Controlled Waters and Climate Change – v2

Posted on by so-admi

# ClimateChange
# DQRA
# CSM

Issue Date: February 2026

Building on our award-winning 2022 guidance, the SoBRA controlled waters and climate change subgroup has released a 2026 update to align with evolving UK policy and guidance, including NPF4, LCRM and WAT-PS-10-02/WAT-G-071.  The revised guidance will further assist land contamination professionals to make informed decisions about future climate risk to controlled waters receptors.  Key enhancements include signposting to updated climate projection databases and further exploring the influence of extreme weather events on the conceptual site model (CSM).  To support practical application, the guidance contains a series of worked examples.

Please note that the information included in this publication is correct as of 30 June 2025. Due to the evolving nature of climate research, policy and guidance, users should ensure they are consulting the most up to date scientific information available to support their controlled waters risk assessments.

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Advice Towards Understanding the Potential for LNAPL Transmissivity and Residual Saturation

Posted on by so-admi

# NAPL
# Petroleum Hydrocarbons

Issue Date: Feb 2026

Ongoing uncertainty about why LNAPL accumulates in wells—even when transmissivity is extremely low—drives misinterpretation of LNAPL well thickness and unrealistic remediation expectations, underscoring the need for clearer understanding of why LNAPL accumulates in monitoring wells.  This document addresses that problem by explaining the principles behind transmissivity and residual saturation, and why accumulations of LNAPL do not necessarily indicate significant mass or recoverable product.  It brings together current understanding of low‑mobility behaviour, including the effects of soil heterogeneity, groundwater fluctuations and changing LNAPL properties, to help practitioners interpret field observations more accurately.  Ultimately, the document provides practical, science‑based advice to support stronger conceptual site models, better risk‑based decisions, and more robust remediation planning at LNAPL-impacted sites.

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Choosing an Appropriate Sustainable Remediation Approach

Posted on by so-admi

# NAPL
# Petroleum Hydrocarbons

Issue Date: Feb 2026

The Society of Brownfield Risk Assessment (SoBRA) is pleased to publish Choosing an Appropriate Sustainable Remediation Approach, the latest addition to our series of guidance documents on the assessment and management of light non‑aqueous phase liquids (LNAPL) in contaminated land settings. This publication provides practitioners, regulators and stakeholders with a clear, practical decision‑making framework for selecting effective, proportionate, and sustainable LNAPL remediation strategies.

Developed by a dedicated SoBRA sub‑group of experienced volunteers, the document addresses recognised knowledge gaps in the existing practice by bringing together current concepts, tools, and best practices. It sets out a transparent process for evaluating LNAPL risks, establishing remediation goals and objectives, and appraising appropriate technologies—supporting technically robust, risk‑based and regulator‑friendly decision making.

We hope this publication will assist members and the wider land contamination community in navigating the complexities of LNAPL behaviour, improving consistency across the sector, and ultimately supporting better environmental outcomes.

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Ground Gas Flux

Posted on by so-admi

# PERMANENT GASES

Issue Date: February 2025

Estimating gas generation and flow in the ground requires a good understanding of the sources and pathways relating to ground gas. Whilst the calculations are not necessarily mathematically complex, the primary consideration is choosing a robust and defensible approach for the assessment and representative input values in order to ensure that any such approach is appropriate for the situation and reflects the site-specific conceptual site model (CSM).

The SoBRA Ground Gas subgroup has produced the following guidance paper to aid practitioners with the estimation of mass flux of ground gas. This paper provides guidance on some approaches for calculating gas generation rates, calculating gas flux where gas monitoring data is available, determining whether gas migration is diffusion or advection dominant and providing context on determining flux significance.

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Conceptualising & Characterising Contaminant Distribution in Soil Top Tips

Posted on by so-admi

# CSM
# CONTAMINANT DISTRIBUTION

Issue Date: November 2023

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.

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Hazardous Ground Gas Top Tips

Posted on by so-admi

# PERMANENT GASES

Issue Date: June 2023

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.

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Controlled Waters and Climate Change

Posted on by Melinda Evans

# ClimateChange
# DQRA

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.

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Baildown Test Guidance for Light Non-Aqueous Phase Liquids

Posted on by Melinda Evans

# NAPL

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.

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