Federal Energy Regulatory Commission Issues Delegated Order on Swan Falls Exploration Drilling Program

Strategic Insights -

The Federal Energy Regulatory Commission has issued a delegated order regarding the Swan Falls Exploration Drilling Program, a project initiated by Idaho Power Company's Chief Dam Safety Coordinator, Mr. Garrett Bishop. The commission's team, led by Acting Regional Engineer Eric Kennedy, has reviewed the project's Drilling Program Plan (DPP) and provided a list of comments and recommendations to ensure the safe execution of the project. The DPP aims to explore the Swan Falls Project area, which includes drilling and borehole completion, to better understand the site conditions and identify potential risks.

Key Takeaways:

  • The commission has expressed concerns regarding the proposed drilling locations, citing potential access challenges and risks of damage to the existing spillway.
  • The DPP should include measures to protect the spillway and its apron from damage caused by the barge and equipment.
  • The commission has requested additional discussion on the risk of hydraulic fracturing, including the potential for boreholes to penetrate or approach the underdrain system or rock anchors.
  • Optical and acoustic televiewer surveys should be used to better observe the conditions of the bedrock-concrete interface, verify the location of the underdrain system, and identify discontinuities.
  • The commission has suggested implementing measures to protect the claystone from erosion by pressurized flows, given its susceptibility to erosion.
  • The DPP should address the need to report headwater and tailwater levels measured at the beginning and end of each work shift in the boring logs.
  • The proposed boring locations are near the spillway's underdrainage system and rock anchors, and the DPP should include measures to protect the spillway's underdrainage system from contamination by drilling fluids.
  • The commission has requested additional information regarding the use of alternate backfill materials, the preparation and finishing procedures for the hole wall, and the minimum wait time for grout to set before operating the spillway gates.
  • The commission has accepted the qualifications of Michael Woodward, Tori Encapera, Ryan Miskowitz, Timothy Burrows, Mike Starling, Chris Peterson, and Aaron Delvalle as professionals with sufficient dam safety drilling experience.
  • The proposed drilling location requires a Temporary Construction Emergency Action Plan (TCEAP), and a plan and schedule to address the comments above must be submitted within 60 days.

Statistics:

  • The proposed borehole completion logs should be submitted to the Federal Energy Regulatory Commission within 24 hours after borehole completion.
  • The field professional supervising the drilling work should document the as-built depth and diameters of the boreholes and the actual and theoretical grout backfill volumes with depth in the drilling logs.
  • The maximum grout stage height and the exceedance threshold should be reduced to limit the potential for blockage in the underdrain system, if the televiewer or other observations indicate that a borehole has penetrated or is in the immediate vicinity of the underdrain system or an open fracture.

Sources:

  • Federal Energy Regulatory Commission
  • Idaho Power Company
  • Mr. Garrett Bishop, Chief Dam Safety Coordinator
  • Mr. Chris Edwards, Exploration Drilling Program Plan (DPP) developer
  • FERC Online Support (866) 208-3676 (toll free) or (202) 502-8659 (TTY)
  • Eric Kennedy, P.E., Acting Regional Engineer, Federal Energy Regulatory Commission