Proceedings of the 2012 Biennial Geotechnical Seminar held in Denver, Colorado, on November 9, 2012. This Geotechnical Practice Publication contains 16 papers that address the complex geotechnical challenges in geologic hazards, nondestructive evaluation, geo-construction, and the ground itself. Topics include: debris flow assessment and mitigation; rockfall rating systems; dam sinkhole evaluation; seismic imaging for landslide remediation; photogrammetry for mapping discontinuities, river morphology, and concrete damage; mine subsidence under levees; laramie formation claystone behavior; underdrains for construction on expansive soils; reinforced soil structures; bedrock settlement under dams; energy foundations; drilled shaft foundations; and tunnel rehabilitation. This Geotechnical Practice Publication focuses on Colorado and the Rocky Mountain West s specific geotechnical practice and experience. It will be valuable to anyone in geotechnical engineering, especially those working in Colorado or similar geologic settings.