A reservoir of data – Comprehensive geophysical and geological site characterization for efficiency and cost savings across the project lifespan

Complex geology poses challenges to construction of major infrastructure. Here we present perspectives from a project to develop a 96,000 acre-foot reservoir with four dams totaling 10,000 linear feet in Colorado’s Rocky Mountains. Proactively building a comprehensive, 3D geologic/geotechnical model has been key to overcoming geologic complexity, and site-wide geophysical imaging has been key to building that model economically and quickly. Gravity surveys efficiently provided the basis for the model and guided dam layout. More involved seismic and borehole investigations then focused on dam alignments and specific areas of interest. The 3D modeling reduced project cost by allowing us to avoid problematic units, take advantage of favorable structures (e.g., bedrock highs), estimate foundation excavation depths, and identify onsite quarry material. We conclude that comprehensive 3D geotechnical models can optimize planning and design, and that geophysics provides a strong base for these models, even in the most challenging geologic settings.