Mary Ellen Ternes has long been recognized nationally in the fields of chemical engineering and environmental law and advocacy. Her practice brings over 30 years of in-depth experience at the intersection of energy, manufacturing, air quality, hazardous waste management, infrastructure and disaster response.
Prior to her 27 years as an environmental attorney, Mary Ellen served the U.S. EPA in emergency response, hazardous waste site remediation and permitting, then industry as a commercial hazardous waste incineration compliance management, and then back to U.S. EPA as a law clerk for EPA’s Office of General Counsel. With this background, she is able to draw on EPA administrative process, technical, chemical engineering and field experience in the most complex and technically challenging environmental matters.
This rare combination brings uncommon insights to environmental challenges revealing efficient solutions for commercial, industrial and governmental entities. Mary Ellen applies this experience to support a broad range of clients in evolving regulatory, transactional and litigation contexts, at a time when fundamental risk management concepts are being reconsidered and companies face an ever-shifting compliance landscape.
Mary Ellen received her B.E. in Chemical Engineering from Vanderbilt University (1984), and a J.D. with high honors, from the University of Arkansas at Little Rock (1995), where she was Managing Editor of the UALR Law Journal and clerked for the U.S. EPA Office of General Counsel, Air and Radiation Division. Mary Ellen is licensed in Arkansas, South Carolina, Oklahoma and the District of Columbia, as well as the U.S. District Courts for the Eastern and Western Districts of Arkansas, Eastern and Western Districts of Oklahoma, and the U.S. Court of Appeals for the Tenth Circuit.
Mary Ellen began her career with U.S. EPA’s Superfund Emergency Response Program, utilizing her chemical engineering degree for chemical release response, remediation and treatment as an On-Scene Coordinator and federal “commander on the scene.” Trained and charged by EPA Region 6 with emergency field response, Mary Ellen characterized root cause, extent and fate of hazardous chemical releases, designing and implementing removal and remedial actions for uncontrolled hazardous waste sites throughout EPA Region 6, including projects like the Vertac dioxin waste site with its on-site incineration remedy in Jacksonville, Arkansas.
After several years in the field she moved to EPA’s Resource Conservation Recovery Act (RCRA) program, becoming an EPA Region 6 hazardous waste incineration RCRA Subpart O permit writer, leading the EPA’s national RCRA incineration permit writer workshop. She left EPA to work for the pervasively regulated hazardous waste incineration industry, managing RCRA, Clean Air Act (CAA) and Toxic Substances Control Act compliance programs for ENSCO, a commercial hazardous waste incineration facility. At ENSCO, Mary Ellen was responsible for permitting, compliance demonstrations and enforcement, including the on-site incineration project at the BROS Superfund Site in Bridgeport, New Jersey.
Through her work with ENSCO’s attorneys while chairing the Permitting Committee for the Hazardous Waste Treatment Council (predecessor to the Environmental Technology Council), Mary Ellen became interested in environmental law, particularly the CAA. While serving as an advisory expert in the litigation surrounding the Vertac on-site incineration project, Mary Ellen met the EPA’s Office of General Counsel staff, and later clerked for EPA’s OGC Air and Radiation Division, where her experience confirmed her decision to change careers from chemical engineering to environmental law.
Since 1995, Mary Ellen Ternes has become well-known for providing sophisticated environmental legal strategies informed by practical EPA, industry sector, and chemical process experience. Her early foundation in emergency response, hazardous waste site remediation, incineration and chemical process safety, permitting and compliance, followed by over twenty years counselling clients through complex regulatory and technical issues provides unique depth in developing effective legal strategies. Relying on this rare breadth and depth, she guides a broad spectrum of industrial, commercial and municipal sector clients through complex projects such as:
Specific examples of past projects include:
Advising an industrial manufacturing client that was implicated when Clean Air Act “stack test” results triggered an enforcement investigation. Mary Ellen assisted the client in demonstrating that the process was not testable, and working closely with technical consultants, negotiated an air permit modification with new compliance strategies. Previously, Mary Ellen had guided the client through:
Assisting a deal team to assess material risk related to the acquisition of a large chemical process facility which had been targeted by local environmental advocacy groups. Mary Ellen was asked to provide legal analysis of traditional legacy environmental risks associated with contaminated properties, as well as the future compliance and enforcement risk of the chemical process facility from all perspectives, including the history of its Clean Water Act and Clean Air Act permitting and enforcement, and applicable elements of the Clean Air Act’s Risk Management Program. Mary Ellen provided the client with a comprehensive understanding of historic, current, and emerging risk for strategic management in this critical transaction allowing a successful closing.
On behalf of a development client, Mary Ellen was retained to develop a remediation strategy for a network of downtown properties in a large metroplex area involving groundwater contamination over which there was planned commercial and residential development. Mary Ellen successfully guided the client through negotiations achieving regulatory approvals for redevelopment, including the environmental application for HUD financing, utilizing separate groundwater and soil “operable units” and institutional controls.
With this unique combination of education, training and work experience in the fields of chemical engineering and environmental law, Mary Ellen has served in various leadership and liaison roles within and between the legal and engineering communities. As a Fellow and past President of the American College of Environmental Lawyers (ACOEL), a Fellow, past leader and lifetime member of the American Institute of Chemical Engineers (AIChE), and a past leader within the American Bar Association (ABA) Sections of Environment, Energy and Resources and Business Law, Mary Ellen focuses on better integrating law and policy with science and engineering. This value of Mary Ellen’s science policy focus has been recognized by the Global Council for Science and Environment, which in 2022, appointed Mary Ellen as a Senior Fellow for Law and Policy. Mary Ellen is a frequent author and speaker particularly as it relates to improving applied science-based environmental policy, especially most recently in the areas of climate change adaptation, renewable energy, plastic and other chemical waste mitigation and regulation.
Mary Ellen is recognized by the International Who’s Who of Environment Lawyers (since 2004); Chambers USA Guide to America’s Leading Lawyers for Business(since 2011), The Best Lawyers in America© (since 2007) (environmental law; environmental litigation; administrative /regulatory law), Oklahoma Super Lawyers (since 2009), in which she was named to its list of “Top 25 Women Oklahoma Super Lawyers,” (2008-2013, 2015-2018, 2021) and Martindale-Hubbell as AV. She was also recognized by Best Lawyers® as Oklahoma City’s “Lawyer of the Year” for Environmental Law in 2011, 2016, 2019 and 2023, and for Administrative and Regulatory Law in 2020, an honor only given to a single lawyer in each legal specialty in each community. Mary Ellen’s efforts have resulted in the Earth & Water Law, LLC Oklahoma City office being ranked regionally by the U.S. News & World Report – Best Lawyers “Best Law Firms” for three of the firm’s primary areas of law: Administrative and Regulatory Law, and Environmental Law and Litigation – Environmental.
Presentations and Speaking Engagements
Publications and Conference Proceedings
Litigation and Published Cases
Professional and Community Involvement