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|State Police #||12-00270|
|Pollutant||Duration||Point Source||Greenhouse Gas||Criteria Pollutant||Ozone forming chemical||Amount of Release|
|Hydrogen Sulfide||2d 7h 10m||Unit 59 South Flare, Unit 45 Thermal Oxidizer, Unit 220 Thermal Oxidizer, Unit 234 Thermal Oxidizer, and Unit 33 Sour Water Tank||NO||NO||NO||7.6 pounds|
|Sulfur Dioxide||2d 7h 10m||Unit 59 South Flare, Unit 45 Thermal Oxidizer, Unit 220 Thermal Oxidizer, Unit 234 Thermal Oxidizer, and Unit 33 Sour Water Tank||NO||YES||NO||829.2 pounds|
|Nitrogen Dioxide||2d 7h 10m||Unit 59 South Flare, Unit 45 Thermal Oxidizer, Unit 220 Thermal Oxidizer, Unit 234 Thermal Oxidizer, and Unit 33 Sour Water Tank||NO||YES||YES||87.8 pounds|
|Carbon Monoxide||2d 7h 10m||NO||YES||NO||477.6 pounds|
|Volatile Organic Compounds (VOCs)||2d 7h 10m||NO||NO||YES||1,428.4 pounds|
|Particulate Matter 10||2d 7h 10m||NO||YES||NO||9.6 pounds|
|Particulate Matter||2d 7h 10m||NO||YES||NO||9.6 pounds|
|Highly Reactive Volatile Organic Compounds (HRVOCs)||2d 7h 10m||NO||NO||NO||0.5 pounds|
|Ammonia||2d 7h 10m||NO||NO||NO||1.6 pounds|
Accident Classified As: Reportable Quantity
Chain of Events: 1/14/12: Hydrocarbon carryover from the Unit 19 Sour Water Stripper caused Unit 220 (sulfur unit) and Unit 45 Thermal Oxidizer to trip. As a result, a sulfur dioxide plume was released from the Unit 45 Thermal Oxidizer. During the release, hydrocarbons from the ammonia acid gas header were steamed out to the flare. Units were then shut down to limit environmental impact. 1/15/12: A similar incident took place approximately four hours after Unit 220 startup. During this incident, the flare valve on the fuel gas absorber knockout drum opened to flare to relieve pressure on the drum. Hydrocarbon from the carryover was also sent to the sour water storage tank, which resulted in the tank venting to the atmosphere. 1/16/12: The flare valve from the fuel gas absorber knockout drum was closed at approximately 9:30, and the incident was then determined to be secure. The entire incident is under investigation. Follow up report issued 2/26/2013 summarizes results of internal Marathon investigation.
The large quantity of hydrocarbon liquid carryover to Unit 19 Fuel Gas Absorber Knock-out Drum was not anticipated.
During the initial upset (1/14/12), Cargill was notified of the plume. All work with the Marathon refinery was put on hold, and the plant's Air Monitoring Team (AMT) was dispatched. The data that they collected is attached to the report. The contents of the Unit 19 Sour Water Storage Tank and ammonia acid gas header were then purged to eliminate existing hydrocarbons. Similar actions were taken to mitigate emissions from the second incident (1/15/12). Units were shut down, the AMT was activated, and fire water was introduced to limit emissions from the sour water tank. This incident was determined to be secured (1/16/12) when the flare valve from the fuel gas absorber knockout drum was closed to the South Flare. An incident investigation was conducted to determine the cause or causes of the incident. Per this investigation, the root cause was identified as Equipment Difficulty-Problem Not Anticipated. The recommendation from this investigation was to review disposition of Fuel Gas Absorber knock-out drum liquid. Report states this action was completed 6/27/12. Only states that SO2 emissions were above reportable quantities.