Bryce Bird, the state's top air-quality regulator, noted that the monthslong public comment period allowed for in-depth input. He noted that the group, Utah Physicians for a Healthy Environment, even worked with a refinery-pollution expert to detail its thoughts about the refinery project.
"They were more technical comments than we'd seen in the past," he said. "We appreciate their work. It added value to the process."
Tesoro has said the modifications were expected to reduce sulfur emissions by nearly 8 percent, about 66 tons per year.
The biggest increase in emissions would be from volatile organic compounds, a key contributor in Utah's summer and winter pollution problems. VOCs, as they are called, would increase by nearly 16 percent, the company reported.
State regulators said that, under Utah law, they could not force further emissions reductions because the refinery will be operating well under its allowed pollution levels even though it is producing more oil. Regulators were limited to considering only the equipment Tesoro is proposing to install over the next two years.
Tesoro spokeswoman Tina Barbee said the company was pleased regulators had approved the permits after "an extremely thorough and independent review."
"We are pleased with the decision that will allow us to continue to be a safe and reliable operator who produces valuable products that help fuel Utah's economy," she said.
Brian Moench, a co-founder of the Physicians for a Healthy Environment, said he had not seen the final permit and would have concerns if the original proposal or anything like it had been approved. For example, he noted, air-quality regulators did not account for the impact of additional truck traffic on pollution in the already overloaded air shed.
"We'll do what we can to prevent any future air pollution from being added in the area," he said, "and we certainly won't rule out legal action."