Board of Directors

Mr. Shelton, a director since July 2006, has also held the position of Chairman of the Board of the Company since December 2014. Mr. Shelton served as the CFO of S K Hart Management, LLC, a private investment management company (“S K Hart Management”), from 1999 until August 2018. Mr. Shelton served as President of Pony Express Land Development, Inc. (an affiliate of SK Hart Management), a privately held land development company, from January 2013 until August 2017, and has served on its board since December 2005. Mr. Shelton served as Director and CFO of S K Hart Ranches (PTY) Ltd, a  private South African Company involved in agriculture, from March 2012 to March 2020. Mr. Shelton has over 20 years of experience as an executive financial officer for several waste management companies, including as CFO of Envirocare of Utah, Inc. (now EnergySolutions, Inc. (1995–1999)), a privately held nuclear waste services company, and as CFO of USPCI, Inc. (1982–1987), then a NYSE-listed public company engaged in the hazardous waste business. Since July 1989, Mr. Shelton has served on the board of Subsurface Technologies, Inc., a privately held company specializing in providing environmentally sound innovative solutions for water well rehabilitation and development. Mr. Shelton has a B.A. in accounting from the University of Oklahoma.

Mr. Bostick, a director since August 2020, is currently the CEO of Bostick Global Strategies, LLC, a position he has held since July 2016. Bostick Global Strategies, LLC provides strategic advisory support in the areas of Engineering, Environmental Sustainability, Human Resources, Biotechnology, Education, Executive Coaching, and Agile Project Management. In February 2021, Mr. Bostick was selected by U. S. Senator Jack Reed, Chairman of the Senate Armed Services Committee, to serve as a member of a new commission consisting of eight appointed individuals, tasked with renaming Confederate-named military bases and property. Mr. Bostick previously served (from November 2017 to February 2020) as the COO and President of Intrexon Bioengineering, a division of Intrexon Corporation (formerly NASDAQ: XON; now NASDAQ: PGEN). Intrexon Bioengineering addresses global challenges across food, agriculture, environmental, energy, and industrial fields by advancing biologically engineered solutions to improve sustainability and efficiency. As the COO and President of Intrexon Bioengineering, Mr. Bostick oversaw operations across the company’s multiple technology divisions and led a major restructuring of Intrexon Corporation.  Mr. Bostick is a member of the board of HireVue, Inc., a privately-held company specializing in online video interviewing services for employers. Since October 2020, Mr. Bostick has served as a board member of CSX Corporation (NASDAQ: CSX), a publicly-held rail transportation company, and since December 2020, as a member of both the Finance Committee and the Governance Committee of CSX Corporation. Effective June 1, 2021, Mr. Bostick joined the Fidelity Equity and High Income Fund Board of Trustees, which oversees the high income and certain equity funds sponsored by Fidelity Investments, Inc., a privately-owned investment management company. Effective March 15, 2022, Mr. Bostick became a member of the board of Allonnia, LLC, a privately-held start-up environmental biotech company whose mission is to leverage the power of biotechnology and engineered systems to create transformative solutions for a waste-and pollution-free world. In addition to Mr. Bostick’s service on the boards of for-profit companies, he has since November 2016 also served on the board of American Corporate Partners, a 501(c)(3) nonprofit organization dedicated to assisting U.S. veterans in their transition from the armed services to the civilian workforce. Mr. Bostick was named as one of 2021’s Most Influential Black Corporate Directors by Savoy Magazine, a national publication that showcases and drives positive dialogue about Black culture. 

Mr. Bostick has also had a distinguished career in the U.S. military, retiring from the US Army in July 2016 with the rank of Lieutenant General. During his distinguished military career, he served as the 53rd U.S. Army Chief of Engineers and the Commanding General of the U.S. Army Corps of Engineers (“USACE”). As the senior military officer of the Army Corps of Engineers, General Bostick was responsible for overseeing and supervising most of the nation's civil works infrastructure and military construction, hundreds of environmental protection projects, as well as managing 34,000 civilian employees and military personnel in over 110 countries around the world with a $25 billion annual budget. As the Chief of Engineers, General Bostick led a $5 billion recovery program after Superstorm Sandy. Before his command of USACE, General Bostick served in a variety of command and staff assignments with the U.S. Army both in the U.S. and abroad.

