The following letters between the Federal Energy Regulatory Commission (FERC) and DWR in October and November discuss the program DWR put in place in September to monitor the conditioning and curing of hairline cracks in structural concrete slabs on Lake Oroville's reconstructed main spillway.
- FERC letter regarding observation of hairline cracks, October 2, 2017
- DWR Technical Memorandum: Investigation and Initial Evaluation, Cracking of Erosion Resistant Concrete Invert Panels in the FCO Spillway, November 2, 2017
- DWR response describing monitoring program and assessment that the presence of hairline cracks was anticipated and is not expected to affect the integrity of the concrete slabs, November 7, 2017
- FERC response agreeing with DWR's assessment, November 21, 2017
Other information about structural concrete cracks:
- American Society of Concrete Contractors position statement on cracks in structural concrete, September 2010
FERC Part 12 D Oroville Inspection Reports
Below are links to the Federal Energy Regulatory Commission (FERC) Part 12D inspection reports about the Oroville Dam facilities. Consistent with the department's policy, the reports were released with Critical Energy Infrastructure Information (CEII) redacted. The FERC Part 12D is a comprehensive assessment of the current health and long-term safety of the dam.
All Part 12D reports for Oroville Dam ended with the conclusion that the project was suitable for continued operation.
The purpose of the Part 12D inspection is to look for the conditions that may develop as described in the Potential Failure Mode Analysis (PFMA) and to document the actual condition of the project structures.
The process for a Part 12D report is iterative. The Independent Consulting Board, required by FERC every five years, provides an independent inspection and evaluation of the facility, and provides recommendations to DWR in their Part 12D report. DWR then submits a plan and schedule to address those recommendations based on priority and risk. In some cases FERC provides feedback to DWR's plan and DWR responds with additional information and planned actions.
In late 2002, FERC, in cooperation with dam owners and Independent Consultants, developed and circulated guidance for carrying out a PFMA. The PFMA process introduced the concept of a Supporting Technical Information Document, which included critical project information from earlier reports. Part 12D Reports were revised to focus on Potential Failure Modes, necessitating a more focused review of previous analyses and initiating new analyses.
FERC Part 12 D Oroville Inspection Reports
Every five years an independent board of consultants inspects and assesses the facilityâ€™s performance and safety. FERC requires dams like Oroville to be inspected and evaluated by an Independent Consultant to identify any actual or potential deficiencies in project works, condition, or in the quality or adequacy of project maintenance, surveillance, or methods of operation, that might endanger public safety. The completed report is then submitted to FERC for review. DWR commonly retains a board of Independent Consultants to ensure that multiple engineering disciplines are represented with appropriate expertise and experience for this task
This report summarizes their inspection findings, conclusions, and recommendations for DWR in regards to Oroville Dam. FERC and California Division of Safety of Dams (DSOD) require that DWR-Operations & Maintenance develop a plan and schedule to address the recommendations, and then implement the recommendations (as appropriate) over the following 5 years.
- Summary of 2014 FERC recommendations and DWR actions
- 2014 Part 12D Safety Inspection Report Part 1 of 4
- 2014 Part 12D Safety Inspection Report Part 2 of 4
- 2014 Part 12D Safety Inspection Report Part 3 of 4
- 2014 Part 12D Safety Inspection Report Part 4 of 4
- Summary of 2010 FERC recommendations and DWR actions
- 2010 Part 12D Safety Inspection Report Part 1 of 2
- 2010 Part 12D Safety Inspection Report Part 2 of 2
2004 Potential Failure Mode Analysis Report (PFMA)
Potential Failure Modes (PFMs) are the hypothetical chain of events that could lead to unsatisfactory performance of the dam or a portion thereof. The PFMA is conducted jointly by the licensee, Independent Consultant and FERC staff to brain-storm about ways the dam could hypothetically fail. Participants also develop Risk Reduction Measures that can help monitor for signs of initiation of hypothetical PFMs. The analysis commonly helps dam owners refine their surveillance and monitoring plans and helps prioritize dam safety studies for various issues.
- 2014 Potential Failure Mode Analysis Workshop
- 2009 Potential Failure Mode Analysis Report (PFMA)
- 2004 Potential Failure Mode Analysis Report (PFMA)
Supporting Technical Information Document (STID)
FERC requires dam owners to prepare a STID to capture the information necessary to have a complete and thorough understanding of the dam and the analyses completed that support the findings regarding the safety of the structure(s).
- 2014 Supporting Technical Information Document Part 1 of 5
- 2014 Supporting Technical Information Document Part 2 of 5
- 2014 Supporting Technical Information Document Part 3 of 5
- 2014 Supporting Technical Information Document Part 4 of 5
- 2014 Supporting Technical Information Document Part 5 of 5
- 2005 Supporting Technical Information Document Part 1 of 2
- 2005 Supporting Technical Information Document Part 2 of 2