A Guide for Assessing Community Emergency Response Needs and Capabilities for Hazardous Materials Releases (2011)

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This chapter brings together your prior work on filling out the hazardous materials portfolio to develop a risk metric that reflects how well your emergency response capability is aligned with the hazmat present in your jurisdiction. A new term, vulnerability, is added to support calculation of the risk metric. Adding Risk to the Hazardous Materials Portfolio Until this point, the various incident scenarios that could occur in the region have been iden- tified and the consequences assessed without regard to likelihood or frequency. The vulnerability term, which will be discussed next, provides a way of assigning a risk level to each scenario. The measure of risk described in Chapter 1 was called the risk metric because it is not a quantitative measure of risk, for example, the risk of an incident occurring involving a hazardous material being released on a local rail line or highway. The risk metric provides a way of prioritizing the emergency response shortfalls. Given that resources are always going to be limited, it is wise to fix the shortfalls that result in the greatest reduction in risk. Addressing shortfalls that would result in only slight reductions in risk might not be worth the cost, even if funds were available. The vulnerability term is a measure of the likelihood that the population or environment will be exposed to threats produced by an incident. There are two ways to address vulnerability: (1) consider potential release probabilities based on historical or scientific data, and (2) consider the quantity and frequency of materials present. In both cases, vulnerability is expressed on an annual basis. Table 20 shows the range of values used in this Guide for the vulnerability term for both of these approaches (based on likelihood of release and based on frequency of presence). These approaches apply to both fixed facilities and transportation. The frequency approach addresses how often the materials are present in sufficient quantities to be of concern at the facility, whereas the transportation approach refers to the frequency of shipments along a particular transportation corridor or through the community. These values could be assigned to Freight Analysis Framework (FAF 2010) truck volume levels and the Commodity Flow Survey (CFS 2007) hazmat percentage of truck tonnage. The vulnerability levels for a particular scenario can often be estimated from experience. For example, the history of hazmat responses can be used to assign an overall vulnerability level for the region. Typically, that level will be high or very high. If a CFS is available, assuming the same incident rate for all transport on each mode, then the vulnerability level by hazmat class and division can be obtained by multiplying the overall likelihood of a hazmat incident in the area by the class/division distribution of shipments from the CFS. If you desire to factor in the likelihood or probability of a package breach given an incident for hazmat like gasoline, the likelihood can be reduced by an order of magnitude (i.e., by a factor of 10), and for other bulk commodities the likelihood can be reduced by two orders of magnitude (i.e., by a factor of 100). The likelihood of a fire or BLEVE is at least two orders of 37 C H A P T E R 7 Aligning Hazardous Materials with Varying Levels of Capability

38 A Guide for Assessing Community Emergency Response Needs and Capabilities for Hazardous Materials Releases magnitude—one vulnerability level—below the vulnerability level assigned using the estimated incident frequency from historical data. For estimating the likelihood of a release at a fixed facility, you must rely on estimates obtained through discussions with the companies that have inventories of hazmat. LEPCs will have access to the company’s safety officer and planning documents for any facility that falls under EPA or Occupational Safety and Health Administration (OSHA) regulations, because hazmat are present above the prescribed threshold values. In some cases, these planning documents will include a discussion of the likelihood of a release requiring non-company emergency response support. If the documents do not include that discussion, you can estimate the likelihood based on discussions with the safety officer. The safety officer will be familiar with process upsets and near-misses, serious incident scenarios that were stopped by the intervention of safety systems or trained operators at the local facility and other similar facilities operating around the United States. The vulnerability level for a serious incident will be one or, in a few cases, two. Thus, if several facilities of similar design have been operating for a total of 1,000 plant years and there was only one known near-miss, then the vulnerability level is probably “low” because there are typically several near-misses before there is an actual release. For purposes of this example, the vulnerability will be judged as “moderate,” somewhere in the range of 10−2 to 10−4 per year (or 1 in every 100 to 10,000 years). There might be more than one type of hazardous material present at a facility, and the vulnerability term could be adjusted upwards accordingly. The size and nature of the facility matters as well. If the facility was the only producer of a key product in a region or had another similar characteristic, the vulnerability level probably should be set higher from a security perspective. The vulnerability term would also be used if the major threat was viewed to be security rather than safety. The vulnerability would be associated with iconic targets or critical infrastructure, and the fraction of the time a material could damage the targets or infrastructure would be used to assign a value to the vulnerability term. Based on the last column in Table 20, the vulnerability term would be assigned as “low” if the hazardous material that could damage the iconic structure or the critical infrastructure were present in the area only a few times a year. When you consider vulnerability from the safety perspective, the term for a transport corridor has several components: number of vehicles carrying the hazardous material, incident rate for those vehicles, hazmat involvement, and hazmat release. While an individual skilled in risk assessment might not have any difficulty assigning values to those terms, a simpler alternative might be to just focus on traffic volume. Consider each mode separately. If the region is traversed by a Class 1 railroad, with 25 or more trains a day traversing the region, a “high” vulnerability should be assigned for all the hazards believed to be present in the area. From an incident perspective, if there were 25 trains traversing the area every day, then there are millions of rail car miles per year passing through the region, and there could be several train incidents per year. It follows Vulnerability Level Approximate Range Value Description Likelihood of Release Frequency of Presence 5 Very High > 1 per year many times per day 4 High 1 to 10-2 per year several times per week to daily 3 Moderate 10-2 to 10-4 per year a few times per month 2 Low 10-4 to 10-6 per year a few times per year 1 Very Low < 10-6 per year < a few times per year Table 20. Vulnerability levels.

