EXXONMOBIL OIL CORPORATION-TERMINALS
hazardous_liquid Incident — — October 14, 2013
Incident Information
| Incident Date | October 14, 2013 |
| Operator | EXXONMOBIL OIL CORPORATION-TERMINALS |
| Commodity | REFINED AND/OR PETROLEUM PRODUCT (NON-HVL) WHICH IS A LIQUID |
| Pipeline Type | hazardous_liquid |
Location
| State | |
| Coordinates | 33.86657, -117.83862 |
Cause
| Cause | INCORRECT OPERATION |
| Subcause | TANK, VESSEL, OR SUMP/SEPARATOR ALLOWED OR CAUSED TO OVERFILL OR OVERFLOW |
Casualties
| Fatalities | 0 |
| Injuries | 0 |
Costs
| Property Damage | $0 |
| Emergency Response | $30,000 |
| Other Costs | $0 |
Location Map
Incident Narrative
THE EXXONMOBIL ATWOOD TERMINAL WAS RECEIVING GASOLINE/WATER MIXTURE FROM M-3 HYDROTEST INTO TANK 14. TANK LEVEL WAS BEING MONITORED BY TERMINAL PERSONNEL FOR SAFE LEVEL SHUT DOWN OF 42FT. AT 13:20, WITH THE TANK LEVEL SHOWING ~41, THE TANK BEGAN TO OVERFILL OUT OF THE THREE LOWER TANK VENTS IN TO SECONDARY CONTAINMENT. EMERGENCY OVERFILL PROTECTION DID NOT ACTIVATE. THE INCOMING PIPELINE WAS SHUT DOWN VIA EMERGENCY SHUT DOWN AND SYSTEM WAS ISOLATED AT THE ATWOOD METER STATION (VALVES #1 & #3 AND MOV #14). ROOT CAUSE OF INCIDENT THE ATWOOD TANK 14 AUTOMATIC TANK GAUGING SYSTEM UTILIZES TWO PRESSURE TRANSMITTERS TO CALCULATE MASS AND DENSITY AND CALCULATES A TANK LEVEL BASED ON THE TANK DIMENSIONS. BECAUSE THE PRESSURE TRANSMITTERS ARE LOCATED AT A FIXED DISTANCE AT THE BOTTOM OF THE TANK, THE SYSTEM DOES NOT HAVE THE CAPABILITY OF ACCURATELY CALCULATING TANK LEVELS WHEN THERE IS STRATIFICATION OF DIFFERENT DENSITY LIQUIDS SUCH AS GASOLINE AND WATER. THIS IS THE DIRECT CAUSE OF THE INACCURATE TANK LEVELS THAT LED TO THE OVERFILLING OF THE TANK.
About This Pipeline Incident
Pipeline incident data is reported to the Pipeline and Hazardous Materials Safety Administration (PHMSA). All significant incidents involving fatalities, injuries, or property damage over $50,000 must be reported.