Posts by Katie Kennedy

News

AGS Magazine: March 2024

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The Association of Geotechnical and Geoenvironmental Specialists is pleased to announce the March 2024 issue of their publication; AGS Magazine. To view the magazine click here.

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

There are a number of excellent articles in this issue including;
AGS Annual Conference 2024 – Page 10
AGS Bitesize Guide: Pile design based on calculation – ground model method – Page 16
Calibration of BRE365 soakaway testing – Page 22
Sharing Ground Models using AGSi – Page 28
Site Supervision – Shouldn’t we be specific? – Page 32
Inside: SoilCloud SAS – Page 34

Plus much, much more!

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

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

Article

BRE365 Soakaway Testing; Discussion on Safety and Alternatives

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Since 2007 when the first SuDS manual was published, AGS members have increasingly been asked to provide services to support design of sustainable urban drainage systems. The author of this article has been working with the BRE365 test since the 1990s and is still supervising, designing and reporting infiltration rate results to designers from trial pit and borehole methods.

AGS has recently been investigating how our industry manages undertaking and reporting infiltration rates for design of devices for discharge of surface water into land including; soakaways, basins, swales and permeable paving. Amongst members, the almost exclusive method requested by clients is to follow the BRE DG365 procedure as discussed in the AGS article (ref AGS magazine Oct 2021).

BRE DG365 is an empirical methodology for the design of soakaways, which includes the test procedure to provide observational data on infiltration rates. It was not intended for either basins or permeable paving. Because of the sparse nature of the test instructions, how it is carried out and reported can vary between practitioners. Concerns were first raised in the AGS safety working group at the same time as general trial pitting methods came under renewed scrutiny. The geotechnical working group was also requested to look at data quality in context, which resulted in the previous article. It is recognised that AGS members’ risk assessments and method statements on trial pitting may have been extended to cover BRE365 by written procedures to keep inexperienced staff safe in conducting these in-situ tests. Innovations and modifications may also have been made to the BRE365 method, to standardise in-house practice and to avoid taking up excessive resources during what can be a logistical challenge of labour, plant and materials.

This article is intended to build on the previous article, briefly cover the test origins and discuss what alternatives might be possible.

The development of technology of infiltration testing can be traced through publications. The following list shows an incomplete chronology.

1973 BRE151 Soakaways – (also NHBC 5.3.11) Soakaways BRE Digest 151, Watford. Building Research Establishment (Digest 151 is presented currently as a method in NHBC Standards https://nhbc-standards.co.uk/5-substructure-ground-floors-drainage-and-basements/5-3-drainage-below-ground/5-3-11-surface-water-soakaways/ )
1991 SR 271 The Hydraulic Design of Soakaways Report The Hydraulic Design of Soakaways Report SR271 1991 by DC Watkins published by HR Wallingford is available as a free resource here https://eprints.hrwallingford.com/311/ and describes the modelled water flow processes in a soakaway.
1991 (latest revision 2016) BRE365 Soakaway Design Empirical method of soakaway design including test for infiltration rate.
1996 R156 Infiltration drainage – Manual of good practice CIRIA report Report 156 1996 Infiltration drainage – Manual of good practice Roger Bettess BSc PhD MCIWEM. Provides an infiltration test procedure similar to BRE365 but with some variations and extra information.
2007 (Version 6 including 2016, 2018, 2019) C753 The SuDS Manual The current reference for Suds Approval Boards/Lead Local Flood Authorities (SAB/LLFA) in the UK is the The SuDS Manual (C753) https://www.ciria.org/ItemDetail?iProductCode=C753&Category=BOOK&WebsiteKey=3f18c87a-d62b-4eca-8ef4-9b09309c1c91.

BRE 151 & NHBC 5.3.11 involves recording the time for a fixed height of water to drain in a small trial hole. The time t is graphically translated to a soakaway size using correlations which have uncertain/unknown justification.

SR271 indicates that flow in unsaturated ground is different to saturated ground in four main respects (head in the fluid is due to suction, storage coefficient and conductivity are variables, and gravity induces vertical flow), and compares in-situ test results with those obtained from numerical modelling using Richards modified equation. By relying on testing at the proposed location of the device and use of bulk factors of safety the design philosophy is confirmed to be experimental. Uncertainties do not include the possibility of significant variations in soil type at the location of the test (and by implication the soakaway).  This may be a point of contention with some practitioners used to UK shallow geology.

The work in R156 was carried out by HR Wallingford under contract to CIRIA in the period October 1991 to March 1995. R156 cites many other sources of information (BRE were part of the steering group represented by Dr John Powell). The extra information in R156 does help to confirm the experimental nature of the test specific to the location of the proposed infiltration device and the intrinsic adoption of bulk safety factors. This requires that the location of the device (test site) must be chosen by a designer.

C753 probably deserves an AGS article on its own. In Chapter 01 – The philosophy of SuDs, the 3-D conceptual model in Figure 1.2 models the underlying geology as a grey monoblock rather than layers of strata for example which is a shame. In nearly 1000 pages of C753 the word geology occurs 16 times, frequently associated with land stability; ecology is listed 42 times and archaeology once. Possibly geology is not that important to the delivery of SuDs, but is regarded as a constraint. AGS members are probably most interested in SuDs Section 25 Infiltration design methods, and specifically 25.3 Infiltration Testing Methods and Appendix B.4 Infiltration Assessment. Appendix B.4 includes a checklist (Table B6) intended for use by the approving bodies (and the designers) which assumes competence in ground assessments, which may not be available in all design teams. There are plenty of apparently excellent SuDS case studies, but they don’t generally include details of the geology or infiltration tests and how infiltration challenges were overcome. Competent ground assessors would surely benefit designers.

Discussion

The SUDS manual is probably the most important document for members and designers to understand. Unfortunately, members may only be requested to perform the BRE365 test and nothing else.

In my experience, over-winter (wosrt-case) water level monitoring has been more frequently requested by designers indicating a more favourable approach to ground modelling.

It seems the current SuDS manual was written with Eurocodes in mind, but apparently not integrated possibly due to the embedded modelling from SR271 between test, device design and bulk safety factors. Mention of 14688 & 14689 in the B6 checklist are assumed to enable initial permeability assessments to be made by designers from descriptions correlated to published permeability values. In such cases, ground practitioners might note subtle fines content descriptors in coarse soils which could lead to significantly different engineering properties in tests. Designers and regulators might just see either SAND or CLAY and get a wrong outcome.