Aligning Hazardous Materials with Varying Levels of Capability 39 that the likelihood of a hazmat release would fall in the high range. If the region has a large rail sorting yard as well, the likelihood might be increased to “very high.” If CFSs show that a specific hazardous material was present as a single car on only a few trains, say less than 10 hazmat cars per day, then a “moderate” vulnerability level should be assigned. Similarly, if only a few cars per year of a specific type of hazardous material were shipped, the vulnerability could be set to “very low,” less than 10−6 per year. Since the goal is to assign a risk metric and not a quantitatively assigned risk value to each scenario, a consistent assignment of vulnerability values is more impor- tant than calculating a quantitative value for each scenario. In some cases, empty cargo tanks or rail cars contain sufficient residue to require hazmat placards. Emergency response personnel might not be able to distinguish the residue nature of the shipment until after initiating response actions assuming a full container. Step 19 Record the appropriate vulnerability value for each scenario in your hazardous materials portfolio, based on the values in Table 20. Depending on the availability of information, it might be difficult to estimate the vulnerability term. You are not required to follow the formal process shown in Appendix B. If the formal process is not used, estimate the risk for the most likely release scenario. This would probably be a Class 3 flammable liquid release. Then use an order-of-magnitude scale to specify a lower vulnerability value for the less commonly shipped materials based on their shipment frequency. Appendix B contains more detailed examples regarding vulnerability calculations. Hazardous Materials Portfolio Example The following discussion uses a hypothetical jurisdiction and evaluates each of the terms in the risk equation to determine a risk metric for each scenario. Since the planning organization has been involved in developing the emergency response plan (ERP) for Facility Z, it is aware that the facility, which produces polyester resins, has several large vessels containing ethylene and receives over 20 rail tank cars of ethylene a week. Ethylene is highly flammable and will auto-decompose at temperatures as low as 150°C. It has a lower flammability limit of 3 percent and an upper flammability limit of 100 percent. The decomposition is catalyzed by iron oxide on the tank surfaces. It is shipped in insulated rail tank cars (e.g., type 105J100W or other DOT-approved tank cars) having a maximum capacity of 25,000 gallons. These char- acteristics make BLEVEs or other explosions a possibility at the facility and on the rail line to the facility. Gasoline is shipped on the roads in the region, so the risk of fire following a road incident must be considered. The manufacturing process also uses small amounts of chlorine, which is also shipped in by rail. This could result in a toxic gas release from both the facility and the rail line. There is a major interstate through the jurisdiction and, from a CFS that the planning agency commissioned, shipments of anhydrous ammonia (considered a toxic gas) and 37 percent hydro- chloric acid are present. No identified shipments of radioactive material or etiologic/biologic agents were identified in the region. When addressing the hazards, you should consider large and small releases. Based on the above hazards, the hazard column in the risk profile can now be filled out as shown in Table 21. The risk metric in Table 21 would suggest that no training would be needed for incidents involving etiologic/biologic agents. That would be an incorrect conclusion because at all tier lev- els, awareness training is required. It might not be required for the area emergency response team to have all the equipment necessary to respond effectively to incidents involving these materials. Through awareness training, everyone would be able to recognize when these materials are pres- ent and also know whom to call for assistance if an accidental release of these materials occurred.

40 A Guide for Assessing Community Emergency Response Needs and Capabilities for Hazardous Materials Releases Hazard [H] Vulner- ability [V] Consequence [C]* Capability [ERC] Response Time [RTF] Risk Metric Facility or Route Description Y/N Pop. Env. Facilit y Z Fire (ethylene oxide) 1 4 3 2 1 12 Roads u, w, x, y Fire (gasoline) 1 4 3 1 4 48 Facilit y Z Explosion (ethylene oxide) 1 2 5 2 1 10 Railroad s BLEVE (ethylene oxide) 1 3 2 2 4 24 Facilit y Z Toxic Gas (chlorine) (L) 1 3 5 1 1 75 Facilit y Z Toxic Gas (chlorine) (S) 1 4 5 2 1 20 Railroad s Toxic Gas (chlorine) (L) 1 3 5 1 3 225 Railroad s Toxic Gas (chlorine) (S) 1 3 3 3 1 9 Roads x, w Toxic Gas (ammonia) (L) 1 2 5 2 4 5 5 5 1 1 1 1 1 1 1 1 1 200 Roads x, w Toxic Gas (ammonia) (S) 1 3 3 1 4 36 Roads x, u Toxic Liquid (37% HCl) (L) 1 2 5 2 4 40 Roads x, u Toxic Liquid (37% HCl) (S) 1 2 3 1 4 24 Radioactivity 0 Etiologic/Biologic 0 *The maximum of the consequence values (population and environmental) are used in the risk metric calculation. (S) small release; (L) large release. Table 21. Completed risk portfolio. The vulnerability values in Table 21 are based on the discussions in Chapter 7 and Appendix B. The consequence values are based on Chapter 5 and Appendix C. Note that in this hypothetical jurisdiction, environmental consequences never exceed human-health consequences for any scenario. Table 21 shows the ERC and RTF terms for each scenario for this hypothetical jurisdiction. It also shows the calculation of the risk metric using the risk equation. The risk metric shows that the dominant risk is from toxic gas releases. If emergency response capabilities were improved for these releases, the risk to the public could be significantly reduced. Step 20 Multiply the values for vulnerability, the maximum of the two consequence values, the capa- bility and response time factor to obtain the risk metric for each release sequence. The results are shown in Table 21. If the assessment tool is used, this step is calculated automatically.