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.

Article

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, blaise.hodges@cognitionltd.com

Andy O’Dea, Technical Director, Cognition Land and Water, andy.odea@cognitionltd.com

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.

Article

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

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Article contributed by:

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

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

Feedback to info@sobra.org.uk

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 https://sobra.org.uk/resources/reports/) 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 info@sobra.org.uk.

References

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 https://www.ags.org.uk/magazine/ags-magazine-january-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].

Acknowledgements

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.

Article Laboratories

PFAS – the greatest challenge for the site investigation and laboratory industries?

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Article provided by Geraint Williams, ALS Life Sciences, Member of the Contaminated Land and Laboratories Working Groups.

“Forever chemicals”.  This is the ominous title often given to PFAS (per- and polyfluoroalkyl substances) which hints at both the reason for their use and their potential impact to human health and the environment.  These substances are the latest entry into the list of contaminants that have resulted in long-term exposure over the last several decades. Their predecessors include lead, asbestos and hexavalent chromium, the focus of the 2000 Erin Brockovich film, plus many more.  But PFAS pose many difficulties their predecessors did not.  This article briefly reviews these challenges and provides an overview of emerging laboratory techniques for analysis of PFAS.

What are PFAS?

In 2015, the Swedish Chemicals Agency (KEMI) identified over 3,000 PFAS on the global market1. A more recent study identified approximately 4,700 Chemical Abstract Services (CAS) Registry Numbers associated with individual PFAS or PFAS mixtures2. In 2019, the US EPA assembled a master list of 6,330 PFAS that combines information from several existing lists into one3. The total number of PFAS may be even larger, given that some PFAS class members lack CAS numbers and many are not intentionally manufactured but are transformed in the environment.

PFAS can be broadly subdivided into four interrelated categories: perfluoroalkyl acids (PFAAs), PFAA precursors, perfluoropolyethers (PFPEs), and fluoropolymers4, 5. PFAAs are the most studied PFAS subgroup. They are recalcitrant and extremely persistent in the environment. Examples of PFAAs include perfluoroalkyl carboxylic acids (PFCAs) such as perfluorooctanoic acid (PFOA), perfluoroalkyl sulfonic acids (PFSAs) such as Perfluorooctane sulfonic acid (PFOS), perfluoroalkyl sulfinic acids (PFSiAs), perfluoroalkyl phosphonic acids (PFPAs), perfluoroalkyl phosphinic acids (PFPiAs), perfluoroether carboxylic acids (PFECAs) such as GenX, and perfluoroether sulfonic acids (PFESAs) such as 4,8-dioxa-3H-perfluorononanoate (ADONA). PFAAs and their precursors are further subdivided according to their chain length, which is viewed as indicative of their bioaccumulation potential.  By convention, the longer-chain PFSAs are those with six or more perfluorinated carbons; longer-chain PFCAs, PFPAs and PFPiAs are those with seven or more perfluorinated carbons5. The definition of longer vs. shorter-chain PFAS is less clear for perfluoroethers.

The focus of risk assessment has been on a very narrow sub-set of PFAAs which are all extremely persistent and are also known to be mobile and bioaccumulative.  This persistence, along with their high solubility, low to moderate sorption to soils, and lack of volatility can result in very extended groundwater plumes (potentially multiple miles).  PFAS have the potential to migrate over a much wider area than conventional contaminants6.

PFAS Regulation

PFOS and its salts, and perfluorooctane sulfonil fluoride (POSF) are listed as persistent organic pollutants (POPs) in Annex B of the Stockholm Convention, whereas perfluorooctanoic acid (PFOA), its salts, and related compounds are listed in Annex A7. Perfluorohexane sulfonic acid (PFHxS), its salts, and related compounds are currently under review for listing8. Several PFAS are included in the European Chemicals Agency’s (ECHA) Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) Candidate List of Substances of Very High Concern (SVHC)9.

The EU annual average environmental quality standard (AA-EQS) for PFOS in surface freshwater is set at a very low criterion of 0.65 ng/l, based on the potential for secondary poisoning in humans due to fish consumption.

The US has set a lifetime health advisory level for PFOA and PFOS, individually or combined, of 70 ng/l in drinking water10.  Several US states have also set their own drinking water guideline levels for PFOA and PFOS.  Whilst in the UK, the Drinking Water Inspectorate (DWI) has recently revised our own standards11 which follow a 3-tier system where PFOS or PFOA requiring monitoring is set at 10 ng/l.  The concentration requiring treatment, as representing a potential danger to human health is set at 100 ng/l for PFOS and PFOA and the concentration at which exposure from drinking water should be reduced within 7 days is set at 1 µg/l.

Toxicology

The toxicology of PFAAs is evolving, but questions remain unanswered about the potential adverse health outcomes, though some are shown in the 2019 film Dark Waters12.  Potential adverse human health effects and risk factors from longer-chain PFAA exposure include increased serum cholesterol13, thyroid disease, immune dysregulation, pregnancy-induced hypertension, and kidney and testicular cancers.  Other studies have found positive correlations between long-chain PFAA exposure and low birth weight in humans, as well as suppressed immune system response, dyslipidemia and impaired kidney function.

The European Food Standards Agency (EFSA) set a new tolerable weekly intake (TWI) of 4.4 ng/kg/bw/pw.  Their opinion focused on the sum of four PFAS: PFOA, PFOS, pefluorononanoic acid (PFNA) and PFHxS14.

When some major manufacturers phased out the production of long-chain legacy PFAS, most industries turned to structurally similar replacements including homologues with fewer fluorinated carbons or other less well known PFAS e.g. per- and polyfluoroalkyl ether-based substances.  These replacement PFAS were marketed by producers as safer alternatives because of their presumed lower toxicity and lower level of bioaccumulation.  There are, however, several studies and growing evidence to suggest that certain replacement PFAS have become regrettable substitutes15.

Less is known about the thousands of polyfluorinated PFAAs precursors, which can transform in the environment through multiple intermediates to ultimately create PFAAs as end-products.  Intermediate transformation products include the 6:2 fluorotelomer sulphonate (6:2 FTS) and 5:3 fluorotelomer carboxylic acid (5:3 FTCA) which are described to bioaccumulate in marine invertebrates and rats respectively, and the final transformation products, the short chain PFAAs are shown concentrating in crops 16, 17.

