On Thursday, the Delaware Department of Natural Resources and Environmental Control announced the refinery will release sulfur dioxide at levels "significantly higher than normal" while repairs are made to a coker carbon monoxide boiler.
During the repair process, the facility will shift from its primary pollution control system to a secondary emissions control method, DNREC said.
According to the U.S. Environmental Protection Agency, sulfur dioxide is harmful to both humans and the environment.
DNREC will monitor the situation and fully expects that these increased emissions, which are expected to last for four weeks, will exceed the limits of the facility's permits and will be assessed for violation and penalties.
A similar shift to secondary emissions control occurred for 17 days in May and June of 2025 while repairs were made at the facility. That incident resulted in a $300,000 penalty, DNREC said.