Risk Management Plan Data Elements

5. Flammables: Alternative Releases

Complete once for all flammable regulated substances held above the threshold quantity in a Program 2 or Program 3 process.

5.1 Chemical: The name of the regulated chemical evaluated in the alternative release scenario.

5.2 Results based on (check one): Indicate with a check mark whether you used the reference tables provided in the OCA guidance or conducted modelling to calculate your alternative release scenario. If you performed modelling, you must also indicate which model was used.

5.3 Scenario (check one): Indicate with a check mark which of the following release scenarios describes your alternative release scenario.

1. Vapor Cloud Explosion: An explosion of a cloud made of a mixture of a flammable vapor or gas with air.

2. Fireball: The atmospheric burning of a fuel-air cloud in which the energy is mostly emitted in the form of radiant heat. As buoyancy forces of the hot gases begin to dominate, the burning cloud rises and becomes spherical in shape. Often caused by the ignition of a vapor cloud of a flammable substance.

3. BLEVE: Boiling Liquid Expanding Vapor Explosion: used to describe the sudden rupture of a vessel/system containing liquefied flammable gas under pressure due to radiant heat flux. The pressure burst and the flashing of the liquid to vapor creates a blast wall and potential missile damage, and immediate ignition of the expanding fuel-air mixture leads to an intense combustion creating a fireball.

4. Pool Fire: The combustion of material evaporating from a layer of liquid at the base of the fire.

5. Jet Fire: Gas discharging or venting from a rupture will form a gas jet that "blows" into the atmosphere in the direction the whole is facing, all the while entraining and mixing with air. If the gas is flammable and encounters an ignition source, a flame jet may form.

6. Vapor Cloud Fire: A flash fire results from the ignition of a released flammable cloud in which there is essentially no increase in the combustion rate.

5.4 Quantity released: Indicate the quantity of the chemical released during the release in pounds.

5.5 Endpoint used: For vapor cloud explosions, the endpoint is 1 PSI overpressure; for a fireball the endpoint is 5 kw/m² for 40 seconds. A lower flammability limit may be listed as specified in NFPA documents or other generally recognized sources.

5.6 Distance to endpoint: This is the distance in miles to the endpoint in miles for the chemical.

5.7 Residential population within distance: Indicate the population within the distance to the endpoint as specified in question 6 of this section. Populations should be estimated within a circle with a center at the point of the release and a radius determined by the distance to the endpoint. Populations estimated need only include residential populations and may be rounded to two significant digits (e.g., 5,500, 11,000).

5.8 Public receptors: These are the public receptors within the distance to the endpoint specified in the alternative release. Check all that apply. See question 2.13 of this guidance.

5.9 Environmental receptors within distance: Environmental receptors should be identified within a circle with a center at the point of the release and a radius determined by the distance to the endpoint. Check all that apply. See question 2.14 of this guidance.

5.10 Passive mitigation considered: Mitigation means specific activities, technologies, or equipment designed or deployed to capture or control substances upon loss of containment to minimize exposure of the public or the environment. Passive mitigation means equipment, devices, or technologies that function without human, mechanical, or other energy input. Check all that were considered in defining the release quantity or rate to the worst-case scenario. See question 4.10 of this guidance.

5.11 Active mitigation considered: Mitigation means specific activities, technologies, or equipment designed or deployed to capture or control substances upon loss of containment to minimize exposure of the public or the environment. Active mitigation means equipment, devices, or technologies that need human, mechanical, or other energy input to function. Check all that were considered in defining the release quantity or rate of the alternative release scenario. See question 3.16 of this guidance.

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