Conceptual Site Models

A robust, site specific Conceptual Site Model (CSM) remains the basis for assessing potential risks.  It is necessary to have a detailed understanding of the topography, geology, hydrology and hydrogeology for all sites.  In addition, knowledge of the types, properties and fate and transport of PFAS along with biotransformation of precursors are all crucial aspects in conceptualising PFAS sources, pathways and receptors.

Because short-chain perfluoroalkyl substances have, to a large extent replaced the long-chain PFAS, the levels of short-chain PFAS such as perfluorobutanoic acid (PFBA), perfluorobutane sulfonic acid (PFBS) and perfluorohexanoic acid (PFHxA), have increased in environmental media.  Short-chain PFAAs are very soluble in water and therefore might represent even more of a risk to drinking water as a result of groundwater contamination.  The shorter chain PFAAs generally have lower organic carbon partitioning co-efficients than longer chain compounds.

The potential presence of PFAS should be taken into account during the preliminary investigation stage.  No direct reference is made to PFAS in the former Department of Environment Industry Profiles, which were written before there was increased awareness of these contaminants, however PFAS might be present at a range of sites including where they are primarily manufactured or have been used in the processing of related products.

The major industries and applications are summarised below:

  • Aviation and aerospace (military and civil airfields)
  • Carpet manufacturing
  • Chemical works (cosmetic/personal care products)
  • Chrome Plating sites
  • Electronics manufacturing
  • Firefighting – class B firefighting foams (fire training area/fire stations)
  • Landfills
  • Military bases
  • Paper and cardboard manufacturing
  • Petrochemical industry
  • PFAS production
  • Photolithography and semiconductor lithography
  • Textiles and leather manufacturing
  • Wastewater treatment works

This list is not intended to be exhaustive.

While PFAS sources are varied, the release of aqueous film forming foam (AFFF) is a common source of PFAS contamination at airports, military bases and major oil and gas facilities.  It is these types of sites that are subject to most investigation currently in the UK.  The combination of complex AFFF compositions and numerous types of foams used throughout decades of fire training, equipment testing and emergency response scenarios has resulted in highly diverse mixtures of PFAS being present in the subsurface.

Perfluoroalkyl sulphonates tend to sorb more strongly than perfluoroalkyl carboxylates of equivalent perfluoroalkyl chain length. Sorption of PFAS can also be influenced by the presence of co-contaminants such as nonaqueous phase liquids and nonfluorinated surfactants, which typically increase sorption potential to soils17.

PFAS can readily penetrate the concrete pad at fire training areas.  PFAS self-assemble on concrete surfaces which are relatively porous.  They then act as a long-term source of contamination in run-off and drainage.

The presence of cationic and zwitterionic precursors in many Class B firefighting foams could act as an on-going source of the more frequently regulated and measured PFAAs such as PFOS, PFHxS and PFOA.  These precursors are incompletely extracted from soils by current analytical techniques essentially developed for anionic PFAS (see below).  The cationic and zwitterionic classes can contribute up to 97% of the total PFAS mass especially in source zones soils18.

The analytical challenges and emerging techniques

PFAS are also challenging contaminants because most constituents cannot be detected by conventional analytical techniques.  Conventional methods used by UK laboratories allow for the analysis of around 20 different compounds.  There are, however, many more PFAS which will be left undetermined including a significant number of polyfluoroalkyl substances.

PFAS are primarily analysed by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS).  Water samples are extracted using solid phase extraction (SPE) and soils extracted with methanol.  As a “targeted” analytical technique, the results are limited to a fixed suite of components.  In other words, the results do not provide a comprehensive measure of the total extent of PFAS that may exist, nor does this approach measure the potential for targeted PFAS formation due to transformation of precursors over time.

In order to identify the presence of precursors, TOP assay (total oxidisable precursors) was developed.  Sample preparation follows the same procedures as are traditionally used for targeted LC-MS/MS analysis. TOP assay converts precursors in a sample which are detectable by routine analysis.  Results are provided both pre and post digest.  The assay includes steps to oxidise PFAAs precursors using heat and alkaline activated persulfate.  During the oxidation process, the assay generates an excess of hydroxyl radicals to convert these compounds.  TOP assay is widely available and has been used to estimate the concentration of PFAS which contain a detectable perfluoroalkyl group.  It is the most selective of PFAS surrogate analytical methods, in that it determines compounds that can be oxidised to form targeted PFAAs.

More recently, there has been increasing focus to develop and validate complementary screening tools that provide a comprehensive measure of total PFAS impact.  This has resulted in several methods for analysing Total Organic Fluorine (TOF) as a proxy for total PFAS contamination.  TOF is determined by Combustion Ion Chromatography (CIC) and measures extractable or adsorbable organofluorine in a range of matrices.

The concept of a “PFAS screening tool” approach is being evaluated by the US EPA, which is in the process of developing a new analytical method for measuring TOF in environmental samples. The USEPA TOF method is anticipated to be published later this year.  TOF analysis could be useful to use along side existing approaches although there is a trade-off between selectivity and inclusivity.

In addition, there have been recent advances in High Resolution Mass Spectrometry (HRMS) such as LC- Quadrupole time-of-flight mass spectrometry (LC-qTOF/MS) and Orbitrap techniques which can be used to determine both the chemical formula and structure of unknown PFAS.  These method have the potential to greatly increase the number of identified PFAS compounds and provide more accurate source identification.  HRMS is best suited for samples in which unknown PFAS are likely to be present in significant concentrations.  LC-qTOF/MS or other HRMS techniques give a more detailed understanding especially where chain-length specific concentrations are required.

Conclusions

As the transformation of precursors to PFAAs can have important implications for risk assessment, understanding their relative contribution to total PFAS concentrations is critical to determining the remediation options for impacted sites.  A robust and reliable CSM is required and techniques such as TOP assay have role to play.

Only a small fraction of known PFAS can been measured via targeted chemical analysis and many more PFAS are likely to occur in the environment than are routinely analysed.

PFAS are used in a wide range of applications and typically occur in complex mixtures which present a unique challenge to laboratories.  In contrast, there is a very limited number of laboratory standards available.

The more we learn about PFAS contamination, we realise that the problem is more widespread than previously thought.  The requirement to investigate much larger areas may become a necessity with better understanding of CSMs.  Non-targeted PFAS analysis could be used to screen extensive areas, identifying hot spots of contamination directing efforts for parts of the site that require further investigation and characterisation with targeted and traditional analytical methods.

