This subpart D applies to any licensed project development that:

(a) Has a dam

(1) That is more than 32.8 feet (10 meters) in height above streambed, as defined in § 12.31(c); or

(2) With an impoundment gross storage capacity of more than 2,000 acre-feet (2.5 million cubic meters), as defined in § 12.31(d);

(b) Has a project work (dam or water conveyance) or any portion thereof that has a high hazard potential, as defined in § 12.3(b)(13)(i); or

(c) Is determined by the Regional Engineer or other authorized Commission representative to require inspection by an independent consultant under this subpart D.

For purposes of this subpart D:

(a) Independent consultant means any person who:

(1) Is a licensed professional engineer;

(2) Has at least 10 years of experience and expertise in dam design and construction and in the investigation of the safety of existing dams;

(3) Is not an employee of the licensee or its affiliates;

(4) Has not been an employee of the licensee or its affiliates within two years prior to performing engineering and/or scientific services for an inspection or assessment under this subpart D; and

(5) Has not been an agent acting on behalf of the licensee or its affiliates, prior to performing engineering and/or scientific services for an inspection or assessment under this subpart D.

(b) An independent consultant team means a group of one or more people that:

(1) Includes at least one independent consultant, as defined in paragraph (a) of this section;

(2) Includes additional qualified engineering and scientific professionals as supporting team members, as needed, who meet the requirements of paragraphs (a)(3) through (5) of this section;

(3) Has demonstrable experience and expertise in dam design, construction, and the evaluation and assessment of the safety of existing dams and their appurtenances, commensurate with the scale, complexity, and relevant technical disciplines of the project and type of review, inspection, and assessment being performed (periodic inspection or comprehensive assessment, as defined in this section).

(c) Height above streambed means:

(1) For a dam with a spillway, the vertical distance from the lowest elevation of the natural streambed at the downstream toe of the dam to the maximum water storage elevation possible without any discharge from the spillway. The maximum water storage elevation is:

(i) For gated spillways, the elevation of the tops of the gates; and

(ii) For ungated spillways, the elevation of the spillway crest or the top of any flashboards, whichever is higher.

(2) For a dam without a spillway, the vertical distance from the lowest elevation of the natural streambed at the downstream tow of the dam to the lowest point on the crest of the dam.

(d) Gross storage capacity means the maximum possible volume of water impounded by a dam with zero spill, that is, without the discharge of water over the dam or a spillway.

(e) Periodic inspection means an inspection that meets the requirements of § 12.35 and is performed by an independent consultant team.

(f) Comprehensive assessment means a project review, inspection, and assessment that meets the requirements of § 12.37 and is performed by an independent consultant team.

(g) Previous Part 12D Inspection means the most recent inspection performed in accordance with the provisions of this subpart D (a periodic inspection, comprehensive assessment, or an inspection performed in accordance with the rules established by Order 122).

(h) Previous Part 12D Report means the report on the Previous Part 12D Inspection.

The project works of each development to which this subpart applies, excluding transmission and transformation facilities, must be inspected on a periodic basis by an independent consultant team to identify any actual or potential deficiencies that might endanger life, health, or property, including deficiencies that may be in the condition of those project works or in the quality or adequacy of project maintenance, safety, methods of operation, analyses, and other conditions. A report must be prepared by the independent consultant team, by or under the direction of at least one independent consultant, who may be a member of a consulting firm, to document the findings and evaluations made during their inspection. The inspection must be performed by the independent consultant team, and the report must be filed by the licensee, in accordance with the procedures in this subpart D. The licensee must ensure that the independent consultant team's report meets all of the requirements set forth in this subpart D.

(a) Upon written request from the licensee, the Director of the Division of Dam Safety and Inspections may grant an exemption from the requirements of this subpart D in circumstances that clearly establish good cause for exemption.

(b) Good cause for exemption may include the finding that the development in question has no dam, canal, or other water conveyance except those that meet the criteria for low hazard potential as defined in § 12.3(b)(13)(iii).

(c) The Director of the Division of Dam Safety and Inspections, for good cause shown, may rescind any exemption from this subpart D granted by the Director, and may require that a comprehensive assessment be completed prior to considering a subsequent request for exemption from the licensee.

(a) The licensee must obtain written approval of the independent consultant team, and the facilitator(s) for a potential failure mode analysis or risk analysis, from the Director of the Division of Dam Safety and Inspections, prior to the performance of a periodic inspection or comprehensive assessment under this subpart D.

