International Approaches to Discrete Aquifer Zone Characterization

November 5, 2025, 9:00 a.m.

Many complex sites have a complicated geologic setting consisting of multiple aquifer and aquitard layers with varying hydrologic and geochemical properties and contaminant distributions. Adequate characterization of these conditions is critical to developing accurate and robust conceptual site models, supporting remedy design and the ability to monitor changing conditions and remedy effectiveness, including post-closure validation monitoring. Groundwater wells installed to characterize and/or monitor the hydraulic head and spatial distribution of contamination in aquifers can be grossly divided into two types: (1) wells that are open to the entire aquifer sequence or a significant portion of it, including long-screened wells or, in bedrock aquifers, open boreholes, and (2) wells that use multilevel sampling or completion technologies (e.g., packer systems, well liners, and/or multi-level well completions) to vertically isolate targeted portions of the aquifer including aquitard layers, if appropriate. These options present tradeoffs in terms of cost, data resolution, and technical constraints, and the benefits of each approach need to be considered in terms of the site geology, monitoring objectives, and site conceptualization. Through a series of international examples, alongside input from site operators and regulators, this case study will examine different approaches to discrete aquifer zone characterization. Collectively, these examples will help provide the basis for future guidance on identifying appropriate groundwater characterization and monitoring approaches in the context of site conditions, remediation objectives, and business case considerations (e.g., cost/benefit analyses, infrastructure requirements, safety considerations, etc.).

Agenda

Timeline (Pacific Time)

Presentation Title

Presenter

Biographies

Moderators

Fred Day-Lewis
Pacific Northwest National Laboratory (PNNL)

Fred Day-Lewis joined PNNL in 2021 as a chief geophysicist and laboratory fellow. Prior to starting at PNNL, he worked for the U.S. Geological Survey for 18 years. Day-Lewis has worked on diverse applied research projects related to subsurface characterization and monitoring, groundwater remediation, and groundwater or surface-water exchange. He currently serves as an associate editor for the journal Groundwater. Day-Lewis is a past president of the American Geophysical Union Near Surface Geophysics section. He was elected fellow of the Geological Society of America in 2015. He is a 2023 recipient of the Harold Mooney Award from the Society of Exploration Geophysicists for contributions to the near-surface geophysics community. He received his PhD from Stanford University.

John Heneghan
Sellafield, Ltd.

John is a hydrogeologist who works as a Contaminated Land Specialist in the Land Quality team for Sellafield Ltd., operator of one of the largest and most complex nuclear sites in Europe. John is currently supporting the ongoing work to manage the continuing leak to ground from the Magnox Swarf Storage Silos (MSSS), one of the legacy solid waste storage facilities on the site and recognized as one of the highest hazard facilities on the site. John is the technical lead on in-ground characterization and mitigation work in support of Sellafield’s leak response which includes the installation of a new array of multi-level sampler wells, work to assess the potential use of in-ground chemical barriers, and novel techniques for the characterization of in-ground structures.

Mike Rivett
GroundH20 Plus

Mike is a contaminant hydrogeologist with 40 years’ experience. He is founding director of GroundH₂O Plus Ltd, a research oriented environmental consultancy (established 2016) based in Birmingham, UK that specializes in the hydrogeological assessment and technical review of groundwater contamination issues. Most of his work has been in contaminated land, especially urban – industrial L/DNAPL and nuclear legacy sites alongside some developing world research, notably in Malawi, Africa.  Due to his research background, 20 years an academic at the University of Birmingham (UK), many of his projects remain research oriented alongside short-course provision to practitioners. He has a significant track record of published research, is an author of guidance documents and has served on professional panels including being past chairs of the IAH – British Chapter and the Hydrogeological Group of The Geological Society, London. He has an on-going interest in L/DNAPLs, Nuclear legacy issues, groundwater – surface-water contaminant exchange and the high-resolution examination of real sites stemming from his early 1990’s contaminant field research at the intensively monitored Borden research site, Canada.

