Pacific Gas and Electric Company Seeks Approval for Revised Tunnel Spoil Pile Management Plan

Strategic Insights -

The Pacific Gas and Electric Company (PG&E) has submitted a request to the Federal Energy Regulatory Commission (FERC) for approval of an amended Tunnel Spoil Pile Management Plan (TSPMP) for the Pit 3, 4, and 5 Hydroelectric Project. The proposed revisions aim to improve the management of spoil piles and mitigate potential erosion and sedimentation. PG&E consulted with agency stakeholders, including the USFS, SWRCB, and CDFW, and received approvals from the USFS and SWRCB before submitting the request.

Key Takeaways:

  • The proposed revisions to the TSPMP aim to improve the management of spoil piles and mitigate potential erosion and sedimentation.
  • The amendments include revised rain-event monitoring triggers, which replace the previous trigger for significant rain events.
  • The new triggers are: * Significant 1-day rain event of 5 inches; * Cumulative event with 15 inches of rain within 15 days or less; and * Cumulative water-year-to-date rainfall amount of 100 inches.
  • PG&E consulted with agency stakeholders and received approvals from the USFS and SWRCB before submitting the request.
  • The document was presented and discussed at the 2024 and 2025 Agency Consultation meetings, and agency stakeholders were provided with over 30 days to review the proposed revisions.
  • The USFS provided concurrence for the proposed amendment to the TSPMP via email on March 14, 2025.

Statistics:

  • 30 days of review period for agency stakeholders to review the proposed revisions to the TSPMP.
  • 5 inches: the revised trigger for significant 1-day rain events.
  • 15 inches: the cumulative event trigger within 15 days or less.
  • 100 inches: the cumulative water-year-to-date rainfall amount to trigger monitoring.
  • March 14, 2025: the date the USFS provided concurrence for the proposed amendment to the TSPMP via email.
  • March 17, 2025: the date PG&E submitted a formal TSPMP amendment request letter to the SWRCB Deputy Director of the Division of Water Rights for approval.
  • September 4, 2025: the date the SWRCB approved the amended TSPMP with an additional condition.

Sources:

  • Pacific Gas and Electric Company. (2025). Notification of Request for Approval of Amendment to License: Pit 3, 4, and 5 Hydroelectric Project, FERC No. 233 License Article 401; SS401 Certification Condition 14, Mitigation Measures 4 & 5 License Article 411; USDA-Forest Service 4(e) Condition No. 20(a) Tunnel Spoil Pile Management Plan Request for Approval of Amendment. FERC.