(b) At least 180 days prior to performing a periodic inspection or comprehensive assessment under this subpart D, the licensee must submit to the Director of the Division of Dam Safety and Inspections, with a copy to the Regional Engineer, a detailed part 12D inspection plan that includes an independent consultant team proposal that describes the technical disciplines and level of expertise required to perform the inspection.

(1) If the independent consultant team comprises one person, the detailed independent consultant team proposal must:

(i) Describe the experience of the independent consultant; and

(ii) Show that the independent consultant meets the requirements as defined in §§ 12.31(a) and 12.31(b)(3).

(2) If the independent consultant team comprises more than one person, the detailed independent consultant team proposal must:

(i) Designate one or more persons to serve as independent consultant(s);

(ii) Describe the experience of each member of the independent consultant team;

(iii) Show that each independent consultant meets the requirements as defined in § 12.31(a);

(iv) Show that each member of the independent consultant team who is not designated as an independent consultant meets the requirements as defined in § 12.31(a)(3) through (5); and

(v) Show that the independent consultant team meets the requirements as defined in § 12.31(b)(3).

(3) If any member of the independent consultant team has performed or substantially contributed to any previous investigation, analysis, or other work product that is required to be reviewed and evaluated by the independent consultant team as part of the inspection being performed, the independent consultant team proposal must include a clear delineation of roles and responsibilities that ensures no team member will be responsible for reviewing and evaluating their own previous work.

(4) If required information about any supporting team member(s) is not available at the time the independent consultant team proposal is submitted to the Director of the Division of Dam Safety and Inspections, the independent consultant team proposal must state that the information will be provided in the preliminary report required by § 12.42.

(5) The 180-day period in paragraph (b) is measured from the scheduled date of the physical field inspection, potential failure mode analysis, or risk analysis, whichever occurs first.

(c) Regardless of experience and qualifications, any independent consultant may be disapproved by the Director of the Division of Dam Safety and Inspections for good cause, such as having had one or more reports on an inspection under this subpart D rejected by the Commission within the preceding five years.

(d) The Director of the Division of Dam Safety and Inspections may, for good cause shown, grant a waiver of the 10-year requirement in § 12.31(a)(2). Any petition for waiver under this paragraph must be filed in accordance with § 385.207 of this chapter.

A periodic inspection must include:

(a) Review of prior reports. The independent consultant team must review and consider all relevant reports on the safety of the development made by or written under the direction of Federal or state agencies, submitted under Commission regulations, or made by other consultants. The licensee must provide to the independent consultant team all information and reports necessary to fulfill the requirements of this section. The independent consultant team must perform sufficient review to have, at the time of the periodic inspection, a full understanding of the design, construction, performance, condition, upstream and downstream hazard, monitoring, operation, and potential failure modes of the project works.

(b) Physical field inspection. The independent consultant team must perform a physical field inspection of accessible project works, including galleries, adits, vaults, conduits, earthen and concrete-lined spillway chutes, the exterior of water conveyances, and other non-submerged project works that may require specialized access to facilitate inspection. The inspection shall include review and assessment of all relevant data concerning:

(1) Settlement;

(2) Movement;

(3) Erosion;

(4) Seepage;

(5) Leakage;

(6) Cracking;

(7) Deterioration;

(8) Hydraulics;

(9) Hydrology;

(10) Seismicity;

(11) Internal stress and hydrostatic pressures in project structures and their foundations and abutments;

(12) The condition and performance of foundation drains, dam body drains, relief wells, and other pressure-relief systems;

(13) The condition and performance of any post-tensioned anchors installed, and other major modifications completed, to improve the stability of project works;

(14) The stability of critical slopes adjacent to a reservoir or project works; and

(15) Regional and site geological conditions.

(c) Review of surveillance and monitoring plan and data. The independent consultant team must:

(1) Review the surveillance procedures, instrumentation layout, installation details, monitoring frequency, performance history, data history and trends, and relevance to potential failure modes; and

(2) Review the frequency and scope of other surveillance activities.

(d) Review of dam and public safety programs. The independent consultant team must review the programs specified in this paragraph.

(1) Hazard potential. The independent consultant team must review the potential inundation area and document any significant changes in the magnitude and location of the population at risk since the previous inspection under this subpart D.

(2) Emergency Action Plan. If the project development is subject to subpart C of this part, the independent consultant team must review the emergency action plan, including the emergency action plan document itself, the licensee's training program, and any related time-sensitivity assessment(s).