Speakers

Beth Parker
Morwick G360, University of Guelph

Dr. Beth Parker is a Professor in the College of Engineering, at the University of Guelph, Director of Morwick G360 Groundwater Research Institute, and Director of the University Consortium for Field-Focused Groundwater Research that fosters field-based groundwater research. She completed her PhD in Earth Sciences at the University of Waterloo in 1996 and her MSc in Civil and Environmental Engineering from Duke University, in 1983. Since 2007, she has held a Natural Science and Engineering Research Council of Canada Senior Industrial Research Chair on Groundwater Flow and Contaminant Plume Behaviour in Fractured Sedimentary Rock. She specializes in high-resolution field methods for groundwater system characterization to improve monitoring system design, contaminant detection, quantitation of transport mechanisms to improve prediction of plume behaviour in complex flow systems including fractured rock.

Steve Chapman
Morwick G360, University of Guelph

Steve is a Senior Research Engineer / Hydrogeologist with focus on contaminant hydrogeology, including the development and application of innovative field methods for high-resolution site characterization in diverse geologic environments including clayey aquitards, heterogeneous sandy aquifers, and fractured rock. Steve is also a specialist in the application of advanced numerical models using high resolution site characterization data sets for assessment of groundwater flow and contaminant transport and fate, including the role of diffusion on plume behavior and impacts on remediation performance. Steve participates in many projects as project manager, technical lead or support, and provides mentoring of junior staff and students.

Murray Einarson
Haley & Aldrich

Murray Einarson is a hydrogeologist with Haley & Aldrich in Bend, Oregon. Murray serves as the national Practice Leader for the Contaminated Site Management (CSM) Practice at Haley & Aldrich.  He has a B.A. in geology from the University of California, Santa Barbara, and a M.Sc. in hydrogeology from the University of Waterloo, where he studied under Prof. John Cherry.  Murray has 45 years of experience as an environmental consultant and groundwater researcher and is a Certified Hydrogeologist in California. His professional interests focus on developing and promoting superior methods and technologies for environmental site characterization and in situ remediation. He holds patents on three widely used site characterization technologies and is a pioneer in the development and application of High-Resolution Site Characterization (HRSC). He has co-authored several technical papers and industry and regulatory guidance documents on this subject.

Dmitri Bugai
Ukraine National Academy of Sciences, Institute of Geological Sciences

Dr. Bugai is a senior research scientist and consultant with 35 years of experience in hydrogeology, radioecology, radiation safety, environmental modelling, and risk assessment. Throughout his career, he has participated in numerous projects in Ukraine and internationally, focusing on groundwater monitoring, assessment, and remediation of radioactively contaminated sites — including Chernobyl, Fukushima, UPLS, and various industrially polluted areas.

John Heneghan
Sellafield, Ltd.

John is a hydrogeologist who works as a Contaminated Land Specialist in the Land Quality team for Sellafield Ltd., operator of one of the largest and most complex nuclear sites in Europe. John is currently supporting the ongoing work to manage the continuing leak to ground from the Magnox Swarf Storage Silos (MSSS), one of the legacy solid waste storage facilities on the site and recognized as one of the highest hazard facilities on the site. John is the technical lead on in-ground characterization and mitigation work in support of Sellafield’s leak response which includes the installation of a new array of multi-level sampler wells, work to assess the potential use of in-ground chemical barriers, and novel techniques for the characterization of in-ground structures.

Rob Mackley
PNNL

Rob Mackley manages PNNL’s Deep Vadose Zone project, which involves multidisciplinary and coordinated research to directly support the complex cleanup mission of the Hanford Site for DOE. His technical career focuses on the research and application of groundwater and remediation monitoring instrumentation; remedy development, implementation, and performance evaluation; and hydrogeologic characterization. Mackley joined PNNL in 2004 and holds BS and MS degrees in geology from Utah State University.