State environmental regulators say they will know in a few more days what test results say about the explosion last week that sprayed crude oil over neighbors of the Holly refinery in Woods Cross.
Meanwhile, neighbors remain uneasy about the health impacts of the oil. And they want to know who can ensure the accident isn't repeated at any of the five refineries in Salt Lake and Davis counties an answer the agencies themselves say they can't provide.
"What kind of measures do they have in place to prevent this from happening in the future?" asked Cecilee Price-Huish, who has led refinery-area residents in watchdogging recent efforts by Holly and other refineries to expand or modify their plants.
"Do we just trust the industry to say we're using the best control practices? How do we know? Who can tell us if this is safe?"
Regulators and residents say HollyFrontier Corp. has responded swiftly to the explosion, which occurred 6:45 p.m. Thursday when a seam ruptured on a heated crude oil storage tank. Some 8,000 gallons of oil spattered over more than a mile from the plant onto cars, homes, yards and anything else in its path.
Mike Astin, the plant's environmental manager, said Tuesday the cleanup tearing out oily lawns and pressure washing homes and pavement probably will continue for weeks. Noting that oil is considered non-hazardous and low in volatile organic compounds, he compared the residual oil to what would happen to an exploded can of motor-oil, only "this is gooier and stickier."
And he cautioned against eating any oil-tainted garden vegetables. "Just because [the oil] is non-hazardous doesn't mean you can eat it," he said.
The Utah Division of Water Quality are awaiting test results of Davis County's Mill Creek and state air regulators will look at whether the company exceeded its daily limit of air pollution.
Amanda Smith, director of the Utah Department of Environmental Quality, noted that although her agency oversees various types of pollution, there is no one, single agency responsible for incidents like this one.
"We are in the process of doing an investigation," Smith added. "We're looking for a full accounting [of what caused the explosion] and a report."
A spokesman for the U.S. Environmental Protection Agency said federal regulators have a limited role in such incidents unless the oil goes into a waterway or the state asks for help.
At the Davis County Health Department, Dave Spence, said his agency will continue to monitor the cleanup even though health-related concerns are minimal.
"From everything we've heard from Holly," he said, "there are no health issues" with the waxy crude spatter.
Though residents might question why officials would take the company's word for it that the oil poses no hazard, Spence said that's the approach on all kinds of spills. "They're the ones [at the companies] that know what's in their product," he said.
As for the question about what agency is responsible for preventing future accidents of this kind, Spence echoed other officials when he said: "That's a tough question, and I don't have an answer for it."
Meanwhile, Brian Moench disputed the notion that oil release poses no harm, and he pointed to a key study linking exposure to oil over a few weeks to lung and chromosomal damage.
"Nobody can say what this can do to any particular person in the short term or the long term," said Moench, who co-founded the group, Utah Physicians for a Healthy Environment, to address concerns about the health impacts of the refineries.