Repair of Full Exclusion Barrier Nets for Floating Surface Collector
The Swift No.1 Hydroelectric Project is part of the Lewis River Hydroelectric Development located in southwest Washington State. It is owned and operated by PacifiCorp Energy. In 2008 the Federal Energy Regulatory Commission issued a new project operating license that called for the construction and operation of a Floating Surface Collector (FSC) in Swift Reservoir to collect migrating fish and then transport them downstream by truck. When installing guidance nets, the effects of pool fluctuation are critical to insure the nets’ supporting structures, positions and exposures to environmental conditions. A previous catastrophic failure of a net provided by others, had occurred within weeks of its deployment at the site, resulting in application failure.
Pacific Netting Products was contracted by PacifiCorp to minimize their cost and salvage some of their investment, and to continue to meet FERC requirements. We quickly mobilized a team and equipment for this first-of-its-kind, in-water renovation resulting in a major redesign and repair of this 2400 ft long, 300 ft deep, 500,000 sq ft barrier net. After on-site redesign and rebuilding, this installation has been effectively deployed since 2015 and is providing fish guidance for downstream migrating smolts. In 2016 PNP added a “lead net” to improve the fish guidance efficiency of the exclusion net. The PNP lead net is placed perpendicular to the current and helps reduce fish from straying by directing them to the collection system for efficient passage.
- Major work completed in 2013
- 600 ft x 60 ft lead net installed in 2016
- Lead net built of 1/4” x 1/4” and 3/32” x 3/32” Dyneema®
- Protected by MultiFunction Boom™ upstream for debris management
- Uses pneumatic floats to reduce pressure on the net by allowing the barrier to sink at pre-determined standards,
allowing spill over the top when flows exceed design standards. Can be used to pass floating debris as well.
- Provides debris control and fish exclusion
- Designed for single direction water flow velocities from 1.0 – 3.0 fps
- Deployed year round
- Minimal maintenance