Of all the changes that EPA OOOOb introduced, the superemitter response program has created the most operational anxiety for midstream operators. It is easy to understand why. Previous LDAR requirements gave operators control over the detection timeline: run your surveys, find your leaks, repair them, document everything. The superemitter response program inverts that control. An external party detects an event at your site, notifies EPA, and now you are responding to a clock that started without your knowledge. The documentation and response workflow that you prepared needs to work under that condition, not just when you are discovering the event yourself.
What Triggers the Superemitter Response Requirement
Under 40 CFR Part 60, Subpart OOOOb, a superemitter notification is issued when an operator's source is identified as emitting at a rate that exceeds the applicable threshold, based on detection by a qualified third-party organization using approved remote sensing or other detection methods. The approved detection methods include aircraft-based optical gas imaging, satellite methane detection systems meeting EPA's data quality specifications, and ground-based or mobile detection systems operated by qualified organizations under the program.
The notification arrives at the operator through EPA's electronic notification system. It specifies the facility or source location, the detection date and method, and the approximate emission rate or detection type. The operator has five business days from receipt of notification to submit an acknowledgment to EPA. The initial investigation report is due within 15 days.
The most important point here is that the five-day acknowledgment clock runs from notification receipt, not from when you had a person read the notification. If EPA's electronic notification goes to an email address that is not actively monitored, or to a facility contact who is on vacation, the clock continues regardless. Setting up automated notification routing to a monitored operations inbox is a basic preparation step that is often overlooked until after the first notification arrives.
Building the Investigation Response Process
The 15-day investigation window is tight for a site that has not built a response protocol in advance. It requires identifying which source or equipment area was the likely emitter, characterizing the emission, determining whether the event is ongoing, and preparing a written report. If you are doing this from scratch after receiving a notification, you are doing facility mapping, equipment identification, and historical data review simultaneously under time pressure.
The investigation report needs to include several specific elements: identification of the specific emission source or the reason why source identification was not possible within the timeframe, a description of the monitoring method and results from your investigation, and a statement of whether the emission event is ongoing, resolved, or not confirmed by your investigation. If the event is confirmed as ongoing, the report also needs to include a corrective action schedule with specific dates.
The preparation that makes this manageable starts before any notification arrives. Three elements matter most.
Current Equipment Registry Mapped to Physical Coordinates
When a superemitter notification comes in with a GPS coordinate or facility area reference, you need to be able to map that to a specific section of your equipment register quickly. If your equipment list is organized by tag number but you do not have a current map showing which tags are physically located in which area of the pad, the identification step alone can consume most of the 15-day window. Maintaining a spatially referenced equipment inventory, even a simple one, is foundational to a usable response process.
Pre-Established Investigation Protocol
Write down the investigation steps before you need them. Who receives the notification? Who dispatches the field team? What monitoring equipment does the field team bring? What is the data collection requirement for the investigation report? If you have to figure this out during the notification window, you will make decisions under pressure that you would have made differently with time to think. The protocol should be a document that any EHS team member can execute, not institutional knowledge held by one person.
Historical Sensor Data as Investigation Context
If you have continuous monitoring data for the site, the investigation of a superemitter notification is fundamentally different from an investigation conducted without that context. Continuous monitoring data lets you identify when the concentration elevation began, whether it has been growing, whether it correlates with a specific operational event, and which part of the site the signal is strongest in. This is material assistance for both the source identification requirement and the corrective action timeline, because you are not starting from scratch on the day of the notification.
Corrective Action Documentation
If your investigation confirms an ongoing emission event, the corrective action requirement under OOOOb has specific documentation expectations. The repair attempt must occur within 30 days of the investigation report or within 30 days of the original notification, whichever is sooner in the rule's interpretation. Verified repair requires follow-up monitoring with the result documented. Both the repair attempt and the verification need timestamps and method documentation.
The documentation format matters because you may be producing it for EPA review rather than for internal use. Write the records with the assumption that an enforcement reviewer with no facility knowledge will read them. "Repaired" is not adequate. "Replaced rod packing on unit 3A cylinder end on [date] by certified compressor technician; re-monitored with continuous optical gas imaging on [date], no detectable leak at 500 ppm methane background" is adequate.
Testing Your Response Plan
A superemitter response plan that exists as a document but has never been tested is not the same as a plan that works. Run a tabletop exercise: designate someone to send a simulated notification to your operations inbox on a date the EHS team does not know in advance. Trace the notification through the five-day acknowledgment workflow. Check whether the automated routing actually delivers it to the right person. Verify that the investigation protocol document is findable. Calculate whether your field team could realistically complete the site investigation and draft the preliminary report within the 15-day window.
Most operators who do this for the first time find at least one gap. The notification goes to a general inbox that is only checked weekly. The equipment map is from a facility expansion three years ago and does not reflect current configuration. The investigation protocol assigns the response to the EHS manager but does not specify a backup. These are gaps that are easy to close in advance and potentially catastrophic if discovered during an actual notification.
What Continuous Monitoring Adds to the Response Picture
An operator running continuous monitoring at a site that receives a superemitter notification has a significant advantage in the investigation phase. Rather than sending a field crew out to investigate an unknown event, they can pull up the monitoring history for the notification date and the preceding days, identify whether there is a corresponding signal in their data, narrow the source area using concentration gradient data from the sensor array, and go into the field investigation already knowing approximately where to look and what magnitude of event to expect.
Continuous monitoring also helps with the situation where the notification identifies an event that your own monitoring program did not flag. This can happen if the event was below your alert threshold, if it occurred in a poorly covered area of the site, or if the event was a brief high-rate release that produced a plume visible to aerial detection but did not sustain long enough to trigger your sensors. Understanding which of these scenarios applies tells you something important about your monitoring coverage and whether adjustments are needed.
This article reflects our interpretation of publicly available EPA regulatory text and program documentation for the OOOOb superemitter response program. It does not constitute legal or compliance advice. The specific procedures and documentation requirements described should be verified against the current regulatory text and discussed with qualified environmental counsel, as regulatory requirements can change and facility-specific circumstances affect applicable obligations.