The Distribution of Asbestos in Soil – what can the data mining of sample results held by UK laboratories tell us?
Issue Date: March 2020
This discussion paper is a continuation of the series of discussion papers that the SoBRA asbestos sub-group has published since 2015. In 2013, SoBRA identified a number of research gaps that had direct relevance to the risk management of asbestos in soil. One of these was the lack of a collective understanding on what typical background concentrations of asbestos in soil across the UK were. To provide a complementary line of evidence to Defra’s recently published Research Project SP1014 (Establishment of typical background levels of dispersed asbestos fibres in urban and rural soils in England and Wales), SoBRA issued a request to major UK soil laboratories to provide SoBRA with anonymised asbestos in soil data. The principal aim of this paper is to provide a factual presentation of the data provided by the laboratories. The information presented may be used by risk assessors and decision makers as a line of evidence as they see fit.
Fine Tuning DQRAs for the Water Environment
Issue Date: 12th May 2019
SoBRA held a one-day workshop in June 2018 entitled on the Fine Tuning DQRA’s for the Water Environment. The objective was to identify common mistakes in controlled waters risk assessment and explore potential solutions. This report presents a written record of the discussions held during the Summer 2018 workshop.
# ACUTE GACs
Development of Acute Generic Assessment Criteria for Assessing Risks to Human Health from Contaminants in Soil
Issue Date: 30th April 2019
This report presents a methodology for derivation of AGAC that risk assessors may choose to use to help in the assessment of acute health risks from short-term exposure to contaminants in soil. In the UK, the assessment of risks to humans from land contamination has traditionally tended to focus on chronic exposure scenarios. However, focusing on chronic exposure may not always be protective of potential acute exposure scenarios, especially in non-residential settings, and/or if statistical methods are used to interpret site soil data. The report was developed to address the absence of such guidance in order to support risk assessment practitioners and promote awareness within the contaminated land sector.
27 July 2020 Corrigendum : The authors of SoBRA’s AGAC report have discovered an error in the calculation of the AGACs for the vapour pathway for benzene (adult and child), phenol (child), trichloroethene (adult and child) and vinyl chloride (child). These had been incorrectly calculated due to use of log Koc rather than Koc in the calculation spreadsheets. A new version of the report (version 2) has been produced with these values corrected (the new AGAC are higher than before) which is available on the link below.
# PRACTICAL TIPS
Practical Tips Documents
In June 2018, the Society of Brownfield Risk Assessment (SoBRA), the Geological Society Contaminated Land Group and RemSoc delivered a conference targeted towards early careers learning. Its aims were:
- To support technical excellence in the assessment, estimation & evaluation of risks and associated uncertainties from land affected by contaminants;
- To encourage “good practice” in the practical application of risk assessment to support decisions regarding the appropriate management of land contamination; and
- To facilitate and widen access to the dissemination of knowledge regarding land contamination risk assessment.
A commitment of this workshop has been the creation of a series of short tabular reports for each of the different discipline areas. We have produced three practical tips documents which include human health risk assessment, controlled waters risk assessment and vapour intrusion (include link).
# SITE INVESTIGATION
Site Investigation and Risk Assessment
for Historic Landfill Redevelopment (SoBRA 2016)
Issue Date: 8th June 2018
SoBRA held a workshop on uncertainty in human health risk assessment in June 2016. The objective of the workshop was to consider key issues associated with the CSM and site investigation for landfill sites. Delegates were asked to consider a wide range of issues to identify those representing accepted scientific understanding and/ or good practice, and those which require further work to extend, improve or clarify current understanding or practice.
Uncertainty in Human Health Risk Assessment (SoBRA 2015)
Issue Date: 24th April 2018
SoBRA held a workshop on uncertainty in human health risk assessment in June 2015. The objectives of SoBRA’s summer 2015 workshop were to define the current state of our understanding of the key issues surrounding uncertainty in human health risk assessment and to establish where there is (and is not) consensus on mitigation measures.
Vapour Intrusion to Support Sustainable Risk Based Decision Making Workshop Report (SoBRA 2017)
Issue Date: 6th March 2018
SoBRA held a workshop on vapour Intrusion to Support Sustainable Risk Based Decision Making June 2017. The workshops aims were to: provide high quality speakers who could outline the challenges faced for their topic area that affect the evaluation of the vapour intrusion pathway, including CSM, site investigation, modelling and installation of mitigation measures; and to break out into workshop groups to discuss issues pertaining to a topic area in more detail and identify how such issues might be resolved. The four topic areas were CSM, site investigation, development of alternative risk assessment techniques based on scientific studies and the evaluation of mitigation measures using quantitative risk assessment.
Discussion Paper on Guidelines for Airborne Concentrations of Asbestos Fibres in Ambient Air: Implications for Quantitative Risk Assessment
This discussion paper explores how air quality values can be derived, and how different modelling assumptions can result in different calculated values. It also looks at how available approaches to calculating values compare to existing standards and guidelines, whether commonly adopted guidelines can be supported by the most recent epidemiological evaluations, and what challenges we still face in coming up with health protective and pragmatic guidelines.
