Posts by Katie Kennedy


AGS Magazine: June/July 2020

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The Association of Geotechnical and Geoenvironmental Specialists are pleased to announce the June/July 2020 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 Video Competition – The Results – Page 4
On-Demand Geotechnical Training – GEO Academy – Page 5
AGS Awards 2020 – Page 6
Ground investigation – Is it time for change? – Page 8
Introduction to AGS’s Instrumentation and Monitoring Working Group – Page 16
Working at Height During Trial Pitting – Page 22
Q&A with Jo Strange of CGL – Page 32

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If you have a news story, article, case study or event which you’d like to tell our editorial team about please email 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 Safety

Working at Height During Trial Pitting: How Far is So Far as Reasonably Practicable?

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This paper was the subject of a presentation at the AGS Safety in Mind conference in November 2019, and started by asking “why this subject, and why now?”.  During a prior AGS Safety Working Group meeting, we had debated whether the Health & Safety Executive approve or agree with the AGS guidance notes?  In particular we debated whether common UK trial pitting methodologies complied with the Work at Height regulations 2005; and specifically, we were interested whether the common practice of standing or kneeling close to the edge of an unprotected trial pit, 2,3,4m+ deep might be deemed in hindsight to not comply with the law. The purpose of the presentation was to raise awareness of the issue to younger practitioners, remind senior practitioners and managers of their duties, to promote debate about the sufficiency of current industry practice, and debate whether current practice meets the legal benchmark of good practice.

There are a number of hazards associated with trial pits, although used generally safely for many decades.  The Work at Height Regulations 2005 clearly apply to this work, and place legal duties on employers.  Very few practitioners have ever experienced an incident involving a fall into a pit.  Nevertheless, we have the opportunity to consider whether we should or could do more to manage the risk from working at height adjacent to unprotected trial pit edges.  The time to have this debate clearly is not when a HSE inspector is questioning you following a serious accident, but preferably by industry collectively and in advance of such an incident ever occurring.

I have been involved in trial pitting since the 1980s, and have learned much about the ground from being up close, which a trial pit allows. My experience of trial pits is that it can be dirty, tiring, and potentially hazardous work. However, they are often fun, provide good information and experience, and sometimes are even a fabulous day out. They are economical, quick to organise, undertake and report.

Conventional machine dug trial pits expose the logging engineer to an unprotected edge of potentially 3 to 4 m depth in order to undertake at least part of their task. This Introduces a risk of becoming unbalanced or tripping at the edge whilst observing, taking measurements, sampling or photography. In my 30 years’ experience I am not aware of a logging engineer falling into a trial pit. A questionnaire survey sent out to AGS members in summer 2019 also concluded that there is no knowledge within the membership of falling into trial pits, although we subsequently became aware of anecdotal experience of 1 non-injury fall into a pit filled with groundwater!  Whilst we know that trial pit faces can collapse and whilst it is theoretically possible for such a collapse to involve the logging engineer, experience over a substantial period of time shows us that logging engineers don’t fall into trial pits, and therefore the proven probability is extremely low to negligible.

However, probability is not the only component of risk, severity of consequence also has to be considered. The consequence of falling two, three or 4 m into a trial pit is likely to be severe, it is likely to involve broken bones, a broken neck or worse. Using typical industry risk assessments, a combination of low or very low probability along with medium to high, to very high consequence generates a medium to high, to very high risk. The risk is significant, such that measures need to be considered to mitigate it.

“SFARP” and the Work at Height Regulations

Regulation 6 of the Work at Height Regulations 2005 is titled “avoidance of risks from work at height”. It describes a hierarchy which employers are required to work through and give consideration to when planning work at height, requiring at each level a consideration as to whether the available controls reduce the risk “so far as reasonably practicable” before discounting a control and using a lesser control.

But what is the required level of the duty of “so far as is reasonably practicable” – how does an employer know how far they need to go? The HSE guide “Working at height: a brief guide” states that “low risk relatively straightforward tasks will require less effort.” They go on to say that “there will also be situations where common sense tells you no particular precautions are necessary “.  Whilst this does not provide any specific guidance in relation to trial pits, it does acknowledge low risk situations (albeit not necessarily low probability situations). By extension, higher risk situations require greater controls.

Case law in respect of SFARP leads us to Edwards v National Coal Board 1949, which established the principle that the quantum of risk is placed on one side and the sacrifice whether in money, time or trouble involved on the other. If it can be shown that there is gross disproportion between them, the duty has been discharged.

So where is trial pitting practice in the 21st-century in relation to SFARP – does it pass “the gross disproportion” test? HSE suggest in their report “Reducing Risk Protecting People” (“R2P2”) 2001 that they regard a risk as not significant if past experience shows the risk to be extremely low (note “risk” not probability). HSE also state that they would consider sources of good practice, standards or guidance agreed by bodies representing industry. They would consider an assessment of the extent to which the practices have achieved general acceptance, and they will decide whether adoption of any authoritative good practice precautions is an adequate response to the hazards. HSE then say that “in most cases adopting good practice ensures that risks are effectively controlled”.

However, HSE go on to say that a universal practice in industry may not necessarily be good practice or reduce the risk sufficiently; they make it clear that duty holders should not assume that it is. They state that there will be times when existing practice is found to result in inadequate control of risks. So, we come to the question which opened this presentation:  is current industry guidance, including AGS guidance on trial pitting and working at height, representative of good practice such that the HSE would consider it as an adequate control of the risks?

The AGS Trial Pitting Survey 2019

In order to get a better understanding of modern common practice, the AGS Safety Working Group circulated a questionnaire to the membership in summer 2019. The main outcomes were summarised at the 2019 conference, and key headlines repeated hereafter.

Guidance used when planning trial pitting Most respondents stated they use the current AGS trial pitting guidance, and a number stated they have in-house / company guidance of some kind.
Several respondents suggested that they refer to BS5930 although there is only limited safety guidance there.  A number of respondents refer to HSE “working at height a brief guide” and HSE CIS614 Excavations, although neither of these provide much useful guidance in relation to trial pits.
No respondents identified the existing AGS guidance on Working at Height as informing their working arrangements.
Competence to work near an unprotected trial pit edge Almost all respondents had some form of assessment of competency and a period of supervised handholding typically 3 to 6 months.
Some have in-house trial pitting and work at height awareness elements of training
Many use CITB SMSTS or similar.
Most use CSCS, however usually not on its own.
How duty holders address the hierarchy of controls in Regulation 6. Many respondents prevent access anywhere near the trial pit by other workers
The vast majority do not make use of protection such as barriers or fall prevention/protection using harnesses, mostly on the grounds of perceived or experienced impracticability.
Some practitioners have tried to use mobile barriers, staging boards, fall protection harnesses
Some practitioners try not to use trial pits.
Some practitioners leave the JCB bucket in the hole to reduce height of fall.
Demonstration of SFARP at each level of the hierarchy, for example by considering risk against cost and benefit. No respondent stated that they undertook such a specific assessment
Some respondents believe that SFARP was embedded in their company work procedures and training of staff, the use of risk assessments, method statements and CDM design risk assessments, and through following AGS and HSE guidance documents.

