The IES Land Condition Symposium

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The Institution of Environmental Sciences (IES) are holding Land Condition Symposium in London on the 8th March 2018.

Are you an expert practitioner, remediator, consultant, academic, researcher, or a central, regional or local government officer working in land condition? Then this event is for you.

This one-day technical symposium will focus on knowledge exchange, debate and discussion addressing topical issues at the centre of land condition.

The confirmed speakers include:
1. Claire Dickinson, Director at Geo-Environmental Matters Ltd
2. Harry Burchill, Planning Policy Officer at RTPI
3. Nicola Harries, Project Director at CL:AIRE
4. Peter Atchison, Managing Director at PAGeotechnical Ltd
5. Eric Dede, Research Engineer at University of Reading

Download the programme and see the full list of eminent speakers presenting at this event.
To book your place for the event, please click here.
Sponsorship and Exhibitor spaces are available at this event, visit the IES website for more information.


PCBs: What are they, and which Suite do I need for my Site Investigation?

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By David Bowen, Senior Chemistry Supervisor at TerraTek

There are 209 Poly-Chlorinated Biphenyl (PCB) congeners, named in simple terms using BZ numbers, ranging from BZ#1 (2-Chlorobiphenyl) to BZ#209 (2,2’,3,3’,4,4’,5,5’,6,6’-Decachlorobiphenyl).
Of these 209 congeners however, only the EC7 and WHO12 congeners are routinely tested for by commercial environmental testing laboratories. So why only these 18 congeners (one congener, BZ#118, appears in both suites) you may ask? And what about the other 191? Furthermore, which of these PCB suites would be the most suitable for your site investigation?
Poly-Chlorinated Biphenyls (PCBs) are Biphenyl organic compounds, C12H10, with the hydrogen atom substituted by a Chlorine atom. There can be from one to ten substituted atoms, C12H10-nCln (where n= 1 to 10). Depending on the number and position of the Chlorine atom/s around the Biphenyl, denotes which congener the PCB is, and named accordingly.

Figure 1. PCB structure

Commercial production of PCB mixes (e.g. Aroclors) began in the early 1930’s up until the 1970-80’s when they were phased out due to environmental concerns. PCBs are particularly useful for their electrical insulation properties, low flammability, and stability. Subsequently, they were used in transformer oils, coolants, paints, and flame retardants, to name just a few. Unfortunately, also due to these properties, they pose a significant risk to the environment, and were classified as one of the initial 12 Persistent Organic Pollutants (POPs) under the Stockholm convention1. According to the European Food Safety Agency (EFSA) 2 however, only 130 of the 209 PCB congeners have been reported in commercial Aroclor mixes and environmental samples.
PCBs can be sub-divided into two categories; the coplanar and non-coplaner congeners.
The co-planer congeners either have a single or no Chlorine atoms substituted for a Hydrogen in the ortho position (figure 1. A single or no Cl in position 2, 2’, 6 or 6’) on the phenyl rings. They are dioxin like in character, there are twelve of them, and are recognised by the World Health Organisation (WHO) as being used to determine Toxicity Equivalent Factors (TEFs) in relation to the most toxic dioxin 2,3,7,8-Tertrachlorodibenzo-p-dioxin (TCDD). Health risks include reproductive and developmental toxicity, and / or immune suppression.3
The non-coplaner congeners have more than one Chlorine atom substituted for a Hydrogen in the ortho position on the phenyl rings. These congeners are considered to be less toxic, as they do not bind to the aryl hydrocarbon receptor which causes the health effects associated with the dioxin like PCBs. However, they are still toxic, and have shown to elicit neurological, endocrine and immunological effects, and are 4% more abundant in soil and 5% more in food, than the dioxin-like PCBs.3
So which PCB suite would you select for a site investigation?

