Successful completion of the 7.5-MW Youngs Creek project in Washington State shows it is possible to develop new small hydro facilities that are both cost-effective and meet high environmental standards. The project has been operating since October 2011.

The 7.5-MW Youngs Creek hydro project, which began operating in October 2011 about 4 miles south of the city of Sultan in Washington State, generates an average of 2.5 MWh per year of clean, reliable, renewable power for the Snohomish County Public Utility District. The PUD developed this project on a quick timeline of just 2.5 years and at a total cost of $29 million. It will provide power to more than 2,000 homes, on average, in Snohomish County PUD's service area.

In February 2012, the Renewable Energy World network, which includes five print magazines and four websites, presented project owner Snohomish County PUD its Project of the Year Award for hydro. To be eligible for an award, a project needs to have been completed in 2011 in North America and make a significant impact on the entire renewable energy industry. When judging the finalists, network editors considered the technology that was employed, as well as the projects' impact on the industry at large and on the communities in which they were installed.

Below is the story behind the development of Youngs Creek, the first new hydroelectric plant built in Washington State in nearly 20 years.

Choosing the project

Despite the recent economic slowdown, Snohomish County PUD, located north of Seattle in Washington State, expects rapid growth, adding up to 40% to its customer base over the next 20 years. The utility currently serves 320,000 customer accounts in urban, suburban and semi-rural communities. Its elected Board of Commissioners made a commitment as part of its climate change policy in 2007 to meet additional load growth through aggressive energy conservation and renewable energy sources. Small hydropower projects are key components of the utility's energy mix.

"We want to develop these resources to the extent possible within our own service territory," said Snohomish PUD General Manager Steve Klein. "By doing so, we can better determine and guide our own destiny and provide economic development and jobs within our own community."

The story behind the Youngs Creek facility demonstrates that new small hydropower sites can be developed in ways that make them cost-effective while still meeting high environmental standards.

The powerhouse for the 7.5-MW Youngs Creek project in Washington State is a concrete block structure with a metal roof. It contains a single two-jet horizontal Pelton turbine.

The utility purchased the land for its Youngs Creek project in 2008. The site had an existing license from the Federal Energy Regulatory Commission, which was originally issued to Puget Sound Energy. The previous site owner had developed some initial designs but never moved forward on the project. Snohomish PUD officials worked with FERC to assume the license, with the condition that the hydropower project would be built by the end of 2011.

As they assessed the Youngs Creek site, PUD staff saw several benefits. Like other PUD small hydropower projects, it is located outside of sensitive areas, such as designated wilderness lands. The powerhouse and intake are above a natural barrier, a waterfall, so there are no issues related to migrating fish. The project also is located close to two other PUD hydropower projects - the utility's 650-kW Woods Creek and 112-MW Jackson projects - so it can be easily operated and maintained by existing staff.

"We see small hydropower as a resource that's competitively priced or cheaper than other green energy sources," said PUD Manager of Generation Engineering Scott Spahr. "These projects give us greater flexibility with our power supply as they're locally generated, reliable resources that provide energy at times of the year when it's needed the most."

The Youngs Creek project will generate the highest levels of energy during the winter months, the utility's highest demand period. In drier summer months, it will operate in limited capacity or be shut down temporarily for maintenance.

The short FERC project deadline put the PUD on the fast track, but the utility was able to tap existing staff and assemble a project team to meet multiple construction deadlines. Extremely wet conditions in fall 2010 also created challenges in the timing of some construction.

Construction work

Snohomish County PUD began project design work in 2008. EES Consulting of Kirkland, Wash., was the design consultant for the project. The utility engaged with multiple stakeholders during its planning process, including local tribes, environmental groups and regulatory agencies. It worked closely with the Washington Department of Fish & Wildlife, other state and federal agencies and local tribes to ensure that the project was designed to provide adequate levels of river flow and fish protection.

In 2009, they obtained permits from the county, U.S. Army Corps of Engineers and regulatory agencies and began material procurement.

The PUD broke ground on the project in 2010 and started construction of the intake, penstock, powerhouse, and transmission line. The 12-foot-long diversion weir across the river impounds a 0.25-acre area of water.

A 12-foot-long diversion weir impounds a 0.25-acre area of water, which is fed through an intake into a penstock that drops 920 feet in elevation to the powerhouse to provide flow up to 120 cubic feet per second.

The 14,300-foot-long underground penstock was 48 to 51 inches in diameter and was made of welded steel supplied by Ameron International of Pasadena, Calif. The penstock drops 920 feet in elevation from the intake to the powerhouse to provide flow up to 120 cubic feet per second. The powerhouse is a concrete masonry unit (concrete block) structure with a metal roof. It measures 60 feet by 40 feet and is 35 feet high.

TEK Construction of Bellingham, Wash., was general contractor for the construction work, and Strider Construction Co. of Bellingham served as civil contractor for the earthwork and pipeline installation. Gilbert Gilkes and Gordon of Kendal, Cumbria, United Kingdom, supplied the single two-jet horizontal Pelton turbine for the plant, while Hyundai Ideal Electric of Mansfield, Ohio, supplied the synchronous generator with exciter. North American Phoenix Energy Services of Phoenix supplied the powerhouse controls. Hawkeye Construction of Hauppauge, N.Y., built the transmission system.

The community of Sultan, about 4 miles from the project site, received an economic boost during the construction phase, as contractors' crews coming through the area increased revenues for local hotels, restaurants and various retailers.