Reasons why control measures are considered to be SFARP

Some respondents suggested that they do not provide fall protection for walking down a flight of stairs, where there is clearly a fall hazard of a highly frequent nature, and potentially just as severe as a fall into a trial pit perhaps.
Respondents said that the staff are aware of the risk of falls into trial pits, and they have the ability to stop work if they consider it unsafe.
Some respondents referred to the HSE guidance which flags up that there are some low risk solutions which suggests precautions may be unnecessary.

It would appear that a specific consideration of SFARP / gross disproportion is not an adopted basis of decision-making within the industry. Note however that it is not a legal duty to demonstrate SFARP, it’s just a legal requirement to be SFARP.  Many respondents referred to the very low probability of an incident. Comments included “ … falls from height incidents in company history were zero …”;  that “… there is not a great deal of empirical evidence to say there is a recognised pattern or trend of significant danger of falls…”;  and a number of respondents stated that in circa 20 to 30+ years, they have never encountered nor heard of any injury from falling into a trial pit. Finally, many respondents reiterated that trial pitting is an essential method of investigating the ground.

The questionnaire responses presented a widespread belief throughout industry that other potential methods such as barriers and harnesses, even remote tools, were impracticable on the basis of cost, the introduction of other more prevalent hazards and risks, and the maintenance and inspection requirements and training. Many respondents believe that such measures are not necessary nor appropriate, given the very short duration of a trial pit.

Finally, respondents were asked what additional controls they would consider adopting if it could be achieved practicably.  Responses included “… a safe excavation cover…” ; “… a barrier that was lightweight, affordable and practicable, which could be used to protect up to the edge or even over the excavation …” ; “… extendable trial pit covers …”; “… purpose designed lightweight edge protection barrier system …”; “… an open lattice to prevent a fall to no more than ground level …”; “ … a standard type of barrier system, aluminium, easily folded up and deployed”.

Tolerability of Risk

We’ve noted the potential and the risk of a fall, looked at the law and guidance, and at a subset of industry views on trial pitting. Does it help us determine whether current practice is good practice, and whether we need to be doing more?

Perhaps instead we can ask ourselves: “Can we tolerate the consequence of a fall?” HSE state (“R2P2”) that “tolerability does not mean acceptability. It refers to the willingness to live with a risk to secure benefits, in the confidence that it is being properly controlled. This means that we do not regard it is negligible or something we might ignore rather as something we need to keep under review and reduced to further if and as when we can”.  And that is the point of this initiative from AGS: to keep our measures under review.

Were one to examine the adopted common controls against the levels of the Regulation 6 hierarchy, we see the majority of our current controls sit very close to the bottom of the hierarchy, and particularly in the “others” category. There is a noticeable gap the within the “prevention of falls” and also the “Minimising the distance and consequence of falls” levels, conventionally those areas where other industries focus their controls.

Over the past decade at least, various practitioners have experimented with the use of harnesses to some fixed point, and staging boards with fixed scaffold barriers to view trial pits from, and encountered impracticability’s, not least the consequent and guaranteed introduction of a number of other risks which are more likely to cause an injury.

However, using the benefits of modern innovations that are now available to the market, there are products which are beginning to be used in the construction industry to minimise fall distances in particular, and whose prime benefit is that they are lightweight and portable.  AGS would be very interested to gain feedback of the use of such equipment for trial pitting.

In conclusion, trial pits are immensely valuable to good ground engineering. Much of that only comes from seeing first hand into the pit from close up; that involves approaching the edge and crouching down; it allows the taking of well composed photographs of features that you only see because you can look inside. The time of exposure to risk, and the probability of falling into a trial pit when logging is low to very low and possibly unheard-of. However, the consequence of a fall is probably serious injury or even fatality, certainly life changing.  If we wish to continue to use trial pits:

  1. ethically we should only specify them when we are really going to make proper use of them
  2. we should continue to look to use modern technology to improve our protection from falls from height.
  3. we should think more about emergency arrangements (including a rescue plan), in advance of when we need them.

AGS are establishing a trial pitting subgroup of the Safety Working Group and would be interested to hear your experiences, viewpoints or potential involvement.


  2. The Work at Height Regulations 2005
  3. HSE 2014 Working at Height :a Brief Guide. INDG401 Rev 2
  8. Reducing Risk, Protecting People (R2P2) HSE Books
  9. Edwards v National Coal Board [1949] 1 KB 704; CA [1949] 1 All ER 743

Photo Acknowledgements

Oxford Safety Components Ltd; Structural Soils Ltd; Jacobs; BAMRitchies;

Article provided by Steve Everton, Jacobs, CEng MICE, Construction Health & Safety Registered (Advanced)

Article Geotechnical

Ground Investigation – Is it time for change?

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The article entitled “are traditional sampling techniques really that bad” published in April’s AGS Magazine has provoked much discussion and debate amongst AGS members and within the industry.  The Geotechnical Working Group has been exploring how the UK geotechnical industry can respond to the demands of our clients and updates to Eurocodes and other standards to deliver investigations that enable project design of appropriate quality.  This article is intended to put the views expressed in the April article into context and propose how the full range of investigation options can be better used to deliver projects that meet the challenges of delivering our client’s needs now and in the future.

Whilst design, analysis, and construction techniques have evolved and benefited from market innovation and new techniques, many of the ‘traditional’ investigation methods have not changed in the past 100 years.  For example, the process of driving piles now benefits from instrumentation and automatic logging of construction conditions and the driving process. This enables the piling specialist to feed this data back to designers and contractors to allow rapid verification of pile capacity, design modification, and communication to the supply chain.  In contrast, the humble SPT, which forms the basis of much of the foundation design delivered in the UK, has not benefited from any significant improvement in the way information is gathered about the in-situ state of the ground.

It is true to say that there is often a conflict between cost and perceived benefit and for the uninitiated the decisions which determine the methodology used to investigate the ground conditions and the determination of design parameters is often, if not invariably, determined by cost rather than technical requirement or necessity.

This conflict has in the past been minimised by using large factors of safety. Historically, geotechnical engineers have used this factor of safety and combined it with engineering judgement to allow for variations and uncertainties within the ground, however, it is now far too often just used as a margin for error or in many cases poor quality control. This latter approach provided the comfort of knowing that even if the results were not that accurate, it really did not not matter, because failure was very unlikely. It is important to note that whilst there have been few foundation failures as a result of bearing capacity, the same is not true of structural distress due to differential settlement. This fact reflects more about our inability to accurately determine soil stiffness rather than determine the undrained shear strength. The advent of Eurocode and more precisely the use of limit state design and partial factors has removed the comfort which for many years has disguised poor practice or inappropriate investigation methods.

It is true that many clients and design teams have not fully embraced Eurocodes, however, there is a misconception that there is a choice to design either using the old methods or Eurocodes. This is a dangerous path to tread, because the old standards are no longer supported by BSi and effectively are now obsolete. The UK has always been fully committed to using Eurocodes or perhaps more correctly the new British Standards and Codes of Practice which are fully complimentary with Eurocode. The decision to follow this route was made many years ago and was embraced by our governing bodies and Institutes and indeed the UK, through AGS and other bodies, has and still does play a significant role in their content.

