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Stone Announces Expansion to European Union

Strategic Expansion Elevates Client Engagement and Collaboration

Stone Environmental, a 100-percent employee-owned consulting firm based in Montpelier, VT, USA, has expanded its services to the European Union (EU) with the addition of an Austrian branch in 2021. Stone’s new branch office serves a broad range of clients with regulatory and environmental policy decision-making support, providing high-level consulting expertise integrating geospatial analysis methods with field to watershed scale hydrologic and water quality modeling.

"Stone has worked in the area of environmental exposure modeling in Europe for many years and we have considered establishing a local office for some time," says Stone Vice President and Environmental Systems Modeling Service Leader Michael Winchell. "Now was the right time to move forward with opening a branch office within the EU, which allows us to further elevate engagement and collaboration with our EU colleagues and clients. Our new location also helps attract additional talent to join our growing team of scientists and engineers."

The branch office has currently two employees: Hendrik Rathjens, Ph.D. and Jens Kiesel, Ph.D., who are in Bartolomäberg, Austria, and Fulda, Germany, respectively. Rathjens and Kiesel are part of Stone's Environmental Systems Modeling team, which has over 20 years of experience in pesticide fate modeling, hydrologic and hydraulic modeling, custom software and interface development, and spatial analysis. Currently, Dr. Rathjens and Dr. Kiesel are working on a variety of international modeling projects in Europe (Belgium, France, Germany) and Africa (Somaliland).

Meet the Team!

Hendrik Rathjens, Ph.D

Senior Environmental Modeler


Dr. Rathjens began his career as a post-doctoral research assistant at Purdue University (Indiana, United States) and joined Stone in 2016. He has managed the Stone Environmental EU office since January 2021. Dr. Rathjens specializes in developing and applying environmental chemical exposure models for predicting chemical fate and transport in the environment. He has conducted numerous agricultural chemical exposure assessments using established regulatory and customized aquatic exposure models to produce exposure predictions in surface and groundwater.

Jens Kiesel, Ph.D

Environmental Modeler


Dr. Kiesel is a civil engineer and began his career as an independent consultant. He has more than 10 years of international experience in project planning and implementation in Europe, Africa, and Asia. Dr. Kiesel joined the Stone EU branch in August 2021 and works on predicting natural and anthropogenic impacts on water resources and agriculture, including sediment transport, nutrient, and chemical fate as well as water quality processes.

Contact information

Stone Environmental, Inc.
Obergantschierweg 36a
6781 Bartholomäberg

Hendrik Rathjens, Ph.D.
Austria: +43-676-537-3384
Germany: +49-190-99088990

Jens Kiesel, Ph.D.
Germany: +49 179 2138668