General Bostick’s military honors and decorations include the Distinguished Service Medal, the Defense Superior Service Medal, the Bronze Star, the Legion of Merit with two oak leaf clusters, the Defense Meritorious Service Medal, the Meritorious Service Medal with four oak leaf clusters, the Joint Service Commendation Medal, the Army Commendation Medal, the Army Achievement Medal with one oak leaf cluster, the Combat Action Badge, the U.S Parachutist badge, the Army Recruiter Badge, and the Ranger Tab.

As a White House Fellow, one of America’s most prestigious programs for leadership and public service, General Bostick was a special assistant to the Secretary of Veterans Affairs. He graduated with a Bachelor of Science degree from the U.S. Military Academy at West Point and later returned to the Academy to serve as an Associate Professor of Mechanical Engineering. He holds Master's degrees in Civil Engineering and Mechanical Engineering from Stanford University and a Doctorate in Systems Engineering from George Washington University.  He is a Member of the National Academy of Engineering and the National Academy of Construction.

Dr. Centofanti currently holds the position of Executive Vice President of Strategic Initiatives. Effective January 26, 2018, Dr. Centofanti was appointed to the position of President of Perma-Fix Medical, a majority-owned foreign subsidiary of the Company.  From March 1996 to September 8, 2017 and from February 1991 to September 1995, Dr. Centofanti held the position of President and Chief Executive Officer of the Company. Dr. Centofanti served as Chairman of the Board from the Company’s inception in February 1991 until December 16, 2014. In January 2015, Dr. Centofanti was appointed by the U.S Secretary of Commerce Penny Prizker to serve on the U.S. Department of Commerce’s Civil Nuclear Trade Advisory Committee (CINTAC). The CINTAC is composed of industry representatives from the civil nuclear industry and meets periodically throughout the year to discuss the critical trade issues facing the U.S. civil nuclear sector. From 1985 until joining the Company, Dr. Centofanti served as Senior Vice President of USPCI, Inc., a large publicly-held hazardous waste management company, where he was responsible for managing the treatment, reclamation and technical groups within USPCI.  In 1981, he founded PPM, Inc. (later sold to USPCI), a hazardous waste management company specializing in treating PCB contaminated oil.  From 1978 to 1981, Dr. Centofanti served as Regional Administrator of the U.S. Department of Energy for the southeastern region of the United States.  Dr. Centofanti has a Ph.D. and a M.S. in Chemistry from the University of Michigan, and a B.S. in Chemistry from Youngstown State University.

Ms. Duggan, a director since May 2021, is the founder and CEO of SustainabiliD, a woman-owned advisory services firm working with gamechangers to equitably solve the climate crisis. She has been named the founding director of the University of Michigan’s SEAS Sustainability Clinic. 

In 2021, Ms. Duggan was appointed to the DOE’s prestigious Secretary of Energy Advisory Board, serving under Secretary Jennifer Granholm. In February 2021, Michigan Governor Gretchen Whitmer also appointed Duggan to the State of Michigan’s Council on Climate Solutions, to advise on the implementation of the MI Healthy Climate Plan, to reduce greenhouse gas emissions and to transition toward economy-wide carbon neutrality. In 2020-21, Ms. Duggan was a member of the Biden-Harris Transition Team on the Department of Energy Agency Review Team. In May 2020, Ms. Duggan was named a member of the Biden-Sanders Unity Task Force on Climate Change, serving as one of Biden’s five delegates alongside Gina McCarthy and Sec. John Kerry; and later co-chaired the climate change policy committee and served as a Surrogate for the Biden campaign.

Previously, Ms. Duggan served nearly seven years in public-service leadership roles, including inside the Obama-Biden White House as Deputy Director for Policy in the Office of Vice President Biden Policy to then Vice President Joe Biden for energy, environment, climate, and distressed communities. Simultaneously, she served as Deputy Director of the Detroit Federal Working Group to support Detroit’s revitalization. Prior to the White House, Ms. Duggan held several senior roles at the Department of Energy, including as Secretary Moniz’s embedded Liaison to the City of Detroit (where she championed a citywide LED streetlight conversion), and in the Office of Energy Efficiency & Renewable Energy as Director of Stakeholder Engagement, Director of Legislative, Regulatory & Urban Affairs, and as a Senior Policy Advisor. 