It is interesting to read the views given on the use of the SPT and the premise that these tests are often adopted rather than rotary coring. This is a misconception which has no technical foundation, perhaps we forget that the SPT was originally developed as a sampling tool and not an in-situ test. It was configured as a split spoon with an open shoe and in this form is a thick walled sampler in current terminology. The number of blows to drive the sample was originally something which was added to provide a bit more information on ease of penetration.  More importantly under Eurocode 7 the SPT is classified as a secondary investigation method which should be used to complement soil strength measurements derived from laboratory testing of Class 1 soil samples.  Unfortunately, in many cases, the SPT is still presented as the primary source of data to interpret in-situ soil strength.

The SPT, as we know it today, was first described by Karl Terzaghi and Ralph Peck in their book published in 1947.  At that time, the equipment had been in use for more than 30 years as a sampling tool, albeit rather crude. The sample is invariably highly disturbed and of limited value. The original equipment was modelled around similar equipment used in the USA and attributed to Colonel Charles R Gow in 1902. The original sampler, which was 1 inch in diameter, was driven at the bottom of the borehole using a 110lb hammer. Around 1927, part of the Raymond Piling Group, the Gow Company began using a split spoon sampler of 2 inch diameter. Around the same time, a similar system was being used by Sprague and Henwood. In both systems the weight was winched by hand and released at a fixed height. The split spoon sampling tool which comprised a thick walled tube with a cutting shoe on one end was driven into the bottom of a borehole with blows from the hammer. The use of powered winches was not reported until 1937. The equipment was not standardised and it is recorded that the drop weight ranged from 110lb to 140lb whilst the height the weight was dropped was related to that which men could comfortably lift, usually 30 inches. It was not until Terzaghi and Peck (1947), when describing the sampling system, suggested that the number of blows be recorded as those required to drive the sampler 1 foot following seating the sampler 6 inches beyond the base of the borehole. Terzaghi suggested that by recording the number of blows valuable information might be obtained at little cost and that the information may be of some use in soils where little other information could be obtained such as granular (coarse) soils. Up to this point there were no other tests which might indicate the potential competence of granular (coarse) soils. Terzaghi proposed to use a 60 degree cone rather than an open shoe and then count the number of blows taken to drive the cone a given distance. This has been standardised into the test form we use today. It should also be noted that the test has only recently been standardised around the world and in some countries the test still does not follow a unified method.

The open shoe often blocked off on gravel and would then produce erratic results.  For much of the next 70 years or more, the SPT was used to give something to assist engineers to determine the nature of granular (coarse) soils. Various authors have attempted to derive more useful parameters from these basic results. Many of these relationships are based on sound research but most are only relevant to the original site the work was carried out on and are not readily transposable to other sites.

It was in the 1980s that the now common use of taking an SPT in fine soils began to gain acceptance, again, several authors attempted to develop relationships which are at best tentative.

The SPT test is at best crude and often a blunt tool used to provide information of debatable value. In practice the cone is driven dynamically over a distance which far exceeds any strains the ground will be subjected to by loadings from foundations. The SPT is certainly not a replacement for laboratory testing of good quality soil samples no matter how cheap.

It is interesting to see the energy ratio (calibration) test results for the five hammers used by Soils Consultants. It is true that the introduction of an annual inspection and test has undoubtedly improved the maintenance of the equipment. However, the variation in the obtained energy ratio values reflects the inherent uncertainty of the test and probably also points towards the variation in the different equipment used to measure energy ratio by different test houses.  It also highlights how the test can be affected by numerous other factors which were described by Clayton, 1982 as ‘parasitic effects’. The suggested energy ratio calculation can create some inconsistencies between individual calibration tests and test houses as it only requires the energy ratio to be reported as the mean value of at least five measurements (blows). Extensive testing and analysis by the Equipe Group has proven that by recording at least ten blows can provide a more representative mean value and can also eliminate the effect of spurious results. Some test units simply take the average of the five blows no matter how wide the range of individual determinations might be. It is clear the test should be more rigorous, limiting the range not to exceed values of say no more than 10% of the mean. Note that BS EN ISO 22476-2 suggests that measured energy for dynamic probing equipment should not deviate more than 3% of the theoretical energy. Hammers testing outside this range should be considered as defective as any results obtained from this equipment are unlikely to be reliable, consistent or representative. The uptake of such testing has improved in recent times but it is interesting to note that BS EN ISO 22476 – 3 was published in 2005. However, it was not until 2008 when Equipe introduced an independent testing service were we in the UK, able to even measure the energy ratio.

The previous article, published in the May edition of the AGS Magazine, has presented data showing a wide scatter of test results from various methods (Graph 1). This graph provides evidence that the London Clay is far from homogeneous, with values of Cu and SPT varying considerably through the formation. This is not surprising when considering the work of King et al, 1981 which identified some four divisions and 12 subdivisions in the formation. Indeed, a visit to the classic exposure at Whitecliff Bay, IOW will demonstrate how much variability is contained within the sequence.

The data in Graph 1 reinforces the need to investigate each site as an individual location and to use the best possible methods to obtain reliable data to ensure that the parameters sourced are as representative as possible for the specific design requirement of any particular site. Indeed, the data presented demonstrates how difficult it is to try to over simplify the data and analyse amalgamated results. Designers all too frequently seek to draw straight lines which are used as design lines or even give an upper and lower bound. This design approach often ignores the natural variability of the materials. This variability is further demonstrated by Standing, 2018 who used water content to determine the boundaries between the divisions identified by King. His work clearly identifies the variability of water content in the various divisions and geotechnical practitioners are very aware that water content will directly affect the measured undrained shear strength.

Whilst not wanting to disregard all of the current investigation methods used to obtain geotechnical parameters for design purposes, it is important to bear in mind that sampling methods which use driven thick walled sampling tubes will produce disturbance of both structure and water content distribution through the sample. This is clearly demonstrated by the fact that much of the London Clay is laminated but it is very rare that these laminae are seen in driven tube samples whilst they are seen to be present in high quality rotary cores. Tube samples usually exhibit a softer outer skin which is developed by pore water suctions being developed as the tube is driven, causing water to migrate from the centre of the core to the outer edge. This moisture migration will affect the undrained shear strength when tested in the triaxial apparatus.

U100 sample taken in a stiff laminated clay showing acute sample disturbance (The lump at the base is wax.)

The variability of the London Clay is also clearly exhibited by CPT tests carried out within the sequence. These demonstrate the variability over short distances and reinforce the argument that the formation does not conform to straight lines. Therefore, designs which result from straight line analyses are likely to be prone to simplifying the in-situ ground conditions which could lead to errors in interpretation..

