Vapour Intrusion

Guidance Notes for Assessment in Contaminated Land Scenarios in the UK

Following the recommendations of the SoBRA Summer 2017 workshop and the publication of the SoBRA Groundwater Vapour Generic Assessment Criteria (GACgwvap), SoBRA has now published a series of accessible and concise practitioners’ guides to support informed decision making with respect to vapour intrusion (VI) risk assessment within the UK. It is acknowledged that there is already an extensive portfolio of existing industry guidance available both within the UK and internationally in relation to VI risk assessment, nevertheless, these practitioners’ guides aim to provide high level summaries of the existing guidance, covering key aspects of VI risk assessment and include signposting to the relevant published industry documents for more detailed information, where required.

The topics covered by the SoBRA practitioners’ guides published comprise:

1A. Conceptual site model development for assessment of VI contaminant linkages in the UK

1B. Benefits of soil vapour sampling for assessment of VI risks

1C. VI data collection considerations

Controlled Waters and Climate Change

Issue Date: August 2022

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.

Baildown Test Guidance for Light Non-Aqueous Phase Liquids

Issue Date: May 2022

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.

SoBRA Asbestos in Soil Human Health Risk Assessment (AiSHHRA) Toolbox

Issue Date: December 2021

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.