A heavy plume of black smoke billowed out of the Suncor refinery in Commerce City on Wednesday, smudging part of the northern Denver skyline and rattling nearby residents who said the air smelled acrid. The smoke followed a shutdown and flaring at one of the refinery’s processing units as crews worked to steady equipment. While the company moved through maintenance and restarts, officials said they were tracking air monitoring networks to see what, if anything, the plume meant for people on the ground.
Refinery Shutdown And Visible Plume
Suncor temporarily shut down Plant 2 after what it described as a possible electrical issue, and the company warned nearby neighborhoods that “increased smoke from the flare may be visible for several days as the plant undergoes maintenance that requires shutdown and restart of equipment,” according to The Denver Post. The outlet also reported that Plants 1 and 3 were already offline for planned maintenance and that the state’s Air Pollution Control Division had dispatched an inspector to the site to check emissions firsthand.
Air Monitoring And What Sensors Showed
Despite the thick, visible smoke, Suncor’s incident report and Commerce City’s community monitors did not register acute spikes in sulfur dioxide, carbon monoxide or fine particulate matter during the malfunction, according to Suncor and the local monitoring network. The company notes that it “continuously monitors the air around our operations and provides air quality data and information to our neighbors and the public through near real-time community and fenceline monitoring systems,” as outlined on its safety and environment page at Suncor.
Regulatory Backdrop
State oversight of the Commerce City refinery has been intense for years. In February 2024, the Colorado Department of Public Health and Environment rolled out an enforcement package worth about $10.5 million tied to past air quality exceedances and ordered expanded fenceline monitoring at the site. CDPHE said the conditions were intended to cut down on repeat incidents and give nearby communities better real-time data when something does go wrong.
Neighbors And Alerts
Residents downwind of the complex said alerts pinged their phones as the plume climbed into the sky, and some posted video of the thick flare. A clip aired by CBS News Colorado showed the dark smoke and highlighted the notifications sent to neighbors. The station reported that refinery crews were on scene and that people were reviewing air readings while officials worked to collect more information.
State and company officials said they would keep monitoring air quality as crews continue stabilizing the troubled unit. Kate Malloy with the state’s Air Pollution Control Division told The Denver Post the agency would track pollution levels and investigate any potential permit exceedances. For now, community and fenceline sensors are not showing acute health level spikes, but regulators and residents alike said they plan to keep a close eye on the data as maintenance and restarts play out.
