Dam Safety Facts - Risk reports for declared dams

What is a risk report?

Under the Dams Safety Regulation 2019, a risk report is a written report that a dam owner must produce on all foreseeable risks to their declared dam. The report must follow the risk management framework in clause 14 of the Dams Safety Regulation 2019.

Do all declared dams need a risk report?

Yes, all declared dams require a risk report that is specific to each dam.

Risk reports are needed for new dam designs and for dams undergoing major change

The owner of a proposed declared dam must produce a risk report at the time the new dam is being designed. Similarly, a risk report is required to be produced when a major change to a declared dam is being designed.

I own a dam that is not complex – can I apply for an exemption?

While the Dams Safety Regulation 2019 allows the owner of a ‘declared dam that is not complex’ to apply for an exemption against some aspects of the risk framework, Dams Safety NSW considers it is important that every declared dam’s risk position is determined using the full risk framework.

Dams Safety NSW would consider an exemption for future risk reports once an initial risk report for a non-complex dam has been produced against the full risk framework in the Dams Safety Regulation 2019.

Is a specialist consultant needed to prepare the risk report?

The calculations needed to produce the risk report can be complex. If a dam owner does not have a dams safety engineer (who is a ‘competent person’ in the terminology of the regulation) within their organisation they will need to engage a ‘competent’ dams safety engineer to help prepare the report. The Dams Safety Regulation 2019 requires that a ‘competent person’ signs off the societal and individual risk rating calculations within the report. For extreme, high A and high B consequence category dams, the calculations must be reviewed by another independent competent person.

The dam owner should clarify with the specialist what assumptions and what level of precision they will use in the risk analysis so that the uncertainty of the result is understood. This is particularly useful information when comparing two or more specialists’ proposals. The risk assessment needs to be able to determine the dam’s individual and societal risk rating in relation to the safety threshold (refer to clause 15 of the Dams Safety Regulation 2019). Sensitivity analysis is useful in determining the level of uncertainty associated with the result.

An owner of a ‘dam that is not complex’ should expect that the cost and complexity of undertaking a risk report is proportionate to the complexity of the dam. Simpler dams will incur lower costs and require a narrower range of ‘competent person’ expertise from a specialist consultant.

A risk report for each declared dam is required every five years. By what date does a dam owner need to produce a report?

Dams Safety NSW has prepared a schedule of risk report due dates for all declared dams.

The risk report schedule covers a five-year period from December 2022 to December 2026. This aims to spread the demand for competent specialist resources as evenly as possible over that period.

To prepare the schedule, Dams Safety NSW considered a dam’s consequence category, whether a dam’s risks are known, and other risk factors. All dam owners should have received a letter from Dams Safety NSW confirming the risk report due date for their declared dams.

How must a dam’s risk report be presented?

The risk report must cover all aspects of the risk framework in clause 14 and the risk rating calculations in clause 15 of the Dams Safety Regulation 2019. For example, the report must include:

• key data, conclusions and results presented graphically and in tables so important information is at the front of the report - and not buried in words
• details of the foreseeable risks identified for the dam
• a description of the dam’s failure modes
• the analysis of dam failure modes used in the quantitative risk analysis methodology
• the risk evaluation and risk treatment process for the dam
• the dam’s societal and individual risk ratings
• clear explanations about decisions and assumptions and sensitivities which affect the calculations and conclusions
• sufficient evidence to clearly show that risks have been reduced to a ‘so far as is reasonably practicable’ level, including any cost-benefit analyses undertaken to support this.

The report should incorporate, or be accompanied by, a declaration, signed by the dam owner or the competent person(s), that confirms that they are competent to carry out the tasks in accordance with clauses 3, 14, and 15 of the Dams Safety Regulation 2019. Refer to Provide Dams Safety NSW with a declaration of competency’ fact sheet for further information.

For Extreme, High A, and High B Consequence Category dams, the report must incorporate, or be accompanied by, the comments of an independent ‘competent’ peer reviewer of the risk report.

Note: More detailed technical requirements for a risk report are included at the end of this fact sheet under "Guidance for competent persons: how to present a risk report."

Is the report required to be provided to Dams Safety NSW?

The report must be sent to Dams Safety NSW if the risk rating in the risk report is above the safety threshold. There is a maximum penalty of $1,100,000 if a dam owner does not comply with this requirement.

Dams Safety NSW may also request a dam owner provide a copy of a risk report. If a formal request is made under the Dams Safety Act 2015 there is a maximum penalty of $275,000 if a dam owner does not comply with this request.