It is tempting to assume that permeability and infiltration approximate to the same value but that may not be accurate. Scale & geology variations mean that measurements of permeability in small laboratory samples cannot be representative unless part of a fully developed ground characterisation. In any event permeability cannot be used in exactly the same way as infiltration rate due to the modelling/empirical link between test and the device design. It is the device (soakaway/basin) that has a characteristic design value of infiltration (usually the tested soil worst-case), and potentially too conservative if water will find preferential pathways and bulk safety factors are deployed. Whilst the SuDS manual includes falling head tests in ISO 22282-2:2012 as acceptable in principle, there are conditions and limitations. There may be parallels here with the recent AGS presentation on sample disturbance where taking a few high quality and well-selected data sets might be considered “better” than many more data of variable/unknown control. We might assume that falling head test data should be presented as a part of a full Eurocode characterisation of the ground to be compliant. Simply replacing isolated infiltration data from a trial pit with more falling head tests in a borehole is likely inadequate, although potentially safer for operatives and might use less resources.

Use of boreholes as a device for obtaining infiltration data is a natural ambition for AGS members seeking compliance with standards and health and safety. However, if the depth of infiltration is limited, for example, by the Environment Agency through planning to less than 2m depth (as been the experience of the author) then the preference for using trial pits is understandable. A daisy-chain or in series hierarchy approach from initial water harvesting to bulk basin attenuation with limited shallow infiltration finally to deep soakaways for overflow situations might be good design but is not necessarily supported by case study.

There is also Geotechnical investigation and testing – Geohydraulic testing – Part 5: Infiltrometer tests (ISO 22282-5:2012), which exclusively describes the various types of ring infiltrometer test; single or double ring, open and closed. In these tests, flow through the side is not included, therefore not compatible with the SR271 modelling. However, the ring infiltrometer would logically be more appropriate for plane devices such as permeable pavements if the modelling is different. Again in my experience, It seems shallow depth BRE365s is preferred by designers for permeable paving.

Conclusion

From this discussion, there are no obvious “off the shelf” replacement alternatives to the BRE365 test to recommend to members.  Noting the fundamental link in the digest between the design output and the in-situ test. However, practitioners might note that although BRE365 was most recently updated in 2016, Bettes 1996 (R156) is the primary reference in the SUDs manual.

The alternatives to BRE365 should be ISO 22282-2 or ISO 22282-5 neither is wholly recommendable (or likely to be accepted nationwide) as a direct replacement.

To support a sustainable agenda wider use of understanding ground models at the initial stage is recommended and not to rely on limited study & a small data set of BRE365 tests. A site where there is a 3m thick layer of clay over 10m of unsaturated permeable sands; three 2m deep tests would indicate infiltration is not possible resulting in the design of an attenuation basin occupying potentially unnecessary space and wasting other resources. A conceptual model, initial investigation and targeted deeper BRE365 tests may result in a much more sustainable scheme.

BRE365 and the SuDS manual could be updated to include the modern context such as health and safety including the gravel filling of test pits, responsible use of resources/logistics and adoption of dataloggers. Guidance could be provided on the benefits of a good geological characterisation and what benefits could be gained from having representative/characteristic high quality data rather than the adoption of worst-case values because of limited data. More case studies might be expanded to include problem solving where poor draining geology has been overcome by engineering for example using linear features which can intercept preferential pathways in variable soil/rock. Or combined systems featuring infiltration devices of limited/known capacity linked to bulk attenuation and final overspill into deep borehole soakaways.

The AGS is keen to hear examples of good practice for safely undertaking the BRE365 methodology and examples where SuDs design has been informed by alternatives to the conventional BRE365 method.  Please contact the AGS at ags@ags.org.uk with examples or comments.

Article provided by James Harrison of 4D Geo Limited

Article

INSIDE SOILCLOUD

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Name: Tomasz Daktera

Job title: President

Company name: SoilCloud SAS

What does the company do and what areas does it specialise in?

SoilCloud provides a Geotechnical data management web software (AGS compatible). We are leading the digital transition of geotechnical engineering in France (over 60% of all geotechnical data and tests in France are being analysed by our system). We are also present in the UK and 5 other countries around the world.

Where is SoilCloud located?
Our Headquarters are located in France, Paris.

How many people does the company employ?
We are 7 fascinated engineers at SoilCloud.

How long have you worked at SoilCloud?
Together with Lucas Janodet, we have co-founded SoilCloud in 2018.

What is your career background, and what enticed you to work for SoilCloud?
Together with Lucas Janodet, both geotechnical engineers, we have founded SoilCloud to engage the digital transition in the industry and to make more efficient.

What is your current role within SoilCloud and what does a typical day entail?
As president, I am dealing with medium term and long projects as well as product development, global strategy and international sales.

What are the company’s core values?
Our core values are related to the way we operate. We put our clients and their needs and feedback first.

Are there any projects or achievements which SoilCloud are particularly proud to have been a part of?
In 2023, we have won the Solscope Innovation award, which is the most prestigious prize in geotechnical engineering in France (distributed once every two years). SoilCloud’s software and vision has been recognized as a global change in the whole French geotechnical industry.

How does SoilCloud support graduates and early career professionals who are entering the industry?
In our team, one of our IT developers is an apprentice still attending school 2 days a week. Young professionals have a great amount of positive energy which encourages the whole team to work together to deliver a great product.

Why do you feel the AGS is important to the industry?
As a leader in the digital transition of the geotechnical industry, SoilCloud is strongly promoting the AGS format around the world. The AGS format is something that was ahead of its time in the previous years and the industry is, just now, understanding the great added value of it.

What are SoilCloud’s future ambitions?
2000 satisfied users in 2024. Today, we have about 1800 users and counting.

Article

AGS Early Careers Webinar Series – Common Risks of GIs, Identification and Mitigation Summary

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On 24th January 2024, the AGS held an Early Careers webinar entitled Common Risks of GIs, Identification and Mitigation.