For many years the geotechnical community have chosen to ignore the obvious and often stated limitations of both the SPT test and driven samples. Of the SPT, Clayton et al stated that in granular (coarse) soils, the SPT results can only be correlated in a general way with physical properties whilst in cohesive (fine) soils the results can be regarded as generally unreliable. This was further reiterated in 1995 by Clayton and again in 2001 by Prof. Paul Mayne. Simons, 2001 cite sound research to support these opinions.

The evidence produced by many authors shows that both thick walled sample tubes and SPT testing provides very poor results and cannot be recommended for the reliable determination of design parameters.  Eurocode clearly labels these samples as Class 3 or 2 and as such unsuitable for strength or deformation testing. The UK’s recommended design methods using codes which have been decades in their production and compiled by respected members of our engineering community require that good practice must be followed to ensure a safe and economic design. The essence of Eurocode is one of a complete document which serves to ensure the design method is supported by good practice and not a document where specific parts can be lifted as one feels fit, whilst other parts are ignored.

Surely it is time that we embrace the technology at our disposal to ensure ground investigation is conducted properly and to the standards we would expect in almost any other walk of life. Relying on the results of a steel rod or tube knocked into the ground does not constitute best design practice in the 21st century.

We are not advocating that the SPT is going to be consigned to the museum, however, as a start point we must surely be able to take out some of the errors which are sadly still apparent, this might include electronic measurement of the depth of penetration along with the number and energy of blows delivered to the rods.

There is still much to do if we are to move on from the SPT and driven sampling methods, however, we do need to put our faith in our ability to find solutions. It is time to invest in research to develop reliable methods to determine water content, density and stiffness. It is only by doing this, that we will be able to provide workable economic designs and alternatives to outmoded and scientifically unsuitable methods.

There is little point in appeasing the client by keeping costs as low as possible and then providing the wrong answer which can tarnish professional reputations and test the strength of your PI insurance..


King C. 1981. The stratigraphy of the London Basin and associated deposits. Tertiary Research Special Paper, 6 Bachuys Rotterdam.

Standing J. R. 2018. Identification and implications of the London Clay Formation divisions from an engineering perspective. Proceedings of the geologists association 2018.

Clayton C.R.I, Simons N.E. and Mathews M.C. 1982. Site Investigation. Granada

Clayton C.R.I. 1995. The Standard Penetration Test (SPT): Methods and Use. CIRIA Report 143. London: CIRIA 143.

Simons N. E. and Menzies B. K. 2001. A short course in foundation engineering. (2nd edition) Thomas Telford Publishing London.

Mayne P. W. 2001. Ground property characterisation by Insitu tests. Proc.15th ICSMGE Istanbul.

British Standards Institute. 2015. BS 5930 Code of Practice for Site Investigation.

Article provided by Peter Reading (Geotechnical Consulting) and Stephen Lawrence West (Ramboll)

Article Instrumentation & Monitoring

Introduction to the AGS Instrumentation and Monitoring Working Group (I&MWG)

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In March last year an international Instrumentation and Monitoring (I&M) Conference in London concluded with a Ground Engineering Round Table debate intended to identify matters within the I&M sector that needed attention.

It became apparent that there were key areas of concern about the need for education, training, and qualifications.

Taking an active part in the Round Table debate was Jonathan Gammon, Non-Executive Director and Advisor at I&M specialists Geotechnical Observations Limited and a Past-Chairman of AGS.

Jonathan believed that AGS was well-placed to take forward the matters discussed and subsequently submitted to AGS a proposal for the formation of an Instrumentation and Monitoring Working Group (I&MWG). AGS’s Executive approved the proposal towards the end of 2019 and invited Jonathan to be its Leader.

The role of I&M
“It’s easy for those of us directly involved in I&M to understand the importance of I&M” Jonathan recognises “but I hope the following diagram – my “GeoWheel©” – illustrates just how important it is:

The GeoWheel© is a means of:
• showing how ground engineering can be divided into distinct activities and how these activities interact,
• introducing Clients to the scope and range of services available to them,
• showing the nature, ownership, and progression of reports that are generated during a project’s lifecycle, and
• identifying key areas of “know-how” required of staff seeking professional qualifications such as Incorporated Engineer (IEng), Chartered Engineer (CEng), and Chartered Geologist (CGeol)

The four activities beyond the rim of the GeoWheel© (e.g. Project Management), hold steady the dynamics of the GeoWheel©.

The “R&D” activity that features at the hub of the GeoWheel© is short-hand for a range of activities such as Advanced Numerical Modelling Physical Modelling, Innovation, and the like … as well as Research & Development.

I&M lies at the hub of the GeoWheel© – indeed, forms its axle – and is therefore critical to both the rotation and the stability of the diverse activities around the GeoWheel© and those neighbouring activities at the hub itself.

I&M relates not only to geotechnical engineering and engineering geology but also to tunnelling, environmental engineering (including contaminated land and environmental monitoring), and structural engineering.”
It is important to note that the GeoWheel© does not identify the necessity to consider I&M on a Whole-Life basis, taking in long-term as well as baseline requirements. These may extend well beyond construction or implementation and include asset management, decommissioning, and demolition, as appropriate.

The Aims of the I&MWG
The importance of I&M, the need for it to be placed on the education curriculum, the need for formal programmes of training, and for there to be recognised qualifications for all those involved in I&M are the key drivers of the Aims of the I&MWG:
• To promote geotechnical, structural, and environmental instrumentation and monitoring (I&M) to the geotechnical, geoenvironmental, and wider ground engineering community.
• To raise awareness to clients, asset owners, their professional advisors, and related parties, of the need for baseline (i.e. pre-implementation/construction), project implementation, and post-implementation I&M for all types of projects and asset management.
• To be a focal point for the education and training of those engaged, or seeking to be engaged, in I&M including, but not limited to: the design and manufacture of instruments and related software and research and development, the design of and specification of I&M, the procurement of I&M, the installation of instruments, and the interpretation and presentation of I&M and related software.
• To identify and define an appropriate data format to effect the transfer of I&M data for interpretation, analysis, and presentation.

These Aims are contained in the “Terms of Reference and Modus Operandi” document as a necessary feature of the proposal to form this new Working Group.

The document then sets down how these Aims are to be achieved through the Group’s Activities, by:
a) promoting the activities of the I&MWG to the AGS Membership and to the wider industry.
b) maintaining a watching brief on I&M activities of the wider national and international engineering and related communities, and reporting these to the membership.
c) organising and running I&MWG initiatives and events on behalf of AGS.
d) being involved closely in the drafting and reviewing of national and international standards, codes of practice and other definitive guidance.
e) being represented on national and international Technical Committees, and the like, in addition to d), above.
f) being pro-active at all levels of education and technical and professional training.
g) establishing and promoting recognised qualifications for all those engaged in I&M work.
h) striving to become a leading national authority on I&M matters affecting the AGS Membership and the wider industry.

Promotion of the I&MWG within AGS and the Founding Members of the I&MWG
Existing Members of AGS were contacted to identify individuals who could be the Founding Members of the I&MWG. “My ambition was initially to establish what I saw as a “critical mass” of at least ten members forming the I&MWG”, reports Jonathan.