Figure 2. Site investigation

A WHO-12 PCB suite is used to monitor the TEFs of dioxin-like-PCB compounds for a site investigation of human health risk assessments. If a site analysis was restricted to only the WHO-12 PCBs however, it is worth remembering that they are less abundant in the environment than the non-dioxin-like PCBs, and only make up by weight <4% of the commercial Aroclor mixtures produced. Therefore, even if a negative result for the WHO-12 PCBs is received, the site could still potentially contain a significant amount of the non-dioxin-like congeners. The PCB 7 suite was initially selected by the International Council for the Exploration of the Sea (ICES) as a PCB screen for monitoring biota and sediment samples, and became a mandatory requirement of the OSPAR Co-ordinated Environmental Monitoring Programme (CEMP).4 Subsequently, this became the recommended suite by the European Union Community Bureau of Reference for monitoring PCBs, and was also specified and a limit assigned in the UKs Landfill Directive for Waste Acceptance Criteria. These seven PCBs were selected as indicators as they make up ~20% by weight of PCBs in commercial mixtures3, they have a wide chlorination range, and one dioxin-like congener is included (BZ118). They are more likely to be found in environmental samples and at higher concentrations compared to the WHO-12.
Figure 3. A PCB 7 suite is routinely requested for sites containing Electrical sub-stations and transformers.

To cover all the PCBs present, an Aroclor matching total PCB suite could be performed. This covers all PCBs present and are quantified against the nearest matching Aroclor standard, although does not identify individual congeners and LODs are very high compared to the PCB7 and WHO12 screens.
So which suite should you select? Ultimately, the historical use of the site and the subsequent risk assessment of it would dictate the choice. Regardless of this however, the advantages of requesting a PCB-7 and a WHO-12 together cannot be underestimated in providing a full indication of the PCB contamination present at trace levels if any. Alternatively, if only a PCB-7 suite was requested, and the dioxin-like-congener (BZ#118) was found, an additional WHO-12 PCB test would be advantageous in assisting in the risk assessment process.

1. Stockholm Convention,
2. European Food Safety Authority, ‘Results of the monitoring of non dioxin-like PCBs in food and feed’, EFSA Journal 2010, 8, 1701;
3. RSC, Environmental Chemistry Group, Bulletin, January 2014
4. ICES, Techniques in Marine Environmental Sciences, Determination of PCBs in Sediment and Biota, No.53, July 2013

This article was published in the November/December issue of the AGS magazine. Click here to view the full magazine.

Article Laboratories

Explaining Laboratory Proficiency Testing

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by John Masters, Director of Geolabs

The use of Proficiency testing and Interlaboratory comparison schemes is an invaluable tool for laboratories to assure the quality of their test and calibration results. Often seen as simply a necessity to satisfy an accrediting body, the benefits of participation in proficiency testing and interlaboratory comparison schemes are greatly underrated.

The ILAC publication ‘Benefits for Laboratories participating in Proficiency Testing Programs’ highlights that ‘the basic purpose of proficiency testing is to assess performance of laboratories for their conduct of specific test, measurements or calibrations. Many laboratories operate in isolation from other laboratories and do not have ongoing opportunities to compare their data with others. Without such opportunities there are risks that a laboratory’s data may have errors, biases or significant differences compared to similar laboratories.

Proficiency testing provides an opportunity to undertake such comparisons and to have an independent appraisal of the laboratory’s data compared to reference values (or other performance criteria) or to the performance of similar laboratories. The results from such participation provide laboratory managers with either a confirmation that the laboratory’s performance is satisfactory or an alert that investigation of potential problems within the laboratory is required’.

As defined, Proficiency Testing (PT) is generally run by an independent third party and allows laboratories to objectively monitor the reliability of their test results by the use of standardised test materials, whereas Interlaboratory comparisons (ILC’s), when performed in accordance with ISO/IEC 17043:2010, require the measurement or test of test items in predetermined conditions by two or more laboratories.