After her time in federal service, Ms. Duggan co-founded the Smart Cities Lab, was a Partner with the Honorable Thomas J. Ridge’s firm, RIDGE-LANE Limited Partners, and served on the external advisory board of the University of Michigan’s Erb Institute for Global Sustainable Enterprise and was a Board Member at the Global Council for Science and the Environment. She has also served as a Trustee of the University Liggett School, the oldest independent co-educational day school in Michigan. In 2018, Ms. Duggan was named to the prestigious “40 Under 40” list by Crain’s Detroit Business and their 2022 inaugural “Notable Leaders in Sustainability” list. She previously worked at the League of Conservation Voters in Washington, D.C.

Currently, Ms. Duggan serves as a senior advisor at The RockCreek Group, LP. She also sits on the corporate advisory boards of Our Next Energy, Inc. (ONE), Aclima, Inc., BlueConduit, Walker-Miller Energy Services, L.L.C., HEVO, Inc., Commonweal Investors, and Arctaris Impact Investors, LLC.

Ms. Duggan earned her B.S. in Environmental Studies from the University of Vermont and her M.S. in Natural Resource Policy & Behavior from the University of Michigan.

Mr. Grumski, a director since February 2020, has served since April 2020 as the President and CEO of TAS Energy Inc. (“TAS”), a wholly-owned subsidiary of Comfort Systems USA, Inc. (NYSE: FIX), a publicly-held company that provides mechanical and electrical contracting services in 139 locations and 114 cities throughout the United States. Prior to the acquisition of TAS by Comfort Systems USA, Inc., Mr. Grumski served as President and CEO and a board member of TAS from May 2013 to March 2020. From 1997 to February 2013, Mr. Grumski was employed with Science Applications International Corporation (“SAIC”) (NYSE: SAIC), a publicly-held company that provides government services and information technology support. During his employment with SAIC, Mr. Grumski held various senior management positions, including the positions of President of SAIC’s Energy, Environment & Infrastructure (“E2I”) commercial subsidiary and General Manager of the E2I Business Unit. SAIC’s E2I commercial subsidiary and Business Unit is comprised of approximately 5,200 employees performing over $1.1 billion of services for federal, commercial, utility and state customers. Mr. Grumski’s many accomplishments with SAIC included growing SAIC’s $300 million federal environmental business to a top ranked, $1.1 billion business; receiving the National Safety Council “Industry Leader” award in 2009; and receiving highest senior executive performance rating three years in a row. Mr. Grumski began his career with Gulf Oil Company and has progressed through senior level engineering, operations management, and program management positions with various companies, including Westinghouse Electric Corporation and Lockheed Martin, Inc. Mr. Grumski received a B.S. in Mechanical Engineering from The University of Pittsburgh and a M.S in Mechanical Engineering from West Virginia University.

Mr. Reeder, a director since 2003, is a principal shareholder in the law firm of Greenberg Traurig LLP, one of the nation's largest law firms, with 41 offices and 2,400 attorneys worldwide, for which Mr. Reeder served as Shareholder-in-Charge of the law firm’s Mid-Atlantic Region from 1999 to 2008. His clientele includes celebrities, heads of state, sovereign nations, international corporations, and law firms. As the 14th Undersecretary of the U.S. Army (1993-97), Mr. Reeder also served three years as Chairman of the Panama Canal Commission's Board, overseeing a multibillion-dollar infrastructure program. For the past 18 years, he has served on the Canal’s International Advisory Board.  He has written extensively in leading journals on the subject of corporate cybersecurity, served on the boards of the National Defense Industry Association (“NDIA”), chairing NDIA’s Ethics Committee, the Armed Services YMCA, the Marshall Legacy Institute, and many other private companies and charitable organizations. Mr. Reeder served as a director of ELBIT Systems of America, LLC, (2005-2020), a subsidiary of Elbit Systems Ltd. (NASDAQ: ESLT), a multi-billion-dollar provider of defense, homeland security, and commercial aviation system solutions. Mr. Reeder has served as a director of WashingtonFirst Bank, the bank subsidiary of WashingtonFirst Bankshares, Inc., from 2004 to 2017; as a director of WashingtonFirst Bankshares, Inc. (NASDAQ: WSBI), from 2009 to 2017; as a director of Sandy Spring Bancorp, Inc. (NASDAQ: SASR), from 2018 to 2020, and as a member of the Advisory Board of Trustar Bank, a Virginia state-chartered bank (2022).

