Geo Enterprises

Our story began with Larry and Aaron Marshall, a father-and-son team united by a passion for drilling and service. Larry, a South Dakota native, spent a decade living in three African countries, where he began his drilling career by providing fresh-water wells to remote villages in need. After returning to the United States, he turned his attention to geothermal well drilling and later joined Aaron in founding Geo Enterprises. Larry served as our president until his passing in 2009. Since then, we have continued his legacy under Aaron’s leadership, guided by the same commitment and purpose.

Aaron is a licensed well driller in South Dakota and an International Ground Source Heat Pump Association-accredited geothermal system installer. He earned a Bachelor of Science in Business Management from the University of Colorado in 1999 and has participated actively in the Rapid City building industry since 2000. Our experienced drilling team includes IGSHPA-accredited geothermal installers, and we work with homeowners, HVAC providers, architects, and engineers to evaluate site geology and determine suitable geothermal methods for heating and cooling projects.

We have drilled numerous water wells and thousands of geothermal wells across western South Dakota, the Black Hills, and surrounding areas. Our primary focus is residential and commercial new construction, although we also undertake selected work for existing homes and facilities. Our services include residential, commercial, agricultural, and municipal water-well drilling; residential and commercial geothermal well-field drilling; well abandonment; water-well and geothermal well-field repairs; geothermal test wells; and system flushing and filling. For thermal-conductivity testing, we drill and prepare the test well, then use specialized equipment to collect continuous temperature data over a period of more than 40 hours. Once testing is complete, the well can be repurposed for the planned geothermal heat-pump installation. Throughout our work, we emphasize precision, responsible drilling practices, quality materials, and procedures intended to support lasting investments.