The total workforce employed by Stone and Webster of Boston Massachusetts (Northwestern Electric Company’s contractor) averaged 900 men during the 11 months required to build the Condit dam and powerhouse. Most of the men were recent Greek immigrants, having been contracted through an employment firm in Portland, OR.
After diverting the river’s flow, the next major step in dam construction involved preparing the river channel for pouring of the dam foundation. This highly illustrative photo shows important components of this work, including survey of river channel, using high pressure water jets to wash sediment from the bedrock channel, and hoisting of resulting debris from the canyon for disposal. Meticulous cleaning of the dam’s foundation was absolutely critical to preventing water leakage below and through the dam, which could cause subsequent erosion and dam failure.
Up to 12 feet of alluvium (i.e., river rock) had to be removed from the original river bed before reaching stable bedrock. By all accounts, an excellent job was accomplished by Stone and Webster. The integrity of the dam’s concrete and foundation are still excellent today
Above is a downstream view of the dam site. The photo below shows an upstream view… both taken 99 years ago. Remember that you can click on any of the images in this blog for a larger view.