The webinar was chaired by Harry McAllister (Senior Consultant, TRC Companies) and included presentations from Lauren Hunt (Geoenvironmental Consultant, Arcadis), Vicki Morten (Associate Technical Director, Arcadis), Will Capps (Technical Manager, Delta-Simons), Amy Juden (Head of Geoenvironmental at The Environmental Protection Group), Leo Phillips (Environmental Monitoring Manager at The Environmental Protection Group) and Jon Rayner (SH&E Director, AECOM).

Lauren Hunt and Vicki Morten began the webinar with their insights on Site Supervision and Regulations, highlighting the role of the Site Supervisor and Construction Design and Management (CDM) Regulations. This was followed by a presentation from Will Capps on Buried Utilities Do’s and Don’ts, where Will provided an overview of methods available to avoid striking underground utilities during Site Investigation. Amy Juden followed with a presentation on Asbestos in Soil: Exposure, Risk and Mitigation, focusing on exposure risk from asbestos in soil and how to effectively manage it when planning and undertaking site works. Leo Phillips then spoke about Ground Gas Risks: Key Considerations When Completing Field Work, before Jon Rayner’s final presentation on Safety Culture, Putting Your Right Foot Forwards. The webinar ended with a group Q&A.

If you missed the webinar, the recording is now live on the AGS website and is free for AGS members and non-members.

Article

Gain Skills to Champion Excellence in the Geoprofessions at GBA’s Annual Conference

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Geoprofessionals from across North America will gather at Geoprofessional Business Association’s (GBA) 2024 Annual Conference, April 18-20, 2024, at the JW Marriott, Anaheim Resort in Anaheim, California. With a theme of “Champion Excellence,” conference participants will gain the skills and knowledge to actively promote and support the pursuit of exceptional performance, quality, and success in all aspects of their firm.

Keynote speakers include New York Times best-selling author and innovation consultant Diana Kander and famed one-handed Major League Baseball pitcher Jim Abbott.

The event offers opportunities for development of highly sought-after skills such as communication, innovation, and overcoming adversity, as well as Business Round Table Sessions – the unique chance to discuss problem-solving, best practices, and strategies with geoprofessional peers about the issues impacting the industry.

Those who are newer to the geoprofessions can engage with executive-level industry leaders, connect with new mentors, and boost their professional profiles. Mid-level geoprofessionals can unlock new leadership opportunities, exchange best practices for risk management, and network with hundreds of like-minded professionals. Seasoned geoprofessionals can share strategic insights as they address industry challenges and contribute to the elevation of the profession with their invaluable experiences.

The GBA Annual Conference offers up to 6.5 professional development hours.

Early registration rates are now in effect, but rates will increase on March 1.

Learn more and register here.

News

AGS Magazine: January 2024

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The Association of Geotechnical and Geoenvironmental Specialists is pleased to announce the January 2024 issue of their publication; AGS Magazine. To view the magazine click here.

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

There are a number of excellent articles in this issue including;
UK’s premier geotechnical conference returns in 2024 – Page 6
New version of AGS Piling released – Page 9
AGS Annual Conference 2024 – Page 12
Geotechnical unit, Ground models and Geotechnical Design Models– what are these, what do they cover and who is responsible? – Page 19
Calibration of Whatman Grade 42 filter paper for soil suction measurements – Page 22
AGS Guide to Welfare: A step in the right direction – Page 28
Inside: Igne Group – Page 34

Plus much, much more!

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

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

Article

INSIDE IGNE

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Name: Peter Widdowson

Job title: Director Business Development

Company name: Igne Group Limited

What does the company do and what areas does it specialise in?

Igne is the new brand for six combining businesses which share a group history of 350 years’ service in site investigation, materials testing, unexploded ordnance threat mitigation, water well drilling, geothermal borehole drilling and geo-environmental consultancy.

We know our collective services must be delivered more effectively and sustainably than ever which is why the businesses have fused together to respond more efficiently to our customers in the pre-construction and construction phase environments.

Our vision is to become the most trusted tier-one partner for environmentally sustainable site investigation and drilling services across the entire construction and infrastructure lifecycle in built environments throughout the UK.

Any single part of Igne can respond to customers’ needs in each of our specialist areas, simplifying the process for clients and consistently ensuring the provision of the same level of service and expertise.

Where is Igne located?

Igne has offices in Aberdeen, Airdrie, and Hamilton in Scotland; Preston, Chester le Street, Birmingham, Aylesbury and Gillingham in England; and Presteigne in Wales.  Our head office is Ross on Wye, a beautiful part of Herefordshire.

How many people does the company employ?

We employ circa 300 full time staff and rely on many exceptional contract staff who support us when we need to call on them.

How long have you worked at Igne?

I joined Igne in a brand-new role for the company in June 2023 (so 6 months and happily counting.)

What is your career background, and what enticed you to work for Igne?

I am a professional Civil Engineer and a member of the Institution of Civil Engineers.  My background has been in tier 1 and 2 civil engineering and building construction contracting, working across Scotland principally, but also supporting businesses in the North of England, around Manchester and Warrington.

Over the last 10 years, my roles have focused more on business development and work winning.

When the opportunity came to join Igne ahead of its official launch on 2nd October 2023, I was really excited for a variety of reasons.  Firstly, I would be able to expand my own knowledge across a number of new sectors.  I was most commonly on the receiving end of site investigation reports – now I would get to promote best practice in site investigation for clients.

Secondly, I would be able to start working more directly in an area that I believe is one of the future solutions to decarbonising heat in the UK, harnessing geothermal energy.

Finally, I would be able to start practising what I have always preached; that the greatest risk to any construction project lies in the ground.  Understanding the ground conditions early on can help project teams understand the hazards and provide mitigation solutions to problems that can otherwise cause severe delay, disruption and additional costs to a project.

At Igne, I now represent a business that gets its hands dirty, so to speak, and does the work that I know is critical for a project’s success.  We are one of the specialist contractors, and consultants, who will lead with the advice and intelligence that we can provide, backed by the expertise that we have, to ensure our clients’ successes.

What is your current role within Igne and what does a typical day entail?

There are several threads to my role within Igne as I support each of our business units and service streams.

I led on the communication to all current and previous customers relating to our change to becoming Igne from 2nd October 2023.  Some parts of the now-combined business had incredibly well-established names and were known by many as the ‘go to’ supplier for their work.  Changing the brand to Igne is significant but has been well-supported by all involved.  The communication piece was critical to tie up all loose ends.