Use of TOP assay in combination with other less selective methods like TOF may become a popular approach to gain additional information about the nature of the unidentified fluorine fraction and its relevance as a source of PFAAs.  The addition of HRMS for non-targeted and suspect screening analyses can offer valuable information about the unidentified fraction of organic fluorine.

References

  1. KEMI (Swedish Chemicals Agency). 2015. Occurrence and use of highly fluorinated substances and alternatives. Report from a government assignment. Swedish Chemicals Agency (KEMI) Stockholm, Sweden
  2.  OECD. 2018. Toward a New Comprehensive Global Database of Per- and Polyfluoroalkyl Substances (PFASs): Summary Report on Updating the OECD 2007 List of Per- and Polyfluoroalkyl Substances (PFASs). Series on Risk Management No. 39. ENV/JM/MONO(2018)7. Paris, France: OECD.
  3. U.S. EPA. 2020b. PFAS Master List of PFAS Substances (Version 2).
  4. Wang Z, DeWitt JC, Higgins CP, Cousins IT. 2017. A never-ending story of per- and polyfluoroalkyl substances (PFASs)? Environ Sci Technol 51(5):2508–2518.
  5. Buck RC, Franklin J, Berger U, Conder JM, Cousins IT, de Voogt P, et al. 2011. Perfluoroalkyl and polyfluoroalkyl substances in the environment: terminology, classification, and origins. Integr Environ Assess Manag 7(4):513–541.
  6. Ross I., Donough J., Mile J., Storch P., Kochunarayanan T., Kalve E., Hurst J., Dasgupta S., Burdick J. A review of emerging technologies for remediation of PFASs Remediation 2018: 28 101-126.
  7. UNEP (United Nations Environment Programme). 2020. All POPs listed in the Stockholm Convention.
  8. POPRC (Persistent Organic Pollutants Review Committee). 2020. POPRC recommendations for listing chemicals.
  9. ECHA (European Chemicals Agency). 2020. Candidate list of substances of very high concern for authorisation.
  10. U.S. EPA (U.S. Environmental Protection Agency). 2020a. Drinking water health advisories for PFOA and PFOS.
  11. Drinking Water Inspectorate (2021) Guidance on the Water Supply (Water Quality) Regulations 2016 (as amended) specific to PFOS (perfluorooctane sulphonate) and PFOA (perfluorooctanoic acid) concentrations in drinking water.
  12. C8 Science Panel. 2012b. Probable link evaluation of thyroid disease. 30 July 2012.
  13. Skuladottir M, Ramel A, Rytter D, Haug LS, Sabaredzovic A, Bech BH, et al. 2015. Examining confounding by diet in the association between perfluoroalkyl acids and serum cholesterol in pregnancy. Environ Res 143(pt A):33–38, PMID: 26432473, 10.1016/j.envres.2015.09.001.
  14. EFSA (2020) Risk to human health related to the presence of perfluoroalkyl substances in food
  15. Brendel S, Fetter É, Staude C, Vierke L, Biegel-Engler A. 2018. Short-chain perfluoroalkyl acids: environmental concerns and a regulatory strategy under REACH. Environ Sci Eur 30(1):9, PMID: 29527446, 10.1186/s12302-018-0134-4.
  16. Caverly Rae, J. M.; Craig, L.; Slone, T. W.; Frame, S. R.; Buxton, L. W.; Kennedy, G. L. Evaluation of chronic toxicity and carcinogenicity of ammonium 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy)- propanoate in Sprague-Dawley rats. Toxicol Rep 2015, 2, 939− 949.
  17. Langburg, H. A., Breedveld G.D., Gronning H. M., Kvennas M., Jenssen B.M, Hale S. Bioaccumulation of Fluorotelomer Sulfonates and Perfluoroaklyl Acids in Marine Organisms Living in Aqueous Film-Forming Foam Impacted Waters
  18. Guelfo, J. L., & Higgins, C. P. (2013). Subsurface transport potential of perfluoroalkyl acids at aqueous film-forming foam (AFFF)-impacted sites. Environmental Science & Technology, 47(9)
  19. Nickerson A., Maizel A.C., Poonam R., Kulkarni R., Adamson D.T., Kornuc J.J., Higgins C.P. Enhanced Extraction of AFFF-Associated PFASs from Source Zone Soils. Environ Sci. Technol. 2020 54 4952-4962

 

 

Article

AGS Yellow Book Photography Competition – The Results

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In November 2020, the AGS launched their second photography competition, this time to source a suitable cover for the third edition of the UK Specification for Ground Investigation (Yellow Book) which is due to be published in early 2022.

A staggered 83 entries were submitted, each covering a range of topics across the geotechnical and geoenvironmental sector including site work, team work, landscape imagery and machinery shots.

AGS Chair, Sally Hudson, AGS Past-Chair, Julian Lovell and AGS Instrumentation and Monitoring Leader, Jonathan Gammon took on the challenging task to judge the images by scoring across four criteria;

  • Originality and Relevance
  • Composition
  • Colour, Lighting, Exposure and Focus
  • Overall Impression, Impact and Visual Appeal
  • Suitability for Yellow Book

Four images were shortlisted, and we’re pleased to announce that Mark Lindahl of Bridgeway Consulting was the overall winner of the competition and won a luxury Fortnum and Mason Hamper.

Our three runners up, who each won a bottle of Champagne are Bryan Laycock (Dunelm Geotechnical & Environmental Ltd), Jim Shields (BAM Ritchies) and Jon Ohashi (Soils Limited).

WINNING IMAGE 

Mark Lindahl, Bridgeway Consulting

Image description: Rotary percussive drilling to inform the design for new lift shafts under the access for all scheme on behalf of Network Rail Design Delivery Group. 20m borehole with SPT’s and Ut100 sampling

FIRST RUNNER UP

Bryan Laycock, Dunelm Geotechnical & Environmental Ltd

Image description: The photo was taken on a job in Co. Durham drilling a 150m deep borehole look at the feasibility for a mine water heat project. The borehole was sank using 4 strings of casing aiming for a roadway within a coal seam at approx. 158mbgl.

SECOND RUNNER UP

Jim Shields, BAM Ritchies

Image description: rotary coring setups for main ground investigation for Viking Wind Farm in Shetland Mainland.  Coring using T2-101 water flush.  Water being supplied to the drilling location by helicopter.

