Welcome, TerraSite Design, to the Interstate Engineering Team!

Led by Values, Driven by Purpose.

Our leadership brings technical expertise, real-world insight, and a people-first mindset to every decision, so our clients and communities always come first.

Our Board of Directors and Executive Team are a multi-disciplinary team of professionals supported by a wide-reaching staff of planners, surveyors, engineers, construction observers, and specialists. Together, we provide full-service guidance to clients across the Great Plains region.

With decades of experience across civil, structural, aviation, and environmental disciplines, our leadership designs with intention, advises with care, and builds with longevity in mind.

Executive Team

Headshot of Lonni Fleck wearing a black blazer

Lonni Fleck, PE

Principal Engineer
Chief Executive Officer

Travis Dillman, PE

Principal Engineer
Chief Growth Officer

Mike Bassingthwaite, PE

Principal Engineer
Chief Operations Officer

Man wearing glasses and a collared shirt with the Interstate Engineering logo on it

Wade Senger, PE

Principal Engineer
Chief Administrative Officer

Coming Soon

Chief Revenue Officer

Coming Soon

Chief People Officer

Regional Vice Presidents

Man wearing a black blazer and white shirt

Steve Sullivan, MBA

Principal
Minnesota Region Vice President

Man wearing a vest and button-up shirt

Jim Dahlman, PE

Principal Engineer
North Dakota East Region Vice President

Brent Moore, AICP

Principal Planner
Montana Region Vice President

Adam Thompson, PLS

Principal Surveyor
South Dakota & Wyoming Region Vice President