The Founding Members of the I&MWG are:
Jonathan Gammon Geotechnical Observations Limited [I&MWG Leader]
Neil Atkinson Arcadis
Paul Bailie Arup
Katharine Barker Campbell Reith
Tom Birch Geotechnics
Philip Child Bentley Systems
Chris Crosby Bridgeway Consulting
Emma Leivers Geotechnical Engineering
Mario Markos Miletic Fugro
Rachel Monteith BuroHappold Engineering
Andrew Ridley Geotechnical Observations Limited
Alice Shrubshall BuroHappold Engineering

“In time, and as we work our way through our planned activities, the size of the Group will grow, probably to a maximum of 20 members”.

Promotion of the I&MWG beyond current AGS Members
Some companies and organisations who are actively involved with I&M, including public and private sector Client organisations and institutions such as the Royal Institution of Chartered Surveyors (RICS), are not Members of AGS.

The I&MWG has also been brought to the attention of a wider audience as a result of articles published by Ground Engineering on its website “This is a welcome opportunity to thank Michaila Hancock at GE, in particular, for her articles about I&M and the I&MWG.” Jonathan adds.

First Meeting of the I&MWG and Current Status of Aims and Activities
As a result of COVID-19 restrictions, the first meeting of the I&MWG took place online on Friday 24 April 2020.

With reference to the Aims and related activities:
a) Action relating to promotion of the Group has already been described in this article. Although the cancellation of the AGS Members Conference in April prevented an introduction to the I&MWG taking place at that time, this article is intended to make up for that lost opportunity.
b) Concerning wider national and international communities, contacts have already been established with various organisations and individuals. These include leading I&M practitioner John Dunnicliff, author of the world-famous book “Geotechnical Instrumentation for Monitoring Field Performance”, who asks the I&MWG to acknowledge “the importance of human factors in geotechnical and structural monitoring programs”. A proposal to form a parallel I&MWG at AGS in Hong Kong was surprisingly unsuccessful although AGS(HK) have identified a point of contact with their existing Working Groups. A favourable response has been received from the British Tunnelling Society to contribute to revisions to their “Tunnelling Specification” and “Monitoring Underground Construction” documents.
c) A one-day AGS seminar (“Critical Links in Ground Engineering”), was planned by AGS at the time the I&MWG was formed. Scheduled initially for 15 July, a postponed date for this event in November is currently being sought, at which time it is likely to take the form of a webinar (c/o Caroline Kratz at AGS).
d) Regarding standards and the like, AGS’s revision of the “Yellow Book” – the UK Specification for Ground Investigation – will now include input from the I&MWG. BSI’s BS5930:2015+A1:2020 “Code of Practice for Ground Investigations” has just been published and includes a section on I&M.
e) Relating to Technical Committees, I&MWG member Andrew Ridley is Chairman of the ISSMGE’s Technical Committee TC220 “Field Measurement in Geomechanics” and is a member of the ISO’s Technical Committee ISO/TC182/WG2 “Monitoring in Geotechnical Engineering”. Andrew is also Chairman of the Organising Committee for the 12th FMGM Symposium to be held in early September 2022 at Imperial College, London.
f) g), and h). The I&MWG has already been represented at training events [f)] including a British Drilling Association Seminar and it plans to extend its engagement with education and technical and professional training and the establishment of recognised qualifications as soon as possible.

The I&MWG will be contributing to an AGS initiative relating to Procurement as influenced by the Institution of Civil Engineer’s “Project 13” and encompassing related issues such as Specifications and NEC4 (and its application, for example, to Ground Investigation).

Matters such as data format and management will be tackled in conjunction with AGS’s Data Management Working Group and there are other examples of where an ability to engage directly with another AGS Working Group will be to the I&MWG’s advantage.

And now there is a new matter needing the I&MWG’s attention: The impact of COVID-19 on I&M in the future.

Contact for the I&MWG
To contact or register interest in the I&MWG, please email Katie Kennedy at



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This new standard is intended to raise the reliability of sampling soils for determination of VOCs in the UK, by introducing methods that have been common use in countries such as Australia and the United States for over twenty years. It has been known for decades that the methods commonly used in the UK do not provide reliable results and can lead to loss of VOCs during sampling, and consequentially underestimation of potential risks to humans and other receptors.

The primary purpose of the draft standard is to provide risk assessors and managers with data that is as representative as possible of conditions in the field, in relation to volatile elements that might otherwise be lost in the sampling and analytical processes. In this context, it is the limits of detection of concentrations in the field that are of primary importance, rather than the limits of detection in the laboratory, although of course the latter can also be a major influence on the former.

The introduction of the new standard will have a significant impact on how companies carry out sampling for VOCs and require close cooperation between those carrying out field work and analytical laboratories.

BS 10175:2011 + A2:2017 states in Clause 8.3.2 that when collecting samples for determination of volatile compounds the sampling technique employed should minimise the loss of volatiles. It is noted that a methodology for the collection of soil samples to minimize loss of volatiles is given in BS ISO 18512: 2007 (this refers to methanol immersion). The new standard should make it easier to comply with this recommendation.

BS 10176 will be a standard specification which means that its requirements must be closely followed to claim compliance. It thus differs from other standards such as BS 10175 and the BS ISO 18400 series which provide guidance and permit, and indeed rely on, the user using their judgement when applying them.

The new standard specifies sampling procedures for application in the field.

Analytical procedures are outside of the scope of the standard and the standard makes clear that it is the responsibility of laboratories to adopt analytical procedures that will provide accurate analytical results for samples as presented to them.

Laboratories are required by BS 10176 to provide pre-prepared sample containers complying with the specification provided in the standard. These are to be used in the field in strict accordance with the procedures described in the standard. Samples must be transported to the analytical laboratory in strict accordance with the prescribed method.

Preparation of the New Standard

Approval for the production of the standard was given by BSI committee EH/4 in October 2017. The decision was “advertised” in an -mail dated 31 October 2017 widely distributed to the contaminated land community by Mike Smith, the Vice-Chair of EH/4. Inter alia, the e-mail invited applications to join the Drafting Panel. The Drafting Panel began its work in May 2018 under the leadership of Geraint Williams. The Draft for Public comment (DPC) was circulated in July 2019.

The draft standard was prepared drawing on existing published guidance and standards, and the personal experience of the members of the Drafting Panel and others. It was recognised and anticipated that there were points of detail that laboratories, consultants and others might query. However, none of the comments submitted via the regular BSI process, suggested that there was anything fundamentally wrong with the standard and all such comments were readily dealt with following the usual BSI comment review process.

As mentioned in the Introduction to the standard, the use of methanol immersion to preserve samples containing VOCs is already required or recommended in a number of British Standards. The procedures specified in the standard amplify those in BS EN ISO 15009, BS EN ISO 16558-1, BS ISO 18512 and BS EN ISO 22155 for the application of the methanol immersion method. The specification also introduces procedures for application of the sodium hydrogen sulfate (sodium bisulfate) solution immersion method.

