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Valero (26003), Norco

Causal Factor: Human Factors

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

primary seal: Floating Roof Tank 150-13
Cause: : Operator/s failed in draining the drum to the slop system, as all liquids (rather than just the sour water) were drained and coker gas entered the floating roof rerun tank, T-150-13. The pressurized gas bubbled through the tank carrying slop oil onto the roof and released to the atmosphere.

Followup: Yes

Notes: Gases leaving the tank were dispersed into the atmosphere. Slop oil on the roof was recovered and returned to the process. The roof was cleaned and the coker off gas knock out drum drain valve was closed immediately upon discovery.
Hydrogen Sulfide: 625.0 pounds

CCU Flange
Cause: On 3/6/11 at approximately 6:04pm, Mr. Charles Knock of Valero made notification that two contract employees working in the catalytic cracking unit (CCU) during maintenance availability had been exposed to hydrogen sulfide. In addition to the exposure, contractors also sustained other injuries related to falling and were hospitalized. Trooper Sparks met with Valero representatives on the day of the incident. State Police and Occupational, Safety, and Health Administration (OSHA) officials have met with Valero representatives as part of the ongoing investigation into the cause of this event. It appears that the contractors were exposed to hydrogen sulfide escaping from an improperly installed blind during steaming of the line.

Followup: No

Notes: The discharge was detected at 3/6/11 at 3:00pm. Affected workers were transported to area hospitals at approximately 3:35 pm. The leaking piping system was secured approximately 93 hours later and during that time no appreciable quantities of hydrogen sulfide were measured. Hydrogen sulfide dispersed into the atmosphere. Measured hydrogen sulfide in the vicinity of the incident revealed that the concentrations in the air were substantially dissipated prior to leaving the process unit and posed no threat to the public. Work in the immediate area was stopped while an investigation was conducted to identify the source of the hydrogen sulfide. When the source was identified, he defectively installed blind was replaced under observation by the State Police. Monitoring was conducted to confirm that the replacement blind was not leaking. Measures to prevent recurrence will be identified as part of a pending investigation. There were two injuries from this incident, one of which resulted in a fatality. State officials are investigating the fatality to determine the cause of death. The second injured person was treated at an area hospital and released.
Hydrogen Sulfide: 30.0 pounds