- Location: Snoqualmie, Washington
- Owner: Puget Sound Energy
- Engineer(s): Klohn Crippen Berger
- Contract Type: Design-Assist (negotiated), Guaranteed Maximum Price
- Status: Completed
In 1898, an ambitious engineer named Charles H. Baker, set out to tap the energy he saw produced each day by the cascading waterfall on the Snoqualmie River. He designed and constructed with minimal crew an underground powerhouse carved out of bedrock on the river’s left bank at the base of the falls, hand-mining a 270-foot shaft for access and the penstock. In 1910, the group now running this generating facility decided the river could handle an additional penstock and powerhouse on the other bank, tunneling under a cliff for a flowline that then fed external penstocks down a steep slope to a second powerhouse on the river bank. Those activities and the fact that they remained operational all of this time remain remarkable achievements to this day.
Redeveloping and expanding the capacity of this one-of-a-kind power operation became all the more complex 100 years later when Puget Sound Energy (PSE) began the relicensing process with the Federal Energy Regulatory Commission (FERC). Barnard joined the team addressing these challenges in the design phase, striving to develop the best way to approach work on Plant 1 updating the world’s first completely underground powerhouse, an 11.98 MW facility, by refurbishing four generators and replacing a fifth as well as enlarging the plant’s cavern and 270-foot-deep shaft, replacing the elevator, replacing the penstock and draft tube, realigning the riverbank, reconstructing the river intake, and other work. On the other side of the river, our work on Plant 2 involved construction of a new river intake, the upsizing and relining of the flowline tunnel, and construction of new site chambers, new penstocks, and a new powerhouse which included installation of a new 12.5 MW turbine generator. Challenges not faced in the 1800s spanned the gamut, from the existence of a five-star lodge perched on a cliff above the Plant 2 intake, to the constant stream of tourists to the falls, roughly 2 million per year, through the middle of the project site.