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Independent regulatory commissions

Revised Colgate Tunnel and Penstock Outage Project Submittal

Strategic Insights

— 1 min read

The Yuba County Water Agency has submitted updated information for the Colgate Tunnel and Penstock Outage project to the Federal Energy Regulatory Commission. The updated information includes revised drilling program plans, contractor resumes, and a revised Foundation Grouting specification section. The revised plans address concerns raised by the commission in its February 28, 2024 letter, including the use of grout in the project. The agency clarifies that no grouting is planned within the Colgate Tunnel, and the proposed rehabilitation of the tunnel incorporates the installation of steel rock dowels and shotcrete application to ensure long-term tunnel stability.

Key Takeaways:

  • The Colgate Tunnel and Penstock Outage project was awarded to a joint venture between Drill Tech Drilling and Shoring and Obayashi Corporation in January 2025.
  • The project involves the rehabilitation of the Colgate Tunnel, including the installation of steel rock dowels and shotcrete application to ensure long-term tunnel stability.
  • No grouting is planned within the Colgate Tunnel, as stated in the revised drilling program plans.
  • The revised plans address concerns raised by the commission regarding the use of grout in the project.
  • The agency has provided a revised Foundation Grouting specification section, which is to be used by the contractor if the contingency plan is activated during construction of the thrust block foundation.
  • The revised plans include contractor resumes and a Grouting Program Plan prepared by the contractor.

Statistics:

  • The project was awarded to a joint venture between Drill Tech Drilling and Shoring and Obayashi Corporation in January 2025.
  • The project involves the rehabilitation of approximately 1 mile of the Colgate Tunnel.
  • The tunnel rehabilitation is expected to be completed within 12 months.
  • The agency has provided 4 revised drilling program plans and 1 revised Foundation Grouting specification section.
  • The revised drilling program plans were submitted to the Federal Energy Regulatory Commission on June 11, 2025.

Sources:

  • Mr. Frank L. Blackett, P.E. Regional Engineer Federal Energy Regularity Commission 100 First Street, Suite 2300 San Francisco, CA 94105-3084 Re: Project No. 2246-CA New Bullard's Bar Dam - Colgate Tunnel and Penstock Outage Maintenance (dated June 11, 2025)
  • Yuba County Water Agency Letter to Federal Energy Regulatory Commission (dated June 11, 2025)
  • Drill Tech Drilling and Shoring and Obayashi Corporation Resumes (enclosed in Appendix A and B)
  • Foundation Grouting specification section (enclosed in Appendix C)
  • Grouting Program Plan prepared by the contractor (enclosed in Appendix D)

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