FEATURED PROJECT: Lake Cushman Net Transition Structure & Floating Surface Collector
Lake Cushman Net Transition Structure & Floating Surface Collector
As part of Tacoma Power’s Cushman Hydro Electric Project, Thompson Metal Fab supplied both the Net Transition Structure (NTS) and the Floating Surface Collector (FSC). The NTS is a polygonal horn shaped structure with a length of just over 103’ and an opening of roughly 36’ x 36’. The NTS was manufactured in a modular and structural/panel type fashion and was constructed in the field upside down. When the completed structure was deployed into the lake, the pontoons (also fabricated by TMF) were then strategically filled and emptied so the structure could roll into the correct orientation. The NTS acts as a ‘funnel,’ guiding the fish into the Floating Surface Collector.
The FSC is a collection of individual modules which were fabricated and progressively assembled (for fit-verification) in our shop. When complete, the FSC was 48’ wide x 92’ long x 10’-9” high. The FSC houses pumps and other equipment to create a ‘false current’ to attract the fish into the facility. When there, the fish can then be tagged, sorted, and safely moved (by way of hopper) to the other side of the dam.
Like the fabrication, the coating system too was unique. Much of the coating took place in confined spaces, and some of it—particularly the Polyurea Polyflex 301— required an application of 40-60 mils. Additionally, the paint required specialized removal and disposal to make it non-leachable.