THIRD RUNNER UP

Jon Ohashi, Soils Limited

Image description: This was taken using a 360 camera. The image was taken in the following weeks after Rob Ainsworth sadly passed away, I was pretty close with that guy and was fortunate to be able to call him my friend, not just a brilliant boss! He always pushed for me to take photos not only for work but because he really liked them (I hope 😅) and he thought I had an eye for it.

The AGS would like to thank all those who took the time to enter the competition. The overall standard of entries was extremely high, and the judging panel found the task challenging in shortlisting the top four entries.

Article

Ground Risk: Landslide Risk Reduction Webinar Summary

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On 29th April, the AGS held their first webinar on the subject of ground risk, focusing on landslide risk reduction. The event was sponsored by RST Instruments, Geotechnical Engineering and Structural Soils.

This webinar saw Professor Mike Winter, (Director at Winter Associates Limited), Ian Nettleton, (Technical Director at Coffey Geotechnics Limited, A Tetra Tech Company) and Dr Andrew Ridley, (Managing Director at Geotechnical Observations Limited), discuss ground risks associated with slope instability. The event touched on risk assessment of landslide hazards, and the practical features to look for in the field. The speakers also provided insights into the instrumentation and monitoring of slope movements.

This paid for event was rated 4.5 stars out of 5, by our 125 registered delegates who attended from countries across the globe including Canada, Spain, Norway and Romania.

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.

 

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

AGS Annual Conference 2021

The AGS are pleased to announce that the Annual Conference is back at the National Motorcycle this year on Wednesday 22nd September.

This full day seminar is open to both Members and non-Members of the AGS and will focus on the work, findings and achievements of the geotechnical and geoenvironmental industry. A full speaker programme will be released in due course.

We have a limited number of complimentary tickets available for AGS Member companies (T&C apply). Additional tickets cost £60 for Members and £120 for non-Members (prices ex. VAT).

To register to attend this year’s event please fill out a registration form and return to ags@ags.org.uk before Friday 10th September.

Click here to download the AGS Annual Conference registration form

Event Programme

The importance of Geo Engineers in the response to the symptoms of a changing climate: Luke Swain, Principal Route Engineer (Geotech), Network Rail

This keynote presentation will look at what climate change means for our industry, and discuss how Geotech/Geo Environment graduates of all levels can adjust to ensure we are focused on asset resilience and recovery as we inevitably will be suffering from the symptoms of warming global temperatures. 

Misuse of Monitoring and Testing: Ian Webber, Managing Director, Coffey Geotechnics Limited

The presentation discusses the misuse of monitoring and testing regimes.  The mistakes that have been made are illustrated by case histories some of which have ended in litigation.  Examples include Inclinometer testing, pile records, integrity testing, basement movement monitoring and pile testing.  The lessons learnt are primarily about the mis interpretation of test and monitoring results and the need to maintain a link between the designer, the ground conditions and the monitoring results.

Sponsorship

This annual event has proven to provide an excellent platform for companies looking to increase their profile and raise awareness of their company initiatives through the use our sponsorship packages.

We currently have a limited number of Emerald, Gold and Silver sponsorship packages available, please click HERE for full details.

If you’d like to confirm your support please email Caroline Kratz on ags@ags.org.uk before Friday 6th August.

Event Sponsors

SOCOTEC

SOCOTEC is the UK’s leading provider of testing, inspection and compliance services, with comprehensive solutions in Infrastructure & Energy, Environment & Safety, Building Control and Fire Consultancy. Committed to continuous improvement, innovation and quality, SOCOTEC delivers tailored solutions to meet clients’ challenges, including an integrated package of site investigation services. For more information please visit https://www.socotec.co.uk/


 

Soil Engineering

With over 50 years of experience, Soil Engineering are one of the country’s foremost Ground Investigation and Specialist Grouting Contractors. The comprehensive in-house geotechnical laboratory, continually updated plant fleet, and ongoing investment in training and staff development, allow Soil Engineering to provide a reliable and cost-effective solution for any geotechnical project, throughout the UK. For more information please visit www.soil-engineering.co.uk


Concept Engineering Consultants

Concept Engineering is an innovative and dynamic site investigation specialist, with over 20 years’ experience providing award-winning geotechnical, environmental and structural investigation services and advice. Concept operate nationally from ISO and UKAS accredited offices and laboratories in London, Coventry and Yorkshire using a fleet of in house rigs and resources. For more information please visit www.conceptconsultants.co.uk


 

Insitu Site Investigation

In Situ Site Investigation is a specialist geotechnical and geo-environmental site investigation company carrying out all aspects of Cone Penetration Testing (CPT) techniques as well as all methods of Pressuremeters. Our expanding array of rigs and equipment enable us to work on any site across the UK and worldwide. For more information please visit www.insitusi.com


 

BAM Ritchies

BAM Ritchies is the ground engineering division of BAM Nuttall. We provide fully integrated services for a wide range of main contractors – both public and private sector, from small local projects to national infrastructure projects. Over 60 years, we’ve built a reputation as the go-to ground engineering team for complex problem solving and best-value, sustainable delivery – with no surprises. For more information please visit www.bamritchies.co.uk


 


Geotechnical Engineering

Geotechnical Engineering Ltd is the UK’s largest privately-owned ground investigation contractor, renowned for providing a range of innovative ground investigation services for thousands of land-based projects since 1961. From Utility Surveying to all aspects of ground investigation and having our own UKAS accredited laboratory, we are proud to call ourselves industry experts. For more information please visit https://geoeng.co.uk/ 


 

Structural Soils

Structural Soils Ltd has evolved into an award winning national, multidisciplinary, integrated geotechnical and geoenvironmental site-investigation company with the proven capability, capacity and confidence to undertake contracts of any size, in any location and virtually any scope. In 2020, we won ‘The Big 3’ GE awards,  Ground Investigation Specialist of the year, Contractor of the Year, Ground Investigation Project of the Year. For more information please visit www.soils.co.uk or contact us at ask@soils.co.uk


 

RST Instruments

RST Instruments’ fully integrated suite of geotechnical monitoring sensors gives our clients the reliable, real-time data they need to save time, money and, most importantly, reduce risk at every stage of their projects. For over 40 years, we’ve been a trusted partner to engineers, consultants and contractors, providing engineered instrumentation, custom solutions and matchless industry expertise to keep clients’ projects–and reputations–safe.  For more information please visit https://rstinstruments.com/


 

ACS Testing

ACS provide a seamless all-in-one service for geotechnical and chemical laboratory testing, site investigation and geotechnical and contaminated land consultancy. ACS delivers high quality testing of construction materials, and substances that are harmful to health, property and the environment, while offering a first-class professional service tailored to our client’s requirements. For more information please visit: www.acsgroupofcompanies.co.uk