After successive 4-year appointments by Virginia Governors Mark Warner and Tim Kaine, Mr. Reeder served seven years as Chairman of two Commonwealth of Virginia military boards, and 10 years on the USO Board of Governors. Appointed by former Governor Terry McAuliffe to the Virginia Military Institute’s Board of Visitors (2014), he was reappointed in 2018 by former Virginia Governor Ralph Northam, with his term ending in 2022. Mr. Reeder, who has been a television commentator on legal and national security issues, has consistently been named a Super Lawyer for Washington, D.C., most recently in 2021. 

In May 2018 Mr. Reeder was appointed to the Advisory Council Bid Protest Committee to the United States Court of Federal Claims.

A West Point graduate who served in the 82nd Airborne Division after Ranger School, Mr. Reeder earned his J.D. from the University of Texas, and L.L.M. from Georgetown University.

Mr. Wamp, a director since January 2018, is currently the President of Zach Wamp Consulting, a position he has held since 2011.  As the President and owner of Zach Wamp Consulting, he has served some of the most prominent companies from Silicon Valley to Wall Street as a business development consultant and advisor. From September 2013 to November 2017, Mr. Wamp chaired the Board of Directors for Chicago Bridge and Iron Federal Services, LLC (a subsidiary of Chicago Bridge & Iron Company, NYSE: CBI, which provides critical services primarily to the U.S. government). From January 1995 to January 2011, Mr. Wamp served as a member of the U.S. House of Representatives from Tennessee’s 3rd Congressional District. Among his many accomplishments, which included various leadership roles in the advancement of education and science, Mr. Wamp was instrumental in the formation and success of the Tennessee Valley Technology Corridor, which created thousands of jobs for Tennesseans in the areas of high-tech research, development, and manufacturing. During his career in the political arena, Mr. Wamp served on several prominent subcommittees during his 14 years on the House Appropriations Committee, including serving as a “ranking member” of the Subcommittee on Military Construction and Veterans Affairs and Related Agencies. Mr. Wamp has been a regular panelist on numerous media outlets and has been featured in a number of national publications effectively articulating sound social and economic policy. Mr. Wamp’s business career has also included work in the real estate sector for a number of years as a licensed industrial-commercial real estate broker, for which he was named Chattanooga’s Small Business Person of the Year. He is a founder and Board Chair of Learning Blade, the nation’s premiere STEM education platform, which is now operating in six states with deployment in another 10 states. Learning Blade is owned and operated by SAI Interactive, Inc., d/b/a Thinking Media, a privately-held educational products and services company. 

Mr. Zwecker, a director since the Company's inception in January 1991, previously served as the CFO for JCI US Inc. from 2013 to 2019. JCI US Inc. is a telecommunications company and wholly-owned subsidiary of Japan Communications, Inc. (Tokyo Stock Exchange (Securities Code: 9424)), which provides cellular service for M2M (machine to machine) applications. From 2006 to 2013, Mr. Zwecker served as Director of Finance for Communications Security and Compliance Technologies, Inc., a wholly-owned subsidiary of JCI US Inc. that develops security software products for the mobile workforce. Mr. Zwecker has held various other senior management positions, including President of ACI Technology, LLC, a privately-held IT services provider, and Vice President of Finance and Administration for American Combustion, Inc., a privately-held combustion technology solutions provider. In 1981, with Dr. Centofanti, Mr. Zwecker co-founded a start-up, PPM, Inc., a hazardous waste management company. He remained with PPM, Inc. until its acquisition in 1985 by USPCI. Mr. Zwecker has a B.S. in Industrial and Systems Engineering from the Georgia Institute of Technology and an M.B.A. from Harvard University.