U.S. EPA Contaminated Site Cleanup Information (CLU-IN)

U.S. Environmental Protection Agency
U.S. EPA Technology Innovation and Field Services Division

1,4-Dioxane: Science, Characterization & Analysis, and Remediation

Sponsored by: Interstate Technology and Regulatory Council

Archived: Tuesday, October 18, 2022
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In 2020, ITRC's 1,4-Dioxane team created multiple tools and documents that provide information to assist all interested stakeholders in understanding this contaminant and for making informed, educated decisions. Since the 1950s, 1,4-Dioxane has seen widespread use as a solvent stabilizer. The use of solvents through the 1980s suggests its presence at thousands of solvent sites in the US; however, it is not always a standard compound in typical analytical suites for hazardous waste sites, so it previously was overlooked. The U.S. EPA has classified 1,4-Dioxane as "likely to be carcinogenic to humans." Some states have devised health standards or regulatory guidelines for drinking water and groundwater standards; these are often sub-part per billion values. These low standards present challenges for analysis, characterization, and remediation of 1,4-Dioxane.

The 1,4-Dioxane: Science, Characterization & Analysis, and Remediation training is a series of six (6) modules. The six individual modules will be presented together live, and then archived on the ITRC 1,4-Dioxane training webpage for on demand listening.

The modular 1,4-Dioxane training series provides an overview of 1,4-Dioxane and presenting six sections from the ITRC guidance document (1,4d-1, 2021):

  • History of Use and Potential Sources (Sect 1)
  • Regulatory Framework (Sect 2)
  • Fate and Transport (Sect 3)
  • Sampling and Analysis (Sect 4)
  • Toxicity and Risk Assessment (Sect 5)
  • Remediation and Treatment Technologies (Sect 6)

After the six-part 1,4-Dioxane: Science, Characterization & Analysis, and Remediation series, you should understand:
  • The history of 1,4-Dioxane manufacturing and usage and the potential sources of releases of 1,4-Dioxane to the environment.
  • Primary state and U.S. federal regulatory programs of relevance to 1,4-Dioxane
  • Key physical/chemical properties, and fate and transport processes that are relevant for 1,4-Dioxane
  • Benefits and limitations of the available analytical methods
  • Risk drivers for human health and how ecological risk compares
  • How/when/why different treatment technologies are appropriate

We encourage you to use the ITRC 1,4-Dioxane products (14d-1) and these training modules to learn about 1,4-Dioxane and how you can apply these best practices to improve decision-making at your sites.
For regulators and other government agency staff, this understanding of 1,4-Dioxane can be incorporated into your own programs. This training summarizes the current understanding of 1,4-Dioxane. While the training makes every effort to keep the information accessible to a wide audience, it is assumed that the participants will have some basic technical understanding of chemistry, environmental sciences, and risk assessment. As with other emerging contaminants, our understanding of 1,4-Dioxane continues to advance. This training provides the participants with information on areas where the science is evolving and where uncertainty persists.

Accessibility, Recording, and Content Disclaimer

Rehabilitation Act Notice for Reasonable Accommodation

It is EPA's policy to make reasonable accommodation to persons with disabilities wishing to participate in the agency's programs and activities, pursuant to the Rehabilitation Act of 1973, 29 U.S.C. 791. Any request for accommodation should be made to the ITRC Training Program at 202-266-4932 or , preferably one week or more in advance of the webinar, so that EPA will have sufficient time to process the request. EPA would welcome specific recommendations from requestors specifying the nature or type of accommodation needed. Please note that CLU-IN provides both alternate phone call-in options and closed captioning for all webinars, and requests for these specific accommodations are not necessary.

Webinar Recording

By participating in this CLU-IN webinar, you automatically agree to authorize recording of audio and visual content presented during this live event and consent to subsequent use of this recording in the public domain by the U.S. Environmental Protection Agency. This recording may include questions, comments and poll responses provided by you during the live event in addition to your name, voice, image or likeness. This recording will be made available after the conclusion of the live event as part of the CLU-IN webinar archives, and will remain available indefinitely. If you do not wish to consent to the recording, please do not join the live event, and contact Jean Balent at 202-566-0832 or to discuss your concerns.