 

i2 Analytical

i2 are a leading independent environmental testing laboratory, which performs a full range of chemical and geotechnical analyses to MCerts and ISO 17025 accreditation. Using the newest laboratory techniques we provide testing solutions for soils, waters, leachates, air, building and waste materials. For more information, please visit: www.i2analytical.com/


 

Landmark Information

Landmark Geodata, part of Landmark Information, provides digital mapping, site-specific environmental risk information and consultancy to the property industry.  We are the leading licensed partner of Ordnance Survey® and also maintain the UK’s largest collection of historical maps dating back to the 1840s. Our flagship data solutions – Promap and Envirocheck – with over 20,000 users, provides vital intelligence to architects, surveyors, planners, environmental professionals, real estate lawyers and developers.  For further information visit: www.landmark.co.uk/landmark-environment-and-mapping


Geosense

Geosense is a leading UK manufacturer of Geotechnical Instruments for the Geotechnical, structural, mining and site investigation industries. Geosense specialises in Vibrating Wire, MEMS & wireless technology to provide real-time trusted data. Utilising our expertise, clients have installed our sensors across more than 75 countries on some of the world’s largest and most prestigious projects. For further information visit: https://www.geosense.co.uk 

Fugro

We are the world’s leading Geo-data specialist, collecting and analysing comprehensive information about the Earth and the structures built upon it. Through integrated data acquisition, analysis and advice, we unlock insights from Geo-data to help our clients design, build and operate their assets in a safe, sustainable and efficient manner. For more information, please visit: www.fugro.com

Speakers

Sally Hudson
AGS Chair and Regional Manager & Associate at Coffey Geotechnics Limited, A Tetra Tech Company

Sally has 30 years’ experience in the ground engineering industry and has responsibility for the delivery and management of geotechnical risk on a wide range of projects.

She has worked in the site investigation field for specialist contractors and for design consultancies on many major transport and energy infrastructure schemes, on earthworks design schemes and asset management in the road, rail and energy sectors.

Sally has more recently concentrated on business development and technical management of geotechnical operations within Coffey in the UK and is a past AGS Business Practice Working Group Leader.

Luke Swain
Principal Route Engineer (Geotech) Network Rail

Luke Swain is a Geotechnical Engineer at Network Rail. He is responsible for the managing of Geotechnical Assets on the UK railway infrastructure, with a working area that includes the West Coast Mainlines. He is a Chartered Geologist with 15 years of experience in Engineering Geology.

Ian Webber
Managing Director at Coffey Geotechnics

Ian has over 35 years’ experience in geotechnics, specialising in providing design services (including alternative designs) to contractors on design and construct and DBFO schemes throughout the UK and Ireland. His particular expertise is in earthworks design, geotechnical processes and buildability, deep excavations, bridge substructures and retaining walls.  In recent years Ian has been regularly called upon to provide expert evidence in relation to claims and litigation on a variety of geotechnical subjects.  He has provided expert testimony in cases where the value of the geotechnical claim has been in excess of £175 million.

Article News Contaminated Land Data Management Executive Instrumentation & Monitoring Loss Prevention Safety

AGS Award Results 2021

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The results are in! We’re pleased to announce the winners of this years AGS Awards:

Loss Prevention

  • Rachel Griffiths (Award)
  • Russell Jones (Award)

Instrumentation and Monitoring

  • Philip Child (Award)

Safety

  • Julian Lovell (Commendation)
  • Madeleine Bardsley (Commendation)

Contaminated Land

  • Mike Smith (Commendation)

Services to the Association

  • Jim Cook (Award)

Data Management Working Group

  • Mark Bevan (Award)
  • Tony Daly (Award)
  • Romain Arnould (Award)
  • Steve Walthall (Award)
  • Jerome Chamfray (Award)
  • Ian Linton (Award)
  • Philip Child (Award)
  • David Entwisle (Award)
  • Edd Lewis (Award)
  • Len Threadgold (Award)
  • Jackie Bland (Award)
  • Simon Miles (Award)
  • Leon Warrington (Award)
  • Paul Chaplin (Award)
  • Joshua Bradley (Award)
  • David Farmer (Award)
  • Craig Brown (Award)
  • Phil Wade (Award)
  • Peter Hepton (Award)
  • Roger Chandler (Award)
  • Neil Chadwick (Award)

 

All Award and Commendation winners had been nominated by their prospective Working Group Leaders before being formally confirmed by our then AGS Officers; Julian Lovell, Sally Hudson, Neil Parry and Ken Marsh.

Congratulations once again to you all.

Article Safety

Expectant and New Mothers in Construction

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Article contributed by Roseanna Bloxham, Senior Geo-Environmental Engineer, RSK and AGS Safety WG Leader.

Pregnancy is a part of life, its something us humans go through to keep our species alive. So why does it present such a stigma in the world of construction? Having done some research there is no official guidance to help employees and employers when pregnancy occurs for a woman working in the construction industry. This is, in part, due to its male dominated past.

We have taken the opportunity to talk to a number of women in the industry, to understand the challenges they faced and how we can help in the future.

Could you continue your role as normal when you were pregnant?

The experience for the woman during pregnancy is dependent on the physicality of their original role and the communication provided from their employer. The women interviewed that had a more office-based role found that during the pregnancy they were able to work as normal, however the women with a more site-based role had a very different experience.

It is obvious that a site role is going to cause challenges, especially when standard tasks include handling of heavy objects or working with contaminants. The majority of responses we received were positive, with women commenting that companies provided specific risk assessments and arranged for alternative staff to do manual tasks or cover the on-site portions of the project. However, in the absence of guidance, many contractors approached the issue differently. ‘It was interesting that each Framework Contractor approached my “condition” very differently with one Contractor actually not allowing pregnant women on to site at all.’

Did you feel supported by your company throughout the pregnancy?

The majority of women felt supported by their main employer including being offered flexible working hours to attend appointments. ‘I was able to take time for antenatal classes and go to various appointments.’

The support provided is somewhat dependent on the employer and line manager, some women felt isolated and ignored with little to no communication. ‘I was not consulted about my risk assessment, merely sent the assessment to sign, and the document implied that I had written it myself.’

Is there anything your company could have done differently to help you?