All laboratories accredited to ISO/IEC 17025(E) : 2005 are required to have procedures in place to monitor the validity of test results (and calibrations) undertaken.
Clause 5.9.1 of ISO/IEC 17025(E) : 2005 states that:
‘The laboratory shall have quality control procedures for monitoring the validity of tests and calibrations undertaken…. This monitoring shall be planned and reviewed and may include, but shall not be limited to;
a) Use of certified reference materials
b) Participation on interlaboratory comparison or proficiency testing programmes
c) Replicate testing
d) Retesting of retained items…’

Whilst ISO/IEC 17025(E) does not stipulate a mandatory requirement for accredited laboratories to participate in proficiency testing, it recommends that laboratories participate in quality assurance schemes such as interlaboratory comparison or proficiency testing.

However, Accrediting Bodies (UKAS for the United Kingdom) ARE required to ensure that ‘its accredited laboratories participate in proficiency testing or other comparison programs, where available and appropriate, and that corrective actions are carried out when necessary’(clause 7.15.3 of ISO/IEC 17011:2004).

The UKAS policy on proficiency testing is specified within UKAS Technical Publication TPS47 – UKAS Policy on Participation in Proficiency Testing, which states that:
‘4.1 all accredited laboratories shall participate in PT/ILCs where such schemes are available and relevant to their scope of accreditation’.

In August 2013, AGS produced a Position Paper (, in which the AGS highlighted the necessity for proficiency testing to promote best practice and improve professional standards in the geotechnical & geo-environmental laboratory community.

Geolabs Limited has been running a Proficiency and Interlaboratory Comparison Testing Scheme (PICTS) since 2005. The Scheme is run every other year although there have been some years where ‘mini-schemes’ have also been run to accommodate certain specific tests and requirements.

The 2017 Scheme was limited to UK laboratories only, initially for 16 BS1377 geotechnical and chemical tests. A further 8 tests were requested for inclusion, but only 4 attracted sufficient interest to be included. Therefore 20 tests were included in the 2017 scheme.

51 laboratories fully participated in the 2017 Scheme. Each participating laboratory was provided with a unique Participant ID, known only to them to maintain confidentiality at all times.
Four types of standardised material were used in the Scheme, from sandy silty clay to very sandy gravel, all prepared from documented procedures before being sent to participating laboratories.

When all participant test data is received, each participating laboratory is provided with a report with tabular and/or graphical reporting formats, and statistical analysis of each test with the Participant ID being their unique laboratory number.

The 2017 scheme report will be issued once data from all of the participants has been received, collated and analysed. It is envisaged that the report will be issued to all participants, UKAS and to Ground Engineering magazine by end November.

Participation in Proficiency Testing and Interlaboratory Comparison schemes is not just an accreditation requirement, it is essential for any laboratory looking to demonstrate technical competence and to provide confidence in the quality, reliability and integrity of the test data they produce.

This article was included in the November/December 2017 issue of the AGS magazine
Click here to view the full magazine


Informal Review of 2nd generation Eurocodes – prEN 1990 and prEN 1997-1

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Structural Eurocodes are being developed into second generation of the documents that are expected to be published soon after 2020. The first drafts of the new EN 1990 and EN 1997-1 are now available for review and informal comment. The window of opportunity to review and comment is very short.

An introduction to the changes in the codes and the requirements for comments will be presented in a webinar on 30th November at 14:00. Details can be found here. All geotechnical design engineers are urged to participate in this process to ensure the UK voice is heard and that practice is improved. AGS liaison should be directed via the Geotechnical Working Group.

Comments should be entered into the appropriate comments tables. Comments should be constructive and will only be accepted if a clear proposed revision is included. Completed comment sheets should be returned to AGS at by 12th January 2018.

Please find the first drafts below:
EN 1990
EN 1997-1

Please find the comments tables below:
EN 1990 Comments Table
EN 1997-1 Comments Table


CL:AIRE Launches Verification of Gas Protection Systems Training

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CL:AIRE has recently launched a series of one day training dates on Verification of Gas Protection Measures. This course will cover in detail the approach to verification and is being delivered by two experienced trainers who have a good and pragmatic understanding of membrane installation and verification.

