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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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  • 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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  • Worst case release scenario for toxic and flammable substances in same Program 1 process

    Under the risk management program regulations in 40 CFR Part 68, if a Program 1 process contains a threshold amount of both a regulated toxic substance and a regulated flammable substance, should a worst case release scenario be analyzed for each of the substances in the process? Yes, a worst…

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  • Definition of off-site for identifying public receptors

    My processes are fenced, but my offices and parking lot for customers are not restricted. What is considered offsite? What is considered a public receptor? The unrestricted areas would be considered offsite. However, they would not be public receptors because you are responsible for the safety of those who work…

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  • What measures qualify as "passive mitigation"?

    Passive mitigation is defined in § 68.3 as "equipment, devices, or technologies that function without human, mechanical, or other energy input." Passive mitigation systems include building enclosures, dikes, and containment walls. Measures such as fire sprinkler systems, water curtains, valves, scrubbers, or flares would not be considered passive mitigation because…

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  • Ammonia (concentration 20% or greater) and Ammonia (anhydrous) Alternative Release Scenarios

    Pursuant to the Risk Management Program regulations, the owner or operator shall identify and analyze at least one alternative release scenario for each regulated toxic substance held in a Program 2 or Program 3 process above its threshold (40 CFR §68.28). If a facility has both ammonia and ammonia (anhydrous)…

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  • Are rivers used for recreation 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 in 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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