The Suncor Energy refinery in Commerce City blew black smoke into the sky after workers restarted parts of the refinery after completing routine maintenance.
The company issued an alert at 10:01 a.m., Tuesday that said increased smoke may be visible at its Commerce City plant because of unit startup activities.
On July 22, Suncor notified the public that it was conducting planned maintenance activities and that visible smoke would be possible for several days.
The company twice spewed smoke into the air this spring that generated public concern.
In May, thick, black and yellow plumes billowed from two smokestacks at the refinery after a power outage caused the three production plants to shut down.
And in April, the refinery shut down one plant because of a possible electrical issue, sending black smoke upward.
The refinery’s emissions increase whenever workers need to shut down or restart one of the three plants at the facility.