This full day course provides participants with a detailed theoretical and practical understanding of the requirements for verifying the installation of gas protection systems. It is an essential introductory learning package for environmental and construction professionals engaged in gas protection verification. The main focus is verifying gas membranes but it will also cover venting systems, what to consider when specifying integrity testing or checking that correct testing procedures are followed on site.
The course is specifically targeted at consultants, contractors and other stakeholders/dutyholders involved with the verification, assessment and management of gas protection systems. Each course is restricted to 10 delegates to ensure good trainer to delegate ratio for the practical work.

A certificate of attendance will be provided on completion of attendance.

Dates available:
24th October 2017
30th November 2017
19th December 2017

Course costs: £375.00 + VAT (CL:AIRE membership discounts apply)
Location: Doncaster

For further information or to book a place:


LQM Training Courses 2017

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Tags: article

Land Quality Management’s 5-day series Introduction to Contaminated Land Management starts on 2nd February 2017 – attendance for all 5 days is heavily discounted or you can just attend one or more days to suit your needs.

Land Quality Management have also introduced a new one-day hands on GIS for Contaminated Land course using readily available free open source GIS software. It is ideally suited to those with no previous GIS experience or people looking to apply and develop skills within the QGIS environment.

It should be a busy (fun packed!) day with the following learning outcomes:
• Build up your site conceptual model using Open datasets and mapping layers
• Import and create your own site specific data layers
• Import and Query site investigation / geological data / photographic evidence to help understand or plan additional SI or remediation works
• Undertake some simple geoprocessing tasks (e.g. buffering)
• Create informative maps extracting better value from your hard earned datasets
• See how to develop more efficient and effective ways of integrating large spatial datasets

Visit here for more details.

LQM have also resurrected the one-day Introduction to Contaminated Land which is ideally suited for those new to the area of contaminated land or time-short requiring only an overview of the process, details on this course can be found here.

Other popular courses are also available: Chemistry, CLEA and Hydrogeological Risk Assessment – full details on these courses can be viewed here.

Article Contaminated Land

SoBRA – Accreditation Scheme Launched July 4th 2016

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The Society of Brownfield Risk Assessment (SoBRA) was established in 2009 to support the growing number of professionals working in land contamination risk assessment. It recently launched a new accreditation scheme to demonstrate competence as a land contamination risk assessor. This is a standalone scheme. However, the scheme presents an opportunity for its members to demonstrate to a Suitably Qualified Person (SQP), under the Land Forum’s upcoming National Quality Mark Scheme, that they are sufficiently competent to support the SQP in undertaking or reviewing the risk assessment element of their project. For the many members of the AGS interested in land contamination this a great opportunity to demonstrate competency recognition.

SoBRA is a learned society for individuals, with membership drawn from the private, public, voluntary and academic sectors.  Its goals are to improve technical knowledge in risk-based decision-making related to land contamination applications and to enhance the professional status and profile of practitioners.

Risk assessment is a critical element in the evaluation of land affected by contamination and provides the cornerstone for wider decision making in land management.  To date there has been no single industry-wide scheme to demonstrate competence as a risk assessor. The SoBRA Register of Risk Assessors has been developed to fill this gap, recognising and rewarding the technical skills associated with land contamination risk assessment.

Inclusion on the SoBRA Register of Risk Assessors will not demonstrate that an individual is an expert but will demonstrate that the individual possesses the technical, scientific and communications skills required to design, perform and critically evaluate land contamination risk assessments.  The scheme is focussed on the technical detail associated with risk assessments but also requires that applicants have a broader understanding of the context and impact of risk assessment on the management of land affected by contamination.

The SoBRA Register of Risk Assessors has two grades of membership to reflect an individual’s experience and skills.  The entry level is Registered Grade; individuals who are capable of undertaking and/or reviewing routine generic quantitative risk assessments without supervision but who are likely to need some assistance or guidance in conducting more complex risk assessments.  The advanced register entry will be the Fully Accredited Member Grade which would be someone with a thorough understanding of land contamination risk assessment, with experience of carrying out and/or reviewing more detailed and site specific risk assessments.  On admission to the register, individuals will be permitted to use the post-nominal signature designations of RSoBRA and ASoBRA respectively.