The inclusion of methanol immersion in these existing standards is an indication that it is internationally recognised as a desirable methodology for certain purposes and as noted in the standard, there are also descriptions of the procedure in standards and guidance in the USA and other countries. In addition, a number of major UK consultancies already make use of such methods on a regular basis and there is reference to it being used in the UK at least twenty years ago. It is not a novel procedure and it was consequently considered reasonable to assume that at least some UK laboratories are already familiar with the process.

The use of immersion in sodium hydrogen sulfate solution is not so well known in the UK but it is a standard procedure in the USA and other countries.

The procedures described in the existing BS ISO standards are not very precise and so it was deemed desirable to produce a more detailed specification that would help to ensure consistency of application and would be amenable to auditing (by UKAS etc. or clients as part of QA/QC) if required. Although the specification is of necessity prescriptive, it does recognise the need for flexibility to permit application in a variety of situations. Detailed procedures can always be deviated from provided what has actually been undertaken and the reasons for the deviation are properly justified and recorded.

Feedback to BSI on experiences of application of the new standard will be important to its successful application and help to ensure that it can be updated as necessary in due course. Feedback and queries should be sent to the Jessy Mathew, the Manager of BSI committee EH/4 ( )

BS 10175:2011 + A2:2017 Investigation of potentially contaminated sites – Code of practice
BS EN ISO 15009 Gas chromatographic determination of the content of volatile aromatic hydrocarbons, naphthalene and volatile halogenated hydrocarbons – Purge-and-trap method with thermal desorption;
BS EN SO 16558-1 Risk–based petroleum hydrocarbons Determination of aliphatic and aromatic fractions of volatile petroleum hydrocarbons using gas chromatography (static headspace method);
BS ISO 18512 Soil quality – Guidance on long and short term storage of soil samples;
BS EN ISO 22155 Gas chromatographic determination of volatile aromatic and halogenated hydrocarbons and selected ethers – Static headspace method

Article provided by Mike Smith

News Business Practice Contaminated Land Data Management Executive Geotechnical Laboratories Loss Prevention Safety

AGS Awards 2020

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Below are the list of recipients of this year’s AGS Awards. We would like to thank all Working Group participants for their hard work over the last year in raising standards across the industry and increasing the profile of the AGS on the whole.

AGS Safety WG Award
Madeleine Bardsley
Madeleine has been a stalwart of the SWG for a number of years and her experience and knowledge of working on contamination sites has been invaluable in producing and reviewing a wide range of publications and guidance documents. Madeleine is a regular attendee at our quarterly meetings and is always keen to be fully involved in the lively and frank discussions.

AGS Safety WG Award
Steve Everton
Steve is a very active member of the SWG and has been a committee member for several years. Steve has been recently involved in providing further input into the updated asbestos risk assessment working in collaboration with the CLWG. Lately, Steve has been instrumental in our current view of the safety of trial pitting from a working at height perspective and is currently working on analysing the questionnaire shared throughout our industry with future magazine articles. Steve also delivered a thought provoking presentation at the recent “Safety in Mind” conference on the subject of trial pitting.

AGS Safety WG Commendation
Roseanna Bloxham
Rosey is a relatively new member of the SWG committee, but has quickly established herself as a key member of the team. Rosey has contributed and worked on new and current safety guidance. Notably, Rosey delivered an excellent workshop using Lego at the recent “Safety in Mind” conference with a follow-up article in the recent e-magazine.

AGS Business Practice WG Award
David Hutchinson
Although David is the newest member of the Business Practice Working Group, joining in 2019, he has already proved to be a very valuable member of the team. He has been prolific in providing analysis key to the endeavours of the group and has produced several documents in a very timely manner for review and publishing. We thank him very much for his continued willing and cheerful assistance to the AGS overall and to the Business Practice Working Group in particular.

AGS Business Practice WG Award
Neil Parry
It goes without saying that Neil, as Past Chair and a long-standing AGS contributor, has provided a great deal of value to the Association over the years and his dedication to the AGS cause has been consistent and diligent since 2007. Neil has previously led the Business Practice Working Group and remains an active member, contributing greatly to AGS governance and marketing and providing valuable insight at meetings.

AGS Business Practice WG Commendation
Ken Marsh
For unfailing support and diligence in participation to Business Practice activities for many years in addition to his responsibilities as AGS Treasurer. Ken has provided invaluable advice and input to the strategy of the AGS through Business Practice contribution.

AGS Loss Prevention WG Award
Jo Strange
This is to reflect Jo’s long standing and active contribution to the LPWG over more than 10 years. Jo has been involved in the research and preparation of the Loss Prevention Guidance, Newsletter articles and some Loss Prevention Alerts. Jo has always been generous with her time and always helpful in reviewing and commenting upon many and various documents published by the LPWG. Her comments are always kind, useful and improve the advice. In particular, Jo was a great Chair of the Loss Prevention conference earlier this year and is repeating her contribution in Manchester this coming January. On the basis of all of this contribution, I would very much like to recognise Jo’s significant contribution to the LPWG with an AGS Award.

AGS Data Management WG Award
Roger Chandler
Roger Chandler joined the AGS Data Management Group in 1999. The group has proposed him for this Award in recognition of his tireless work on behalf of the AGS at conferences and elsewhere in promoting use of the AGS ‘Electronic Transfer of Geotechnical and Geoenvironmental Data’ format (data transfer format).

Over the last 20 years he also has been very active in promoting the AGS Format throughout the world, including Australia, New Zealand and Hong Kong, but especially in the USA. In 2005, Roger was invited to join a group there which was tasked with creating a global geotechnical data exchange format. Their plan was to use AGS 3.1 as the basis for their XML format. Whilst DIGGSml now has a good following in the United States, the UK was unable to make a workable version for its users and in 2010 our paths diverged and AGS 4.0 was created. Roger has maintained his ties to the US project and gives us regular updates on its development.

In his new role as Director Geotechnical Information Management at Bentley Systems, he is no longer able to attend all our meetings, but we still hope to see him occasionally.

AGS Executive Award
Vivien Dent
Viv has led the Contaminated Land Working Group with vigour and enthusiasm and has always been an active member of the Executive Committee. Viv has been instrumental in helping the AGS to develop and deliver extremely high standard conferences and has persuaded high level speakers to be involved. She has also continually encouraged her working group to produce interesting and informative articles for the AGS Magazine helping to keep the members aware of the working group activities, issues and hot topics. She is a great ambassador for the AGS and clearly enjoys her work and long may this continue.

Article Loss Prevention

Q&A with Jo Strange

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Full Name: Jo Strange
Job Title: Technical Director
Company: Card Geotechnics Limited (CGL)

I am a chartered civil engineer and environmentalist with over thirty years of experience. I’ve worked for multi-disciplinary consultancies before joining specialist geotechnical and geo-environmental consultancy, CGL. I am responsible for delivery of mostly brownfield projects involving due diligence, audits, planning, management, design, specification, implementation and interpretation of site investigations, risk assessments and remediation. I occasionally take on Expert Witness projects also. I manage SHEQ across the company and supervise technical staff towards Chartership with the ICE and IES. I am a STEM ambassador and involved with the ICE as a Reviewer, on Standards Panel and author of their guidance on Contaminated Land.