(3) Public Safety Program. The independent consultant team must review the public access restrictions and public safety warning signs and devices near the project works pursuant to § 12.52.

(4) Owner's Dam Safety Program. If the project is subject to subpart F of this part, the independent consultant team must review the implementation of the licensee's Owner's Dam Safety Program with respect to the project development being inspected under this subpart D.

(a) Scope. The report must include documentation of all the items listed in § 12.35.

(b) Specific evaluation. The report must include specific evaluation of:

(1) The history of performance of the project works through visual observations, analysis of data from monitoring instruments, and previous inspections;

(2) The quality and adequacy of maintenance, surveillance, methods of project operations, and risk reduction measures for the protection of public safety and continued project operation;

(3) Potential failure modes, including:

(i) Each identified potential failure mode associated with the project works and whether any potential failure mode is active or developing; and

(ii) Whether any inspection observations or other conditions indicate that an unidentified potential failure mode is active, developing, or is of sufficient concern to warrant development through a supplemental potential failure mode analysis;

(4) Whether any observed conditions warrant reconsideration of the current hazard potential classification; and

(5) The adequacy of the project's:

(i) Emergency action plan;

(ii) Public safety program; and

(iii) Implementation of the Owner's Dam Safety Program with respect to the project development being inspected under this subpart D.

(c) Changes since the previous inspection. The report must include a status update and evaluation of any changes since the Previous Part 12D Inspection concerning:

(1) Hydrology. Identify any events that may affect the conclusions of the hydrologic or hydraulic analyses of record and evaluate the effect on the safety and stability of project works.

(2) Seismicity. Identify any seismic events that may affect the conclusions of the seismicity analyses of record and evaluate the effect on the safety and stability of project works.

(3) Modifications to project works. Identify any modifications made to project works and evaluate the performance thereof with respect to the design intent.

(4) Methods of operation. Describe any changes to standard operating procedures, equipment available for project operation, and evaluate the effect on the safety and stability of project works.

(5) Results of special inspections. Summarize the findings of any special inspections (dive inspection, rope-access gate inspection, toe drain inspection, etc.), if any.

(6) Previous recommendations. List and document the status of recommendations made by the independent consultant(s) in the Previous Part 12D Report, and any earlier recommendations that remained incomplete at the time of the Previous Part 12D Report.

(7) Outstanding studies and studies completed since the previous inspection. List and document the status of any studies completed since the Previous Part 12D Inspection and those that remain outstanding at the time of the periodic inspection.

(d) Recommendations. Based on the independent consultant team's field observations, evaluations of the project works, and the maintenance, surveillance, and methods of operation of the development, the report must contain recommendations by the independent consultant(s) regarding:

(1) Any corrective measures, described in § 12.41, necessary for the structures, maintenance or surveillance procedures, or methods of operation of the project works;

(2) A reasonable time to carry out each corrective measure; and

(3) Any new or additional monitoring instruments, periodic observations, special inspections, or other methods of monitoring project works or conditions that may be required.

(e) Dissenting views. If the inspection and report were conducted and prepared by more than one independent consultant, the report must clearly identify and describe any dissenting views concerning the evaluations or recommendations of the report that might be held by any individual consultant.

(f) List of participants. The report must identify all professional personnel who have participated in the inspection of the project or in preparation of the report and the independent consultant(s) who directed those activities.

(g) Statement of independence. Each independent consultant responsible for the report must declare that all conclusions and recommendations in the report are made independently of the licensee, its employees, and its representatives.

(h) Signature. The report must be signed and sealed, with a professional engineer's seal, by each independent consultant responsible for the report.

A comprehensive assessment must include:

(a) Review of prior reports and analyses of record. The independent consultant team must review and consider all relevant reports on the safety of the development made by or written under the direction of Federal or state agencies, submitted under Commission regulations, or made by other consultants. The licensee must provide to the independent consultant team all information, reports, and analyses of record necessary to fulfill the requirements of this section.

(1) In addition to the requirements of § 12.35(a), the independent consultant team must have a full understanding of the risk associated with the project works.

(2) The independent consultant team shall perform a detailed review of the as-built drawings; monitoring data; and the methods, assumptions, calculations, results, and conclusions of the analyses of record pertaining to:

(i) Geology and seismicity;

(ii) Hydrology and hydraulics;

(iii) Stability and structural integrity of project works; and

(iv) Any other analyses relevant to the safety, stability, and operation of project works.

