The CL:AIRE “Professional Guidance: Comparing Soil Contamination Data with a Critical Concentration” publication (v 1.1 February 2021) emphasised the importance of developing, refining and thoroughly understanding the Conceptual Site Model (CSM) prior to considering whether statistical analysis would be applicable for a soil contaminant data set.
In response to this publication, SoBRA set up a sub-group in 2022 with the intention of providing technical guidance to support risk assessment practitioners to understand the soil contaminant element of the CSM prior to carrying out any generic or detailed quantitative risk assessment (and any associated statistical analysis). The guidance provides a series of tips on the key data sources that should be considered and the questions that should be answered by risk assessment practitioners, to ensure that the soil contaminant distribution is correctly interpreted, not only in the context of its chemical properties and the environmental setting, but also how the distribution and CSM may change over time through human and environmental influences.
Announcing the publication of the first document from the Ground Gases sub-group.
In 2020, SoBRA created the ground gases sub-group to support technical excellence in the assessment, estimation and evaluation of risks associated with ground gas.
The SoBRA Hazardous Ground Gas Top Tips document provides succinct, comprehensive guidance covering all aspects of assessing ground gas risk from desk study through to site investigation, monitoring, risk assessment and gas protection design. This document aims to improve and encourage best practice to support practitioners when assessing the risks from ground gases.
In 2021, SoBRA established a controlled waters and climate change subgroup to address the need to incorporate the effects of climate change into contaminated land risk assessments.
Climate change has the potential to significantly impact the predicted risks posed by land contamination in certain scenarios and whilst Cl:AIRE published a SUBR:IM bulletin on climate change, pollution linkages and brownfield regeneration back in 2007 there has not been any further published guidance for risk assessors in the UK on how to incorporate climate change considerations into controlled waters risk assessment over and above FAQ number 8 published in the Environment Agency’s Guiding Principles for Land Contamination (GPLC) Part 2 in 2010. SoBRA’s publication by the climate change and controlled waters sub-group sets out the current regulatory and guidance context, identifies current sources of authoritative information on climate change impacts for the UK, and sets out an approach for a qualitative appraisal of climate change impact at the Preliminary Risk Assessment stage, and a series of “What If” scenarios to be considered at GQRA. The report identifies the limitations that existing standard DQRA modelling software (such as RTM and ConSim) have when looking to model the short-term, transient nature of many climate change impacts, and recommends a series of steps to mitigate this in DQRAs.
Announcing the publication of the first document from the NAPL sub-group.
In 2019, SoBRA created a sub-group to support technical excellence in the assessment, estimation and evaluation of risks associated with non-aqueous phase liquid (NAPL) in the sub-surface. The sub-group has undertaken to produce a series of documents that address a number of key issues facing practitioners when addressing risks from NAPL.
This document focussed on baildown tests. Baildown tests are commonly carried out in wells that contain light non-aqueous phase liquid (LNAPL) to investigate its mobility, which is an important consideration for risk assessment. This baildown test guidance document provides practical guidance to support UK industry in conducting baildown tests and interpreting baildown test results.
This interactive Microsoft Powerpoint toolbox has been designed by the SoBRA asbestos sub-group to assist risk assessors in undertaking asbestos in soil human health risk assessments. It is a collation of the information sources and practices of the sub-group members, assembled in the form of a flowchart. The toolbox provides users with summary information and links to relevant external reference sources, and advocates a process by which asbestos in soil risk assessment can be carried out. It is hoped that it will aid in the consistency and robustness of asbestos in soil risk assessment.
SoBRA’s asbestos sub-group surveyed UK laboratory methods for the identification and quantification of asbestos in soil back in 2018-2019. With the withdrawal of the Standing Committee of Analysts (SCA) Blue Book method for the quantification of asbestos in soil last year this paper should help in understanding some of the key differences in the methods used by laboratories, and it also makes recommendations for how asbestos results should be reported to best inform subsequent risk assessment.
SoBRA is pleased to announce the publication of further work by its Asbestos Sub-Group. Since a workshop held in April 2019 the sub-group has been working on revision to the discussion white paper published in 2017 on air quality guidelines for asbestos. A key action from that workshop in 2019 was to evaluate the use the linear as well as the non-linear versions of the risk algorithms published by Hodgson & Darnton in 2000. It was the view of the participants of the workshop that the linear model for pleural mesothelioma might be more appropriate for the calculation of risk from low environmental exposures compared to the higher occupational exposures that were the primary focus of the Hodgson & Darnton paper. The updated SoBRA paper presents a comparison of risk models, including the new application of the Hodgson & Darnton algorithms. A beta version of an Excel-based spreadsheet has been developed to support the updated paper, allowing users to select from the algorithm options presented in the Hodgson & Darnton paper, and therefore enabling users to perform model choice sensitivity analysis and evaluate the difference the use of alternative algorithms makes to estimated risk. It is hoped that the updated paper and supporting Excel tool help further our understanding of potential health risk associated with exposure to airborne asbestos.
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.