For the purpose of analyzing the worst-case release scenario required as part of the hazard assessment at 40 CFR Part 68, Subpart B, the worst-case release quantity is identified as the greatest amount held in a single vessel or pipe, taking into account administrative controls that limit the maximum quantity (40 CFR §68.25(b)). Are mechanical controls such as alarms considered administrative controls and therefore limit the worst-case release quantity?
According to the definition in §68.3, administrative controls are written procedural mechanisms used for hazard control. These written procedures must be used to limit the quantity of a substance that can be stored or processed in a vessel or pipe at any one time, or alternatively, occasionally allow a vessel or pipe to store larger than usual quantities. Although mechanical controls such as alarms may also serve to limit the quantity, EPA does not consider them to be administrative controls and therefore the owner or operator should not include them in the quantity determination for the worst-case scenario.
Additional information on offsite consequence analyses can be found in Chapter 4 of the General Guidance on Risk Management Programs for Chemical Accident Prevention (40 CFR Part 68) (EPA550-B-04-001), available at the following URL: