American Electric Power received a letter from the Federal Energy Regulatory Commission acknowledging receipt of the March 25, 2025 letter transmitting the revised Micropile Drilling Program Plan (DPP) for the work supporting the spillway rollway stabilization at the Twin Branch Hydroelectric Project No. 2579. This submittal also included the GEI responses to Review Comments provided in the March 12, 2026 letter, as well as the GEI Technical Memorandum for the Twin Branch vs Prairie Du Sac Comparison.
In addition, American Electric Power transmitted the March 26, 2026 letter providing Dr. Donald Bruce?s summary of his independent review of GEI?s technical memorandum comparing the Prairie Du Sac and Twin Branch micropile designs. The revised DPP adequately addresses Comments 1 through 4 from the March 12, 2026 letter. The Federal Energy Regulatory Commission reviewed the submitted information and provided the following comments: Permitting Requirements: Ensure that all required state, local, and federal permits are secured.
During the drilling program, it is the responsibility of American Electric Power to ensure that construction practices comply with the requirements of the Project License and applicable permits in order to minimize erosion and other environmental impacts. Coordination of Changes: Any change to the plans and specifications must be coordinated between the engineer and Federal Energy Regulatory Commission. Any change to project operations must also be properly coordinated with Federal Energy Regulatory Commission and clearly understood by all operators.
Periodic Drilling Progress Reports: A progress email to Federal Energy Regulatory Commission should be completed each morning following the day?s work. Reporting Aberrant Conditions: Any abnormal or unexpected conditions encountered during the work must be reported to Federal Energy Regulatory Commission as soon as practical, without interfering with any necessary emergency response. Below are the Federal Energy Regulatory Commission personnel that should be notified if Mr. Prieto cannot be reached.
Changes During Drilling Programs: Note that substantial deviations from the approved DPP ? which includes, but is not limited to, changing the location, method, or procedures for any exploration; performing additional explorations not identified in the DPP; and changes to key personnel, such as the drillers or oversight ? are not permitted without prior authorization from the Federal Energy Regulatory Commission office except in response to a condition that affects the safety of project works (as defined in 18 CFR § 12.3).
If unsure whether a potential field change would constitute an unauthorized deviation from the DPP, American Electric Power should contact the Federal Energy Regulatory Commission office immediately. Final Drilling Report: Within 90 days of completion of the Drilling Program Plan, American Electric Power is to file a drilling summary report. The transmittal letter should indicate whether American Electric Power agrees with the findings and information documented in the report and boring logs.
The revised DPP is approved. This letter authorizes American Electric Power to proceed with the proposed drilling for the spillway rollway stabilization in accordance with Revision 1 of the DPP. American Electric Power should file the submittal using the Commission?s eFiling system.
The cover page of the filing must indicate that the material was eFiled.
