Groundwater 2018

• Pinpointing the key objectives and points of advice in the recent CL:AIRE guidance for assessing petrol hydrocarbons
• To what extent has this changed approaches to groundwater risk assessment?
• Practical examples of using new guidance to develop groundwater risk assessment and remediation targets

Duncan Cartwright

Associate Director, Atkins

Former gasworks sites can contain a substantial legacy of recalcitrant hydrocarbon contamination in the form of tars, which present a significant risks to groundwater. To make informed decisions regarding the nature of the risk and extent of remediation required, a combination of geophysical and forensic chemical analytical techniques can be employed. These can enable visualisation of the spatial extent of contamination and degradation products in near real time, together with source appropriation of organic and inorganic contaminants within groundwater plumes, and their in-situ rates of degradation.

This presentation provides a scientific background to the application of the techniques and their limitations, together with case study examples of their use.

Prof Russell Thomas

Technical Director, WSP

Matt Riding

Senior Consultant, WSP

• Exploring the concept of chemical interfaces in contaminant plumes and their role in biodegradation in groundwater
• Illustrating a lab-scale microcosm design to recreate field scale processes which control biofilm development in plumes
• Examining the resilience of microbial communities in biofilms from a phenol-contaminant aquifer to changes in their chemical environment

Juan F. Mujica

Groundwater Protection and Restoration Group (GPRG), Kroto Research Institute, University of Sheffield

• Exploring the latest understanding of the risks from vapour intrusion
• Reviewing the GAC developed by SOBRA for assessing the risks of vapour intrusion from groundwater alongside other industry guidance:
• detailing assumed modelling inputs and parameters
• outlining other criteria and contaminants to be considered

Hannah White

Principal Environmental Geoscientist, Atkins & Vice-Chair SoBRA

• Exploring the challenges of “legacy nitrate”
• How much nitrate is stored in the unsaturated zone and where?
• Examining how the UK fits into the global picture
• Implications for risk assessment and management of nitrate pollution

Matthew Ascott

Hydrogeologist, British Geological Survey

• Assessing the levels of risk to groundwater posed by landfill leachate:
• what is the life-span for specific contaminants?
• identifying any likely peaks and reductions in risk
• assessing the behaviour of the plume over time
• measuring the likely ingress of leachate onto sites adjacent to landfills
• Practical solutions for remediating leachate plumes
• Case study: Assessing and remediating a former landfill site for development

Dan Welch

Hydrogeologist, Atkins

• Identifying the nitrate source using multiple techniques
• mass balance
• isotope fingerprinting
• age profiling
• Understanding the pathways through better geological mapping
• effect of faulting
• drift geology and impact of glaciation
• Working with land-users
• identifying possible land use changes
• talking to land users – what are they already doing?
• focus groups
• Where next?

Mark Morton

Senior Hydrogeologist, Yorkshire Water

• Advances in effective data collection and inputs to inform groundwater fate and transport models:
  • determining the optimum amount and type of data required for more accurate risk assessment
  • successfully interpreting large, complex data sets to extract timely, useful information
  • evaluating the quality of sampling data obtained from different collection and monitoring tools
• Identifying key factors of influence on results and how best to manage them:
  • sources of uncertainty and error
  • parameters of greatest sensitivity
• Overall requirements for data collection, management and risk assessment to inform effective decision-making
• Practicalities of integrating groundwater flow and transport with other environmental models, e.g. water resources planning, surface-groundwater interaction, to consider the wider environment beyond the site boundaries and achieve better decision-making

Jane Dottridge

Technical Director, Mott MacDonald

• Examining the UK regulatory context for NSZD as part of a monitored natural attenuation (MNA) solution to achieve remedial objectives
• Detailing the concept of NSZD as a monitored natural attenuation (MNA) solution for hydrocarbon light non aqueous phase liquids (LNAPL):
  • Methods for evaluation of natural attenuation and source depletion rates
    how the solution has developed
  • comparison of methods with example applications
• Exploring the benefits of NSZD assessment as basis for remedial technology selection or transition to NSZD in a sustainability framework   
• Practical experiences of NSZD with applied R&D, guidance, field trials, and application at a former refinery site

Dr Anwen Hughes

Technical Director & Associate, Golder Associates Golder Associates, UK

Dr Parisa Jourabchi

Senior Environment Engineer, Golder Associates Golder Associates, Canada

• An introduction to the Site Conceptual Model and the contamination challenge faced
• Exploring the technology used - the NET system - and the solution achieved
• Detailing the remediation results and obtaining regulatory sign-off

Dave Rutherford

Zone 1 Development Manager (Enabling Works) - Meridian Water, Enfield Council

• Overview of available in-situ thermal technologies and their potential application to groundwater remediation
• Strategy Development and Remedial Approach: coupling of thermal conductive heating to enhance LNAPL recovery via skimming techniques
• The design of a pilot trial to verify and quantify the benefits of the innovative thermal technology
• Preliminary Results: lessons learnt on how to optimise the remediation application and comparison with standard recovery techniques
• Further verification and full-scale implementation at a former automotive assembly plant