real world I&M data flows.

Few would doubt the value of digital tools for helping us to sort out the data, or the need for common standards for when we need share that data. The opportunity that digital transformation provides is a step change improvement on what we already have Our day to day experience of modern apps and websites has, quite rightly, increased expectations for the user experience of technical software. We want tools that are both smarter and easier to use. However, if we want our software vendors to provide these, then we need to be pro-active in telling them what we really need, and why.

Interpretation: humans vs machines?

Interpretation of data to inform design is perhaps the first flashpoint in the discussion about the nature and extent of machine input to our processes. We all know and accept that ground data is normally less than perfect, with outliers that are outliers for a good reason, albeit we don’t always know the reason at the time. In this country we have been reluctant to use even relatively straightforward statistical methods in our interpretation, so therefore it comes as no surprise to find that many get nervous when the digital evangelists start talking about data driven design and machine learning.

It is right that we should question these. Data driven design is just that. In many cases, a data driven design could give us the right answer, but data is subject to imperfections, bias and limitations. If we are not careful we may end up reinforcing the bias (as Amazon once found out, to their embarrassment), or we could get things completely wrong if we extrapolate outside the valid range of the data.  We also need to ask what is the ‘right answer’ when considering design solutions.  Can a purely data led design provide an answer that is right for the overall needs of a particular client and project that suitably weighs risk.  This is where the human element can provide insight to select the right answer having been guided by information provided from past data.

Machine learning goes further and can potentially unlock more value from our data, but the mantra here is ‘don’t forget the physics’. The realities of the ground are such that the machines will always need a human partner for their learning process, whose role will be to  define the geological and other rules that should be obeyed, and act as final arbiter to select the design ground model.

An example of the above is interpretation of geological horizons from borehole data. We already use computers to help us with this, but at present it typically needs need human intervention to account for features such as buried river channels that may be apparent from the desk study conceptual model, but may be have been missed by the existing boreholes.

Having said all that, the authors believe that we should be embracing these techniques, using them to help us make more informed and hopefully better decisions. The fact that 100 different engineers can come up with 100 different design lines from the same data is not something we should be proud of.

A good example of a positive experience from machine learning was given at the AGS Data Conference in 2017. One of the presentations looked at the machine learning applied to CPT interpretation for a large regional scale dataset. Human verification of selected interpretation was undertaken for control purposes. It was confirmed that some of the machine generated interpretations required correction after review, but these were outnumbered by the number of cases where, after review, the machine was considered to have got it right, not the original human!

Automation of the design process

This is where things start to get really interesting. There is plenty of scope for using automation to help with factual and interpretative reporting, but automation of analysis and design calculations is likely to be one of the main digital battlegrounds in the coming years.

As mentioned above, digital 3D ground models are already a reality on many projects. One area ripe for development is finding a better way to input these models directly into analysis/design software, replacing what is currently mainly a manual process. However, we need to think carefully about what model we use for input. We are most familiar with the ‘geological (observational) model’ which is our best guess of what we think might be going on based on the conceptual model and lessons learned from our education and experience. However, for analysis we should be using a ‘geotechnical design model’ which also takes account of uncertainties and code requirements.  These models can be compiled by an intelligent digital partner by prompting the geotechnical engineer to make key decisions relating to geological setting and how to account for ground related risks.

One of the main concerns expressed about automation of design is that we will forget how to do the design calculations, with the younger generation not learning at all. This is a legitimate concern, and it is by no means unique to ground engineering. If we automate (or perhaps when we automate is more correct) we will need redefine the role of the human in the design process. We will probably still be doing some sort of verification, which should allow us to practice our skills and judgement. We don’t have all the answers to this conundrum, but it would be wrong to allow this to be a barrier to much needed progress. We will have to work through it.

There are some who are ambivalent, or even hostile, to automation, fearing that many will lose their jobs. However, others see the opportunities that it can bring, such as allowing us to do more analysis, considering more scenarios, to create better designs for our clients. If we get this right, we should be able to spend more time on real design and less on manually transferring data from one bit of software to another. We need to make sure that, as an industry, we are all aligned in looking to deliver real change and real benefits. We must avoid being drawn into a race to the bottom (on time/cost). It is within our gift.