My key role day-to-day is to support each business to identify and secure the opportunity to negotiate and tender for future work.  We need to share our broad capabilities with our current customers who may know us primarily for one service – such as UXO or site investigation – but not realise we can now offer them so much more.

We need to understand our customers and future customers and the markets in which they operate, so that we can continually improve for each individual customer.  My role looks at how we deliver today but also how we might deliver tomorrow in partnerships and alliances or through acquisitions.

I truly believe, with a passion, that we can help all clients, whether they are developers, consultants, contractors or individual homeowners, to understand their project better to reduce cost, stay on programme, improve safety, reduce environmental and ecological impact and carbon intensity, and the demand on natural resources.  It is my role to communicate that passion to our future customers and show them what we can do for them.

What are the company’s core values?

Our purpose is to enable sustainable communities and advance positive change. We do this through our values:

Reliability: Whatever the job, we focus on what matters, do things the right way and deliver real results. Dependable, positive and hugely knowledgeable, we provide skills and experience that people can rely on.

Partnership: We work in partnership with clients and stakeholders to find answers and reach shared goals. We build long-term relationships by being open, transparent and easy to work with. We are full of practical ideas that people can put into action.

Quality: We are dedicated to our work and passionate about quality. We set high standards and work hard every day to meet and advance them. We speak up, act with integrity and offer honest advice people can trust.

Are there any projects or achievements which Igne is particularly proud to have been a part of?

Delivering sonic drilling solutions to site investigation challenges in remote and inhospitable parts of beautiful Scotland, whilst also working in environmentally sensitive locations without damaging precious flora and fauna.

This demonstrates our core values in action:

Reliability, we can get the job done no matter the challenges we may need to overcome.
Quality, we deliver the highest quality works maintaining sensitivity to the environment or communities within which we are operating.
Partnership, to work with our client to determine the best way and best value option to deliver the information they need.

Another example is clearing unexploded ordnance from a 5-hectare area of the Dorset coast for the National Trust.  The area had been badly damaged by and exposed several hundred items of live and inert ammunition.  We cleared this former training area, rendering it safe for public access once again.

How important is sustainability within the company?

Incredibly important – sustainability is at the heart of our purpose and is our vision.  In everything that we do today, we are thinking about tomorrow.  It is the very purpose of our business, to provide the data to inform our customers about the most sustainable way to develop their project.

It is also important to us that we continually improve how we go about achieving this, to minimise our own impact.  For example, as we transitioned to become Igne, all our old PPE was recycled with 0% going to landfill.  This ensured we reduced CO2 emissions by 13kg per 1kg recycled – and we reduced water consumption by 1litre per 1kg recycled as the old workwear become new garments.

How does Igne support graduates and early career professionals who are entering the industry?

Our CEO, Rob Hunter, is committed to advancing social mobility and does a lot of work in a voluntary capacity to advance the cause.  Therefore, it is unsurprising that Igne has an acute focus on developing early talent at the heart of its workforce plan.

We have various routes to support young people entering the industries and specialisms we span.  We have graduate and apprentice routes into roles such as engineers, geologists, administrators, marketers, HR professionals, drilling crews and many more.

We go into colleges and universities to teach and help young people understand what the industry is like.  We don’t sugar-coat what life can be like as a driller for example, but for the right people, it is a hugely rewarding career.

We do need to improve how we communicate the available careers to young people, to get them interested in what we do at Igne and in the wider industry.  If we can do this successfully, it will help us to stem the recruitment and people-resource issues that we face.  Attracting the right people in the first place, and nurturing their talent is the route to a more sustainable workforce solution.  It is a core company focus for us.

How has COVID-19 impacted Igne today? Are there any policies which were made during the pandemic that have been kept to improve employee wellbeing and productivity?

Yes, absolutely.  The flexibility we developed across the businesses, which was generated as a result of COVID-19 and the ways of working that we had to adopt, has demonstrated that a hybrid working practice is both possible, in appropriate circumstances, and beneficial to employee wellbeing and therefore productivity.

Our move to hybrid has helped us reduce our carbon footprint through reduced commuting, and our employees continue to demonstrate their commitment to the business reciprocating the trust the business puts it them.

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

I am a firm believer that the ground holds the greatest risk to any construction project no matter how large or small.  It is a constant source of challenge whether through geotechnical ground conditions, historic uses, contamination or protecting sensitive receptors.  If everybody worked in isolation, we would not deliver the results we need to develop our industry.  We must work collaboratively, share best practice and allow ourselves to learn from each other for the good of the planet, our employees and the communities in which we work – and we must enjoy a collective voice.  For me, AGS helps to facilitate the foregoing across our industry, so, it is a ‘no-brainer’ – AGS is critically important to our industry.

What are Igne’s future ambitions?

Our ambition is to consolidate the capabilities from across the group, to enable us to deliver more than the sum of our parts through shared learning and commitment to delivering a holistic and integrated service for our customers.  We are also committed to continuing to grow our capabilities in the direction led by our customers’ needs.  This is what excites me the most.  In doing so, we will become the most trusted partner to the construction industry, providing pre- and post-construction services they can absolutely rely upon.

 

Article Safety

AGS Welfare Guidance, a step in the right direction

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Image provided by AECOM

The industries expectations to all health, safety and wellbeing requirements have changed through the years, as we understand and acknowledge the negative impacts work activities and environments can have. In the late 1980’s and into the 1990’s I recall working on construction projects where the requirements to wear a safety helmet and safety boots were not amongst the site rules, where all materials were required to be carried up a ladder, normally by young inexperienced labourers, and the idea of leading-edge protection was an alien concept.

With all of these examples and many, many more, through the demonstration of the harm captured within accident statistics, the Health and Safety Executive working with industry stakeholders have developed new legislation, approved codes of practice and guidance to reduce the risk of being harmed while at work. This approach has been transformative to the construction and many other industries and benefited those working within them.

Although successful in achieving its outcomes, this change has not always been viewed as positive at the time of its introduction, although few would retrospectively now challenge the requirement to wear a safety helmet where there is a risk of falling objects, etc., as the benefits are clear.