Content Disclaimer

This webinar is intended solely to provide information to the public. The views and opinions expressed as part of this webinar do not necessarily state or reflect those of the U.S. Environmental Protection Agency. It is not intended, nor can it be relied upon, to create any rights enforceable by any party in litigation with the United States, or to endorse the use of products or services provided by specific vendors. With respect to this webinar, neither the United States Government nor any of their employees, makes any warranty, express or implied, including the warranties of merchantability and fitness for a particular purpose, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights.


A photograph of Lauren LarkinLauren Larkin, Minnesota Pollution Control Agency (
Lauren is a hydrogeologist for the Minnesota Pollution Control Agency where she has worked on closed landfills and as part of the Superfund program. Prior to her time at the agency, she worked in environmental consulting. She has a B.S. in physics with a minor in geology from the College of William and Mary, and a M.S. in geophysics from the University of Minnesota.

A photograph of William H. DiGuiseppiWilliam H. DiGuiseppi, Jacobs Solution (
History of Use and Potential Sources & Regulatory Framework
Bill DiGuiseppi is a 30+ year experienced Principal Hydrogeologist with Jacobs in their Denver office. Bill is an expert in the history, occurrence and remediation of 1,4-dioxane and PFAS, and leads Jacobs Emerging Contaminants Community of Practice. Bill co-authored the definitive book on 1,4-dioxane with Tom Mohr, Janet Anderson, and Jim Hatton. He frequently conducts 1,4-dioxane and PFAS training for a variety of groups, including the US EPA, the US DOD, the US DOE and the Society of American Military Engineers (SAME). Bill has been actively engaged with the ITRC 1,4-Dioxane Team, as the history and use writing subgroup co-lead. Bill has also been an instructor on emerging contaminants topics for ITRC for several years. His enthusiastic support of ITRC earned him the 2018 Industry Member of the Year award. Bill is also an adjunct faculty member in the Civil and Environmental Engineering Department at the Colorado School of Mines.

A photograph of Janet Anderson, Ph.D., DABTJanet Anderson, Ph.D., DABT, GSI Environmental Inc. (
Regulatory Framework & Toxicology and Risk Assessment
Dr. Janet Anderson is a Principal Toxicologist with GSI Environmental Inc. with 15 years of experience providing toxicology and risk management strategies to federal agencies, private industry, and municipal clients. She also provides litigation consulting and expert services and is a Diplomate of the American Board of Toxicology. Dr. Anderson specializes in communicating the key findings from toxicology studies used to inform state and federal regulatory policy and public health decisions, and helping stakeholders understand the sometimes-disparate interpretations. She is a recognized leader in unregulated and emerging chemicals, such as per- and polyfluoroalkyl substances (PFAS), 1,4-dioxane, and 1,2,3-trichloropropane. She has developed strategies to mitigate human health risks and address environmental liability associated with unregulated and emerging chemicals for both private and public sector clients. She has extensive experience developing risk communication and risk management strategies for multi-stakeholder groups. Dr. Anderson received her Ph.D. in Molecular and Cancer Biology from the University of Cincinnati, completed a post-doctoral fellowship with the U.S. Environmental Protection Agency, and as a civilian government employee, led the U.S. Air Forces Emerging Contaminants program and advised the Department of Defense on matters related to toxicology and environmental restoration. A skilled communicator, Dr. Anderson is often an invited speaker and panelist at high-level scientific conferences, regulatory and industry meetings, law seminars, technical webinars and workshops, and community stakeholder meetings.

A photograph of David T. Adamson, Ph.D, P.E.David T. Adamson, Ph.D, P.E., GSI Environmental Inc. (
Environmental Fate, Transport and Investigation Strategies
Dr. David Adamson is a Principal Engineer at GSI Environmental Inc. in Houston, Texas with more than 20 years of environmental project experience in academic research and environmental consulting. He has extensive expertise in projects dealing with natural attenuation, high-resolution site characterization, emerging contaminants, matrix diffusion, and the development and testing of innovative monitoring and remediation technologies. He has served as a Principal Investigator or co-Principal Investigator on several DoD-sponsored research projects, including those focused on PFAS and 1,4-dioxane treatment and fate and transport. He is an active member of both the PFAS team and the 1,4-Dioxane team for ITRC, serving as the co-lead of the Training Group for the 1,4-Dioxane team as well as a contributing author for both team's guidance documents. He is a licensed Professional Engineer in Texas and serves as a Lecturer at Rice University in the Civil and Environmental Engineering Department.

