Mark is a partner in the Vorys Cincinnati office and a member of the energy and environmental group.  His practice includes all areas of environmental law, including litigation, dispute resolution, business and transactional matters and advising on regulatory issues.  In 2011, Law360 named him one of four national MVPs in Environmental Law.  He has been listed in Ohio Super Lawyers for 13 years, in Chambers and Partners since 2005, in The Best Lawyers in America since 2006, in 2014 was Cincinnati Environmental Law "Lawyer of the Year," and was named Cincinnati Litigation Environment "Lawyer of the Year" in 2020. 

Career highlights include:

Litigation / Dispute Resolution

  • Representing a sewer district owner in the negotiation and implementation of a Consent Decree in U.S. v. Board of County Commissioners, et al., a multi-billion dollar Clean Water Act case
  • Representing General Electric in a CERCLA cost-recovery case against the US Air Force, settled with an 8 figure payment by the USA for past costs and a super-majority USA share for future costs
  • Representing Fortune 100 Companies in Vapor Intrusion litigation and disputes involving off-site and residential claims and impacts
  • Representing plaintiffs in settling a confidential groundwater consultant malpractice case involving net present valuations of long-term damages
  • Serving as counsel in Siemens v. Koncelik before the Ohio Environmental Review Appeals Committee (ERAC) regarding the scope of Ohio's Voluntary Action Program
  • Representing a major potentially responsible party in U.S. v. Terminix, et al., a Superfund matter, tried on contribution issues
  • Representing a major potentially responsible party and group in U.S. v. Pristine - a group of multiple Superfund cases


  • Representing clients in significant Clean Water Act, wetland, industrial discharge and drinking water matters
  • Serving as counsel for RCRA (Resource Conservation Recovery Act) corrective action sites and as lead counsel for Superfund potentially responsible parties (owners, operators, generators, transporters); worked on issues relating to solid waste permitting and licensing, construction and demolition debris permitting and licensing
  • Advising clients on Vapor Intrusion risks, investigations, and remedies, including off-site and residential impacts
  • Managed a multi-state search for PCB contaminated waste oil, negotiated CERCLA and TSCA cleanups with USEPA on behalf of property owners and remediation companies, advised on new chemical uses, importation / exportation, polymer, and other TSCA (Toxic Substances Control Act) issues, including enforcement
  • Leading and managing multi-media and single-media audits of a wide variety of factories and regulated facilities, including filing violation self-disclosures with the USEPA and state agencies and presenting the results to corporate leadership and regulatory agencies

Transactional / Business 

  • Conducted environmental due diligence and negotiated asset / stock sale and lending / finance transaction terms (including indemnities) for over 25 years, including a wide range of industrial, commercial and multi-family properties involving both public and private companies, both in the US and abroad.  Engaged and supervised Phase 1 and Phase 2 investigations and remediations related to transactions, including Vapor Intrusion
  • Participating in the issuance, to clients and interested parties, of over ten Ohio EPA Covenants Not to Sue under the Ohio Voluntary Action Program
  • Representing clients that have obtained multiple grants resulting in major remediation and redevelopment projects under the Clean Ohio Fund
  • Serving as counsel to developers, sellers, end-users, lenders and public funding entities in transactions involving brownfield development in multiple states

Emergency Response

  • Serving as environmental counsel for a client that was asked by the United States Environmental Protection Agency (USEPA) to implement anthrax decontamination of the U.S. Senate Office Building and the U.S. Postal Service facilities
  • Serving as regulatory counsel in a leaking chemical railcar case with thousands of residents evacuated and roads closed, negotiating with multiple regulators and law enforcement officials and handling risk management, public communication, corporate advising and coordination with litigation counsel
  • Representing a manufacturer in an emergency testing and evaluation as to whether an operating factory must be evacuated

Mark is a member of the Ohio State Bar Association, the Cincinnati Bar Association and the National Brownfields Association.

Mark has given speeches for over 25 years to numerous organizations including the American Bar Association, the Ohio State Bar Association, and multiple local bar associations, trade associations, clients, businesses, universities and law schools.  He has co-taught multi-day environmental law and regulation seminars to environmental professionals for over five years.

Mark received his J.D. cum laude from the Georgetown University Law Center.  He received his B.A. with honors from George Washington University, where he was Phi Beta Kappa.

Honors & Recognitions

Law360 2011 Environmental Law MVP

The Best Lawyers in America, Litigation Environmental "Lawyer of the Year," 2020

The Best Lawyers in America, Environmental "Law Lawyer of the Year," 2014

The Best Lawyers in America, Environmental Law, 2006-2019, 2022-2024; Litigation Environmental, 2011-2024

Ohio Super Lawyers, Environmental, 2004-2016

Ohio Super Lawyers, Top 50 Cincinnati Area Super Lawyers, 2010

Chambers and Partners, Leading Lawyer in Natural Resources and Environment, 2005-2022

Chambers and Partners, Leading Lawyer in Environment, 2023-2024

Who's Who Legal-Environment: The International Who's Who of Environment Lawyers, 2014-2020

Martindale-Hubbell AV Peer Review Rated

Professional & Community Activities

Greater Cincinnati Chamber of Commerce

Hamilton County Environmental Action Commission, Member since 1992

Crossroad Health Center, Cincinnati, Co-Founder, Board Member since 1992

News & Insights




Georgetown University Law Center, J.D., cum laude, 1983

George Washington University, B.A., 1977, with Honors, Phi Beta Kappa

Bar & Court Admissions

  • Ohio
  • U.S. Court of Appeals for the Sixth Circuit
  • U.S. District Court for the Northern District of Ohio
  • U.S. District Court for the Southern District of Ohio
  • Admitted to practice law only in the states listed above.
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