The Chemical Accident Prevention Provisions require the completion of a worst-case release scenario analysis (40 CFR §68.25). This analysis includes estimating the greatest distance to endpoint as defined by the parameters in §68.22. Is there a required minimum or maximum distance for the distance to endpoint in the worst case release scenario?

There is no mandatory minimum or maximum distance that should be provided when modeling the worst-case release scenario.  The minimum or maximum distance to endpoint will often be dictated by the tool used to model the worst case release scenario.

RMP*Comp, an off-site consequence calculation tool provided by EPA, will report any distance shorter than 0.1 mile as 0.1 mile and all distances longer than 25 miles as 25 miles. Other modeling tools may report different minimum or maximum distances to endpoint.  The model used must incorporate the modeling parameters discussed in §68.22 and satisfy the other offsite consequence modeling requirements of the rule.

Further information on off-site consequence analysis modeling is available in the guidance document titled, Risk Management Program Guidance for Offsite Consequence Analysis (EPA550-B-99-009), which is available at the following URL:

https://19january2021snapshot.epa.gov/rmp/guidance-facilities-risk-management-programs-rmp