A photograph of Monica HeintzMonica Heintz, Arcadis (
Environmental Fate, Transport and Investigation Strategies
Dr. Monica Heintz is a Principal Geoscientist at Arcadis U.S., Inc. in Denver, Colorado. She has more than 15 years of experience in academic research and environmental consulting. Dr. Heintz works at the nexus of groundwater hydrogeology, geochemistry, and microbiology. She has extensive project experience developing and refining conceptual site models and designing, implementing, and evaluating monitored natural attenuation programs for a variety of constituents and in a variety of environmental contexts. Dr. Heintz is a subject matter expert in microbial biodegradation and environmental molecular diagnostic tools.

A photograph of Elizabeth DenlyElizabeth Denly (
Elizabeth Denly is based out of Lowell, Massachusetts and is a Technical Director at TRC and the Program Director for TRC's PFAS Group. She is a chemist with 30 years of consulting experience encompassing field and laboratory analyses and audits, quality assurance/quality control, data validation, and consulting for regulatory agencies. Elizabeth is currently focusing on PFAS, specifically the nomenclature, chemistry, sampling procedures, QA/QC, and laboratory analytical methodologies, and has a significant role in educating clients, attorneys, and regulators about PFAS. She has been a leader in ITRC's PFAS Team and received the ITRC's Industry Member of the Year Award in 2017 for her work on this team. Elizabeth earned a bachelor's degree in chemistry from the University of New Hampshire in 1987 and is also a certified manager of quality/organizational excellence (CMQ/OE) by the American Society of Quality.

A photograph of Charles  NeslundCharles Neslund, Eurofins (
Sampling and Analysis
Charles (Chuck) Neslund is the Scientific Officer for Eurofins Lancaster Laboratories Environmental, LLC. And PFAS Practice Leader for Eurofins Environment Testing US. Chuck has worked in environmental analytical chemistry for over 36 years and works out of the Lancaster, PA location. He is a subject matter expert in HRMS analysis and PFAS analysis. He is responsible for identifying and framing trends in analytical testing and equipment. Chuck initiates new methodology and directs research and development. He has a B.S. in Chemistry from the University of Pittsburgh (1982) and two years of graduate study credits in Organic Chemistry from the University of Pittsburgh (1982-1984). He is a member of the American Chemical Society (ACS), Chromatography Forum of Delaware Valley (CFDV), Air & Waste Management Association (AWMA), Society of Environmental Toxicology and Chemistry (SETAC), and Sediment Management Workgroup (SMWG).

A photograph of Barrie SelcoeBarrie Selcoe, Jacobs (
Toxicology and Risk Assessment
Barrie Selcoe is a Principal Technologist with Jacobs in Houston, Texas. Barrie has worked at Jacobs since 2018, specializing in human health risk assessment. She is responsible for planning and overseeing human health risk-based activities at hazardous waste sites across the U.S. and internationally. She utilizes numerous federal (USEPA and Department of Defense) and state guidance documents in risk assessment projects, and is involved in all stages of site planning, investigation and reporting, cleanup level identification, and remedial action planning. She has been involved in risk assessments in 40 states and about 20 countries. She has worked on risk assessments incorporating incremental sampling and site-specific bioaccessibility studies. She has provided risk assessment services for numerous Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA)/Superfund sites, Resource Conservation and Recovery Act (RCRA) facilities, state-program sites, voluntary actions, and international projects. She has prepared risk assessments for various types of sites, including industrial and commercial facilities, industrial and municipal landfills, bulk fuel terminals, rivers, U.S. Department of Defense facilities, and residential areas. Prior to Jacobs (which purchased CH2M in 2018), she worked as a human health risk assessor for 19 years with CH2M, 7 years with Philip Environmental, and 3 years with O'Brien & Gere Engineers. Since 2012, Barrie has contributed as a team member on ITRC's Risk Assessment team, Bioavailability in Contaminated Soil team, TPH Risk Evaluation at Petroleum-Contaminated Sites team, and PFAS team. She earned a bachelor's degree in microbiology from San Diego State University in San Diego, California in 1986, and a Master's of Public Health from the University of Pittsburgh Graduate School of Public Health in Pittsburgh, Pennsylvania in 1999.