Aside from difficulties associated with maternity pay, which affects all industries. The main issue raised was the lack of generic risk assessment. All the women interviewed commented that risk assessments were developed by their company to assess their individual role and outline ways to adapt, however, this is not an instant process. ‘It would have been fantastic if a pre-existing, provisional risk assessment existed before I became pregnant, which could be used immediately and until a more specific one was in place.’

Upon returning to work did you feel supported to progress your career as you wanted?

‘Return to work was not well handled, I felt somewhat forgotten about. Keeping in touch and ensuring that staff are welcomed back is really important.’

The majority of women interviewed felt upon return to work they were treated differently with their role being ‘softened’ despite no longer having the risks associated with pregnancy. ‘Although I know this was coming from a good place, I felt his attitude to me returning to work, and my presumed ability to work, was antiquated.’

Most companies offered flexible working hours to new mothers, enabling them to adapt to the new work-life balance. However, most felt the push was on the mother to be the child carer with little discussion or foresight given to a father wanting the same role. ‘I’d really like to see a gender-neutral approach (post pregnancy of course!) with discussion around shared childcare and parental leave’. The UK government website states that up to 37 weeks of leave can be shared between the two parents, however within the construction industry there still appears to be a stigma over the split.

What was the one major challenge you faced during pregnancy at work?

The responses for this question were quite mixed dependent on the role of the individual.

‘At that time, lack of flexibility to work from home and adjust working hours.’

‘It’s a while ago now, but I can’t really think of one. I feel I have been really fortunate with the support I got during my pregnancies but, more importantly, not side-lined and given boring work when I returned part-time.’

‘Generally feeling unable to carry out, to the best of my ability, my site visits due to the “rules” of differing contractors.’

Coronavirus affecting pregnancy and young mothers

The current Coronavirus pandemic has meant that a larger number of people are working from home, and in some cases caused a disconnect in communication. During our interviews, we identified that some women who were pregnant when the pandemic started felt they were discriminated against because of their situation, with non-pregnant workers being given the majority of the work, causing the pregnant party to feel like that was the reasoning for being furloughed. Whilst this might not have been the companies intention, the lack of communication during the situation made the women feel forgotten.

On the other hand, some found that the pandemic has ‘levelled the playing field between working mothers and fathers’. The school and office closures have forced the main parent or bread winner to be at home at the same time as their children, they have therefore been ‘expected to contribute to the childcare situation more equally than they might have done in the past.’ One woman commented that they have ‘positive attitude shift from the male dominated senior management to leave work on time, keep meetings short etc.’

Whilst the lockdown has been difficult, it has opened up the conversation on not only new and expectant mothers but also childcare in general within the construction industry. This article is a small insight into a much larger conversation. We would like to hear your views on the topic. Do you feel a guidance document is needed? What has been your experience either being a pregnant woman or managing one?

Article

Why? Why? Why? Why? Why? Does Lean help with ground investigation?

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Tags: Featured

Article contributed by Patrick Cox. Managing Director for Environmental Contracting, AECOM and Dr Emma Langman, Managing Partner of BakerFish

The Lower Thames Crossing is described as ‘the biggest road project’ since the M25’. It’s also set to become the third-largest bored tunnel in the world, being built under the river in the heart of one of the world’s busiest cities.  It needs to be right!

The client, Highways England needed to ensure that all the data necessary regarding ground conditions and wider environmental considerations be available to ensure that the project is designed and built safely, efficiently, and with care to protect the natural and human environments.

Perfect Circle Joint Venture (a unique partnership between Pick Everard, Gleeds and AECOM) was appointed through the SCAPE framework to carry out multiple phases of the ground investigation work required.

Phase 3 began in early 2021, just as news began to emerge of the new Coronavirus threat.  The same month that the country went into lockdown, Perfect Circle appointed BakerFish as their Lean Consultant.

Does Lean apply to Ground Investigations? We are different!

Managing Partner, Dr Emma Langman explains:

“In 20 years of working with organisations to apply Lean principles, I have never yet come across one that didn’t claim to be ‘different’ and ‘unique’ and that Lean – with it’s background in manufacturing’ would “not work here.

“The ground investigation sector is no exception to this rule of thumb.

“I remember going head-to-head with one of the leadership team and saying ‘listen – if Lean can work on the oil fields of Iraq, it can certainly work in a farmer’s field in Essex’

“It was one of those moments when a consultant holds their breath to see what will happen. But I knew that Patrick and his team were fully committed to creating a culture of Lean and delivering efficiencies for Highways England, so it didn’t feel too risky to challenge.

“At the end of the day Lean only works when leaders engage and lead it. And in this project they certainly did”.

When you consider the nature of ground investigations, they are “not standard engineering” Emma explains, rather they are “huge open air science experiments, with large samples of soil rather than small samples of chemicals in test tubes”.

In fact, over the course of the Lean intervention, the entire team appreciated that ground investigations are about the flow of data – not of soil!

Did you really become more efficient because of Lean?

Recognising that GI is all about the flow of data through a system, the team used Lean principles to implement some huge savings for their client.

Managing Director, Patrick Cox gives an interesting example of how changing thinking towards a Lean mindset can have incredible results for a tiny investment in this anecdote:

“Before Emma joined the team we had done a lot of ‘common sense’ improvements, which we later learned were examples of Lean Thinking.

“For example, my team went to visit the laboratories in our supply chain to look at best practice for laying out logging and testing facilities.  From this we decided to create a shared logging facility that was specifically designed to provide a number of benefits including protecting our team from bad weather, enabling digital labelling and tracking of samples, providing a controlled environment for sample storage and more.

“This had already achieved savings in the hundreds of thousands of pounds, as well as driving up consistent and efficient ways of working to ensure quality and value for money.

“Even so, towards the peak of the ground investigation fieldwork we found that the logging facility was being swamped by samples for processing.

“Under pressure we slipped back into conventional thinking patterns and considered the solution to running out of space was obvious – increase the space!

“However, the costs of renting more facility space would come at a heavy cost.

“Instead, Emma nudged us on the call to remember that Lean is all about flow and that GI is all about data.

“So keeping front of mind that Lean is about reducing variation and waste, the answer became obvious.  Instead of procuring more space we simply arranged for more frequent ‘drop-offs’ of sample, which ‘smoothed the flow’ through the logging facility, flattening the demands curve, and meant that we saved the cost and effort of extending the facility.

What about improvements in the field?

