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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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  • How does EPA develop a “sampling plan” for a site like the Norwood Landfill Site?

    EPA uses the information available, including community input, regarding the boundaries and geographic areas of waste that may have been deposited or where contaminated soil may have been placed. The team selects its soil sampling locations based on those areas and consults historic aerial images that help depict those boundaries…

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  • Why is it difficult to establish a link between cancers or other illnesses and environmental exposures?

    The complex nature of cancer makes it inherently challenging to identify, interpret, and address cancer clusters. Cancer is a term describing different diseases that share a similar characteristic: uncontrollable cell growth and division. As a group, cancers are very common. Cancers are the second leading cause of death in the…

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  • How do we know our drinking water has not been affected over the past 40+ years when the landfill was operating and after it closed since there were no regulations governing its operation or closure?

    The Norwood community is serviced by a public drinking water source. The public water supply must meet federal and state Safe Drinking Water Act Standards. Public water systems are required to share annual reports that describe what, if anything, is found in the water supply.

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  • Were the homes in the Winona Homes and Norwood Acres neighborhoods built on contaminated fill?

    EPA has received anecdotal reports from residents that materials excavated during the construction of the Walt Whitman Bridge, potentially containing contaminants, were used as fill dirt prior to construction of some homes in the area. During the early stages of the site investigation in 2017 and 2018, EPA sampled the…

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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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