Automation in construction

Digital transformation is not confined to the design office. There are many opportunities for increased use of digital technologies on site.

Digital field capture of data for ground investigation and construction is now starting to become routine, although we still have some way to go on this.

Augmented reality, where models and the real world can be visualised together, is an under-used technology that certainly merits further attention.

Automation of construction processes is the next frontier. Will we see robots running around construction sites?  One day, perhaps, but the reality of construction automation may be slightly more down to earth. For example, it may include automated boring or piling rigs, or earthworks equipment, with humans still in attendance but with more of the work and decision making done by the machines.

Automation of earthworks operations is the one of the main subjects of research and development in the ground domain, and there are already many examples of digital technologies being used to good effect. Typical applications include tracking of compaction plant, to provide information on number of passes, to assess specification compliance. Another example, published recently in NCE, shows how a contractor is monitoring earthworks vehicle movements on a large linear infrastructure site, then using AI to optimise utilisation of the fleet.

This is not digitisation for the sake of digitisation as there are some important additional benefits that can be obtained by automating construction. Firstly, there is the obvious benefit to health and safety if we can keep as many humans as possible out of harm’s way. This is one of the main drivers for research in this domain.

The other benefits are perhaps not so obvious, but should be of interest to ground specialists. Digitisation and automation of construction will very likely lead to increased monitoring of the processes. This additional data could prove very useful, if we choose to leverage it. A further benefit should be improved consistency of processes which, when taken together with the extra monitoring, should leave us with better build quality, and better records.

We will still need humans to keep a close eye on things as the ground never ceases to conjure up surprises, but if we get this right we could end up in a much better and safer place.

Do we all need to be digital experts?

A good question, that has been answered many times by many people, with many different answers given. The reality is that we can only hold a limited amount of knowledge in our heads. It is unrealistic to ask all ground specialists to become digital specialists, and the authors believe that it would be wrong to significantly dilute or reduce most individual’s knowledge of ground engineering (whatever branch that happens to be) to make way for lots of digital skills.

However, getting digital specialists to do all of our digital legwork is not the right answer either. We should aim for a general increase in awareness and knowledge of digital issues and capabilities at all grades, including the oldies. Digital specialists may still be brought in for the heavy development work, but it would also be helpful to have some people with a foot in both camps.

Whatever the arrangement, we need ground and digital specialists to work together to identify the problems that need to be solved, and the improvements that can be made. If we leave it all to the digital people then we may get lots of shiny new toys, but not the ones we really wanted.

In conclusion

Much of this article has talked about some of the potential problems that digital transformation may bring. However, our mission has been to inform, challenge, and hopefully allay some fears. Digitisation is coming, and we should embrace it, as it will offer great opportunities for improvement within our industry and can be seen as an aid to help us communicate even more effectively with our colleagues, clients, and the public.

However, if we are going to get the most from it, we need ground specialists to work with the digital specialists. The digital specialists may know how to get there, but we need to tell them where to go.


Incorporating Drone Technology into Ground Engineering Projects – Transforming the work of a remediation contractor

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Prepared by:

Blaise Hodges, Senior Land Surveyor, Cognition Land and Water,

Andy O’Dea, Technical Director, Cognition Land and Water,

Drones (Unmanned Aerial Vehicles – UAVs) are quickly becoming one of the most useful tools on a typical construction site, offering rapid data collection for topographical surveys or site 4D imagery.  Drone arial footage and 4D model mock-ups allow quick access to valuable site data and visual information.  Whether it’s for initial site pricing strategies, refining pre-design processes or recording work progress, our investment in drone technology is allowing our teams to work safer and more efficiently, whilst delivering tangible benefits for our clients.