Thinking back to my experience of construction site welfare in my earliest career, most projects I worked on had no welfare. Breaks were taken in the back of your van and public toilets, or other alfresco arrangements were used to relieve yourself. Where some form of welfare did exist, the quality and upkeep of it was poor by todays standards.

I worked with a bricklaying contractor on a project on the outskirts of London where a hotel was being constructed. The only welfare on site was a single 16ft canteen with a gas stove, a kettle, tables and chairs, and a solitary portaloo, all of which was supplied by the groundwork’s contractor. I do not recall how many groundworkers there were on the project, but I know there were ten bricklayers and labourers, more than the welfare could cater for by today’s standards. Welfare maintenance was limited to the emptying of the portaloo once a week by the supplier.

It was winter so everything was covered in mud. A few of the groundworkers tools and cans of petrol were stored in the back of the canteen. As expected at the time, there was no soap, detergent, hand towels, cups, tea, coffee, toilet roll, etc. Worst of all and why it sticks in my mind, was the frying pan. At the 10 o’clock break, the groundworkers used to cook a fry up in this massive frying pan on the gas stove. Due to the lack of washing facilities the pan was reused daily without being cleaned, so it was black and charred and there remained a 5mm layer of congealed animal fat in the bottom of the pan. On a few occasions in heavy rain, the bricklayers used to stop work and take shelter in the canteen, the groundworkers didn’t, they just worked through it. If shelter was taken before 10 o’clock, on inspection of the countertop you could see the rat footprints in the frying pan fat, where they had been feasting on it through the night. The pan was always used and never cleaned!

I am glad to say that such situations are a thing of the distant past, and those coming into the construction industry today have an improved experience. Recognising the impact insufficient welfare can have, today’s welfare provision must be suitable to the workforce size, serve the needs of both male and female workers, be well equipped with food and drink receptacles, have supplies of hygiene and cleaning sundries, a supply of fresh drinking water and means of heating food and drink. It should provide storage for clothing, changing areas and heating for the drying of workwear, toilets and wash basins with hot and cold running water, hand health creams, sun protection and ample waste control. Cleanliness and maintenance of welfare must be daily, with replenishment of consumables, etc. to ensure the workforce have everything they need to their work and health.

However, this is not always the case in the pre-construction site works, such as ecology, archaeology, utility mapping, ground investigation, etc.

It is fair to say, depending on the size, scope and location of geotechnical and geoenvironmental projects, our industry has very varied levels of compliance to what should be expected with regard to welfare. While I haven’t seen any frying pans and rat footprints, I have seen inadequate on-site welfare or an absence of it entirely. There are several justifications put forward for such situations, however, none which have the welfare of those working on geotechnical and geoenvironmental projects at its core or which align to legislative requirements. Such justification could include; if welfare is provided, we would price ourselves out of the project, the client has pushed back against the cost of welfare, the project is not long enough to warrant having welfare, etc.

In reality, none of this reasoning will stand up to scrutiny by the enforcement authority, as legislation is clear, Construction Design and Management Regulations 2015 (CDM15), regulation 13.4. ‘the principal contractor must ensure that—(c) facilities that comply with the requirements of Schedule 2 are provided throughout the construction phase’, or within the Workplace (Health, Safety & Welfare) Regulations 1992, regulation 4.1. ‘Every employer shall ensure that every workplace, modification, extension or conversion which is under his control and where any of his employees works complies with any requirement of these Regulations…….’

There are weaknesses within the regulation and guidance, which on their casual reading seem to justify not having on site welfare. Within the CDM15 Schedule 2 (which the above quote relates to) it uses the term ‘….must be provided or made available at readily accessible places.’, and then there is the Provision of welfare facilities during construction work, HSE information sheet 59, which introduces the term ‘transient worker’ and states that ‘it may be appropriate to make arrangements to use facilities provided by the owner of existing premises, in which the work is being done, local public facilities or the facilities of local businesses’.

Considering ‘readily accessible places’ within CDM15. The statement is part of a much longer statement, which includes regulation 13.4.c, stating that ‘the principal contractor must ensure that facilities that comply with the requirements of Schedule 2 are provided throughout the construction phase’. The use of the phrase ‘….must be provided or made available at readily accessible places’ in this context allows the principal contractor to provide the welfare or arrange for a third party to provide it, as long as it is readily accessible. A 7th December 2022 prosecution of Adler and Allan Ltd, highlighted the expectation of the Health and Safety Executive for onsite welfare for brownfield / contaminated sites. However, the context of this case surrounded a worker contracting leptospirosis due to a lack of onsite hygiene facilities, so it should be noted that the contraction of leptospirosis is not linked to brownfield / contaminated sites, but any sites where rats (all year round) or cattle (spring and summer) are present.

HSE information sheet 59 was published 13 years ago, the corresponding construction regulations were the Construction (Design and Management) Regulations 2007, which is referenced within the document on page 1. It goes on to state, ‘principal contractors should make sure that suitable welfare facilities are provided from the start and are maintained throughout the construction phase’ and that contractors ‘should ensure that there are adequate welfare facilities for workers under your control’. The document sets out in significant detail what welfare should consist of and contain.

However, this is ignored by those using it as an argument for using off site publicly accessible facilities, their focus instead turns to the section titled, ‘Use of alternative facilities for transient construction sites’. This states that ‘when undertaking short duration work (up to a week), it may be appropriate to make arrangements to use facilities provided by the owner of the premises in which the work is being undertaken, local public facilities or the facilities of local businesses.

What is not quoted by those using Information sheet 59 as an argument for using off site publicly accessible facilities, is that it then goes on to state ‘clear agreement should be made with the provider of the facilities; it should not be assumed that local commercial premises can be used without their agreement. In all cases the standards above (welfare standards detailed in document) must be provided or made available. Facilities must be readily accessible to the worksite, open at all relevant times, be at no cost to the workers, be of an acceptable standard in terms of cleanliness and have handwashing facilities’. The use of garages, supermarkets, public toilets, etc. whilst often providing basic toilet and hand washing facilities will struggle to meet all the remaining requirements, with issues such as cleanliness, chairs with back support, means of heating food and drink, changing rooms, free of charge to the worker, all preventing facilities being deemed suitable and sufficient before even looking at the definition of readily accessible.

