- Location: Snoqualmie, Washington
- Owner: Puget Sound Energy
- Engineer(s): Klohn Crippen Berger
- Status: Completed
The Snoqualmie Falls Hydroelectric Operations are a prized facility within the PSE system, situated on a pristine river above and below Snoqualmie Falls. Located 25 miles east of Seattle, the diversion dam and 100-year-old Power Plants 1 and 2 required updating and expansion. The site was unique: work took place in-water, on water, below ground, directly upstream and downstream of a 30-story waterfall, down a 60-percent grade slope, directly beneath a luxury hotel focused on its outdoor setting, interspersed with public access for those 2 million visitors, and requiring historic preservation in many areas. In-water work had to be limited to annual “windows” established by state and federal agencies. Milestones were based on an aggressive schedule.
Our Barnard Team reached each milestone set forth in the contract and brought the plant in two years ahead of the Owner’s original schedule, all through careful planning and creative, collaborative problem-solving. Over the course of the project, we placed a temporary diversion dam and constructed a new diversion dam based on minimal geotechnical data and 100-year-old as-built drawings. The project’s essential Long-Term Cofferdams, designed by HDR Engineering, Inc. for Barnard, received regional design awards from the American Council of Engineering Companies and the American Society of Civil Engineers. While performing in-water work, we made sure the water quality was tested both up and downstream at least once per 24-hour period. Sheetpile and cofferdam installation and removal, and riprap armoring all took place without incident in the river.