As our drone uses GPS and obstacle avoidance systems, it can be programmed and manoeuvred accurately to precise locations on site and follow pre-determined flight paths.  This creates an extremely valuable and multi-faceted tool that can be used in a variety of situations. Such tools and facilities have had a big impact on our work, primarily in the management of earthworks projects.  Outlined below are a number of ways in which the application of drone technology and surveying techniques have delivered significant benefits, efficiencies and improvements in data capture and delivery on our projects.

Faster and more accurate site surveys

For most surveyors/engineers, there are two simple reasons for using drones for earthworks – speed and accuracy.  With conventional land-based surveying techniques, it can take many hours to walk the site and measure aggregates and stockpiles.  Subsequently, it often takes several days to process the data and deliver the required volumetric analysis or drawings.  Drone surveys allow all of this work to be done in a fraction of the time.

As an example, our Senior Land Surveyor recently carried out a drone survey of a large construction site in less than 20 minutes to collect data on earthworks stockpiles.  It was not possible to carry out the survey with traditional ground-based systems due to soft and overgrown ground conditions.  The post-survey processing took a matter of hours, despite handling thousands rather than scores of surveyed points across the site surfaces.  In addition to the very significant time saving, the far greater number of survey points provides scope for many more outputs such as an orthomosaic point cloud and a 4D digital terrain model (DTM) of the site.

Using proprietary Pix4D software, access to the survey model can be provided to the client and project team via a simple web link.  This then allows the whole project team to inspect, manipulate and interrogate the model as well as access to high resolution images, on screen visuals and tools to measure terrain dimensions, etc.  Stockpile volumes can be calculated, distances and areas measured, and OS co-ordinates given – all with a few mouse clicks.  It is a truly powerful data and imagery presentation system that is accessible to all.

Performing cut-and-fill volumetric analysis

We often utilise traditional GPS surveying in tandem with drone surveys to extract the best of both approaches.  Traditional ground-based surveying is used for key site features such as bottom of banks, edges showing changes of surfaces and heights. The drone data collection is then carried out on a grid throughout remaining areas, eliminating the risks associated with climbing stockpiles and providing truly accurate data.

Drones have dramatically reduced the manual work needed to perform a cut-and-fill volumetric analysis following the site survey.  Once the aerial data is collected, drone software platforms like Pix4D enables cloud processing and final export into Autodesk file formats like a DXF or a point cloud file that can be used in Civil 3D or LSS design software.

This has allowed us to streamline our cut-and-fill workflow, speeding up the process significantly.  We have estimated that we can now carry out volumetric analysis and cut and fill calculations in about one-third the time it took us previously.  This provides cost savings to our clients and greater time to interrogate the output of the analysis and formulate innovative and novel solutions to the ground engineering problems presented to us.

Verifying work and managing conflicts

During the course of an earthworks project, it is vital to regularly monitor progress, especially at key milestones, to ensure the works are progressing to programme.  Drone surveys have become an invaluable tool in this monitoring and verification process.

We fly our sites as often as is required by the project to satisfactorily record progress.  We then process the images into an orthomosaic, and hence into an elevation map that can be compared to the initial site plans as the project progresses.  This allows for clear and robust recording and monitoring at important phases of the project.  Importantly, this information enables more focused quality control as well as providing site managers with detailed information on progress to allow closer and more accurate management of resources and expenditure.  Such interim surveys also provide robust data for interim works measurement and payment applications.

Site inspections and tender support

We will often use drone surveys in support of our tender and estimating work.  A quick drone survey carried out at the tender stage can provide invaluable information to both the client and contractor on the site conditions, building (current and former) footprints, topography, site restrictions, earthworks volumes, building condition, etc.

Drones can capture images and videos, allowing for detailed mapping and easy access to inspect and prepare volumetric data for cut and fill calculations.  Gathering information through a single drone survey allows for a far better understanding of the key project risks, makes the costings on a project more accurate and saves significant time in the tender stage by avoiding multiple site visits.

The speed at which we can now perform quite complex and detailed imaging, topographic and volumetric surveys means that we will often provide our initial drone survey as a free service to our clients at the tender stage, giving us a clear advantage and differentiator against our competition.

