Appendix L

Federal Energy Regulatory Commission Chapter 14
Engineering Guidelines for the Evaluation of Hydropower Projects
Appendix L
DETAILED RADIAL GATE INSPECTION REPORTS
Revision 3 14-L-1 May 2017

BACKGROUND AND PURPOSE

The FERC Tainter Gate Initiative (TGI) was implemented in 1998 following the forensic
investigation into the failure of a radial spillway gate at Folsom Dam. The purpose of the TGI
was to ensure that there would be periodic review of the design assumptions and up-close
inspections of radial gates at FERC-regulated projects.
Since the 2001 revision to the initiative, each dam with a Category 1 radial gate1 has been
required to submit a detailed Gate Inspection Report (GIR) at a ten-year interval. The GIRs
submitted have varied in quality, scope, and contents; the purpose of this document is to
provide guidance on our minimum expectations for the GIRs.
While this guidance specifically addresses radial gates subject to inspections under the TGI,
the FERC recognizes that many dams have other types of gates that could have dam safety,
operational, or life safety consequences in the event of failure or misoperation. If the D2SI-
Regional Engineer (RE) determines that a gate or set of gates meets the conditions to be
classified as a Category 1 gate, and requires detailed “hands-on” inspections, the guidance
herein shall apply regardless of the gate type.
RADIAL GATE INSPECTION REPORTS
Submittal Procedures
A GIR should be submitted every ten years, or more frequently if determined to be necessary
by the RE. If any conditions are identified during the gate inspection that could reasonably be
considered to constitute a dam safety issue, the licensee should immediately report it to the
RE in accordance with 18CFR §12.10 (a).
A GIR transmittal letter should be addressed to the RE and should include:
 A summary of the key findings of the GIR;

 A summary of key findings of the previous GIR and any work (e.g., analysis, maintenance, or
modifications) performed in the interim;
 A clear statement by the Chief Dam Safety Engineer or Coordinator (CDSE) that they have
reviewed the GIR, concur with its findings, or adequate justification and rationale for any
‘non-concurrence’; and
 A list of recommendations, as appropriate, for routine maintenance, investigation, or major
remediation, as well as the CDSE’s plan and schedule for addressing those items.
1
A Category 1 gate is defined as one for which either of the following is true:
1) A structural failure of the gate, or the gate’s inability to open or close, endangers downstream life
during normal operations or flood events; or
2) A failure to open or close results in a significant uncontrolled reservoir level rise or drop during
normal operations or flood events, affecting upstream life, property, or resources.
The report should be submitted to the appropriate Regional Office per the procedures shown
in the FERC Filing Guide (http://www.ferc.gov/docs-filing/forms/fileguide.pdf). The report
should be securely bound and each copy should include a DVD containing a searchable
electronic version of the report, including appendices. Appendices D and E may be included
in electronic format only, if desired.
Outline of the Gate Inspection Report

The GIR should be organized into the following sections:
1. Inspection Scope
2. Review of Existing Documentation
3. Inspection Findings
3.1. Gate No. 1
3.2. Gate No. 2
3.3. Gate No. 3… [etc.]
4. Recommendations
5. Conclusions
Appendices
Appendix A: Inspection Team Resumes
Appendix B: Status of Previous Recommendations
Appendix C: Drawings and Schematics
Appendix D: Inspection Photos (DVD only)
Appendix E: Inspection Field Notes (DVD only)
Contents of the Gate Inspection Report
Inspection Scope
This section should include the following:
 The Scope of Work for the gate inspection;

 The general qualifications and experience of the inspectors, with a reference to their
resumes (Appendix A); and
 The name of the lead engineer on the team – each team should include at least one engineer
qualified to review and comment on the adequacy of the spillway gate analysis of record;
and
 A statement of independence – if the inspection is performed by a party other than the
licensee, include a statement declaring that the inspection findings, conclusions, and
recommendations were made independent of the licensee and its employees.
Review of Existing Documentation

This section of the report should contain a summary of existing documentation, including gate
analyses, licensee procedures, operational history, and prior GIRs. Any other information
important to the design, operation, and performance of the gates should be included, including
any modifications to the design or operation of the gates. Additional guidance for what to
include in this section of the GIR is described below.
Gate Analysis: The inspection team should review the analysis of record and comment on the
assumptions (including material properties), methods, and results. If the gate analysis is
obsolete, incorrect, or does not exist, the inspection team should immediately contact the
CDSE, who should coordinate with the D2SI-Regional Office to establish a schedule for
completing a new analysis. This section should include a summary of the load cases, material
properties, and other pertinent design basis information.
Structural members and connections should be identified as either critical or non-critical,

based on the analysis results. The failure of a critical member would be expected to result in
either an uncontrolled release of the reservoir or failure of the gate to operate as designed.
Licensee Procedures: Review and comment on the licensee’s procedures for inspection and
maintenance (including lubrication, if required) of the gates, hoist equipment, power sources,
control systems, and cables that comprise the power and SCADA systems. Attention should
be given to discussion of the trunnions, including the manufacturer, installation date, physical
properties, and lubrication requirements.
Operational History: Provide a brief list of significant operational issues during the life of the
gates. For example, misoperation and racking due to chain binding, or dropping of a gate due
to a hoist failure, should be discussed. The annual spillway gate certificates should be
reviewed and the team should comment on any apparent trends, unusual amperage readings,
and power draw in excess of the rated capacity of the motors.
Prior GIR: Provide an update on recommendations from the prior GIR. Critical
recommendations should be discussed in this section; general maintenance items may be
mentioned as necessary or simply included in the table in Appendix B.
Inspection Findings
Each radial gate should be discussed individually. The GIR should include clear, definitive
statements about the condition of structural members and connecting elements, with an
emphasis on those designated as critical based on the review of the analysis. Photos should be
provided for significant observations. It is not necessary to include every photo in the body of
the GIR, though all photos should be included on the companion DVD.
This section of the report should be presented in an appropriate format (e.g., paragraph,
tabular, or diagrams) that clearly conveys the observations. Photos should be used to help
explain any conditions noted. The following items should be addressed in the GIR (this is not
an exhaustive list):