As many risk assessors have differing levels of experience in different practice areas such as human health risk assessment or assessing risks to water environment or ecological receptors, registration entries will be linked to their specific areas of competence.  In very broad terms the two grades have been designed to be consistent with the Level 3 and Level 4 of the SiLC Land Condition Skills Development Framework.

The application procedure will require the submission of written evidence to demonstrate competency, attested by referees and attendance at an interview.  There is also a strict requirement for all register entrants to maintain membership of a professional body and a requirement for those seeking the Fully Accredited Member Grade to be chartered.

The first tranche of applications are anticipated to be accepted from July to October 2016.  If you are interested in being included on the register, then please visit for full details on the application requirements and start gathering your evidence for your written submission!

Follow us also on LinkedIn, for the latest news on technical issues, workshops and updates. See also our summer workshop in Bristol upon Risk Assessment to support Historical Landfill Redevelopment or simply visit our Stand at Contamination EXPO 2016 to learn more!

For editorial comment and contact on this please contact the SoBRA executive committee at


Article Contaminated Land

NHBC Ground Gas Update – Site Assessment, Characterisation and Design of Gas Protection Measures

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NHBC have published an update to their 2007 technical guidance for low-rise residential developments on sites affected by ground gases. The original document, entitled ‘Guidance on evaluation of development proposals on sites where methane and carbon dioxide are present’, included a simple multi stage classification method for low-rise housing, commonly referred to as the “Traffic Light system”.  The fundamental guidance offered in this document remains applicable but, since its publication, there have been a number of advances in knowledge, including guidance on alternative approaches for characterising gas regimes and updated advice on the design of measures to deal with gas risks.  These include the Characterisation of gas risks without gas monitoring on low-risk sites (CL:AIRE, 2012), Verification of gas protection systems (CIRIA C735, 2014) and the British Standard Code of practice for the design of protective measures for methane and carbon dioxide ground gases for new buildings BS8485:2015.

The full article is available at:

NHBC summarise the new guidance and comment on where they consider it to be applicable.  They also explain where their Traffic Light classification can continue to be used, for a “typical house”, as detailed in the figure below.


Model residential property developed for calculated maximum permitted gas concentration within the subfloor void.


They advise that:

  • There have been a number of recent UK publications offering alternative approaches to ground gas risk assessment and improved advice for the design and verification of measures to deal with gas risks.
  • Practitioners undertaking gas surveys and assessing the risks should be conversant with updated guidance.
  • Robust site characterisation is required to design gas protection measures, but designers must also have an understanding of building-related influences, as these significantly govern design and construction options for gas protection measures.
  • Gas protection design, installation approach and verification requirements should be agreed with NHBC in advance of works, as satisfying requirements after construction is extremely difficult, often more costly, and can be disruptive.
  • Specific requirements relating to gas protection measures may be applied under planning and must also be considered.
  • The NHBC Traffic Light guidance can be used where the development proposals are based on the ‘typical house’ used for modelling in the traffic light classification system.
  • Verification evidence will be requested for gas regimes at Amber 2. For developments where the Characteristic Situation is applicable, the BS8485 scoring system requirements should be adopted, and verification evidence could be required for gas regimes at CS2 or above.



NHBC Technical Extra, Issue 20, April 2016.

Contaminated Land: Applications in Real Environments (CL:AIRE) Research Bulletin RB17 – A pragmatic approach to ground gas risk assessment. 2012.

CIRIA C735. Good Practice and verification of protection systems for buildings against hazardous ground gases. 2014.

BSI. Code of practice for the design of protective measures for methane and carbon dioxide ground gases for new buildings, BS8485:2015.


by Neil Parry

Article Contaminated Land

Contamination Expo Series – 12th & 13th October 2016

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Tags: article

The AGS has partnered with The Contamination EXPO Series, a major new European exhibition committed to providing the latest knowledge, products, and innovations to manage all aspects of contamination.