(b) Physical field inspection. The independent consultant team must perform a physical field inspection that complies with § 12.35(b).

(c) Review of surveillance and monitoring plan and data. The independent consultant team must perform a review of surveillance and monitoring plan and data that complies with § 12.35(c).

(d) Review of dam and public safety programs. The independent consultant team must perform a review of dam and public safety programs that complies with § 12.35(d).

(e) Supporting Technical Information Document. The comprehensive assessment shall include a review of the Supporting Technical Information Document.

(f) Potential failure mode analysis. The comprehensive assessment shall include a potential failure mode analysis.

(g) Risk analysis. The comprehensive assessment shall include a risk analysis. The Regional Engineer may, for good cause shown, grant a waiver of the requirement to complete a risk analysis. Any petition for waiver under this paragraph must be filed in accordance with § 385.207 of this chapter.

(a) Scope. The comprehensive assessment report must include documentation of all the items listed in § 12.37.

(b) Specific evaluation. In addition to the items listed in § 12.36(b)(1) through § 12.36(b)(5), the comprehensive assessment report must evaluate:

(1) The adequacy of spillways, including the effects of overtopping of nonoverflow structures, as described in § 12.39;

(2) The structural adequacy and stability of structures under all credible loading conditions;

(3) The potential for internal erosion and/or piping of embankments, foundations, and abutments;

(4) The design and construction practices used during original construction and subsequent modifications, in comparison with the industry best practices in use at the time of the inspection under this subpart D;

(5) The adequacy of the Supporting Technical Information Document and the attached electronic records; and

(6) The adequacy and findings of the potential failure mode analysis and risk analysis report(s).

(c) Analyses of record. The comprehensive assessment report must include the independent consultant team's evaluation of the assumptions, methods, calculations, results, and conclusions of the items listed in § 12.37(a)(2)(i) through (iv). The evaluation must:

(1) Address the accuracy, relevance, and consistency with the current state of the practice of dam engineering;

(2) Be accompanied by sufficient documentation of the independent consultant team's rationale, including, as needed, new calculations by the independent consultant team to verify that the assumptions, methods, calculations, results, and conclusions in the analyses of record are correct; and

(3) If the independent consultant team is unable to review the analyses of record for any of the items listed in § 12.37(a)(2)(i) through (iv); or if the independent consultant team disagrees with the assumptions, methods, calculations, results, or conclusions therein; the independent consultant(s) must recommend that the licensee complete new analyses to address the identified concerns.

(d) Changes since the previous inspection. The requirements of this section are the same as described in § 12.36(c).

(e) Recommendations. The requirements of this section are the same as described in § 12.36(d).

(f) Dissenting views. The requirements of this section are the same as described in § 12.36(e).

(g) List of participants. The requirements of this section are the same as described in § 12.36(f).

(h) Statement of independence. The requirements of this section are the same as described in § 12.36(g).

(i) Signature. The requirements of this section are the same as described in § 12.36(h).

The adequacy of any spillway must be evaluated, as part of a comprehensive assessment or as otherwise requested by the Regional Engineer, by considering hazard potential which would result from failure of the project works during normal and flood flows.

(a) If failure would present a hazard to human life or cause significant property damage, the independent consultant team must evaluate the following for floods up to and including the probable maximum flood:

(1) The ability of project works to withstand the loading or overtopping which may occur during floods;

(2) The capacity of spillways to prevent the reservoir from rising to an elevation that would endanger the project works; and

(3) The potential for misoperation of; failure to operate; blockage of; or debilitating damage to a spillway and its appurtenances (including but not limited to structural, mechanical, and electrical components of gates, valves, chutes, and training walls); and the effect thereof on the maximum reservoir level and potential for surcharged loading or overtopping to occur during floods.

(b) If failure would not present a hazard to human life or cause significant property damage, spillway adequacy may be evaluated by means of a design flood of lesser magnitude than the probable maximum flood provided that the most recent comprehensive assessment report required by § 12.38 provides a detailed explanation of and rationale for the finding that structural failure would not present a hazard to human life or cause significant property damage.

(a) Projects previously inspected by independent consultant. For any project that was inspected under this subpart D prior to April 11, 2022, under the Commission's rules in effect on January 1, 2022:

(1) A periodic inspection or comprehensive assessment must be completed, and the report on it filed, within five years of the due date of the Previous Part 12D Report.

(2) For any report due to be filed under this subpart D after October 11, 2023, the Regional Engineer may require that it be a report on a comprehensive assessment or a report on a periodic inspection.

