As part of a multi-agency federal project, a new salmon detector system was to be implemented at the Bonneville Dam Complex on the Columbia River. PSE provided structural engineering design which included the design of the antenna housing for a Passive Integrated Transponder (PIT) Tag identification system as well as armoring plates to protect the housing from potential log strikes.
We worked with the antenna fabricator and the Radio Frequency Identification (RFID) systems engineers to pioneer innovative approaches to create a cost-effective structural system that can be removed and replaced for upgrades and maintenance. The unique specifications of the antenna required that the antenna and all supporting structural systems be fabricated from non-metallic elements to prevent interference with the Collector, which created unique structural challenges.
For the Antenna housing, PSE designed a unique 18’ square HDPE structural housing using welded high-density plastic to create a non-metallic housing. The structural challenges included designing for a system that was submerged and would be buoyant and subjected to large hydrostatic forces. PSE also worked with an HDPE manufacturer to create a test program to prototype and de-risk the construction prior to on-site construction.
The Antenna is housed in a flume on the Bonneville Dam complex and counts hatchery fish as they pass the dam. The design speed of the flume was 40ft/s and the potential for a large log coming down the flume and impacting the antenna had to be considered. To mitigate the large impact loads (over 200,000 lbs) 4” thick armoring skid plates and damping vibration pads were designed by PSE using fiber reinforced plastic (FRP) to protect the Antenna. The skid plates also functioned to resist the buoyant antenna forces. PSE coordinated with a large commercial ship builder to fabricate the unique FRP Skid plates.
The Antenna performed as expected, and at the time of construction was the largest of its kind by several orders of magnitude.