To improve welfare across the industry, providing clients with an industry benchmark and contractors a level playing field to price against, the AGS has published new Welfare Safety Guidance which is available via the AGS Website. This guidance takes into consideration the vastness of scope, duration, workforce and environment variations which are present across the industry and puts into place a set of welfare standards to ensure the health and wellbeing of those working within the industry. The guidance addresses the application questions posed by conflicting regulations and guidance and provided the industry a simple, clear and concise framework to support the diversity of the workforce.

Our industry should be one that welcomes in early careers and supports existing staff by providing them with suitable and sufficient welfare, ensuring their wellbeing. The work the industry engages in is physical, dirty work, which is undertaken in all weather conditions, year-round. Those that deliver this work deserve the comforts that basic welfare delivers as a minimum.

Article provided by Jon Rayner – AECOM SH&E Director & AGS Safety Working Group Chair

Article Laboratories

Calibration of Whatman Grade 42 filter paper for soil suction measurements

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Abstract

The correlation between the water content of filter-paper disks and the porewater suction in soil samples is used to determine soil suction, and various equations have been proposed to model it. To verify whether the equations in BRE IP 4/93 for determining soil suction based on the water content of Whatman Grade 42 filter paper remain valid and can be used with currently available batches of Whatman Grade 42 filter paper, SSL and i2 Analytical laboratories confirmed experimentally that NaCl solutions can be used to calibrate Whatman Grade 42 filter-paper disks and the equations in BRE IP4/93 remain valid. The method is inexpensive and reliable. Filter paper from different manufacturers or other than NaCl solutions also can be used after calibration.

 

Introduction

Soil suction is the result of the interaction between soil, water and air, and is important in understanding the strength and behaviour of soils, in general, and unsaturated soils in particular. There are numerous direct and indirect methods for measuring soil suction in situ and in the laboratory (e.g. Ridley 2015; Esmaili and Hatami 2017). The filter-paper technique is the most commonly used indirect method for estimating soil suction because of its low cost, simplicity, and wide range of suction values (0-5 MPa). The method evolved in Europe in the 1910s and USA in the 1930s (e.g. Frendlund et al 2012; Fondjo et al 2020).

Soil and filter paper (direct contact), or porewater vapour and filter paper (indirect contact), are equilibrated for several days in an airtight container. Subsequently, the water content of the filter paper is determined, and the soil suction is calculated by using equations that relate the filter paper water content and soil suction (e.g. BRE IP 4/93; ASTM D5298).

The total suction ψ in soil is the sum of the matric suction (ua – uw) and osmotic suction π determined by the direct and indirect contact of soil and filter paper, respectively,

ψ = (ua – uw) + π,

where ua is the pore-air pressure and uw is the porewater pressure.

The calibration of filter paper involves either equilibration of filter paper in a suction or pressure plate at different applied pressures or by non-contact equilibration of filter paper over salt solutions, e.g. NaCl, KCl, Na2SO4, or MgCl2, with different salt content, and then independently determining the filter paper water content (WCFP). The data from various calibration studies suggest that for suctions greater than ca 1000 kPa the total and matric suction calibration curves converge but diverge at lower than 1000 kPa (e.g. Fredlund et al 2012).

Whatman Grade 42 or Schleicher & Schuell No. 589-WH filter papers have been used in soil suction tests, and many studies have established and evaluated calibration equations. Even though filter paper is an industrial product manufactured under strict control, it is not clear if the manufacturing process and thus quality of the filter papers remains the same over the years or if the published calibration curves are applicable to the currently available filter paper batches. Thus, calibration of each batch of filter paper is recommended (Marinho and Oliveira 2005).

This paper describes the calibration study undertaken by SSL & i2 Analytical to demonstrate for accreditation purposes that filter papers can be inexpensively calibrated by using salt solutions, and the equations in BRE IP 4/93 (Crilly and Chandler 1993) can be used with currently available Whatman Grade 42 filter paper batches.

Method

Equipment

  • Ash-free Whatman Grade 42 filter paper (CAT No. 1442-070 & Lot No. 16971096) 70 mm in diameter
  • Thermometer (±1 ⁰C accuracy)
  • Laboratory balance with an accuracy of 0.1% of the weighed mass
  • Oven capable of maintaining the temperature at 105 ± 2.5 °C
  • One pair of metal tweezers
  • 200 ml terrine jars, with mouth size of 100 mm to allow for the filter papers to be placed inside without touching the jars
  • Corrosion-resistant metal or plastic pipe to act as a support for the filter paper disks
  • Glass beads to secure the supports
  • Six aluminium circular tins
  • A large glass flask with distilled or de-ionised water
  • Desiccator
  • Cooler box

 

Method

Salt solutions were prepared by dissolving table salt in distilled water (Table 1). All equipment but the thermometer and filter papers were thoroughly cleaned by carefully washing and rinsing them with distilled water, and then dried. Latex gloves and tweezers were used to prevent the transfer of any oils or other contaminants and handle the filter-paper disks. The filter-paper disks were dried and kept at 105 ± 5 ⁰C.

Clean glass shards or beads were placed at the base of the jar to support the plastic or metallic pipe upon which the filter paper disks were placed. Prior to placing the filter-paper disks, the glass jars were filled with the salt solutions.

Two filter papers were placed above the salt solution on the supports so they had 2 cm clearance from the surface of the solution and protruded more than 1 cm past the support in all directions but were not in contact with the jar. The jar contents were then secured with a water tight  lid. The configuration is shown in Fig. 1.

A set of six jars was placed within a cooler in a temperature-controlled laboratory room (23 ± 2 ⁰C) and left undisturbed for two weeks to equilibrate. Room temperature was maintained at 23 ± 2 ⁰C.

After equilibrating for two weeks, the jars were removed and the filter papers were placed into aluminium tins for initial weighing; this part was performed by two technicians who worked on each jar together to reduce the amount of time that the filter papers were exposed. The aluminium tins were then placed in a dry oven set at 105 ± 2.5 °C for a minimum of 16 hours with the lids half-off to dry completely. The following day the lids were replaced and the aluminium tins containing the filter papers were left to equilibrate in the oven for 5 min before being removed and allowed to cool in a desiccator. After this second dry weighing, the water content was calculated.