Again, since GI work is essentially ‘a giant outdoor science experiment’ it is a great candidate for Lean improvement. The team used tools like TIMWOOD, root cause analysis, the 5 Whys (where you literally ask Why? 5 times) to find a number of improvements. For example, using our partner Equipe to undertake audits on machinery before it was used helped to avoid breakdowns, as well as (most important of all) improving the safety of the workforce.

In Package C, which hosted the Highways England site visit for their lean assessment (Simplified Lean Capability Assessment) the assessors were delighted to see how rig-side layouts were standardised and value-enabling work (such as setting up and taking down fencing etc) were provided by a support team, leaving the highly specialised rig teams free to focus on the ‘value-adding’ work of drilling.

What did the client think of your efforts in Lean?

The Simplified Lean Capability Assessment undertaken by Highways England scored an impressive 3.3 out of 4 (where 4 is ‘world class’ such as Toyota).

What are the key lessons for our readers?

Patrick shares “I was genuinely surprised to see the extent that Lean is applicable to GI work.  It was great to be able to deliver several million pounds worth of efficiency savings to our client while still achieving the project goals and collecting high quality data for the Lower Thames Crossing. Lean was key to that saving being realised”.

Emma says “it’s all about leadership. The Perfect Circle team really led from the top and over 30 managers (including several of the senior leadership team) engaged in one-to-one coaching to help them take on this new way of thinking.  It was also great to see the high levels of partnership working between Perfect Circle and their client team LTC, and Highways England, as well as the enthusiasm and engagement of the specialist suppliers involved in the project.  In twenty years of working in Lean, this was the most ‘joined up’ working and commitment to efficiency and quality I have seen. And that starts from the top”.

For more information and details including 40 different case studies of how Lean improved this project, please contact Patrick.Cox@aecom.com or emma@bakerfish.com.

And, last but not least, if you would like to learn more about the leadership that makes Lean work, take advantage of this offer for AGS readers who can claim a 10% reduction in ticket fees for the Servant Leadership Conference in May 2021. Find out more at www.servantleadershipconference.com and claim your discount using the code: AGSdisc10.

Article

SiLC Annual Forum 2021- Follow up

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Tags: Featured

This year’s SiLC Annual Forum was held virtually on Tuesday 30th March between 09:30-13:30. Over 100 delegates joined us on the webinar.

Hosted by SiLC PTP Chair, Ian Evans (Technical Director at Wood PLC), the event featured a stellar line up of expert, industry speakers, each covering a wide array of topics.

The interactive event encouraged audience participation via live polls, the webinar chat facility and Q&A sessions. Delegates also had the opportunity to network in one of the multiple breakout rooms, each co-hosted by our presenters and members of the SiLC PTP.

The event was sponsored by Jackson Remediation Ltd as the Diamond Sponsor and VertaseFLI Ltd as the Gold Sponsor.

Speakers

Joe Jackson of Jackson Remediation Ltd, presented on Remediation and Risk: Identification, Mitigation and Transparent Apportionment

Joe looked at the importance of Early Contractor Involvement (ECI) and mechanisms to engage with Contractor pre-Contract.  Transparent and collaborative Risk (and Opportunity) identification methods were discussed along with suitable methods of apportionment and mitigation.

Dr. Alan Thomas, Technical Fellow at ERM & Co-Chair of SuRF UK, gave a presentation on The SuRF UK Sustainability Process and Indicator Guidance.

The SuRF UK sustainability indicator set was originally published in 2011 and has been widely used both in the UK and internationally. Following review SuRF UK has further developed the guidance to provide a greater depth in the rationale for each headline and a more explicit set of instructions for their use. Alan provided an introduction and brief overview of this recently revised guidance.

Ellanor Joyce, Project Manager within the Magnox Winfrith End State Project, presented on the phased assessment of land quality for the Winfrith site through the final stages of decommissioning to support site closure

Ellanor is responsible for integrating site restoration objectives, interfacing with decommissioning projects and ensuring effective stakeholder engagement to support the final stages of decommissioning and site restoration.  The Magnox Winfrith nuclear site is moving through to decommissioning process to deliver the next planned land use of Heathland with Public Access and the eventual release from regulatory controls after 60 years of operations.

Ellanor provided an overview of the approach and process for land quality assessment and management across the site to allow the next land use and release from regulatory controls.

Dr. Tom Henman, Director at RSK Geosciences and Deputy Chair of the SiLC PTP, presented on Effective Risk Communication and Stakeholder Engagement

Starting with the question are we paying enough attention to communicating understanding of land contamination risks, Tom provided a reminder of relevant guidance and key principles for effective risk communication and stakeholder engagement. The award-winning Buchanan St. Ambrose Schools independent review was presented as a case study. Here such techniques were applied successfully to achieve a transition from stakeholder concern regarding health impacts and potential links to land contamination at the site and suspicion of public authorities’ motives to one of acceptance, trust and confidence being restored.

Highly experienced contaminated land officers Ann Barker and Rebekah Norbury jointly provided an introduction to the National Contaminated Land Officers’ Group (NCLOG) from inception through to progress to date plus an updated view on NQMS from a Contaminated Land Officer’s viewpoint.

Dr. Paul Nathanail, Technical Director Contamination Assessment and Remediation at GHD UK and Deputy Chair of the SiLC Board, provided an interesting and useful presentation on Professional Qualifications and their recognition in a post-Brexit world.

A professional is someone who is recognised by their peers as having special knowledge or skills and who applies them under a code of conduct.  Working in different jurisdictions as a recognised professional can allow knowledge transfer and provide suitable opportunities for the individual.  With the UK’s departure from the European Union, it is no longer the case that our professional qualifications are recognised within the EU – or vice versa.  Paul reflected on what this means for individuals and their potential clients.

In addition to the webinar speakers and presentations, a workshop on Sustainability was provided by Louise Allan MIEMA, CEnv, who is a Sustainability Manager in the Defence Infrastructure Organisation. Louise provided a workshop during the breakout sessions, bringing with her, 20 years experience in a variety of sustainability and environmental teams across the estate and equipment branches of the Ministry of Defence. Her expertise has lain in the strategic tools and processes that co-ordinate and encompass the many specialist topics under the Sustainable Development banner (including Land Quality objectives). These include Sustainability Appraisals and Strategic Environmental Assessment, Sustainable Procurement, and corporate Sustainability Strategies and governance.
Her current priorities include refining DIO’s Sustainability Strategy and embedding Social Value in infrastructure procurements. Both workshops were well attended and provided some thought provoking discussions.

