Revised Design and Calculation Package for Downstream Parapet Replacement at Rock Island Hydroelectric Project

Strategic Insights -

Public Utility District No. 1 of Chelan County, Washington has submitted a revised design and calculation package for Phase II of the Downstream Parapet Replacement project at the Rock Island Project, which includes a redesign of the Bay 15 corbel from reinforced concrete to structural steel. The redesign aims to avoid disturbing existing electrical/control conduits and has been authorized by the Federal Energy Regulatory Commission. The revised drawings and calculation package have been enclosed and are scheduled to proceed on October 31, 2025, with a request for FERC's review and authorization to proceed by October 22, 2025.

Key Takeaways:

  • The revised design and calculation package for Phase II of the Downstream Parapet Replacement project at the Rock Island Project includes a redesign of the Bay 15 corbel from reinforced concrete to structural steel.
  • The redesign aims to avoid disturbing existing electrical/control conduits and has been authorized by the Federal Energy Regulatory Commission.
  • The revised drawings and calculation package have been enclosed and are scheduled to proceed on October 31, 2025.
  • Public Utility District No. 1 of Chelan County, Washington has requested FERC's review and authorization to proceed by October 22, 2025.
  • The redesign involves connecting the corbels via thru-bolts to spillway Piers 14 and 15, which have been oversized to provide capacity for future AAR related concrete growth.
  • The project meets the Critical Energy Infrastructure Information (CEII) requirements under 18 CFR 388.113c.
  • The District requests that this material not be released to the public.

Statistics:

  • The project is scheduled to proceed on October 31, 2025.
  • The revised drawings and calculation package have been enclosed and are available for review.
  • The redesign involves the use of structural steel instead of reinforced concrete.
  • The through-bolts are oversized to provide capacity for future AAR related concrete growth.
  • The project meets the Critical Energy Infrastructure Information (CEII) requirements under 18 CFR 388.113c.

Sources:

  • Public Utility District No. 1 of Chelan County, Washington to Federal Energy Regulatory Commission, Project No. 943, Accession No. 20250310-5094, (March 10, 2025).
  • Douglas L. Johnson, P.E., Federal Energy Regulatory Commission to Martha Whiteman, Public Utility District No. 1 of Chelan County, Washington, Project No. 943, Accession No. 20250319-3058, (March 19, 2025).
  • Ian Hunter, P.E., Public Utility District No. 1 of Chelan County, Washington to Douglas Johnson, P.E., Federal Energy Regulatory Commission, Project No. 943, Accession No. 20250319-3058, (September 15, 2025).