(3) The first comprehensive assessment under this subpart must be completed, and the report on it filed, by December 31, 2038.

(b) Projects not previously inspected by independent consultant. For any project that was not inspected under this subpart D prior to April 11, 2022, under the Commission's rules in effect on January 1, 2022:

(1) For any development that meets the criteria specified in § 12.30(a)(1) or § 12.30(a)(2), and was constructed before the date of issuance of the order licensing that development, or amending a license to include that development, the first comprehensive assessment under this subpart D must be completed, and the report on it filed, not later than two years after the date of issuance of the order licensing that development or amending the license to include that development.

(2) For any development that was constructed after the date of issuance of the order licensing that development, or amending a license to include that development, the first comprehensive assessment under this subpart D must be completed, and the report on it filed, not later than five years after the date of issuance of the order licensing that development or amending the license to include that development.

(3) For any development not set forth in either paragraph (b)(1) or (b)(2) of this section, the first comprehensive assessment under this subpart D must be completed, and the report on it filed, by a date specified by the Regional Engineer. The filing date must not be more than two years after the date of notification that a comprehensive assessment and report under this subpart D are required.

(c) Subsequent inspections and reports. For subsequent reports filed under this subpart D:

(1) A comprehensive assessment must be completed, and the report on it filed, within 10 years of the date the previous comprehensive assessment report was due to be filed.

(2) A periodic inspection must be completed, and the report on it filed, within five years of the date the previous comprehensive assessment report was due to be filed.

(d) Extension of time. For good cause shown, the Regional Engineer may extend the time for filing the report on a comprehensive assessment or periodic inspection under this subpart D.

(e) Type of Report. For good cause, the Regional Engineer may require that any report due to be filed under this subpart D be a report on a comprehensive assessment or a report on a periodic inspection, notwithstanding the type of review (periodic inspection or comprehensive assessment) scheduled to be performed under paragraphs (c)(1) and (c)(2) of this section.

(a) Corrective measures. For items identified during a periodic inspection or comprehensive assessment as requiring corrective action, the following conditions apply:

(1) Corrective plan and schedule. (i) Not later than 60 days after a report on a periodic inspection or comprehensive assessment is filed with the Regional Engineer, the licensee must submit to the Regional Engineer a plan and schedule for addressing the recommendations of the independent consultant(s) and for investigating, designing, and carrying out any corrective measures that the licensee proposes to implement.

(ii) The plan and schedule may include any proposal, including taking no action, that the licensee considers a preferable alternative to any corrective measure recommended in the report of the independent consultant(s). Any proposed alternative must be accompanied by the licensee's complete justification and detailed analysis and evaluation in support of that alternative.

(2) Carrying out the plan. The licensee must complete all corrective measures in accordance with the plan and schedule submitted to, and approved or modified by, the Regional Engineer, and on an annual basis must submit a status report on the corrective measures until all have been completed.

(3) Extension of time. For good cause shown, the Regional Engineer may extend the time for filing the plan and schedule required by this section.

(b) Emergency corrective measures. The licensee must provide that if, in the course of a periodic inspection or comprehensive assessment conducted under this subpart D, an independent consultant discovers any condition for which emergency corrective measures are advisable, such as a condition affecting the safety of a project or project works as defined in § 12.3(b)(4) of this part, the independent consultant must immediately notify the licensee and the licensee must report that condition to the Regional Engineer pursuant to § 12.10(a) of this part. Emergency corrective measures must be included in the corrective plan and schedule required by paragraph (a)(1) of this section, and are also subject to paragraphs (a)(2) and (a)(3) of this section.

At least 30 days prior to the performance of a periodic inspection or comprehensive assessment, a preliminary report prepared by the independent consultant team must be filed by the licensee with the Regional Engineer to document the initial findings, understanding, and preparation of the independent consultant team.

(a) For any periodic inspection, the 30-day period is measured from the scheduled date of the physical field inspection.

(b) For any comprehensive assessment, the 30-day period is measured from the scheduled date of the physical field inspection, potential failure mode analysis, or risk analysis, whichever occurs first.

(c) If the Regional Engineer determines that the preliminary report does not clearly demonstrate that the independent consultant team is adequately prepared for the inspection, the Regional Engineer may require the inspection to be postponed. Any such postponement shall not constitute good cause for an extension of time under § 12.40(d).

(d) If any required supporting team member information was not provided with the independent consultant team proposal required by § 12.34(b), it must be provided with the preliminary report.