Levels of impact related to injuries to persons, damage to processes, structure, contents and to the environment shall comply with the requirements of Section 304 for design performance levels.
Magnitudes of design events shall reflect the ignition, spill or release, growth and spread potential of hazardous materials that can be reasonably expected to impact buildings and facilities as designed or constructed.
Magnitudes of design events are described in terms of the potential effects given the proposed design, arrangement, construction, furnishing and use of a building or facility.
Magnitudes of design events shall be defined as small, medium, large and very large, where the quantification of the design event is a function of building or facility use and associated performance group.
Quantification of the magnitudes of design events shall be based on engineering analyses of potential scenarios that can be expected to impact a building or facility through its intended life. For each design scenario considered, the analyses shall include the ignitability, reactivity, spill or release potential, the peak release rate, the rate of continued release and expected incident growth, the overall quantity, the toxicity, chemical state and other specific hazards of the material and its impacts on people and property. The physical characteristics and ventilation of the space or area and adjoining spaces or areas shall also be considered.
Multiple scenarios, ranging from small to very large design events, must be considered to ensure that associated levels of tolerable damage are not exceeded as appropriate to the performance group.
The use of the room or area of event and adjoining spaces, in terms of occupant risk, property protection and community welfare (importance) factors, shall be considered in the development of design scenarios.
Justification of the magnitudes of design events shall be part of the analysis prepared by the design professional.