Improved worker safety

In the field, surveyors and engineers spend hours on the ground collecting data or overseeing site-based work.  This is not only time-consuming but can be deemed as a risky activity.  Often, site rules or risk assessments will not allow personnel to access stockpiles or move freely around the site due to plant movement and other site risks.  Traversing steep slopes that are uneven and potentially unstable is an activity fraught with dangers.  This can all be avoided by the use of a drone survey.  Site engineers and personnel can inspect and quantify the site, earthworks, slopes and stockpiles from a safe distance avoiding all associated trip and fall hazards.

To assist with communicating key site risks to the workforce, a drone aerial photography survey will allow for a good overall representation of the site and help provide powerful visual information to site managers for use in site inductions or toolbox talks.  Drone surveys may even be used to conduct safety inspections or audits at large sites and this is something that we are looking to introduce shortly.

A powerful tool

We hope that the examples provided above give a flavour for the powerful benefits that drone surveys have made at our company and how investment in this technology has revolutionised the way in which we inspect, manage, record and report the work we do.  It is fair to say that it have been a game-changer for Cognition Land and Water and we would be happy to share our experiences with you further if that would be helpful.

Cognition Land and Water is a specialist ground engineering and contamination remediation contractor with the capability to deliver all ground-related aspects of construction projects from site investigations, remediation, earthworks and ground engineering, through to civil engineering and concrete-framed structures.


Asbestos in soil and quantitative risk assessment – discussion on a way forward?

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Tags: Featured

Article contributed by:

Jo Wilding, Associate Technical Director, RSK (SoBRA Executive Committee)

Simon Cole,  Technical Practice Lead, AECOM (SoBRA Chair)

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Laboratory reporting of asbestos in soil is a key data component of quantitative risk assessment for human health, and for the risk-based management of asbestos in soils. Asbestos in soil poses a hazard to human health when it becomes airborne, and the inhaled fibres can result in diseases including mesothelioma and lung cancer. Therefore the relationship between asbestos in soil and the resulting fibre concentration in air is a fundamental, but complex, element of human health risk assessment. In the UK, there is no current consensus on which air quality guidelines should be used to assess potential risks to human health from exposure to asbestos in soils once airborne. This in turn means that there is no UK regulatory or industry-agreed good practice for the assessment of risks from asbestos in soils, which are being – or could be – released to air and subsequently inhaled. Key elements to an asbestos risk assessment are (i) asbestos identification and characterisation, (ii) receptor exposure, (iii) an understanding of background exposure and (iv) assessment criteria at an appropriate risk level that distinguish between relative risks from different types and forms of asbestos.

The Society of Brownfield Risk Assessment (SoBRA) has recently published two discussion papers relating to asbestos in soil laboratory analysis and reporting. These were published alongside an update to the discussion paper on guidelines for airborne concentrations of asbestos fibres in ambient air: implications for risk assessment.  All three papers build on the series of SoBRA papers published by the asbestos sub-group in 2015 that looked at sampling protocols, activity-based sampling, conceptual models, and example decision making under Part 2A of the Environmental Protection Act 1990.

Data mining of laboratory data

SoBRA issued a request to major UK soil laboratories in 2016 to provide SoBRA with anonymised asbestos in soil laboratory data. The distribution of asbestos in soil discussion paper provides a factual presentation of the data shared by five UK laboratories (ALS, DETS, Envirolab, i2, and REC). The data presented in the paper is, naturally, a reflection of the soil samples sent to the testing laboratories rather than a reflection of background concentrations of asbestos in soils in the UK.  The datasets do not distinguish between sample origin – be that a greenfield site or a brownfield site nor do they distinguish between large datasets from one or a small number of sites and small datasets from a larger number of sites.

Typically laboratory testing follows a sequential three stage process akin to the one presented in the Standing Committee of Analysts ‘Blue Book’ method (withdrawn in October 2020; SCA, 2017). However, the data presented in the paper is a result of different laboratory methods or sub-sets of methods and will include analysis undertaken by different methods over time by the same laboratory.  The three stages are:

Stage 1: The determination and identification of presence or absence of asbestos using stereomicroscopy, plus higher magnification polarised light microscopy (PLM) analysis for fine fibres (see HSG 248, HSE, 2005).