# GROUNDWATER VAPOUR
Development of Generic Assessment Criteria for Assessing Vapour Risks to Human Health from Volatile Contaminants in Groundwater
Volatile constituents in groundwater have the potential to cause risk to human health via volatilisation and migration of vapours into overlying buildings or outdoor air space followed by inhalation. Where the conceptual site model identifies this contaminant linkage as being of possible concern it is usually necessary to assess the risks further in order to determine whether they are acceptable or not. One method that can be used is to compare measured concentrations of volatile constituents in groundwater with conservative generic assessment criteria (GAC) protective of human health via the inhalation of groundwater-derived vapours pathway. This helps the assessor determine the level of risk associated with this particular contaminant linkage. A working group of the Society of Brownfield Risk Assessment (SoBRA) has developed a methodology and derived GAC for 64 commonly analysed volatile constituents in groundwater. The methodology utilises the Environment Agency’s (England and Wales) CLEA model to estimate the average long-term concentration in shallow groundwater (the GAC) that would lead to tolerable/minimal risk to site occupants from vapour migration and inhalation in indoor and outdoor air from chronic exposure. Screening values have been derived for residential and commercial land-use scenarios. The generic screening values are intended to complement other screening methodologies (such as exclusion depths and distances) for assessing the groundwater vapour contaminant linkages.
# BACKGROUND CONTAMINATION
Historical Development and its Effect on Soil Contamination in Urban Areas
Rebekka McIlwaine, Siobhan Cox, Rory Doherty and Mark Cave (2016)
This SoBRA funded project creates a new methodology for identifying local sources of contamination and relationships between historical urban development and groups of potentially toxic elements (PTEs) in urban soils. The Belfast Tellus data is used to create the methodology, which is then tested on Sheffield using GBASE data. Eleven PTEs are considered within this research; arsenic (As), cobalt (Co), chromium (Cr), copper (Cu), molybdenum (Mo), nickel (Ni), lead (Pb), antimony (Sb), tin (Sn), vanadium (V) and zinc (Zn). These elements are expected to be related to different geogenic and anthropogenic sources within the study areas.
Conceptual Framework for Asbestos Risk Assessment & Control
The aim of the approach is to have a common framework that can scale to any number of activities that might take place prior, pre, during or post development. The key aims are to have a stepwise approach to enable effective screening of potential areas of concern; encourage appropriate and sufficient data collection and site investigation to support robust decision making; facilitate timely identification and understanding of risky activities and identify the point where mitigation and further Quantitative Risk Assessment is necessary to protect vulnerable on and off site receptors.
Design of an Activity Based Sampling Protocol for the Testing of Asbestos Fibre Release Potential from Residential Garden Soil
This protocol provides a draft outline of a potential activity-based sampling approach for the testing of asbestos fibre release potential from residential garden soil as part of a staged investigation strategy for land being investigated under Part 2A of the Environmental Protection Act 1990. The primary objective of the Activity-Based Sampling (ABS) protocol is to provide a reasonable worst-case estimate of current and future fibre-release and subsequent localised airborne fibre concentrations that might be possible as a result of soil disturbance.
Dust Monitoring Protocol for Earthwork Activities at Brownfield Sites
The aim is to obtain robust activity-based dust generation data to be able to risk-rank different remediation, earthwork and construction activities, and better understand potential fugitive environmental emissions and employee exposures. This protocol is designed to provide a monitoring method by which different activities involving earthworks at brownfield sites can be monitored in a consistent way and the data from each monitoring exercise collated to inform the potential for dust release and the subsequent risk ranking of those activities.
Example Part 2a Asbestos Cement Decision Algorithm [Rev01]
This discussion paper presents a decision algorithm for asbestos cement fragments in residential garden soil designed to support a staged investigation strategy for land being investigated under Part 2A of the Environmental Protection Act 1990.
Soil Sampling Protocol for Asbestos in Soil
This protocol provides a draft outline of a potential sampling approach developed by the SoBRA Asbestos-in-soil sub-group. It aims to strike a balance between traditional soil survey sampling strategies and soil sampling strategies designed specifically for known asbestos containing soil, made ground and aggregate.
Risks to Human Health from Asbestos in Soil Workshop Report (SoBRA 2013)
Issue Date: 7th April 2015
SoBRA held a workshop on assessing risks to human health from asbestos in soil in June 2013. The workshops aims were to: support site investigation practice, laboratory analysis methods and examine risks to site workers; evaluate remediation and re-use options; and derive a decision algorithm for existing and future land users. Quantification and management of the risks posed to human health from asbestos in soil are important current topics for practitioners dealing with land affected by contamination. This report will be used to support the chapter on risk assessment in the forthcoming Joint Industry Working Group guidance on asbestos in soil. Proceedings and presentation slides from the workshop are available free to members.
# PETROLEUM HYDROCARBONS
Petroleum Hydrocarbons Workshop Report (SoBRA 2013)
Issue Date: 24th January 2013
SoBRA held a workshop on assessing risks to groundwater from petroleum hydrocarbons in June 2012. The workshop included discussion groups on four key themes: site investigation and sampling; laboratory analysis and environmental forensics; groundwater risk assessment modelling and development of guidance; and assessment of the vapour risk from groundwater. Proceedings and presentation slides from the workshop are available free to members.
Lead Workshop Report (SoBRA 2012)
Issue Date: 20th March 2012
SoBRA held a workshop on assessing risks to human health from lead in soils in June 2011. The workshop included discussion groups on the 4 key topics, namely: toxicology; sources and background concentrations; exposure assessment; and bioaccessibility. Proceedings and presentation slides from the workshop are available free to members.
PAH Workshop Report (SoBRA 2011)
Issue Date: 14th Feb 2011
SoBRA held a workshop on assessing risks to human health from PAHs in soils in June 2010. The workshop included discussion groups on the 4 key topics, namely: toxicology; chemistry and site analysis; exposure assessment; and bioaccessibility and plant uptake. Proceedings and presentation slides from the workshop are available free to members.