Sponsor Overview

Jackson Remediation is a specialist Remediation and Enabling contractor which focusses on value creation and quality delivery, drawing upon deep technical expertise and profound understanding of the construction process. By consistently striving to address contamination issues in the most robust yet cost effective manner, clients never need to choose between price and quality again. https://www.jacksonremediation.co.uk/

 

VertaseFLI are extremely pleased to be sponsoring the SilC conference once again. VertaseFLI are one of the largest remediation contractors in the UK and technical excellence has always been at the core of our offering to clients. Our full range of service can be found at www.vertasefli.co.uk.

 

 

 

 

Contact SiLC@SiLC.org.uk if you have any queries about this event or our future events.

Article

The Big Borehole Dig

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Tags: Featured

Article provided by Steve Thorpe, Geospatial Data Specialist, British Geological Survey

sthorpe@bgs.ac.uk

The “Big Borehole Dig” is a citizen science initiative by British Geological Survey (BGS) to enhance the number of digitised borehole logs we host and make available to everyone. BGS are enabling this call for help by asking all parts of the sub-surface community to join in and digitise borehole scans in the AGS data format using Groundhog geological software or Bentley Holebase/OpenGround.

Unforeseen ground conditions are quoted as being responsible for up to 50% of construction project overruns [1], and BGS aims to minimise this by making early-stage geological information readily available.

This article describes the Big Borehole Dig and all the information you need to join in.

The AGS data format

The use of AGS data format within the geotechnical and geoenvironmental community is growing stronger every day. I’ll assume that everyone reading this article already understands what AGS data is, so I won’t go into the details or its history.

How we use AGS data

BGS has always ingested borehole and ground investigation data. Since the beginning of the organisation in 1835 we have been a repository for geological and subsurface information. We have a store of over 1.4 million digital borehole records, and over 4 km of shelves full of physical samples and paper records. These days of course technology has given us space saving alternatives, so that now the capacity focuses on our servers and digital storage. The AGS data format is a big part of this digital transformation, it allows fast communication of geological data and information between different users and software. In 2014, we began the process of automatically ingesting AGS data – where users submit digital records. We built a database to handle the AGS data, allowing the files to be automatically validated, stored, and served exactly as they were deposited with us. It’s important to note here that no interpretation of the data is done by BGS, it is assumed that the user of the AGS format will check that the files are fit-for-purpose.

The automatic ingestion of AGS data aligns well with the BGS’ open data initiatives and means that the BGS remains a world-leading national repository of geological and subsurface information – a fact that we are very proud of. Anyone starting a new project can access the GeoIndex and find all the information they need, such as boreholes and geological maps, and can start their desk study safe in the knowledge that they have up-to-date BGS digital open data resources.

The Big Borehole Dig

The Big Borehole Dig is a citizen science project aiming to convert the open borehole scans held by BGS into more useable AGS data which will then be available for everyone.

Of the 1.4 million borehole records the BGS hosts, each contains a variety of supporting information called metadata[2]. Attached to the majority of these borehole records is a digital scan of the original drillers log.

These open borehole records can be accessed through the BGS GeoIndex viewer (shown here). Despite being held in digital format (usually PDF), the information within these documents is not standardised and often requires translating and transcribing into borehole software or a database before being able to be used for geotechnical design or creating a ground model.

We believe it is essential that future generations have access to historical borehole data so we came up with a citizen-science project in which volunteers convert our open borehole records into AGS format in order to improve the availability and accessibility of borehole information to a wider audience. This will enable users to build better ground models, save costs on construction projects and reduce the amount of time lost due to unforeseen ground conditions.

We estimate that over 600,000 downhole geology logs exist as PDFs and these will be available as AGS format for everyone to use as the BBD project progresses. These data can feed directly into site investigations, conceptual ground models and academic projects, providing a much greater understanding of the sub-surface just when its needed at the start of projects. The Big Borehole Dig gives people around the world the tools they need to digitise our PDF scans, create an AGS file and send it back to BGS for storage, so that everyone can benefit from it.

You can take part in the Big Borehole Dig by downloading our free Groundhog Desktop software, or alternatively if you have access to OpenGround (or Holebase SI). We have produced a user guide for both software so please download the relevant user guide from the BGS Big Borehole Dig webpage.

In addition to the Big Borehole Dig, BGS is co-leading on the Dig-To-Share initiative with partners Atkins and Morgan Sindall. We are actively encouraging the sharing of data across the construction and civil engineering industry and using AGS boreholes to share the data is central to that philosophy. The Dig-To-Share first-year target was to digitise and release 10,000 boreholes in the AGS data format and we succeeded by releasing over 14,000! The more people that use and share AGS boreholes, the better we as a community understand the challenges of the subsurface and fill in the knowledge gaps. This will drive further innovation and data use, ultimately resulting in better ground models and more certainty in the construction processes. The Dig-To-Share team have created a Super User Network to encourage sharing within various organisations and are actively looking for new recruits.

Concluding remarks

The Big Borehole Dig aims to use volunteers to convert the openly available borehole scans held on the BGS website into AGS data.

The technical advances made by the AGS committee in developing and maintaining the AGS data transfer format allows fast communication and retrieval of borehole data and has been absolutely pivotal in the development of the BGS database, as well as the industry as a whole. It has provided the impetus for change in many organisations, including the BGS and with initiatives like the Big Borehole Dig we are opening people’s eyes to the possibility of sharing data, communicating in a standard way, and producing better ground models. Ultimately, this means that these boreholes will be available for everyone to use in their own projects, and will provide a valuable resource for future engineers and geoscientists.

The novel use of the AGS data format to digitise the thousands of legacy boreholes held by BGS will hopefully be a marker that people look back on as a turning-point in ground modelling. Imagine being able to import an initial 3D geological model made up of a plethora of BGS hosted AGS borehole records in to your virtual report, designing where to investigate based on known unknowns.

Come and join the Big Borehole Dig and play your part in digitising borehole data for the future!

References

[1] Foundations: Proceedings of the Second BGA International Conference on Foundations, ICOF2008. Brown M. J., Bransby M. F., Brennan A. J. and Knappett J. A. (Editors). IHS BRE Press, 2008. EP93, ISBN 978-1-84806-044-9. www.ihsbrepress.com

[2] Information held in the BGS database include: X,Y location, ground level, drilling company, purpose, and date drilled.  Not all boreholes have this information attached but we try to record where it’s available