Stage 2: The removal of asbestos containing material (ACM) and fibre bundles with identification and gravimetric analysis to determine percentage by weight.

Stage 3: The dispersion and collection of free fibres followed by fibre identification, counting and measurement of fibres to determine percentage by weight.

From a dataset of approximately 175,000 samples, during Stage 1, asbestos was not detected in the majority of samples submitted to the five laboratories. When positively identified the majority of asbestos detected was chrysotile. The majority of reported concentrations of free fibres detected in soils that have undergone Stage 3 analysis following a positive identification at Stage 1 were below the method reporting limit of 0.001% wt/wt. (Note that these samples are typically, but not always, those that have had a positive identification at Stage 1; it is rare for samples with a negative ID at Stage 1 to progress to Stages 2 or 3).

Variability in UK laboratory methods and reporting

There is, however, significant variability in UK laboratory methods for the identification and quantification of asbestos in soil. A SoBRA survey of 10 UK laboratories in 2018 raises questions about the data that is reported and its subsequent applicability for use in human health risk assessment.  The survey was designed to complement a similar survey of UK laboratories undertaken by the AGS and reported in February 2019 (Mitcheson, 2019).  The survey highlighted that laboratories do not follow the same sample preparation and analytical procedures, nor do they report in the same way.  Only 70% of laboratories follow the ‘Blue Book’ method; the method used by the remaining 30% of laboratories was not explored.  Even those who follow the ’Blue Book’ implement that method in different ways that could significantly influence the results reported.

When considering accreditation and proficiency, which is a key element for data quality, all laboratories surveyed participated in the HSL Proficiency Testing Scheme Asbestos in Soil Scheme (AISS) but only 70% of the laboratories responded that they held UKAS accreditation for Stage 1 identification of asbestos.

Total sample size (weight) requested, sample size (weight) used in Stage 1, and sample preparation for Stage 1 and Stage 3, varied considerably between laboratories. No laboratory routinely reported at what sub-stage within Stage 1 asbestos was detected (i.e. during visual inspection using stereomicroscopy or during higher magnification PLM microscopy) and therefore when the sample inspection stopped. All such variables could have implications for the determination and identification of presence / absence of asbestos in the soil samples, and the type of asbestos reported to be present in Stage 1.

With regards to the data needed to inform a human health risk assessment, only 20% of laboratory responses indicated that they would routinely provide comment on the condition of the asbestos identified in Stage 1 (i.e. weathered, degraded, non-degraded, disaggregated, not in original form) in addition to identifying the presence or absence of the three principal types of asbestos, and the form of that asbestos. A lines of evidence approach is often needed for asbestos risk assessment. For example, non-degraded asbestos material is that which despite being in or on the ground is in relatively good condition and capable of retaining most of the asbestos fibres. As such, non-degraded asbestos material may pose a lower risk to human health and should be considered within the risk assessment. Asbestos containing materials that have been significantly damaged or degraded will be more likely to release fibres and therefore pose a greater risk to human health.

A small number of laboratories did respond that they could provide asbestos type differentiation at quantification if required during Stage 2 and Stage 3, along with photographic evidence if requested, but this was not routine.

Reporting recommendations

The SoBRA paper on UK laboratory methods for the identification and quantification of asbestos in soil makes a series of recommendations for laboratory reporting of asbestos in soil results based on the requirement for human health risk assessment to be supported by clear, unambiguous laboratory data. One key element is the reporting of types and forms of asbestos, for all each type and form of asbestos identified. Within Stage 1 this should be for each of visual inspection, detailed inspection under x20-x40 stereomicroscope and pinch samples under x80-x500 magnification (PLM). Within Stage 2 individual masses for each type and form of asbestos identified should be reported, with mass reported in mg/kg not %wt/wt.

