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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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  • Worst-case release scenarios for toxics and flammables in same process

    The owner or operator of a stationary source subject to the risk management program regulations must analyze the worst-case release scenario involving a Program 2 or 3 process containing a regulated flammable substance and the worst-case release scenario involving a Program 2 or 3 process containing a regulated toxic substance…

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  • Air dispersion models and accounting for multiple vessels

    Must air dispersion models that are used to analyze worst-case release scenarios under 40 CFR §68.25 be able to account for multiple vessels and how those vessels could impact one another in the event of an accidental release? No. Models used for worst-case release scenario analysis do not need to…

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  • Calculating release rates and quantities for alternative release scenarios

    I am working on the alternative release scenario portion of my risk management plan (RMP), as required by 40 CFR §68.28. Specifically, I am trying to calculate my release rate and release quantity values. The final rule does not specify exactly how to calculate these values for the alternative release…

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  • Acid aerosol reducing additive as passive mitigation

    A refinery uses a special proprietary additive to their hydrofluoric acid (HF) alkylation process. This HF additive has shown in tests to significantly reduce aerosol forms of HF during accidental releases, and therefore reduce the distance traveled by HF releases. The additive is present at all times during the alkylation…

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  • Can positive buoyancy models be used?

    Yes, provided there is a basis for use and the owner or operator explains the rationale for use of positive buoyancy models.

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  • Are valves in piping considered administrative controls?

    No, administrative controls are written procedures that limit the quantity stored or flowing through the pipes. Valves are considered active mitigation systems.

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  • Reporting requirements for oil discharges

    What are the reporting requirements for discharges of oil? If a discharge of oil reaches waters of the United States, it is reportable to the National Response Center under 40 CFR Part 110 , which was established under the authority of the Clean Water Act. Discharges of oil must be…

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  • Atmospheric conditions used for off-site consequence analyses

    What atmospheric conditions must a source assume when performing the offsite consequence analyses required under 40 CFR Part 68, Subpart B? For the worst-case release analysis, 1.5 meters per second wind speed and F atmospheric stability class must be assumed, unless the stationary source owner or operator can demonstrate that…

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  • Program levels and the difference in worst-case release analysis requirements

    The preamble to the Risk Management Program Rule ( 61 FR 31668; June 20, 1996 ) states that "one worst-case release scenario will be defined to represent all toxics, and one worst-case release scenario will be defined to represent all flammables held above the threshold at the source" ( 61…

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  • Methods to identify affected populations

    As part of the risk management program, a facility owner or operator must prepare an off-site consequence analysis (OCA) and estimate in the risk management plan (RMP) the residential population within the geographical area that could be affected by the hypothetical worst-case or alternative releases that the facility has analyzed…

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  • Definition of recreational area for determining offsite impacts in RMP

    What is considered a recreational area? Recreational areas would include land that is designed, constructed, designated, or used for recreational activities. Examples are national, state, county, or city parks, other outdoor recreational areas such as golf courses or swimming pools and bodies of waters (oceans, lakes, rivers, and streams) when…

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