Discussion

The data from the calibration tests at the SSL Bristol and i2 Analytical laboratories are given in Table 1. The 0% NaCl solution was deionised water. The filter-paper water content data suggest good reproducibility and repeatability between and within laboratories, respectively. The suction values at 23 ⁰C were calculated using the online molality calculator of omnicalculator.com.

The osmotic suction π values in Table 1 are compared with the values generated by using the equations in 1) BRE IP4/93 for matric suction and 2) Leong et al. (2002) for total and matric suction (Fig. 2):

1a) log kPa =  4.84 – 0.0622 × WCFP                    15% ≤ WCFP ≤ 47%

1b) log kPa = 6.05 – 2.48 × WCFP                   WCFP > 47%

2a) log kPa = 8.778 − 0.222 × WCFP             WCFP < 26%

2b) log kPa = 5.31 − 0.0879 × WCFP             WCFP ≥ 26%

The data in Fig. 2 suggest that the non-contact calibration data represent total suction values and agree with the convergence of matric and total suction values at approximately 1000 kPa (log kPa = 3) and at about 25% WCFP.

At filter-paper water content greater than 25% the calibration data well agree with the Leong et al. 2002 equation for total suction, suggesting that the Whatman Grade 42 filter paper produces data consistent with published calibration equations.

The equations in BRE IP 4/93 and Leong et al. 2002 for matric suction are in good agreement, which suggests that the equations in BRE IP 4/93 can be used to calculate soil suction, with currently available batches of Whatman Grade 42 filter paper.

There are no calibration data for matric suction; however, considering the agreement between the test data and equations 1a and 2b above, it is reasonable to argue that the currently available calibration equations, including the ones in BRE IP4/93, can be trusted to return reliable suction values.

Conclusions.

NaCl solutions can be used to calibrate ash-free Whatman Grade 42 filter paper. The calibration method is simple and non-expensive. Furthermore, the results strongly suggest that the equations in BRE IP 4/93 can be used to determine soil suction in the laboratory, with currently available batches of Whatman Grade 42 filter paper.

Acknowledgements

Tabetha Hellard, Elizabeth Hort and Kellon Booker at SSL and Dariusz Piotrowski, Ewa Plona, and Aleksandra Jurochnik at i2 Analytical kindly agreed to perform the calibration tests.

References

ASTM D5298-16 (2016) Standard test method for measurement of soil potential (suction) using filter paper, ASTM International, West Conshohocken, PA, 2003, DOI: 10.1520/C0033-03, www.astm.org.

Crilly, M.S. and Chandler, R.J. (1993) A method for determining the state of desiccation in clay soils, BRE information paper, IP4/93. HIS BRE Press, Bracknell, UK.

Esmaili, D. and Hatami K. (2017) Comparative Study of Measured Suction in fine-grained soil using different in situ and laboratory techniques, International Journal of Geosynthetics and Ground Engineering, 3:27

Fondjo, A.A., Theron, E., and Ray. R.P. (2020) Assessment of various methods to measure the soil suction, IJITEE, Vol. 9, Issue 12, pp. 2278–3075 (online).

Fredlund, D.G., Rahardjo, H., Fredlund, M.D. (2012) Unsaturated soil mechanics in engineering practice, pp 939, John Wiley & Sons, Inc., Hoboken, New Jersey.

Leong, E. C., He, L., and Rahardjo, H., (2002) Factors Affecting the Filter Paper Method for Total and Matric Suction Measurements, Geotechnical Testing Journal, Vol. 25, No. 3, pp. 321–332.

Marinho, F.A.M. and Oliveira, O.M. 2005. The filter paper method revisited, Geotechnical Testing Journal, Vol. 29, No. 3, pp. 1–9.

Ridley, A.M. (2015) Soil suction — what it is and how to successfully measure it, Proceedings of the Ninth Symposium on Field Measurements in Geomechanics, Australian Centre for Geomechanics, Perth, pp. 27-46.

Fig. 1. Test configuration for (a) a single jar (left) and (b) six jars during the two-week equilibration period (right).

Fig. 2. Filter-paper calibration test data compared to published calibration equations.

Article provided by Dimitris Xirouchakis, Director at Structural Soils Ltd

Article Geotechnical

Bitesize Guide – Geotechnical unit, Ground models and Geotechnical Design Models– what are these, what do they cover and who is responsible?

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Introduction

This note has been prepared based on a review of the draft prEN 1997 dated August 2022.

Geotechnical Unit

A geotechnical unit is defined in prEN 1997-1 as a ‘volume of ground that is defined as a single material’. Ground can be soil, fill or rock existing in place before any construction works, each with its own hydraulic conductivity.

A unit will have a description and classification based on designation of material parameters and identification of the data used in the selection of representation values of ground properties.

These units are normally identified prior to the start of the ground investigation as part of the initial desk study, site inspection and preliminary investigation (prEN 1997-2, 5.2.2 to 5.2.4). These are required as part of the planning of the design investigation (5.25) and develop as the project cycle evolves. The ground investigation should identify strength, stiffness, anisotropy and geometrical variation of the units.

Normal UK practice would give responsibility for these initial works either to the Specialist Ground Investigation Contractor, or sometimes to a Geotechnical Consultant appointed at an early stage in the Project.

Ground model

The concept of the Ground Model is familiar to all practitioners site specific outline of the disposition and character of the ground and groundwater based on the results of ground investigations and other available data. These conditions will have an influence on the site (and this may also need to include the recognition of potential ground conditions and sources outside the site boundary), on the design itself, and finally the construction of the project.

The draft prEN 1997-2, 4.1 states that a Ground Model shall comprise the geological, hydrogeological and geotechnical conditions of the site as determined by the ground investigation, and is one of the main outputs to be included in the Ground Investigation Report (GIR). The Ground Model also forms the basis for development of Geotechnical Design Model [GDM] for each geotechnical design situation and each geotechnical structure (prEN 1997-1, 4.2.3).

As an example, the Ground Model should consider, but not be limited to, the geomorphology of the site, geometrical and geotechnical properties of the geotechnical units, but also discontinuities and weathered zones. The Ground Model shall state the variability and level of uncertainly of the conditions and properties alongside derived values from relevant ground properties of all geotechnical units encountered.

Without the Ground Model, the GIR would not be able to identify the derived values of the geotechnical units.

