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Marathon Ashland Petroleum (3165), Garyville

Releases of Isobutylene

LDEQ Accident Number
Accident Date
Point Source(s) Notes Amount of Release

RBS Flare
Cause: False reading on the 66LT0511 level controller caused the two NC4 compressors to trip. The high pressure on the receiver, due to high liquid level, caused the 66PC0507 valve on the receiver to open the RBS flare. Approximately 6.67 lbs of VOCs were released as a result.

Followup: No

Notes: The operator blew down transmitter 66LT0511 and opened the bypass valve on the receiver to send the liquid back to the RBS tank. The faulty level transmitter was taken out of service and repaired.
1.1 pounds

North Ground Flare, Heaters on Unit 243, Unit 43, and Unit 59
North Ground Flare
Cause: According to the the 60-day report, the Triconix safety control system inadvertently tripped the Unit 247 Amine Unit Lean Amine Pumps. The pump shutdown caused lean amine to stop circulating to the Fuel Gas Treaters which caused high H2S-laden fuel gas to be sent to the Unit 243 Fuel Gas Drum. In addition, untreated fuel gas was sent to the Unit 43 Fuel Gas Mix Drum. The Fuel Fuel Gas Mix Drums were supplying fuel ga to 26 different process heaters and boilers with the refinery during the incident. As a result, each heater and boiler experienced an increase in SO2 emissions above the maximum allowable permitted lbs/hr rate. In addition, the Unit 247 Flash Drum overfilled into the vapor line to the Unit 210 Compressor Suction Drum, thus causing the compressor to temporarily shut down which resulted in venting to the North Ground Flare.

Followup: Yes

Notes: The refinery Air Monitoring Team was dispatched inside and outside the refinery fenceline. All SO2 and H2S readings were non-detect except for one 4ppm SO2 reading on Marathon Avenue in the refinery. No elevated ambient air monitoring readings from MPCs four ambient air monitoring stations were detected during the event. Operations re-started the Unit 247 lean amine pumps and re-established amine circulation to the Amine Treaters. This recirculation brought the H2S amounts in the fuel down to acceptable levels. The reportable quantity for sulfur dioxide was exceeded during the event. In addition, the permitted SO2 and the NSPS Subpart J/Ja SO2 limit for the emission sources was exceeded for multiple hours. The opacity limits for the above listed heaters and boilers were exceeded. Report was unable to be uploaded. Recommendations made for the Root cause were:1) Human Performance- Revise the Unit 19 Start up procedure with more detailing events on when to the internal lean circulation line while starting up Unit 25 with the appropriate line terminology, label lines accordingly, and retrain operators with the revision. 2) Equitment Difficulty- Evaluate the design of the existing steam tracing for the analyzer, and recommend proper mitigation.
0.5 pounds