MARTINEZ, Calif. – Last month’s incident at Shell Martinez Refinery caused the release of thousands of pounds of uncombusted gases, information provided by Contra Costa County Health Services said.
The July 6 incident started when flare pilot lights were extinguished by the carryover of water from flare lines during an incident at 1:03 a.m.
That’s when a loss of pressure in the instrument air header opened a separator vessel’s depressuring valve, said the refinery’s report sent Aug. 3 to Randall L. Sawyer, the county’s chief environmental health and hazardous materials officer.
“A mechanical failure on an air drier caused the loss of pressure on the instrument air header,” the report said.
The pilot lights could not be relit before a second flaring event occurred at 3:10 the same day, so unburned rather than combusted gases were released, the report said.
The later flaring incident was caused by an automatic trip of the second stage hydrocracker unit after reactor temperatures rose rapidly after feed flow was lost to the unit during a small lubrication oil fire on the first stage recycle gas compressor, the report said.
The fire was caused by the release of lubrication oil from the bearing when it came into contact with a hot surface, either a turbine case or steam piping located before the compressor dock, the report said.
A total of 257 pounds of hydrogen sulfide, 860 pounds of hydrogen, 1.481 pounds of methane and 5,656 pounds of nonmethane hydrocarbon were released that morning, the report said.
“The root cause of the event was an accumulation of water in the flare line and the extinguishment of the LOP (light oil processing) flare pilot flames when the water was carried out of the flare tip during a flaring event,” the report said.
“The accumulation of water in the flare line was primarily caused by steam condensing at the flare tip and flowing back into the flare line towards the drain manifold,” the report said. “The investigation uncovered that the drain system was ineffective at removing the water from the line.”
The report said refinery employees tried to relight the flare pilot lights, but the flame front generator lines were plugged by corrosion. “This caused the pilots to remain unlit until the second flaring events occurred.”
At the time of the incident, it was described as a “unit upset.” Even though the Level 2 advisory was issued, the refinery’s external relations manager Ann Notarangelo said that day, “To this point, we have not seen anything on our fence line monitors or through our community monitoring.”
Subsequent reports filed by the refinery confirmed her assessment that monitoring by the refinery and Contra Costa County had found no evidence of off-site impact.
One of those reports listed preventative measures the refinery promises to take to prevent a recurrence. Some have been completed, but most won’t be finished until Jan. 6, 2019.
A letter sent July 18 to Sawyer by Gordon Johnson, the refinery’s manager of environmental affairs, again said the hydrocracking unit was unexpectedly shut down and lost pressure because of the lubrication oil fire. When the pilots couldn’t be relit by the time of the unit shutdown, the gases were released without being combusted.
Johnson wrote that the refinery acted that day to minimize the length of the venting.
Because the release of 257 pounds of hydrogen sulfide exceeded maximum limits of 100 pounds in a 24-hour period, the refinery notified the California Governor’s Office of Emergency Services and the National Response Corporation.
Another report from refinery environmental engineer Kathy Wheeler said the incidents caused no injuries, although the Level 2 Community Warning System advisory was issued.
In a timeline listing in her report, Wheeler said the refinery notified the Contra Costa County Health Services Hazardous Materials Program (CCCHSHMP) about the incident at 2:37 a.m., when conditions warranted only a Level 1 announcement through the Community Warning System. That was increased to Level 2 at 3:27 a.m. and a public health advisory was issued for parts of Pacheco and Martinez.
For the most part, no odors were detected related to the incident, although tests were made at the refinery, on Shell, Monterey, Marina Vista avenues, Court Street, Pacheco Boulevard, Arthur Road and southbound Interstate-680.
At 4:31 a.m., slight odors were detected intermittently along Shell Avenue, her report said. Tests continued until 5:16 a.m., and the health advisory remained in place until the pilots were lit. Sawyer recommended lifting the advisory at 8:45 a.m. The situation was considered “all clear” by 9:46 a.m., Wheeler’s timeline said.
Reports to the county indicated fence line monitors detected none of the released materials, and community sampling found no offsite readings. Only one complaint was received related to the incident.
An invoice from Contra Costa County Health Services showed the refinery was billed $5,880 for reimbursement of the services of seven employees.
The Aug. 3 report sent to Sawyer said the refinery has completed interim mitigation with a block in the nitrogen to the 8-inch and 10-inch lines as well as the valves from the lines to the collection header to mitigate the potential of vapor entering the system through that route.
The refinery also has increased its draining to two times a week and has installed jam nuts on all set screws for valve linkages on instrument air driers. It has replaced keys for the valve stem or valve collar on instrument air driers if those keys don’t fit well.
Nine more projects to be wrapped up early in 2019 including evaluating the function of the flare line drain pot. If it doesn’t function well, the refinery will troubleshoot the equipment and ensure its repair.
The refinery also will examine the draining of the entire flare liquid collection system and engineer a way to minimize the risk of water accumulation in the flare line downstream of the seal pot.
Other tasks the refinery promises to finish by 2019 are determining “clear ownership” for technical assurance of the flare line drain pots; updating the flare pilot relighting procedures; clarifying how and when the flame front generator lines need to be blown out; and updating the time needed to purge lines prior to ignition.
The refinery also says it will examine carbon steel portions of the flame front generator lines that aren’t already slated to be upgraded to stainless steel to see if more upgrades are needed; reclassify flare pilot systems and pilot ignition systems for all flare systems as critical equipment, making sure they’re kept in good condition; and pulling and inspecting a separator depressurizing valve to determine the actuator’s condition, repairing it if needed.
During the next revalidation cycle, the refinery will add a scenario of liquid accumulation in the flare line extinguishing the flare pilots to its light oil processing flare process hazard analysis.
Finally, the refinery promised to investigate the cause of the lubrication oil fire and develop recommendations to address the occurrence.
When asked to comment about the incident, Shell Community Liaison Officer Michele Corey, said, “In our operations, we have multiple layers of ongoing monitoring. In the unlikely event where an incident happens, we have multiple layers of warning systems, alarms and containment systems. Our 24-hour response team can be mobilized at any time to respond to the incident, prioritizing the community and the environment.”
Martinez Councilmember Mark Ross also is a member of the Bay Area Air Quality Management District. He said the District is conducting its own investigation of the incident.
“I’m very concerned that there may have been both releases of toxic air contaminants,” he said. He’s also worried about the way the incident originally was characterized and described.
“The flare system is an important part of the safety structure of a refinery,” he said.
According to a 2014 report by Prateek Kumar of Ohio State University describing the purpose of flaring, a flare stack has a constant burning flame, similar to the burner of a gas stove that has constantly operating pilot lights. He called it part of the safety and defense components in petrochemical and gas-producing plants. It’s also used in some operations to remove unwanted gases.
In an emergency or “upset,” Kumar wrote, extremely flammable hydrocarbons need to be vented out, but to turn those gases into carbon dioxide and water vapor, a flame is kept burning in the stack.
That the Shell refinery’s pilots went out and could not be reignited is one of the things that worry Ross. “They couldn’t get it lit for six hours,” he said.
“It’s concerning that toxic air contaminants are being emitted into the air shed,” he said.
Ross acknowledged Shell Martinez Refinery “has a relatively safer record than other refineries,” but added that record “does not mean much” to someone affected by the gas release.
He said the air quality management district is issuing a notice of violation. “The air district is more concerned about getting things fixed than getting fine money,” he said.