The SoBRA recommendations (the full detail of which is presented in the SoBRA paper) for laboratory reporting of asbestos in soil results would ensure that the data provided by the laboratory is clear and unambiguous. With the withdrawal of the of the SCA ‘Blue Book’ method for the determination of asbestos in soil, now is an opportune time for industry to adopt a new approach the analysis and reporting of asbestos in soil. Consistency is required in sample preparation, analytical procedures and reporting to ensure the resulting human health risk assessment can be undertaken with confidence.

When considering the data required within a human health risk assessment, there are other laboratory test methods that focus less on the reporting of the mass of asbestos present in the sample and focus more on the potential for airborne asbestos fibres arising from asbestos in soil. Two such methods that have been developed, or are in the process of being developed, by UK laboratories are:

  • Respirable fibre count per unit weight of sample (this can be used to estimate airborne fibre numbers in association with airborne soil particles), and
  • Dustiness tests (modified HSL drum tests designed to estimate the releasibility of asbestos fibres and provide normalised fibre to dust concentrations akin to those reported by Addison et al 1988).

Air quality guidelines for use in human health risk assessment

The SoBRA discussion paper on guidelines for airborne concentrations of asbestos fibres in ambient: implications for risk assessment was initially published in 2017. The paper has been prepared as an evidence base, with the aim of supporting the development of good practice for assessment of potential risks from asbestos at sites affected by land contamination.

The paper sets out a series of issues that need to be resolved before a UK air quality guideline value can be proposed for asbestos, but calls for the Asbestos in Soil Joint Industry Working Group to formulate a position regarding an air quality guideline for asbestos in the UK.

There are a range of existing air quality guidelines for asbestos fibres, provided both by international bodies (e.g. World Health Organisation) and national bodies (e.g. Health Council of the Netherlands). There are also different approaches in literature for calculating air quality guidelines for asbestos fibres, dependent on the exposure scenario under consideration. The SoBRA paper summarises a selection of internationally published air quality guidelines, together with the data upon which these are based, as well as calculating air quality guidelines using two different modelling approaches from literature. The existing air quality guidelines, and SoBRA calculated guidelines, are compared alongside published ambient background airborne concentrations to understand variability in thresholds for asbestos in air and the potential practicalities of those guidelines.

All models are having to extrapolate from relatively high occupational exposures that form the empirical evidence on which the models are based down to much lower environmental exposures.  The authors of these models differ in their interpretation of that empirical data and as a consequence there is variance in the model outputs for a given input exposure.  Risk estimates from these models can vary by an order of magnitude, and published air quality guidelines by more than two orders of magnitude due to differing assumptions on the relative potency of different asbestos types.

The updated paper includes risk estimates calculated using SoBRA’s workbook (beta version freely available at using the linear as well as the non-linear version of the Hodgson & Darnton model (Hodgson & Darnton, 2000) as well as updates on the age adjustment calculations. The paper recommends that the linear version of the Hodgson & Darnton model for pleural mesothelioma is used to estimate risk and calculate air guideline values in conjunction with the non-linear variants for peritoneal mesothelioma and lung cancer.

The tool allows users to select from the algorithm options presented in Hodgson & Darnton (2000), and enables users to perform model choice sensitivity analysis and evaluate the difference the use of alternative algorithms makes to estimated risk.  It is hoped that the tool will provide a consistent basis for the calculation and reporting of risk estimates and feedback on the tool is welcomed at


Addition, J, Davies LST, Robertson, A, Wiley, RJ (1988). The release of dispersed asbestos fibres from soil. IOM Historical Research Report TM/88/14.

HSE (2005). Asbestos: The analysts’ guide for sampling, analysis and clearance procedures.

Mitcheson, B (2019). Variability in asbestos analysis in soil, AGS Magazine, February 2019

SCA (2017). The quantification of asbestos in soil (2017), Methods for the examination of waters and associated materials, Standing Committee of Analysts, April 2017 [Withdrawn in October 2020].


The authors would like to acknowledge the work of the SoBRA asbestos subgroup, and in particular Barry Mitcheson for the development of the workbook tool, and both Barry and Simon Hay as primary authors of the risk calculations presented in the SoBRA air quality guidelines discussion paper.