Comparison of the Proposed EPA Risk Management Program with OSHA's Process Safety Management Program cont'd

DOE-HDBK-1101-96

significant accidental releases on the public health and environment. OSHA's PSM Rule requires

only a qualitative evaluation of a range of possible safety and health effects on employees in the

work place resulting from a release.

The hazard assessment of a regulated substance requires evaluation of a range of accidental release

scenarios, including:

"Worst-case" accidental releases

Other more probable releases

Potential offsite consequences

Five-year accident history for the facility.

The proposed EPA rule defines "worst-case" release as the instantaneous loss of all of the regulated

substance in a process, with failure of all passive and active mitigation systems. Once the worst-case

and other significant accidental scenarios are identified, facilities would be required to analyze the

potential offsite consequences associated with these scenarios using source release and air dispersion

modeling. This analyses would include fires, explosions, and hazard material releases.

Air dispersion modeling would be used to evaluate the fate and transport of the regulated substance

for the offsite consequence analyses. At a minimum, the offsite analyses would estimate the

possible rate of release, the quantity released, the duration of the release, and the distances in any

direction that the substance could travel before it dispersed enough to no longer pose a hazard to the

public health or the environment.

Along with calculating the severity of the consequences, source term modeling would be used to

calculate release rate as a function of time and other release characteristics.

Under the proposed EPA rule, facilities would be required to update the offsite consequence

analyses of their risk management plans every five years. Updates would be required sooner, if

changes at the facility or its surroundings might change the results of the risk management plan to

any significant degree.

A final element of the hazard assessment is compiling and documenting a five-year history of

releases of the regulated substances. EPA's RMP would require the facility to document the releases

that caused, or had the potential to cause, offsite consequences. The accident history must include:

The substance and quantity released

The concentration of the substance when released

Duration of the release

Date and time of the release

Offsite consequence(s) (e.g., evacuations, injuries).

Note that most of the releases that meet the criteria of the proposed EPA RMP are already reported

under CERCLA and SARA Title III. Most of the information needed to define accidental release

scenarios will be derived from the process hazard analysis.

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