TD&H is an engineering consulting firm based in Great Falls. Established in 1965, TD&H has since grown to include offices in Bozeman, Helena, and Kalispell, Montana; Spokane, Washington; Lewiston, and Twin Falls, Idaho; Watford City, North Dakota and Media, Pennsylvania. We serve a diverse clientele ranging from unincorporated communities to large cities and from individuals to large corporations. We assist our clients through all project phases, from planning through warranty assistance. TD&H is a 100% employee-owned corporation of over 120 employees. Our staff includes licensed professional engineers, registered land surveyors, certified engineering technicians, GIS/CAD operators, Industrial Hygiene technicians, planners, landscape architects, construction managers and administrative support staff.