Some residents of Salt Lake City and south Davis County were roused by strange sounds and lights early Tuesday morning.
Ryan Cronin, a resident of the city’s Marmalade neighborhood, said his wife woke him around 1 a.m. after hearing a strange, rhythmic groaning, “almost like something was stuck in [the] dryer.”
After searching his home for the source of the noise, Cronin was about to give up and go back to bed when he looked out the window and saw an orange light in the night sky.
“I thought one of our neighbor’s houses might be on fire,” Cronin said, “so I put on a jacket and ran out.”
After reaching the end of his street, he realized what was actually happening — one of the refineries was undergoing some intense and loud flaring. He said it lasted around 30 minutes.
“It’s unnerving and it’s also kind of suspicious,” Cronin said. “It’s a business, why are they doing this in the middle of the night?”
Several refineries operate near the border of Salt Lake and Davis counties, but Cronin said he is fairly certain the flaring was coming from the Marathon Petroleum Company at 474 W. 900 North in Salt Lake City. The refinery has operated since 1908.
Cronin said he has lived in the area for more than a year and has never seen anything like the intense flaring he witnessed Tuesday morning.
“I think the biggest question on everyone’s mind is what is the environmental ramification of having that happen for 30 minutes, so close to a metropolitan area?” Cronin said. “That’s where my head is at.”
Asked for comment, a spokesperson for Marathon confirmed the noise came from the company’s facility, and it was part of planned maintenance.
“Flares are safety devices that allow for the safe combustion of excess materials under certain operating conditions,” the spokesperson said in an emailed statement. “There is no risk to [the] community and no action that needs to be taken.”
Although it is inversion season in the Salt Lake Valley, where weather conditions can trap unhealthy smog and fine particulate pollution for days, the Department of Environmental Quality reported air quality as “good” in both Salt Lake and Davis counties Tuesday.
Ashley Sumner, a spokesperson with DEQ, said the department is following up with Marathon to see if the event is something that would require reporting. Staff with DEQ’s Division of Air Quality reviewed video of the flaring, Sumner said, and determined it appeared “normal.”
“We completely understand why this would be concerning to folks, but flaring is a regular safety procedure that prevents excess pollutants from entering the air,” Sumner said in an email. “As far as the noise and the size, the size of the flare and the sound will vary depending on how much fuel and how long it is diverted to the flare.”
Refineries are required to report any emissions that exceed the standards outlined in their permits, according to Bryce Bird, director of the Division of Air Quality. But flaring actually helps refineries remove the dangerous pollutants they could potentially release, like cancer-causing benzene and harmful volatile organic compounds.
“In most cases, the results [of flaring] are carbon dioxide and oxides of nitrogen,” Bird said, “which are less concerning.”
Refineries sometimes use flaring in emergency cases to reduce pressure in their systems which could cause explosions, Bird said. Or they use it in cases of maintenance, as Marathon reported, when they need to take certain units offline and conduct repairs.
Still, it remains unclear why Marathon would undergo such loud maintenance late at night, given its proximity to neighborhoods and sleeping Salt Lakers. State regulators don’t tell refineries when they can and can’t run those processes, Bird said.
His division reviewed data from state air quality monitors in Bountiful and Rose Park, however, to see if they detected any pollution spikes early from the Marathon flaring.
“Neither of them detected spikes or elevation in particulate matter last night,” Bird said.
In a typical inversion event, when the Wasatch Front is socked in with smog, refineries typically contribute 3% of the trapped pollution. Vehicles, by comparison, contribute 48% of the particulate matter, with diesel trucks being the worst offenders.
This year’s inversion season has been notably mild due to the number of snowstorms blowing in and stirring up the airshed.
Bird encouraged Utahns who witness unusual emissions, from smoking vehicles to spewing smokestacks, to report them by using DAQ’s online form or by calling 801-536-4000.