Our Staff

Brigitte Griswold.

Brigitte Griswold Executive Director

As Executive Director of Groundwork, Brigitte oversees the organization's efforts to create sustainable environmental change in Yonkers through community-based partnerships that promote equity, youth leadership, and economic opportunity. Prior to joining Groundwork, Brigitte was the Director of Youth Engagement Programs for the Nature Conservancy, where she managed all education, volunteer, and employment programs for young people.  Brigitte is a 2009 Fellow of Green for All, a national organization dedicated to building an inclusive green economy, and a 2010 Fellow of the Center for Whole Communities, which promotes stronger connections between people, land, and community. Her work has been recognized by The Environmental Protection Agency, The National Park Service, Westchester County, and The City of Yonkers, and she has also received notable awards from The Conservation Fund, The Disney Worldwide Conservation Fund, The Edison Award Honoring Innovation and Innovators, The US2020 STEM Mentoring Award for Excellence in Public-Private Partnerships, and the Nature Conservancy’s Conservation Achievement Award for individuals who demonstrate creative strategies, courage in execution and leadership in achieving results. Brigitte holds a B.A in Communications and English literature from the University of South Carolina.

Kathleen Bartels Administrative Assistant

Kathy graduated from Blessed Sacrament/St. Gabriel High School in New Rochelle with 1st Honors and studied Italian for three years in High School. Kathy attended Iona College in New Rochelle for 2 years as a Business major. She worked at the Community Planning Council of Yonkers from 1992 through 2006 as an Administrative Associate to the Executive Director. Kathy also currently works at CLUSTER Community Services in the Westchester and Rockland Mediation Center Department as an Administrative Assistant to the Director and works at Groundwork Hudson Valley part-time as an Administrative Assistant.

kathleen bartels
Jason Bonet

Jason Bonet Sustainability Education Associate

A lover of all things nature and a native New Yorker, Jason grew up enjoying the many parks New York City has to offer. He cultivated his love for nature at the High School for Environmental Studies in Manhattan and then later earned a degree in Conservation Biology from SUNY College for Environmental Science and Forestry. Before joining Groundwork, he was the Garden and Volunteer Manager for the Kingsbridge Heights Community Center, teaching workshops and classes on gardening, nutrition, and ecology. He’s an avid birdwatcher, edible mushrooms and plants forager, and backpacker, as well as a beekeeping hobbyist. Jason is also a member of Latino Outdoors, a national nonprofit that engages Latino communities in the outdoors.

Jerome Cunningham Development and Communications Associate

Since 2015, Jerome has worked as the Youth Engagement Operations Program Coordinator at The Nature Conservancy, where he oversaw a nationwide environmental school grant program, managing a database of grantees, organizing site visits, crafting bi-monthly newsletters, and leading garden build events for over 130,000 school children across the country.

Before joining Groundwork, Jerome honed his environmental skills through multiple internships with the Trust for Public Land and The Nature Conservancy, where he focused on both traditional conservation practices such as GIS mapping, kiosk modeling, and invasive species management along with donor communications, social media, marketing, and philanthropy. Throughout his career, he has worked to connect his passion for nature with his creativity as a spoken word artist, while simultaneously managing complex projects that serve to protect and build a more sustainable world. Jerome is currently serving as a Regional Fellow with the Environmental Leadership Program, a highly selective program that supports visionary, action-oriented, and diverse leadership for a sustainable future by providing emerging leaders with the support and guidance they need to launch new endeavors and rise to new leadership positions.

Jerome is a graduate of CUNY’s City College of New York, where he received his Bachelor’s degree in Communications, Advertising, and Public Relations. Jerome is a self-proclaimed ‘Harlemite’, born and raised in the Sugar Hill district.

Jerome Cunningham
Miriam Foley

Miriam Foley Business Manager

Miriam holds a B.A in Computer Science from Queens College and started her career as a computer programmer. While taking time off to raise her two sons, she became very involved in the Yonkers community and held many positions, including President of the Yonkers Council of PTA/PTSAs. By combining all of the knowledge and skills she acquired, Miriam returned to paid work in the nonprofit sector as a Grants and Finance Manager for local community organizations. As the Business Manager for Groundwork, Miriam provides office support for all of Groundwork’s community programming, which reflect her interests in the local community (especially the schools), the environment and the arts.


Oded Holzinger Climate Resilience Manager

Oded is an urban planner with a strong passion for environmental justice, community planning and outdoor education. He worked as an outdoor educator and regional manager for a nonprofit working with youth from marginalized communities in Israel. After moving to the U.S., Oded worked as a site manager for a summer camp in the Catskills, where he also helped to develop a unique outdoor education program bringing high schoolers from underserved communities in the NYC Metro Area for wilderness training programs on the campgrounds. After starting his advanced academic studies, Oded interned with the NYC Department of Transportation Bicycle and Greenway Group where he helped to plan and design bike lanes and greenways all over NYC. Prior to joining Groundwork Hudson Valley, Oded worked as a community planning fellow with Brooklyn Community Board 14 on developing a neighborhood greening project. In addition, Oded is a licensed drone pilot who is interested in the intersection between technology and environmental conservation. As Groundwork’s Rivers and Trails Program Manager, he works on greenway development, watershed restoration, and climate change mitigation, bringing together his passion for the natural environment, community engagement, environmental education and planning.

Oded holds a BA in Urban and Environmental Geography with a certificate in GIS from the Hebrew University of Jerusalem and a Master’s in Urban Planning with a focus on Environmental Planning from Hunter College.