Dam owners may email their risk reports to info@damsafety.nsw.gov.au.

Dams Safety NSW will review the risk report for those dams with ratings above the safety threshold and will also review what measures the dam owner proposes to take to reduce the risks. If necessary, Dams Safety NSW may direct the dam owner to take measures to reduce the risk rating to the safety threshold or lower.

For dams with risk ratings below the safety threshold, Dams Safety NSW will audit a sample of risk reports every year, and also review risk reports as part of scheduled audits of dam owners’ safety management systems.

More information on risk reports

For more information on risk reports and the risk management framework, refer to the Dam Safety Management System guideline, pages 10 to 17.

Guidance for competent persons: how to present a risk report

The risk report is a document that describes the analysis that is carried out in accordance with the application of the risk management framework. It:

• describes all the risks to the declared dam,
• analyses the risks
• presents the resulting societal and individual risk ratings and
• demonstrates how the ‘So Far As Is Reasonably Practicable’ position has been reached

A clearly presented risk report will help dam owners understand how to prioritise their operations, plan capital works, and how to plan and carry out maintenance.

You are required to follow the latest gazetted version of the Societal and individual risk rating methodology and Declared dams consequence category assessment and determination methodology. Failure to do so may result in incorrect or misleading understanding of the risks, with serious consequences. At best the risk report may be required to be reworked.

Records of dam performance, photographic evidence, dambreak studies and other information may be used to feed into the risk assessment. Other information can also be derived from surveillance activities, as described in Appendix 1 of the Dam safety management system guideline.

The basic sequence of activity for risk assessment can also be found in current versions of ANCOLD Risk Management Guidelines, USBR Dam Safety Risk Analysis, US Army Corps of Engineers publications, and in other best practice dam safety risk assessment reference documents.

A dam’s risk report should include:

• a declaration signed by the dam owner or the person completing the risk report, using this form, that states the report has been signed off by a ‘competent person’. In addition, if the dam has an extreme, high A, or high B consequence category, the regulation requires that the risk report must be reviewed by another competent person who is independent of the calculation process.

  NOTE: The Dams Safety Regulation 2019 states that a ‘competent person’ is one who has acquired, through training, qualification and experience, substantial knowledge and skills in dam design or risk analysis in relation to the type of dam being assessed. For the risk report, a competent person must have substantial knowledge and skills in dam risk management frameworks to the standard set out in the regulation and methodologies, and be familiar with the referenced documents. The analysis may also require input from other persons with competencies in specialities such as hydrology, geology, seismology (refer to the definitions in the regulation for a list of specialities).

• an executive summary – Important information summarised at the front of the report - not buried in the report.
• a description of the dam and its systems
• a summary of, or reference to, operation, maintenance, and monitoring as described in the Operation and Maintenance Plan for the dam
• a list of reference documentation and information sources available. The level of assessment can depend on the amount of information available.
• a table showing failure modes including those included for analysis and those excluded – and why – (with discussion)
• an estimate of the likelihood of annual failure due to these failure modes. What is the annual probability of a loading event? If this occurs, what is the probability of failure? Discuss the assumptions and uncertainties.
• an estimation of loss of life consequences for each failure mode
• the dam’s individual risk rating calculations and the societal risk calculations, including F-N plots (see Figure 1, below)
• an estimation of the severity of damage and loss for each failure mode. The consequence category methodology applies, which requires dam owners to assess each element of the severity of damage and loss. Therefore, reference must be made to all elements of Tables 3A (infrastructure), 3B (environment) and 3C (health and social). It is not acceptable to give a blanket assessment for severity of damage and loss. The severity of damage and loss is not plotted on the F-N plot, nor does it directly contribute to the societal or individual risk rating. However, it is a consequence of failure and must be addressed as a part of the risk framework.
• a risk analysis process – see above, (describe which failure modes contribute most to the overall risk to the dam).
• a risk evaluation – prioritise the order in which risks must be mitigated.
• a risk treatment process for the dam. How the risks being treated? What action will be taken, by whom, and when?
• a clear demonstration that the risks have been reduced so far as is reasonably practicable, including any cost-benefit analyses undertaken to support this.
• key data, reasoning, and conclusions should where possible be presented in tables and must also be presented graphically in accordance with the methodology (see sample Figure 1, below).

Figure 1: A dam can have several credible failure modes. The annual probability F and consequence N of each failure mode are plotted and added to produce a cumulative plot. The apex of this plot gives the Societal Risk Rating.