Q861. How are owners/operators expected to review facility data for the purposes of identifying Other Large Release Events?

A861. EPA recognizes that not every fluctuation in facility operating records or SCADA data is indicative of a major release event that should be reviewed by the reporter to identify each “other large release event” from the facility. Rather, EPA expects that reporters are familiar with their facility data and aware of what would be unusual disruptions indicated by facility operating records or SCADA data that would be indicative of a potential well blowout or similar readily identifiable major release event that they are required under the regulation to review to determine if an "other large release" event has occurred. Additionally, per 40 CFR 98.233(y), if a super-emitter program notification from the EPA, or if EPA- or facility-funded monitoring or measurement data indicate methane emissions exceed the 100 kg/hr threshold, facility records must be reviewed to identify the expected source of the emissions (e.g., blowdown, liquids unloading, leak) and, if necessary, identify the start and end time of the event. If the event coincided with a liquids unloading event or some other activity for which emissions calculations are provided in subpart W, reporters would first determine whether the emission rate is 100 kg/hr more than the emissions that would be calculated for that source (i.e., whether the event meets the definition of other large release event). For events meeting the definition of “other large release” event, then reporters would review facility data to help calculate the duration and emissions from the event. For events not meeting the definition of an “other large release” event, determining the start or end time of the event is not necessary.  For example, if the suspected event occurred coincidental with a process unit blowdown, then the event, by definition, is not an “other large release” event.