EPA alters shape of risk management plan

EPA has issued an addendum to its risk management program (RMP) under the 1990 Clean Air Act Amendments. Changes in the plan include a redifinition of worst case release and a tiered system of reporting releases, which satisfy critics who charged that EPA`s original proposals were a near-impossible mission. The RMP`s hazard assessment clause calls for disclosure of a range of releases at a plant, including disclosure of worst case scenarios. One change is a new definition of a worst case: the release of the largest quantity of a regulated substance resulting from failure of a vessel or process piping. The analysis involves a 10-minute release under worst case meteorological conditions. Critics contend that EPA`s previous definition-an instantaneous release of a plant`s entire process system-is physically impossible at complex facilities.