Q496. May engineering calculations be used for flare gas composition in equations W-19 through W-21 if the flared stream is a combination of gases from before and after the demethanizer as well as hydrocarbon product?

A496. EPA agrees that in the event that it is not possible to distinguish the source streams from the processing facility being flared, whether being located upstream or downstream of the demethanizer, or being a hydrocarbon product stream, reporters may use engineering calculations based on process knowledge and best available data.