The Upriver Hydroelectric project located on the Spokane River has spillway discharge capability provided by a concrete gravity dam. It is a high hazard dam founded on a gravel foundation. There are eight tainter gates that control the spillway.

Tetra Tech INCA provided static and seismic gravity dam stability analysis. Normal Operation, Flood, ICE Loading, and Earthquake load cases were considered. Work included review of FERC safety program reports, technical reports, static stability analyses and sensitivity analyses, seismic analyses, draft and final report.

INCA performed a stability analysis of the Upriver Dam spillway dam per the FERC guidelines and a sensitivity analysis of the dam stability based on different hydrostatic uplift pressures and foundation soil strength parameters.