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ExxonMobil Chemical Plant (286), Baton Rouge

LDEQ Accident Report

Accident #113260
State Police #No Information Given
Accident Date2009-03-09
Report Date 2009-03-16
Follow-up Date 0000-00-00
Follow-up: No

Pollutants Released

Pollutant Duration Point Source Greenhouse Gas Criteria Pollutant Ozone forming chemical Amount of Release
BenzeneNo Information GivenWILA tanks #8 and 9NONOYES15.0 pounds
IsopentaneNo Information GivenWILA tanks #8 and 9NONOYES237.0 pounds
PentaneWILA tanks #8 and 9NONOYES159.0 pounds
IsohexaneWILA tanks #8 and 9NONONO43.0 pounds
HexaneWILA tanks #8 and 9NONONO37.0 pounds
3-MethylpentaneWILA tanks #8 and 9NONOYES23.0 pounds
MethylcyclopentaneWILA tanks #8 and 9NONONO12.0 pounds
2,3-DimethylbutaneWILA tanks #8 and 9NONOYES11.0 pounds
2,2-DimethylbutaneWILA tanks #8 and 9NONOYES10.0 pounds
CyclohexaneWILA tanks #8 and 9NONOYES9.0 pounds
HeptaneWILA tanks #8 and 9NONOYES7.0 pounds
CyclopentaneWILA tanks #8 and 9NONOYES6.0 pounds
2-MethylhexaneWILA tanks #8 and 9NONOYES6.0 pounds
3-MethylhexaneWILA tanks #8 and 9NONOYES5.0 pounds
ButaneWILA tanks #8 and 9NONOYES4.0 pounds
TolueneWILA tanks #8 and 9NONONO4.0 pounds
2,4-DimethylpentaneWILA tanks #8 and 9NONOYES2.0 pounds
2,3-DimethylpentaneWILA tanks #8 and 9NONOYES2.0 pounds
OctaneWILA tanks #8 and 9NONOYES1.0 pounds
IsooctaneWILA tanks #8 and 9NONOYES1.0 pounds
3-MethylheptaneWILA tanks #8 and 9NONOYES1.0 pounds
MethylcyclohexaneNONONO5.0 pounds

Accident Classified As: Reportable Quantity

Cause of Problem: Process Upset

The release was caused by the pumping of low flash material into WILA Tanks 8 and 9. The material evolved a greater amount of vapor than the tank's vapor recovery system could manage. The evolution of the vapor caused the pressure in the tanks to exceed that of the pressure vent set point.

Discharge Preventable - No

There was no reasonable way to verify that the flashpoint of the material was low enough to cause overpressure when introduced into Tanks 8 & 9

Notes/Remedial Actions

Introduction of low flash point material into these tanks was immediately halted. They could not expect the flash material to evolve too much vapors. Tanks could not handle the vapors and valve lifted. Operators will be trained to communicate better to prevent the overpressure happening again. RQs exceeded for benzene. Total release of hydrocarbons is 600 pounds.