Oded Holzinger

Victor Medina Youth Programs Manager

Victor joins us from Lowell National Historic Park in Massachusetts, where he worked for over five years as a National Park Ranger. He led both interpretation programs for visitors and youth engagement programs, which created lasting connections between the park’s resources and the community it serves. Victor developed an early passion for conservation as a student at the High School for Environmental Studies in New York City. He participated in a wide range of activities including the Recycling Club, family beach cleanups, and internships at the New York League of Conservation Voters and the Nature Conservancy. Victor is also a member of the Appalachian Mountain Club’s Youth Opportunities Program. As Groundwork’s Youth Programs Manager, Victor continues to inspire youth to take on conservation challenges in their communities and cultivate a more sustainable world for future generations.

Victor holds a B.A in Geography, Globalization, and Urban Studies and Planning as well as a certificate in Geographic Information Systems (GIS) from the University of Albany. In addition, Victor holds a certificate in Community Leadership and Social Change from Tisch College at Tufts University.

Candida Rodriguez Director of Community Relations

Candida is responsible for implementing community engagement programs, event organization, and developing public relations strategies, promoting Groundwork’s mission. Candida has experience working alongside community members, local nonprofits, international organizations, and government entities. Her expertise expands through climate change policy, gender equality, migration, education, youth development, and poverty reduction. She began her journey as an international development professional designing and leading community development programs and projects with local nonprofits and later, with international organizations such as the United Nations Development Programme (UNDP). While at UNDP, she led communications initiatives and strategies, organized events, and supported a whole-of-government approach to gathering national climate data, and drafting national climate reports and plans.

Throughout her career, she has worked and lived in Fiji, Spain, the Dominican Republic, and Nicaragua. Candida is passionate about the inclusion of vulnerable and underrepresented populations in decision-making, especially on issues pertaining to environmental justice. She enjoys being outdoors, taking up a new hobby, and traveling. She holds a Bachelor’s in Sociology from SUNY Buffalo State College and a Master’s in Migration and Development Studies from the University of Almeria in Spain.

Joel rodriquez

Joel Rodriguez Sustainability Education Program Manager

Joel is a skilled sustainability professional with over eighteen years of experience in program development and management, environmental education, and community engagement in the nonprofit sector. He has developed dynamic programming for schools and diverse community stakeholders rooted in the principles of sustainability. In his past role as Director of Environmental Education at the City Parks Foundation, he oversaw the creation, implementation and expansion of school day, afterschool, and summer enrichment programs across all 5 boroughs of New York City, with a particular focus on underserved communities. He continues to serve as the Sustainability Coordinator and member of the Zoning Board for his hometown of Elmsford, where he guides sustainability initiatives and represents the village on the Bronx River and Saw Mill Watershed Advisory Boards. He also consults as a subject matter expert on several projects in the Catskills that are focused on permaculture and climate change resiliency. In his free time, Joel enjoys studying invertebrates, both terrestrial and aquatic, fungi, fossils, and has a special interest in waste reduction, upcycling/repurposing and food security.

Joel holds a B.A. in Environmental Studies from the University at Buffalo, a graduate certificate in Higher Education Administration from Northeastern University, as well as a graduate certificate in Climate Change and Sustainability and a M.A. in Global Sustainability from the University of South Florida.

Ellen Theg Director of Programs and Operations

Ellen began her environmental work studying ecology. After interning at the Council on Environmental Quality for a political perspective, she turned to research science at Duke University. Choosing to pursue a secondary interest in film sparked by exposure to classic Japanese and European art films, she settled into the distribution side of the film and television business, developing her skills in intellectual property rights licensing as VP of Business & Legal Affairs for a major European media company. From there, she earned her MBA with a special focus on environmentally sustainable business practices, and brought this perspective to her contribution to The Five Horsemen of the Modern World, Daniel Callahan’s book examining the ‘wicked’ problems of climate change, food and water shortages, chronic health issues and obesity. Ellen joined Groundwork Hudson Valley in 2014 to build its grant and business processes, and served as Principal Investigator for Groundwork’s climate resiliency education grant from the National Oceanic and Atmospheric Administration and project manager for the initial stages of the construction of the Yonkers Greenway. She now serves as Director of Programs and Operations, managing a team of talented professionals in the areas of Rivers & Trails, Youth Employment and Sustainability Education.

Ellen holds a B.A in Biology from Wellesley College and an MBA from NYU’s Stern School of Business.


Karen Tumelty Director of Development

Karen’s career has ranged from working as on-air DJ for a commercial radio station, to product manager for the Irish-American Hip Hop group House of Pain (of Jump Around fame), to building and executing fundraising and growth strategies for organizations including Human Rights First, Riverkeeper, and Greyston.

At Riverkeeper, highlights of her achievements included working with allies like Whole Foods to build awareness about the environmental and cultural importance of the Hudson River. The Earth Month campaign that she created for all of the NYC Whole Foods Markets increased web traffic to over 1,000,000 hits per month and significantly increased online donations. Her non-confrontational approach to story-telling has created new levels of understanding of people and communities that have been marginalized and excluded. For example, while at Greyston, she inspired one of the most iconic social enterprises,The Body Shop, to adopt Open Hiring practices at the distribution center and in their retail stores. This, in turn, resulted in increased donor confidence and gift size. She works from a core value of listening to people and helping them connect to the work that will help them be the change they want to see in the world.

Karen is an avid cook who enjoys exploring new cultures through flavor and is also an accomplished knitter. She was raised in Yonkers and has lived in our community for much of her life. She has served as Vice Chair of the Yonkers Human Rights Commission, was the founding Chair of the Yonkers Alliance for Latino and Immigrant Services, and was the Formation Chair for the Yonkers St. Patrick’s Day Parade for many years.