Ketchikan Public Utilities Submits Notification for Penstock Dewatering

Strategic Insights -

Ketchikan Public Utilities (KPU) has submitted a notification to the Federal Energy Regulatory Commission (FERC) regarding the planned dewatering of Penstocks No. 3 and 4 at the Ketchikan Lakes Hydroelectric Project, FERC No. 420. The dewatering is scheduled for August 13, 2025, and is expected to last approximately 24 hours. Penstock No. 5 will remain watered to provide flow to Ketchikan Creek and the Deer Mountain Hatchery. This is the second time Penstock No. 3 has been drained in recent years, following a replacement of the emergency instream flow bypass valve in November 2024.

Key Takeaways:

  • The planned dewatering of Penstocks No. 3 and 4 at the Ketchikan Lakes Hydroelectric Project is scheduled for August 13, 2025, and is expected to last 24 hours.
  • Penstock No. 5 will remain watered to provide flow to Ketchikan Creek and the Deer Mountain Hatchery.
  • This is the second time Penstock No. 3 has been drained in recent years, following a replacement of the emergency instream flow bypass valve in November 2024.
  • KPU's dewatering procedure has been attached to the notification, outlining the necessary steps to ensure safe and efficient dewatering of the penstocks.
  • Jennifer Holstrom, P.E., CDSE/Regulatory Compliance Manager, is responsible for ensuring compliance with FERC regulations and notification procedures.
  • The dewatering procedure includes steps to ensure the valve at the upstream end of the pipe is inspected, and to prevent any issues with the emergency instream flow bypass valve.

Statistics:

  • Duration of planned dewatering: 24 hours (August 13, 2025 at 12:00 PM to August 14, 2025 at 12:00 PM).
  • Number of penstocks to be dewatered: 2 (Penstocks No. 3 and 4).
  • Number of penstocks remaining watered: 1 (Penstock No. 5).
  • Date of previous dewatering of Penstock No. 3: November 2024.
  • Date of previous dewatering of Penstock No. 4: 2005 (previous dewatering for installation of flow meters).
  • Number of emergency instream flow bypass valves replaced: 1 (on Penstock No. 3 in November 2024).

Sources:

  • Ketchikan Public Utilities, Electric Division (2025). 36" Penstock Dewatering Sequence, Ketchikan Lakes Hydro Project. Standard Operating Procedure (SOP) 36" Penstock Dewatering Sequence, Ketchikan Lakes Hydro Project.
  • Federal Energy Regulatory Commission (2025). Notification of Planned Penstock Dewatering, Ketchikan Lakes Hydroelectric Project, FERC No. 420.
  • Ketchikan Public Utilities (2025). Notice of Planned Penstock Dewatering, Ketchikan Lakes Hydroelectric Project, FERC No. 420.