Characterization of Accidental Chemical Releases
The 1990 Clean Air Act Amendment (CAAA) section 112 (r) Prevention of Accidental Releases requires the United States Environmental Protection Agency (EPA) to establish measures for owners and operators of facilities processing or handling hazardous materials to prevent accidental releases of regulated substances and other extremely hazardous materials to the air. Additionally, it requires the consequences of releases to be minimized by focusing preventative measures on those chemicals that pose the greatest risk. Section 112® begins with a general duty clause requiring owners and operators to: · Identify hazards that may result from releases · Design and maintain a safe facility · Minimize the consequences of releases when they occur. Another provision of section 112(r) is the requirement to promulgate a list of at least 100 substances, including threshold quantities, that are known to cause, or may be reasonably anticipated to cause, injury or serious adverse effects to human to health or affect the environment when released to air. The list and threshold quantities would be used as a basis to determine which facilities would be required to comply with the accident prevention provisions. Other requirements were “reasonable regulations and appropriate guidance” to provide for the prevention and detection of accidental releases and for pre-planned responses to such releases.1 The enabling legislation for 112(r) of the CAAA was published in October 1993 as proposed rule 40 CFR 68 Risk Management Programs for Chemical Accident Prevention. Due to numerous industry groups, states and other implementing agencies said that EPA had underestimated the cost of the proposal. In response, EPA trimmed back the proposed requirements in a separate notice in March 1995. In March 1996, the agency plans to issue a final rule that would require compliance within three years.2 When the rule is finalized, it will require affected facilities to establish Risk Management Programs (RMP). The RMP rule is designed to reduce the risk of accidental releases of acutely toxic, flammable, and explosive substances. The RMP is organized into three major categories: 1. Hazard Assessment 2. Accident Prevention Program 3. Emergency Response Program. If a facility has on-site threshold quantities of any of the 77 acutely toxic, 63 flammable or Department of Transportation-classified explosive substances, an RMP will need to be developed. The focus of this paper is to characterize various potentially hazardous scenarios that would require a hazard assessment. This paper will discuss the type of models that can be used to determine the consequences (off-site impact) due to the potential hazard scenario. The off-site impact study information will influence the RMP planning process.