Information on December 11 "operational upset"

Dec. 11 Suncor occurrence

Frequently Asked Questions


What happened at the Suncor facility?
On the morning of December 11, employees at the Suncor refinery in Commerce City attempted to start up a Fluidized Catalytic Cracking Unit, which had been shut down for maintenance. The device was not performing as expected, and employees observed visible emissions from the unit. At that point, they halted the start-up process and sounded the facility’s vapor release alarm. Suncor has acknowledged that it did not stop the process soon enough after observing the emissions.
The Air Pollution Control Division learned of the unusual emissions activity, and immediately contacted the facility. 
Suncor has called the occurrence an “operational upset.” What does that mean?
“Operational upset” is a term used by Suncor and other regulated facilities-- companies usually define it to mean that equipment failed to operate in a normal and expected manner. We do know there was unusual activity, and that's why we are investigating the incident and will be reviewing the activity logs. We will also require Suncor to give us any data they have.
What danger did the emissions pose for people living or working near the refinery?
The primary emissions from this event were small particles that can be breathed into the lungs, known as particulate matter. Particulate matter is a pollutant that can cause health problems at high levels. It also can affect air visibility. The department’s air monitoring data show the particulate matter was not at levels that exceeded the National Ambient Air Quality Standards (NAAQS), which provide public health protection.
The National Ambient Air Quality Standards for one form of particulate matter, PM10, is 150 micrograms per cubic meter of air (abbreviated as ug/m3), based on a 24-hour average. For another form of particulate matter, PM2.5, the National Ambient Air Quality Standards is 35 ug/m3 as a 24-hour average. 
On Dec. 11, the high 24-hour PM10 average at monitors in the area was 61 ug/m3. A monitor immediately north of the refinery recorded a spike of 160 ug/m3 for a one-hour average around 9a.m. Based on the timing, it is possible that the elevated reading was influenced by the release at Suncor, but this level of particulate matter on a one-hour average is not unusual during winter temperature inversions, like the one we experienced on Dec. 11. We did not see any elevated hourly values of PM2.5.
Based on our initial review of the available data, the level of emissions around the facility were well below the level of the National Ambient Air Quality Standards. We will continue to monitor the air quality nearby and seek more monitoring results. 
Residents in the area reported that ash fell on their cars. What was in the ash?
Suncor stated the material is catalyst from one of the units at the refinery. We are investigating to  verify Suncor’s statements and testing dust samples from the area. We will share those results as soon as they are available. We control emissions of particulates like these to protect health and visibility.  Excess emissions are not acceptable.
Were any other chemicals released?
In their initial report to the department, Suncor reported elevated emissions of carbon monoxide and opacity. The company didn’t report any other elevated emissions. 
Were there any reports of elevated sulfur dioxide levels in the area?
The division has three air monitors in the area with continuous sulfur dioxide monitoring capabilities. We saw no indication of elevated levels of sulfur dioxide on any of those monitors. 
What is the state doing to address the situation with Suncor?
The department has ordered Suncor to provide information and data as part of the investigation. Suncor has complied and provided a report in which it took responsibility for the incident and acknowledged exceeding legal emissions limits for carbon monoxide and opacity. The department will take appropriate actions for these violations. We require a full accounting of what occurred and will pursue appropriate action.
We are already undertaking investigation and enforcement activities for other prior violations. The public can review the compliance advisories and the enforcement guidance online. 
Is the state taking any additional actions to monitor air quality in the area?
The division has placed three particulate matter air monitors near the refinery at the following locations:
  • The Denver Metro Wastewater Reclamation building at 6450 York Street (northwest of the refinery)
  • The South Adams County Water and Sanitation water tank on 64th Street east of Colorado Boulevard (north of the refinery)
  • The South Adams County Water and Sanitation water tank at 56th and Niagara (southeast of the refinery)
Did the Fluidized Catalytic Cracking Unit start up again?
Suncor started up the device on January 7, with a state inspector on site to observe the process.