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United States. Federal Energy Regulatory Commission

FERC Approves Revised Construction Loading Slope Stability Analyses for Spillway Embankment Improvements

Strategic Insights

— 1 min read

The Federal Energy Regulatory Commission (FERC) has issued a delegated order approving revised construction loading slope stability analyses for the Fallasburg Hydroelectric Project, FERC No. 7223. The revised analyses, submitted on May 30, 2025, provide justification for utilizing a larger excavator on the right embankment and remote dike to perform sheet pile installation as part of the spillway embankment improvements. The FERC has authorized the use of a PC 490 excavator on the right embankment, which is expected to be needed on the left embankment as well due to the length of the sheet pile sections planned.

Key Takeaways:

  • The FERC has received revised construction loading slope stability analyses for the Fallasburg Hydroelectric Project, FERC No. 7223, which provide justification for utilizing a larger excavator on the right embankment and remote dike.
  • The revised analyses were submitted on May 30, 2025, and include increased pressure from a PC 490 excavator in scenarios of tracking across working matts on the remote dike and installing sheet pile from working matts and tracking across the working matts for the right embankment.
  • The analyses indicate that the increased loading from the larger excavator is negligible, and the critical slip surfaces on the downstream slopes are shallow and do not undermine the matts on the crest.
  • The use of the PC 490 excavator on the right embankment is authorized, and it is anticipated that the excavator will be needed on the left embankment as well due to the length of the sheet pile sections planned.
  • The revised construction loading slope stability analyses for the left embankment are expected to be provided by June 15, 2025.

Statistics:

  • The PC 490 excavator will be used to safely perform sheet piling installation on the right embankment.
  • The increased loading from the larger excavator is estimated to be negligible.
  • The critical slip surfaces on the downstream slopes are shallow, ranging from 2 to 4 feet.
  • The length of the sheet pile sections planned for the left embankment is expected to require the use of a PC 490 excavator.
  • The revised construction loading slope stability analyses for the left embankment must be provided by June 15, 2025.

Sources:

  • Document Accession #: 20250530-3083, Filed Date: 05/30/2025, FERC.
  • Washington: FEDERAL ENERGY REGULATORY COMMISSION, Office of Energy Projects, Division of Dam Safety and Inspections - Chicago Regional Office, 230 South Dearborn Street, Suite 3130, Chicago, Illinois 60604, 312.596.4430 Office.

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