Away from work, my passion is my horses, especially side saddle riding and Cleveland Bays.

What or who inspired you to join the geotechnical industry?
It happened a bit by accident. My MEng was in civil and environmental engineering from Liverpool University, when environmental engineering was still in its infancy. I joined Mouchel as a graduate and was duly dispatched to ‘the Grotto’ where the geotechnical team were based. At the time David Jones was developing contaminated land capabilities and I got involved through him on projects like Thurrock MSA. After a couple of years rotation around the various departments, designing shopping centres, (The Wellington Centre in Aldershot and The Peacocks in Woking all have a bit of me in them!), post tensioned bridges, grain conveyors, David invited me back to work on contaminated land projects and as they say…. the rest is history.

What does a typical day entail?
There isn’t really a typical day, as every day is different, with the numerous projects on the go at any one time and my various management roles. The day always starts with checking emails for what might have happened that requires an urgent response. Next, there will be project reports to write, check or review; technical queries to respond to, proposals to write, discussions with Clients, contractors, CGL project managers and engineers; internal / external or site meetings, planning of training and compliance audits and actions… and not forgetting finding time to catch up with the great bunch of people who work at CGL!

Are there any projects which you’re particularly proud to have been a part of?
All of then really, as I hope I give all my projects 100% to get the best answer, but if I have to pick, it would be the Blue Print industrial Estate in Portsmouth. This was an early project with BG Properties Gasworks. More recently, the ground investigation at the old New Scotland Yard which had some serious logistical challenges and currently the remediation of Royal Wharf with Ballymore which has transformed for the better that stretch of waterfront.

What are the most challenging aspects of your role?
Juggling time and energy to support staff and projects on the technical side whilst developing new works and delivering quality results and advice. Keeping a life/work balance is important.

What AGS Working Group(s) are you a Member of and what are your current focuses?
Loss Prevention Working Group; there are lots of things on the go, from looking at the impacts of contract clauses, poor wording in reports, disputes and events and trying to use a crystal ball to see what commercial issues may be arising in future.

What do you enjoy most about being an AGS Member?
Being part of a group and network of intelligent interesting professional people who are passionate enough about what they do to want to share their experience. It is also a great forum to exchange ideas and thoughts.

What do you find beneficial about being an AGS Member?
Following on from the previous answer, the library of information and guidance is amazing and it is easy to forget how comprehensive and accessible it is. Although, I haven’t used them very much, knowing that the ‘helplines’ are there and the knowledge/ experience of the people behind them, is re-assuring.

Why do you feel the AGS is important to the industry?
The industry has such a variety of skills and technologies that the AGS provides a central ‘hub’ and place of reference, where ideas, latest thinking and best practice can be collated and disseminated and provides a single point of contact enabling the ground engineering industry to present a coherent and consistent face to the construction and land management sectors.

What changes would you like to see implemented in the geotechnical industry?
Recognition of the value and importance of what ground engineering, (be it geotechnical or geoenvironmental), brings to construction projects. We so often see that the lowest price is the deciding factor, when high quality data and advice is what is needed to get the right and most economic answer first time.

John Burland was so right when he said you would pay for a ground investigation whether you have one or not, but the flexibility and benefits of having quality up front information, with some exceptions, doesn’t seem to be a message that gets much further than the ground engineering specialists.


AGS Video Competition – The Results

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Following on from our hugely successful photography competition, in winter 2019, the AGS launched a video competition to view the industry’s most creative clips.

A whole range of videos were submitted from members including recordings of rigs, ground improvement projects, geology models and concrete testing. The AGS Officers had the difficult task of reviewing each of the entries, and have shortlisted three outstanding clips:

1ST PLACE: In Situ Site Investigation, Rail Rig Time-Lapse Video

A time-lapse video which shows the simplicity of using CPTs on a railway using an RRV from the on-tracking process. Tests were completed either side of a bridge abutment to provide information about the ground material in order to rebuild a bridge.

2ND PLACE: Harrison Group Environmental Limited, Geology Model Video

A geology model representation of an investigated feature. The clip showed how data can be interpreted from geology “sticks” at each investigation location into triangulated surfaces. The resulting output helped to explain what occurred in the area and could be analysed further with tools such as section profiling.

3RD PLACE: Jones Bros and BWB Consulting, Sheet Piling and Ground Improvement Project

A short video showcasing sheet piling and ground improvement works on a geotechnically challenging project along a dual carriageway link road in Wigan.

Congratulations to In Situ Site Investigation who have won a Fortum and Masons Tanner Hamper worth £85. The hamper features an assortment of Fortnum’s classics, including sweet and savoury jars, a tea tin, biscuits and confectionery delights. Harrison Group Environmental Limited and Jones Bros & BWB Consulting, have each won a bottle of Champagne.

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



Article Loss Prevention

Useful guidance regarding COVID-19 from Beale & Co

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AGS Affiliate member, Beale & Co have produced several materials including guidance notes and updates in relation to COVID-19 to assist with legal and commercial risks. These materials can be accessed on Beale & Co’s website:

If you’re an AGS Member and are looking for legal advice, please contact Beale & Co on 020 7469 0400 and quote ‘AGS Helpline’ where the first 15 minutes of legal advice will be free of charge.

Article Contaminated Land

AGS Contaminated Land WG Update

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Vivien Dent, AGS Contaminated Land Working Group Leader, has provided an update from the Groups most recent meeting, which was held virtually on 28th April. Here is an overview on the top topics which are currently in discussion:


We’re currently in the final stages of reviewing the AGS Guide to Asbestos, and are close to completion. The guide will be published on the AGS website in due course.


The Contaminated Land Working Group have decided to create a key reading document. This will be primarily aimed at graduates or those new to the industry, and will feature a reading list of key documents across all areas to educate and guide individuals who are new to the field.

We’re keen to engage with graduates and early career professionals, so this working group task is specific for this new generation of geo-environmentalists.


UKAS plans to establish a pilot programme for the development of ISO/IEC 17020:2012 accreditation for the inspection of land for the presence of asbestos.

The AGS CLWG have concerns that the scheme has not considered broader land contamination issues and that people who are unqualified will attempt to do the role of a contaminated land engineer. Whilst an asbestos surveyor might be qualified to look into asbestos, it’s unlikely that they’ll understand all documentation and the processes for all contaminants.

Naturally we don’t want there to be a situation where projects are required to have both an asbestos surveyor and a contaminated land surveyor. This would be an additional project expense and create additional work and expense for the client.


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

News Safety

AGS Guidance on Safe Ground Investigations in Light of COVID-19

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COVID-19 is an infectious disease caused by a newly discovered coronavirus (SARS-CoV-2) which is commonly spread through coughing and sneezing, through close personal contact or touching an object or surface (fomite) that has the virus on it and then touching your eyes, nose or mouth without having first cleaned your hands.

The AGS Safety group has developed this guidance in anticipation of a general return to site to carry out geotechnical, contaminated land and other ground investigation activities.  It will be reviewed and revised in the coming weeks in line with government and industry advice.  Readers are encouraged to make comments, offer suggestions and send in photographs of site work that can be added to the document.