A photograph of Caitlin Bell, PECaitlin Bell, PE, Arcadis U.S., Inc. (
Remediation and Treatment Technologies
Caitlin Bell, PE is based out of Seattle, Washington and is a Technical Expert and 1,4-Dioxane Lead for Arcadis North America. She is a chemical and environmental engineer with more than a decade of experience in environmental remediation and compliance. Ms. Bell focuses on treatment of soil and groundwater using ex situ and in situ techniques. Specifically, she focuses on in situ bioremediation applications for a variety of chemicals of concern, including emerging contaminants. She serves as a technical resource on topics such as molecular biology tools, bioaugmentation, and compound specific isotope analysis. Ms. Bell was a member of the ITRC Environmental Molecular Diagnostics team and is the lead author of the 2019 Emerging Contaminants Handbook.

A photograph of Ted TylerTed Tyler, Cardno now Stantec (
Remediation and Treatment Technologies
Ted Tyler has 28 years of experience as a project manager and engineer providing soil, groundwater, wastewater, and air quality assessment, treatment design, permitting, construction management, and operations and maintenance services. His work has entailed sites impacted by chlorinated solvents (e.g., PCE, TCE, CT, TCA, etc.); 1,4-dioxane, PFAS, gasoline, diesel and jet fuels; perchlorate; dioxins/furans; pesticides and herbicides, metals (e.g., Cr(VI)., arsenic, etc.). He is experienced in selecting and implementing the right solution for contaminated sites including the use of physical, biological, and chemical treatment technologies, and holds a U.S. Patent for an in situ bioremediation process (No. 8,580,114). He has developed column, bench, and field pilot studies to further evaluated treatment technologies prior to implementation. Mr. Tyler is a long-term member of the Interstate Technology and Regulatory Council (ITRC) and is a frequent presenter/author regarding assessment and treatment technologies at conferences such as Battelle.

A photograph of Fritz KrembsFritz Krembs, TriHydro (
Remediation and Treatment Technologies
Fritz Krembs, PE, PG is an environmental engineer based out of Trihydro Corporation's Golden, Colorado office. He has over 17 years of experience working in environmental remediation. He has extensive experience with in-situ chemical oxidation (ISCO), in-situ bioremediation (ISB), monitored natural attenuation, phytoremediation, and other technologies. He is Trihydro's Subject Matter Expert on 1,4-dioxane. He has led technical trainings on 1,4-dioxane, ISCO, ISB, and phytoremediation for government and private clients. He is a graduate of Colorado School of Mines and serves as a guest lecturer for their graduate level in-situ remediation course.

A photograph of Francisco BarajasFrancisco Barajas, AECOM (
Remediation and Treatment Technologies
Francisco Barajas is based out of Omaha, Nebraska and is an Environmental Engineer and Treatability Subject Matter Expert at AECOM. He has four years of experience in environmental consulting and over 10 years of experience conducting bench-scale laboratory tests for treatment of contaminants, including emerging contaminants such as 1,4-dioxane and PFAS, in groundwater, soil, and wastewater. He has been a member of the ITRC's 1,4-Dioxane Team for two years. Francisco earned a bachelor's degree in chemical engineering from the University of Sonora (Mexico). He also holds a doctorate degree in environmental engineering from Clemson University where he researched bioremediation approaches for 1,4-dioxane including aerobic metabolism and cometabolism.


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Jean Balent
Technology Integration and Information Branch

PH: 202-566-0832 | Email:
Michael Adam
Technology Integration and Information Branch

PH: 202-566-0875 | Email: