Ammonia (concentration 20% or greater) and Ammonia (anhydrous) Alternative Release Scenarios
Pursuant to the Risk Management Program regulations, the owner or operator shall identify and analyze at least one alternative release scenario for each regulated toxic substance held in a Program 2 or Program 3 process above its threshold (40 CFR §68.28). If a facility has both ammonia and ammonia (anhydrous) on site above their respective thresholds, does the facility owner or operator need to complete an alternative release scenario for both ammonia and ammonia (anhydrous) or can they complete just one?
Ammonia (concentration 20% or greater) and ammonia (anhydrous) are listed separately in §68.130 Table 1 under different CAS numbers and different threshold quantities. Ammonia (concentration 20% or greater) and ammonia (anhydrous) should each be treated as individual toxic substances, and as such, each require their own alternative release scenario if in a Program 2 or Program 3 process.
However, if the same substance (e.g., ammonia (anhydrous)) is above the threshold in several processes or locations, you need only analyze one alternative release scenario for it.
The EPA’s Risk Management Program Guidance for Offsite Consequence Analysis (EPA 550-B-99-009) provides additional information on the number of alternative scenarios to analyze and report in the RMP.