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John Day Dam Powerhouse

John Day Dam Powerhouse
Rufus, Oregon

John Day Dam on the Columbia River was completed in 1967. Since that time, there has been physical evidence that the foundation rock beneath the powerhouse and spillway may be deteriorating. The objective of the instrumentation program was to develop a plan for in situ testing and instrumentation supplemented by laboratory testing to permit evaluation of the deformability, rate of deterioration, and relative permeability of the foundation rock. The work was accomplished in two phases. Part 1 was completed to establish the processes, instrumentation, testing methods, installation requirements, and fixed costs to permanently record deformations/tilting within the foundation rock and the overlying powerhouse monolith. GRI directed the drilling and coring of a 240-ft-deep boring through the dam and into the foundation rock to evaluate and locate existing or potentially deleterious foundation materials or groundwater problems and install a reliable long-term foundation and monolith instrumentation system that will monitor minute cyclical deformations.

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