Overview

The purpose of this action is to identify hazards (of natural or accidental origin) and threats (of malicious or deliberate origin) that have the potential to disrupt energy or water supply to the site. This information is a key input into the risk assessment. The identification of hazards and threats begins the process of building risk scenarios across critical loads.

In-Depth

In this action, the resilience planning team identifies hazards and threats that could lead to an energy or water disruption as an input for risk assessment. This is the first step of building the risk scenarios (see call-out box) that the TRN risk assessment model is based upon. Risk assessment requires sites to identify and characterize site-specific hazards and threats, which can be categorized as:

• Natural hazards resulting from acts of nature and severe weather and future weather variabilities (such as severe winter storms, floods, hurricanes, storm surges, solar flares, fires)
• Technological hazards resulting from accidents or the failures of systems, structures, or operator error (such as a cause of bridge collapse or grid outage)
• Threats, or malicious incidents resulting from intentional actions of an adversary (such as cyber or physical acts of terror).

Characterizing Hazards and Threats

In the risk assessment, different sites may require different levels of specificity when it comes to characterizing hazards and threats. The TRN divides hazards and threats into two types: (1) “grouped hazards and threats,” which are groups of hazards and threats that may disrupt primary energy or water supply for about the same outage duration but would not affect onsite redundant systems (this is sometimes called an “all-hazards” approach), and (2) “dual-impact hazards and threats” that would not only result in loss of primary supply, but may also impact onsite redundant systems.

Estimate Frequency and Outage Duration for Hazards and Threats That Cause Energy and Water Disruptions

Consider how frequently the site has lost primary energy or water supply and how long those outages have lasted. What has been the cause of energy or water loss? Consider plans and other information collected in the Site-Level Planning module—what hazards and threats have previously been identified in site and regional plans as relevant for the site? From that set, which have the potential to disrupt access to energy or water at the site?

Assess the frequency of occurrence of the identified hazards and threats and estimate the primary energy and water system outage durations associated with them. The frequency of occurrence can be based on historical data and experience, but, given that the past is not always the best predictor of the future (see TRN Resource: Probability of Experiencing Hazards to see how likely it is that a staff member who has worked at the site for a given number of years will have experienced a hazard or threat that occurs at a given frequency), the assessment should also include projected changes in conditions as necessary (such as storm surge increases, changes in wildfire frequency or severity, chance of cyber or physical attack). Use data from well-validated sources. Because of the significant uncertainties in the characterization of some hazards or threats, the participation of subject matter experts will be crucial in producing a robust, defensible assessment that represents the best available knowledge.

Grouped Hazards and Threats: Hazards and Threats with the Potential to Impact Primary Energy and Water Systems

The grouped hazards and threats approach looks at aggregate sets of hazards and threats that have the potential to impact energy and water systems. Rather than identifying specific hazards and threats and their individual frequencies, the aggregate frequency of all hazards and threats associated with a given outage duration is estimated. For example, if high winds lead to an average of one 1-hour outage every year and grid operation error leads to an average of two 1-hour outages every year, but neither impact onsite redundant systems, the resilience planning team could add a 1-hour outage with a frequency of three times/year to the grouped hazards and threats list. Consider the site’s historical loss of primary energy or water supply—with what frequency would you expect to lose primary energy or water systems for various outage durations? Identify grouped hazards and threats and their likelihood of occurrence in this action’s worksheet. Refer to the TRN Resource: Outage Frequencies for estimates of frequencies of different outage durations for energy and water supply systems.

Dual-Impact Hazards and Threats: Hazards and Threats with the Potential to Impact Onsite Redundant Energy and Water Systems

The TRN Risk Assessment model recognizes that some hazards and threats that cause the loss of primary energy or water supply can also impact onsite current or prospective redundant systems and measures. These are called “dual-impact” hazards and threats within the TRN, and they indicate that the site may have some site-specific vulnerabilities to certain hazards and threats that would benefit from individual examination. Document any dual-impact hazards and threats that will be evaluated for your site in this action’s worksheet. Refer to TRN Resource: Dual-Impact Hazards and Threats for additional information about dual-impact hazards and threats, examples of hazards and threats that could directly compromise the redundant systems, and questions to help assess design resilience to those hazards and threats.

The TRN provides county-level data, based on the National Risk Index, on dual-impact hazards that may be considered for a risk analysis. This includes frequency estimates which can be modified to reflect expectations of how likely those hazards are to lead to an outage of primary energy or water supplies. If generating frequency and outage duration inputs without the TRN hazard data, define the threshold of the dual-impact hazard and threat (e.g., earthquake magnitude, wind speed, hurricane category, and so on) that could potentially compromise onsite redundant systems. For example, if onsite redundant systems would only be impacted by a magnitude 6 earthquake or above, magnitude 5 earthquakes or below would not be considered a dual-impact hazard or threat within the TRN Risk Assessment model; their frequencies and energy/water outage impacts would be accounted for through a grouped hazard.