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Independent regulatory commissions

Update on HS2 Hydroelectric Generating Station Deadman Tendon Investigation

Strategic Insights

— 1 min read

The Arkansas Electric Cooperative Corporation (AECC) has submitted an update to the Federal Energy Regulatory Commission regarding the ongoing investigation of the leaking tieback tendons at the HS2 Hydroelectric Generating Station. According to the document dated August 11, 2025, AECC has agreed with the findings of a 2024 report by GZA GeoEnvironmental and plans to conduct a structural review of the headrace wall structural load calculations and inject grout into the trumpet to address water intrusion.

Key Takeaways:

  • AECC has submitted an update to the Federal Energy Regulatory Commission on the status of the HS2 Hydroelectric Generating Station deadman tendon investigation.
  • The investigation, led by AECC, has confirmed the findings of a 2024 report by GZA GeoEnvironmental, which identified the need for a structural review and grout remediation.
  • AECC plans to conduct a structural review of the headrace wall structural load calculations pertinent to the tendon anchors in Q4 2025.
  • The company also intends to inject urethane or epoxy grout into the trumpet to address water intrusion into the tendon cap, with remediation work planned for 2026.
  • AECC will update the Federal Energy Regulatory Commission on the status of both items in the 2025 Dam Safety Self-Monitoring Report (DSSMR).
  • The investigation is a critical step in ensuring the safety and reliability of the HS2 Hydroelectric Generating Station.

Statistics:

  • 2024: Year in which GZA GeoEnvironmental performed investigations on the HS2 Hydroelectric Generating Station.
  • 2025: Year in which AECC will conduct a structural review of the headrace wall structural load calculations.
  • 2026: Year in which AECC plans to commence tendon trumpet grout remediation work.
  • Q4 2025: Quarter in which AECC anticipates beginning the structural review of the headrace wall structural load calculations.

Sources:

  • Arkansas Electric Cooperative Corporation. (2025, August 11). Letter to Federal Energy Regulatory Commission.
  • GZA GeoEnvironmental. (2024). Evaluation of Deadman Tendon Leakage - HS2.

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