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  • Priest Rapids Downstream Fish Passage - spillway


Project Highlights:

  • New fish bypass for migrating salmon
  • Modification of three spillways for top spill fish passage
  • Modification to spillway gates and the spillway ogees and aprons
  • Underwater concrete for apron extension
  • Concrete piers extended
  • Periods of 24 hour/day, 7 day/week work
Annotation 2019-09-04 100505

Project Summary

Client: Grant County Public Utility District
Location: Desert Aire, WA
Service Provided: Construction Inspection
In order to provide migrating salmon with a non-turbine downstream passage route at the Priest Rapids Dam, modifications to the spillway gates, ogees, and aprons were necessary.
The solution was a top spill method of fish passage. Three spillways were modified to accommodate the new top spill fish passage, and top spill prototype equipment was relocated.
Construction activities included a temporary breakwater to facilitate underwater construction of concrete forms for apron extension, partial demolition of the existing structure, extension of existing concrete piers, and significant height additions to the spillway ogee concrete.
Due to in-water work window constraints, there were periods of 24 hours/day, 7 day/week work and inspections.
MacKay Sposito served as the owner’s representative, providing construction inspection services and quality control.