As the Ground Model is one of the principal outputs from the initial desk study, site inspection, preliminary or design investigations and is to be included in the GIR, development of the Ground Model is usually the responsibility of the Specialist Ground Investigation Contractor, or is sometimes passed to a Geotechnical Consultant appointed at an early stage in the Project.

The draft prEN 1997-2 states the Ground Model shall be developed and updated as new potential information is made available. Without the ground model, a GDM cannot be developed and validated. Any changes to the ground model shall be documented in the Geotechnical Design Report (GDR). Updating the Ground Model at this stage may therefore fall to the Geotechnical Designer rather than the original Specialist Ground Investigation Contractor.

Geotechnical Design Model

The GDM is a conceptual representation of the site derived from the ground model for the verification of each appropriate design situation and limit state. It is based on the Ground Model which has verified against the variability and uncertainty of the ground conditions.

The GDM should include, but is not limited too

  • tabulation or graphical cross sections of the geotechnical units
  • representative values of ground properties for all the geotechnical units encountered in the zone of influence.
  • inclusion of groundwater table
  • and the process of compiling the GDM.

The GDM should also consider the

  • variations of groundwater in all directions within each geotechnical unit. There may be occasions where groundwater pressures may be classified as accidental actions, as detailed in prEN 1997-1, 6.1.
  • identification of any spatial trends

Normal practice in the UK is that the development of individual GDMs would be the responsibility of the Geotechnical Specialist appointed to design each geotechnical structure for the appropriate geotechnical design situation and then included in the GDR. On most projects, there may be multiple GDRs often prepared by different designers. Guidance on the content of the GDR is given in prEN 1997-3. The individual GDRs may be collated into a single Project GDR.

The reliability of the GDM must be validated using the guidance given in prEN 1997-1, Table 4.6 for the appropriately selected Geotechnical Category [GC]. The GC would have been selected as part of the GIR. Table 4.6 has been reproduced as follows:

The validation process should also review the quantity, quality and appropriateness of the information taken from the GIR.  This is done to determine sufficient confidence in the GDM to ensure the level of reliability required by prEN 1990 is obtained, and additionally, that the measures taken to validate the GDM according to the GC are adequate. If neither condition is met, or there is insufficient confidence in the level of reliability then additional ground investigation shall be performed.

The GDM is reported in the GDR for each geotechnical design situation and for each geotechnical structure. Guidance on the content of the GDR is given in prEN 1997-3.

The AGS Geotechnical WG are preparing a number of other Bitesize Guides covering various Second-Generation EC7 topics, and if anyone has a burning desire to say something, get in touch with Katie, Alex Dent or Chris Raison via ags@ags.org.uk.

Guide produced by Emma Cronin, SOCOTEC.

 

 

Article Geotechnical

AGS Bitesize Guides – Introduction – prEN 1997:202x

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The second-generation of Eurocodes is proposed as the first major revision of the Eurocode suite of standards since original publication in 2004. This process has been underway for at least 10 years. Initially this comprised a series of Evolution Groups, set up by all the major National Standards Bodies [including BSI], tasked with reviewing the first-generation Eurocodes and identifying area where improvements, clarification, simplification, and harmonisation could be applied to improve the documents. Proposals were then passed to Task Groups for updating and preparing new drafts. The final process was a series of reviews by both the public and by the National Standards Bodies themselves [in UK by the BSI Committee B/526].

The Structural Eurocodes are a series of interlocking standards that interact as a whole and require designers to have access to and understand many different codes which link to yet more material, execution, and testing codes. The draft prEN 1997 is a work in progress and currently comprises three parts as follows:

prEN 1997-1:202x         Eurocode 7: Geotechnical design — Part 1: General rules

prEN 1997-2:202x         Eurocode 7: Geotechnical design — Part 2: Ground properties

prEN 1997-3:202x         Eurocode 7: Geotechnical design — Part 3: Geotechnical structures

prEN 1997 in turn is dependent on the over-arching Eurocode EN 1990, now titled ‘Basis of Structural and Geotechnical Design’. EN 1990 is an integral part of design to prEN 1997. BS EN 1990:2023 was published by BSI in August 2023.

Details of the timeline for final completion and publication of prEN 1997 has been given by Andrew Bond [chair of B/526 and past-chair of TC250/SC7] in a recent article published in Ground Engineering [November 2023 pp30-32]. Some topics were covered by the recent AGS webinar [September 2023] and parallel webinars held by NEN [Nederlands Normalisatie Instituut], acting as Secretariat for the revisions to prEN 1997.

Because of the imminent publication date and the large number of new topics, revisions to layout and structure and introduction of some new concepts, the AGS Geotechnical Working Group thought it timely to issue a series of Bitesize Guides covering prEN 1997. These are intended to introduce topics selected from the current drafts and to give personal views and understanding of the requirements gleaned from the code as actually written. It is believed that review and comments from representative members of the target audience rather than knowledgeable experts closely involved in the development will help to identify areas of ambiguity or lack of clarity. Finally, the publication of bitesize guides will hopefully generate some discussion and dialogue from other members of AGS.

The bitesize guides can be downloaded from the AGS website here.

Article provided by Chris Raison, Raison Foster Associates

News Data Management

New version of AGS Piling released

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A new draft of AGS Piling has been released for industry comment.

AGS Piling is a data transfer format for piling data which includes design schedule information, the construction record, as built information and pile test data. It is being developed by the Association of Geotechnical and Geoenvironmental Specialists (AGS) in collaboration with the Federation of Piling Specialists (FPS), with support from the Deep Foundations Institute (DFI).

The latest draft (version 0.4.0) is based on industry feedback received as part of a recent HS2 innovation project. In addition, it also trials a new approach to both the schema design and the file format itself. This is in response to the experience gained with AGSi, the relatively new transfer format for ground models and interpretative data. The documentation for the previous version of AGS Piling remains available to facilitate comparison between the different approaches.

Documentation for the both the new and previous versions is available on the AGS website.

A working group has been formed to continue the development of AGS Piling towards a formal release. This operates as a specialist subgroup of the AGS Data Management Working Group but includes representatives from the FPS and piling specialists.

The working group is keen to receive feedback on the draft, or any thoughts on the general concept of AGS Piling. Information how to get in touch is given on the AGS website.