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CHAPTER 5 Potential Consequences of Incidents Involving the Identified Hazardous Materials Once you have determined which hazmat are present in your jurisdiction, either at fixed facilities or along transportation corridors, you need to assess the potential consequences that would result from an incidental or intentional release of those materials. Since you have an idea of the quantities present in each location, you can use this information to help determine the potential impacts from a complete release. The Guide builds on the hazardous materials portfolio and adds columns to address potential consequences. Defining Consequences The potential consequences term is a measure of the potential impacts to the population or environment from a release of hazmat. There are many factors to consider when estimating these impacts. Since consequences to people and the environment are typically measured in different ways, this Guide uses the CARVER method to assign a relative value for the two differ- ent types of consequences. (CARVER is an acronym for criticality, accessibility, recuperability, vulnerability, effect, and recognizability and is employed by the U.S. Department of Defense.) The CARVER method uses a range of values that approximate a logarithmic scale for each measure that needs to be estimated. For both population and environmental consequences, this Guide uses values from 1 to 5 as defined in Table 13. The next section will help you determine the consequence value for each scenario in the hazardous materials portfolio. The method of assessing consequences should be consistent with the capability of the emer- gency response planner or planning team. For many areas, the emergency response teams commonly use plume modeling to identify areas where precautions to protect against the release should be directed. Others might only have the most current version of the ERG (2008). The hazard distances in the ERG can be used in lieu of modeling the release, and a realistic fraction of the people exposed to the release could be expected to require medical treatment. This number can be used in conjunction with the consequence scale to conservatively estimate impacts. The following paragraphs discuss some of the approaches to addressing the consequence term. The approach selected should be the one that best matches the capability of the emergency response planning team. These consequences are measured assuming no effective emergency response (identified above as potential unmitigated consequences). This enables the effectiveness of the emergency response to be captured in the response time and emergency response capability terms in the risk equation. For each scenario in the risk portfolio, both population and environmental consequences will be estimated and the maximum of the two estimates will be used in the risk equation. 28