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GGA Board of Directors


Geysers Geothermal Association

Danielle Matthews Seperas
Manager, Government & Community Affairs
The Geysers

Danielle Matthews Seperas joined Calpine's Geysers team in 1998.  Danielle oversees Calpine's Geysers outreach efforts, interacting with local community and working with local government on energy and related issues.  Her responsibilities include expanding geothermal energy education in the community, promoting The Geysers through community tours and overseeing Calpine's Visitors Center operations. Danielle holds a Bachelor of Science degree in History and Government, a Master's degree in Public Administration.

Danielle Matthews Seperas


GGA Chief Financial Officer Treasurer

Paul Brophy

EGS, Inc.

Waterfall Towers
Suite A112
2455 Bennett Valley Rd
Santa Rosa, CA 95404

Paul Brophy



GGA Vice President

Mark Dellinger

Full Circle Utility Services

5853 Single Spring Dr.

Kelseyville, CA 95451

Mark Dellinger




Christopher Cameron
Jay Hepper has lived in Sonoma County and came to The Geysers in 1978, starting his geothermal career at what was then known as the Hughes Thermogenics Unit #15 project. He joined the GGA in its founding year as a regular member and feels fortunate to have the opportunity to serve on the board since 2015. He has been involved in almost every aspect of the Geysers Operations, including project exploration, testing, construction, development, O&M, R&D and project retirement. An additional 5 years of his career was spent at Sacramento Municipal Utilities District (SMUD) in Sacramento on a job transfer opportunity. Over half of his Geysers time has been in various supervisory or management positions. His geothermal experience also includes consulting and job transfer work at other projects in the western U.S. He enjoys staying involved in the Geysers and has represented the industry giving tours, volunteering time at informational booths at various local, county and state fairs. At the State Fair he was a goodwill ambassador for Lake County which included education and promotion of the geothermal industry with the general public. Jay also became a member of an associate organization, the Geothermal Resources Council (GRC), in 1983 and presently remains an active member which has similar goals in promoting the geothermal industry on a world-wide level.

Jay Hepper

GGA Scholarship Chairman


Ben came to The Geysers in 1978 from Union Oil's Research Department and spent fifteen of the next twenty one years here. Trained and registered as a petroleum engineer, Ben was involved in research on water injection, drilling operations, property taxation and strategic planning. During a five year assignment with Philippine Geothermal, he was the manager of computer services as well as reservoir engineering. When Calpine bought Unocal's holdings in 1999, Ben set up his own reservoir engineering consultancy. Although most of his practice now takes him far from The Geysers, he continues to take a keen interest in its progress.

Ben Barker


Frank Obertance

Frank Obertance has nearly 31 years of experience working at The Geysers in various management positions.  Before retiring in July 2013, he was General Manager for Calpine, responsible for the management of seven operating geothermal power plants and eight steam fields.  Frank has continued to be active in GGA and leading Geysers tours during retirement and most recently has returned to working at The Geysers to assist Calpine with the Valley Fire Recovery projects.  Earlier in his career, Frank w orked in power plants in the New York area before relocating to T he Geysers .  Prior to that he sailed as a licensed Marine Engineer on U.S. merchant ships.

Frank Obertance


Ed Voge

Reservoir Engineer


Ed Voge has worked The Geysers since 1988 in various engineering capacities. He has worked as a reservoir and production engineer for Unocal Geothermal, a plant engineer for Calpine Corporation and is currently the steam field reservoir engineer for Northern California Power Agency. He has a B.S. degree in Mechanical Engineering from the University of Utah and a M.S. degree in Petroleum Engineering from the Colorado School of Mines.

Ed Voge



Blaydes & Associates

1275 Fourth Street #214

Santa Rosa, CA 95404

Paula Blaydes

Gene Suemnicht

Dorothy Beebee

GGA WebMaster




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Geysers Geothermal Association Website (This page updated March 02, 2019)
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