The series encompasses six different co-located events: Land Remediation Expo, Spill Response Expo, Clean Air Technology Expo, and Hazardous Material Expo, as well as Geotechnical & Geoenvironmental Expo and Nuclear Decommissioning and Remediation Expo, all under one roof with their own conferences and workshops.

With 120 seminars and 200 suppliers, this lively environment will be the top networking event in the industry, bringing together all parties from across the sectors. For more information, or to register for your free tickets, please visit


ExCeL, London

Event website


+ 44 (0) 117 990 2005



Article Loss Prevention

Potential Pitfalls for an Expert Witness

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by Peter Witherington and Hugh Mallett


Many of us in the technical services industry aspire to be experts in our field.  To receive a request to provide expert witness services can be flattering and could be seen as validation of that status.  However, ultimately provision of this service can result in the requirement to provide expert evidence at an inquiry or in court where rules and behaviour can be very different to our day to day experience.

Therefore, before accepting instructions to provide expert witness services on a particular matter, practitioners from member companies would be well advised to;

  • refer to the recently published LPA 62 [Advice to Expert Witnesses] and
  • reflect upon the following Magnificent Seven potential pitfalls drawn from recent experience, that potential expert witnesses can face and must fully understand:

1.  Responsibility of an expert.

First and foremost experts must be aware that their responsibility is to provide independent evidence to the court unaffected by any desire to support their client’s case (see also LPA 62).  An expert should be formally instructed by the solicitor acting for the client and this should clearly define the terms of reference and responsibilities.

2. Ensure you are Fully independent.

Before accepting an instruction, an expert must carefully consider if there are any conflicts in the appointment.  This could be a question of being previously involved in the case, a connection with other parties dealing with or affecting the case or a less obvious connection with a matter that could influence the case.  As a minimum the expert should advise the instructing solicitor and be entirely transparent in the proof of evidence of the potential conflict and how it could have affected the opinions given.

3.  Ensure you really are an expert.

Although you might be expert in the general aspects of the case consider whether you truly are an expert in all the specific details you are required to give evidence on. For example you might be an expert remediation engineer but have never dealt with a petrol filling station. If the case is about a PFS, you should seriously consider whether you should accept or decline the instruction.

4.  Make sure you are fully conversant with all the documents

It is easy to be tripped up if you are unaware of documents. On cross examination of a politician who admitted she had not had time to read all the documents, the barrister stated “Madam, you do not have an opinion!”

5.  Make absolutely sure your proof of evidence is correct

There is nothing a barrister likes more than to find errors in a proof of evidence. So when writing your expert report or proof of evidence make doubly sure that everything is factually correct, that any calculations you have made are not flawed and your opinions cannot be disputed or undermined by virtue of simple factual or typographic errors. There is nothing worse than having to amend errors in a proof identified during cross examination and the barrister will use this to question the reliability of all your evidence. Although it is your evidence it always makes sense to get another expert to undertake a sense check before it is submitted to the court

6.  Do not be drawn under cross examination to stray beyond your area of expertise.

It is very easy to be drawn under cross examination to make statements that are be beyond your area of expertise. A common pitfall is to bluff your way through but this could destroy the credibility of your entire evidence. It is far better to admit the limitations of your knowledge and not offer an opinion that is outside your area of expertise.

7.  And finally

It is important to recognise the seriousness of being an expert. This is not just an exercise in mental gymnastics; beware that barristers do this day in day out and excel in getting under your skin to undermine your credibility – this is what they are paid to do! If anyone needs a confirmation of how merciless the process can be, it is worth reading the judgement of Justice Aikenhead on the Corby case and how he dealt with some of the witnesses.  But more important than personal credibility, many of these cases can affect the lives of real people (as in the Corby case) and we must remember we have a responsibility to them as well.