 Bent, deformed, or missing members or connecting elements;

 Weld defects: identify any instances of cracking, problematic details, or visibly poor weld
quality;
 Mechanical fasteners: bolts and rivets should be compared to the information shown on the
drawings. Loose fasteners, those visibly cracking or deformed, and those that do not conform
to the record drawings, should be identified;
 Corrosion protection: discuss the condition of the coating system and whether there is a
need for repair. If there is a cathodic protection system, indicate whether it is well-
maintained, functional, and installed correctly;
 Corrosion: provide clear indication of the type of corrosion (e.g., surface, pitting, etc.), the
location and percent of the member affected, and whether it may have structural
implications;
 Drainage and debris: identify the location of any ponding water and discuss whether
drainage should be provided. Accumulation of debris, including excessive animal waste,
should be discussed;
 Seal condition and serviceability (including side, bottom, and top seals, as applicable);
 Lifting devices and attachments (including cables, chains, eyebolts, clevises, sheaves, etc.);
and
 Mechanical and electrical components of the hoist equipment.
Operation Test: The inspection team should observe each gate moving through its full range
of motion, fully closed to fully open and back, and provide observations and comments. If the
requirement for a full open test does not coincide with the year of the GIR, it is acceptable for
the GIR to include a review and comments on the previous full open testing, provided there is
sufficient documentation available from that test for the inspection team to make an informed
conclusion regarding the operational condition of the gate (e.g., real-time power draw plots,
video with audio, etc.).
Recommendations
The GIR should include recommendations for how any and all identified deficiencies should
be addressed. Recommendations should be flagged according to the importance of the issue.
For example, categories could be:
 Critical, dam safety-related

 Potential dam safety issue requiring investigation
 General maintenance
Conclusions
The inspection team should provide an overall conclusion regarding the fitness of the gates
for continued safe and reliable operation. The discussion should include an assessment of how
the overall condition of each gate has changed since the previous GIR.
Appendices for the GIR

Appendix A: Inspection Team Resumes. Include resumes of the inspection team, including
the qualified engineer who reviewed the prior gate analysis. That individual should either be a
licensed Structural Engineer or have sufficient work experience to demonstrate a
comprehensive understanding of issues associated with radial gates.
Appendix B: Status of Previous Recommendations. The status of previous recommendations

should be updated in a tabular format. Critical recommendations are to be discussed in detail
in the body of the report.
Appendix C: Drawings and Schematics. The drawings and schematics included in this section
should convey all required information about the structural members and connecting elements
of the gate, anchorage, and hoist equipment. As-built drawings and any drawings depicting
significant modifications since original construction are recommended. Drawings should be
printed at 11x17 inches and should be clear and legible to the unaided eye.
Appendix D: Inspection Photos (DVD only). If desired, this appendix may be included only
electronically and not in hard copy. All inspection photos should be included at full resolution
and in folders organized by gate number.
Appendix E: Inspection Field Notes (DVD only). The inspection team field notes should be
scanned and included for reference. If desired, this appendix may be included only
electronically and not in hard copy.
Previous FERC Letters Regarding Radial Gates

Refer to the following pages.

Original Tainter Gate Initiative (1998)



Tainter Gate Initiative, Revision 1 (2001)



Tainter Gate Initiative, Revision 2 ( 2002)




10-Year Gate Inspection Reminder (2009)



Annual Spillway Gate Operation Certificate

A link to download the most recent version of the annual spillway gate operation certificate
can be obtained at the following address:
http://www.ferc.gov/industries/hydropower/safety/guidelines/eng-guide.asp

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Federal Energy Regulatory Commission Chapter 14

Engineering Guidelines for the Evaluation of Hydropower Projects

Revision 3 14-L-1 May 2017

BACKGROUND AND PURPOSE

RADIAL GATE INSPECTION REPORTS

A GIR transmittal letter should be addressed to the RE and should include:

 A summary of the key findings of the GIR;

Outline of the Gate Inspection Report

Contents of the Gate Inspection Report

 The Scope of Work for the gate inspection;

Review of Existing Documentation

Revision 3 14-L-3 May 2017

Structural members and connections should be identified as either critical or non-critical,

Revision 3 14-L-4 May 2017

 Bent, deformed, or missing members or connecting elements;

 Critical, dam safety-related

Appendices for the GIR

Appendix B: Status of Previous Recommendations. The status of previous recommendations

Previous FERC Letters Regarding Radial Gates

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Original Tainter Gate Initiative (1998)

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Tainter Gate Initiative, Revision 1 (2001)

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Tainter Gate Initiative, Revision 2 ( 2002)

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10-Year Gate Inspection Reminder (2009)

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Annual Spillway Gate Operation Certificate

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