News | April 26, 1999

Risk Management Guidance Updated

EPA has released a new guidance document, "Risk Management Program Guidance for Offsite Consequence Analysis," for the owners and operators of facilities covered under the Risk Management Program (RMP) rule. It replaces "RMP Offsite Consequence Analysis Guidance" published May 1996.

Facilities covered under the RMP handle, manufacture, use or store certain toxic and flammable substances. Specific information about facilities and chemicals covered under the rule and the software that performs the calculations to determine the offsite consequence analysis (OCA) are available at Use of the new guidance information is optional. Facilities that have already performed OCA using the May 1996 version of the document can continue to use those calculations in RMP submissions.

The new document provides a simple methodology for conducting OCA, including worst-case release and alternative release scenarios. The worst-case release scenario is the largest quantity of a regulated substance that could be released from a single vessel or process line failure that results in the greatest amount of contamination or damage from a toxic vapor cloud, heat from a fire or a blast wave from an explosion. Alternative release scenarios are incidents that are more likely to occur than the worst-case scenario but that can still have an environmental or health impact offsite.

General reference tables of distances that are applicable to most of the regulated toxic substances, and chemical-specific tables of distances for anhydrous ammonia liquefied under pressure, aqueous ammonia, chlorine and sulfur dioxide are provided. The guidance document also includes reference tables of distances for consequences of fires and explosions of flammable substances.