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  • Definition and data sources of "environmental receptor"

    The Risk Management Program rule requires owners or operators of covered processes to define in the risk management plan (RMP) the potential offsite public and environmental receptors within the impact range of identified worst case and alternative release scenarios. What is the definition of "environmental receptor"? What data sources are…

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  • Worst-case Release Scenario for Separate, Interconnected Vessels

    Pursuant to the risk management program regulations, facilities must perform an offsite consequence analysis for the worst-case release scenario. Do the quantities of two separate vessels that are interconnected with a closed valve need to be aggregated for the worst-case release scenario analysis? No. Worst-case release is defined as the…

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  • Worst-case release scenarios for toxics and flammables represented by Program 2 or 3 processes

    A stationary source subject to the risk management program regulations at 40 CFR Part 68 comprises multiple Program 2 and Program 3 covered processes. The owner or operator must do a single worst-case release analysis to represent toxic regulated substances and a single worst-case release analysis to represent flammable regulated…

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  • Non-residential population in off-site consequence analyses

    Must an owner or operator include in their risk management plan (RMP) estimates of the non-residential population when defining off-site impacts for the off-site consequence analysis? Owners or operators are required to note in the RMP the presence of any major institutions (i.e., schools, hospitals, or prisons), public recreational areas…

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  • Are barracks and family housing units on military bases considered public receptors?

    Barracks are not considered public receptors, family housing units are. Public receptors include any "offsite residences ... inhabited or occupied by the public at any time without restriction by the stationary source where members of the public could be exposed to toxic concentrations, radiant heat, or overpressure, as a result…

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  • Are on-site areas with unrestricted access considered public receptors?

    A process covered under 40 CFR Part 68 is eligible for Program 1 requirements if it meets all of the criteria listed at 40 CFR §68.10(b). One of those criteria is that the distance to a toxic or flammable endpoint for a worst-case release assessment is less than the distance…

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  • Are areas occupied solely by employees considered public receptors?

    When analyzing off-site consequences for the purpose of a worst-case or alternative release scenario under the risk management program regulations (40 CFR Part 68), are areas occupied solely by employees at the source considered to be public receptors? No. Such areas at the stationary source are not to be included…

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  • Do the quantities of interconnected vessels need to be aggregated for the worst-case release scenario analysis?

    Pursuant to the risk management program regulations, facilities must perform an offsite consequence analysis for the worst-case release scenario. Do the quantities of two separate vessels that are interconnected with a closed valve need to be aggregated for the worst-case release scenario analysis? No. Worst-case release is defined as the…

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  • Active mitigation systems (e.g., scrubbers) and alternative release scenarios

    I run a wastewater treatment plant that is subject to the risk management program regulations in 40 CFR Part 68 for a covered process containing chlorine. A chlorine scrubber system at the plant is designed to prevent any possible releases from reaching a toxic endpoint offsite. How does this active…

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  • Identification of Industrial Buildings, Commercial Buildings, and Recreational Areas

    Pursuant to the hazard assessment requirements in 40 CFR Part 68, Subpart B, an owner or operator is required to conduct an offsite consequence analysis and analyze a worst-case release scenario and alternative release scenarios as part of a risk management plan (RMP). When completing these scenarios, public receptors need…

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  • Why were ERPG-2 values selected as toxic endpoints instead of ERPG-3?

    An endpoint is needed for analysis of offsite consequences of potential accidental releases of regulated substances. The endpoint to be used for each regulated toxic substance is provided in Part 68, Appendix A, and is the Emergency Response Planning Guideline level 2 (ERPG-2) developed for the substance by the American…

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  • Release scenarios for substances exhibiting flammability and toxicity

    Under the hazard assessment requirements in 40 CFR Part 68, Subpart B, an owner or operator must analyze worst-case release scenarios and more likely alternative release scenarios, and must document a five-year accident history. If a regulated substance exhibits characteristics of both toxicity and flammability, should owners and operators consider…

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  • Worst-case “quantity released” reporting for a mixture

    In section 2, element 2.5, of an RMP, facilities must report the quantity of toxic chemical that the facility used for the worst-case analysis. When reporting this data element in RMP*eSubmit for a mixture, should facilities report the entire weight of the toxic mixture potentially being released or only the…

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  • Worst-case release scenarios for salt domes

    Would all of the regulated substances stored in a salt dome be assumed to be released in the worst-case scenario? The worst case scenario for salt domes would be examined in a manner similar to that for underground storage tanks. Reservoirs or vessels sufficiently buried underground are passively mitigated or…

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  • Air dispersion models for release scenarios

    Under the hazard assessment requirements of 40 CFR Part 68, Subpart B, an owner or operator is required to analyze a worst-case release scenario and more likely alternative release scenarios. Has EPA developed any air dispersion models for conducting these evaluations? Is EPA's TScreen model an appropriate technique? EPA has…

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