Air monitor review — DEQ proposes ending SO₂ monitoring requirement at refinery

The Wyoming Department of Environmental Quality’s Air Quality Division is proposing to approve a request from Wyoming Refining Co. to remove the sulfur dioxide (SO₂) ambient air monitoring requirement at the Newcastle refinery, opening a public comment period before making a final decision.

According to a public notice issued by the DEQ, the proposed action would eliminate the refinery’s requirement to operate an ambient SO₂ monitoring station. The agency is accepting written comments on the proposal through 5 p.m. on Monday, Aug. 17.

The proposal represents one of the final regulatory steps before the monitoring station can be shut down and its equipment removed, according to a response provided to the News Letter Journal by the company’s environmental manager, Tina Hutt.

In the company’s response, Hutt said the refinery has been required to operate an approved ambient SO₂ monitoring program since October 2005. The monitoring network includes sulfur dioxide monitoring equipment, along with wind speed and wind direction instrumentation, with data submitted quarterly to the DEQ under an approved quality assurance plan.

According to the company, those requirements originated from a March 17, 2005, permit authorizing modifications to the refinery’s hydrodesulfurization unit.

On Sept. 26, 2024, Wyoming Refining submitted an application requesting permission to discontinue the ambient SO₂ monitoring program. The company said it believed sufficient monitoring data had been collected demonstrating that emissions from the Newcastle refinery were not exceeding federal or state sulfur dioxide air quality standards.

The company stated it has consistently complied with those standards and remained well below applicable emission limits.

Hutt said the DEQ approved the company’s request to begin decommissioning the monitoring station in a Nov. 5, 2024, letter, provided the refinery collected and submitted additional air quality data as part of the decommissioning process. According to the company, the refinery has continued operating the monitoring station while completing those requirements.

If the DEQ grants final approval, the monitoring station would be shut down and removed. The company noted that removing the SO₂ monitoring requirement would not eliminate its obligation to comply with air quality regulations.

“Until that time, WRC will continue monitoring as required by SO₂ WDEQ/AQD,” Hutt wrote. “WRC also will continue to comply with all air quality regulations by maintaining other equipment at the facility that monitors ambient meteorological data, such as temperature and wind direction.”

The DEQ has made the permit application, agency analysis and public notice available for public review through its OpenAir website using Facility ID F000980 and Permit No. P0039436. The documents are also available on a public computer at the Weston County Library and at the Weston County Clerk’s Office in Newcastle.

Written comments may be submitted by mail to Amber Potts, administrator of the DEQ Air Quality Division, by fax, or electronically through the division’s online comment portal. Comments submitted by email will not be included in the administrative record.

The DEQ said a public hearing will be held only if sufficient public interest is generated or if requested by an aggrieved party.

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