 Any suggestions for modifications to equipment need to have been fully risk assessed for any risks they introduce. For instance, screens fitted to rigs reduce the ability to hear each other and Perspex scratches very easily and also goes opaque quite rapidly, reducing visibility. Likewise lifting “extensions” can introduce additional manual handling risks.

 This guidance is based on UK Government and CLC advice. The Government issued generic guidance on 11 May 2020: Working safely during COVID-19 in construction and other outdoor work: Guidance for employers, employees and the self-employed.  Other restrictions and advice may apply in Scotland, Wales and Northern Ireland however this guidance is intended to apply throughout the UK.  The Construction Leadership Council (CLC), on 19 May 2020, issued Site Operating Procedures (SOP) version 4 based on this Government guidance.  The key premise of this guidance is to stick as close as possible to the CLC v4 guidance as possible noting the CLC reminder to comply with the latest Government advice on Coronavirus (Covid-19) at all times.

The guidance can be downloaded here.

If you have any comments or suggestions for the guidance, please email

Article Safety

We’re going on a bear hunt…

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…Safe access onto GI sites

Well, maybe not a bear hunt, but if you have small children you will be able to relate to mud…you can’t go under it, you can’t go over it, so let’s go through it….squelch, squelch, squelch.

Following the record-breaking winter of 2019-2020, where wet weather continually interrupted and caused havoc on sites throughout the UK, The AGS Safety Working Group has been looking at appropriate solutions for gaining safe access onto ground investigation sites.

The nature of our work often involves accessing sites with heavy plant, vehicles and machinery. In addition to the many health and safety issues whilst using this equipment, other considerations include damage to agricultural land, potential habitat loss and more often unhappy landowners who were unprepared for the potential damage and disruption we may have caused.

Consideration of ground disturbance during the contract is often neglected within the framework of the Construction, Design and Management Regulations (CDM 2015) and is often a major factor in contractual disputes. Additionally, there is often a significant time lapse and delay between the tender stage and site mobilisation, with deteriorating weather conditions having a significant impact on the underlying ground conditions.

In this article we explore how we can work together to avoid these situations. A walkover of the site by both the Designer at the design stage and the Contractor at tender stage is a good first start. This will determine an early appreciation of the likely site access conditions and limitations and enable consideration of the potential options to consider for gaining safe access to and on the site.

The Role of CDM

Under CDM, the Client must make sure there is sufficient time and resources allocated, the Designer must manage, monitor and coordinate health and safety in the construction phase of a project and the Contractor must prepare the construction phase plan (CPP), including the risk assessment and method statements.  Contractors must ensure that the plant and support vehicles engaged on the site are suitable for the task, e.g. with all-terrain tyres or tracks. All drivers must be competent to drive all-terrain vehicles through appropriate training and experience. The potential recovery of bogged down vehicles must also be considered and documented, with a safe method of recovery using appropriate equipment, training and resources.

Access Options

There are broadly three types of methods to gain access to site:

No ground protection: Direct access by vehicles and machinery with the intention to reinstate on contract completion. This method has several disadvantages including delays caused by bogged down vehicles; unsafe ground conditions including rutting and consequently slip, trips and fall hazards; harm to protected species particularly on fragile grasslands; damage or destruction of habitats; damage to the ground; and mud and debris spread onto the highway. An issue with this method is the unknown amount of reinstatement that will be required on completion, whether it will be the satisfaction of the Investigation Supervisor and landowner and who covers the costs which could be significant.

Roadway Construction: Construction of a temporary roadway using imported granular materials is classified as temporary works with associated implications. Importation of road construction materials requires good source and site control to prevent potentially contaminated materials entering site, particularly when recycled aggregate is used which may contain metal, asbestos fragments, tarmacadam and organic materials. A geotextile type membrane is often placed between the imported materials and the original ground surface. Further issues may include construction time of the road before ground investigation can commence; poor drainage and soft ground beneath the roadway; costs associated with the temporary works; and removal and controlled disposal after the works are complete.

Ground Protection: Roadways and paths can be protected from extensive damage from vehicles and footfall using ground protection in the form of temporary trackway mats. Trackway has the advantage of being generally portable, reduce reinstatement work and costs, can be site specific, and reduces the likelihood of vehicles becoming stuck.

How CDM and the options work together

Preparation of the CPP for either of the chosen access methods listed above will require a consideration of hazards and regulations. Particular hazards to consider are:

The Designer and Contractor also have responsibility to recognise the possible damage to the ground surface when carrying out construction-based activities. Whatever the activity, ground disturbance almost always happens to some degree and can be very weather dependant. Leaving the ground in a safe condition at the end of works is a primary requirement but leaving it so that it looks as “if you wouldn’t know we’d been” is practically impossible.The pre-construction Health and Safety assessment must identify these hazards specific to the site. With knowledge of these hazards the Client must allow sufficient time and resources to the project to allow safe access. This means enough time for safe access to be resourced for. It is the Designers duty to eliminate, reduce, isolate or control foreseeable risks that may arise perhaps by considering if the work at that location is actually required, considering and arranging different access points, changing the type of work therefore reducing equipment and vehicle movements or how to control the hazards by the type of ground protection required. It is the Contractors duty to ensure that the activities are carried out to the design, safely. This includes the installation and removal of ground protection as per the manufacturer’s instructions.

The Specification

The UK Specification for Ground Investigation addresses ground disturbance in Clauses 3.15, 3.16 and 3.17. Particular reference should be made to Clause 3.15.1:”all work shall be carried out with the least possible damage to the site and its environs” and Clause 3.16.1: “the whole of the site and any ancillary works shall be left in a clean and tidy condition”.

The site-specific specification then often lists a lot of subjective statements that are difficult to accurately cover at tender stage such as:

It is required that wherever the ground surface (hard or soft finish) is disturbed by the investigation activities, the contractor will reinstate the surface fully using the same materials to match as closely as possible to the original finish to the satisfaction of the property owner.

The Contractor shall make good damage, whether in the vicinity of the hole or on the access route there to the satisfaction of the Investigation Supervisor.

To avoid prolonged contractual arguments regarding the reinstatement, the Designer should ensure that all CDM responsibilities are upheld, the Client is fully briefed into what to expect during and after the works, and that there is sufficient site specific detail to allow the Contractor to adequately and fairly cover reinstatement costs in the contract.

Ground Protection Methods – Track Mats

There are many suppliers of ground protection mats within the UK construction industry. When selecting the type of track mat to be used the following can be considered:

Typical ground protection products are summarised below:


Elizabeth Withington Principal Engineering Geologist CC Ground Investigations Ltd

Marcus Oliver Product Development Manager Ground Guards UK


The Construction (Design and Management) Regulations 2015

The Manual Handling Operations Regulations 1992

The Provision and Use of Work Equipment Regulations 1998

The Lifting Operations and Lifting Equipment Regulations 1998

Wildlife and Countryside Act 1981

UK Specification for Ground Investigation Second Edition 2012

The AGS Guidance on Working on Soft Ground can be downloaded here.