Delaware City Refining Company will be emitting significantly higher-than-normal amounts of sulfur dioxide for several weeks.
photo courtesy of DNREC
The Department of Natural Resources said Thursday that the company has informed the state that it is making repairs on its coker carbon monoxide boiler. The refinery will shift from a primary pollution control process to secondary emissions control.
The refinery also switched to secondary emissions control for 17 days last year. DNREC said it will issue appropriate penalties for expected violations of emissions standards.
During the next approximately four weeks, according to DNREC, increased sulfur dioxide is expected to be released from the facility’s stack high into the air, and it would disperse into the atmosphere. There would be cause for public health of conditions cause the sulfur dioxide to be increased at ground level.
State House Speaker Melissa Minor-Brown, D- New Castle said in a statement that it is “incredibly disappointing and extremely unacceptable” that the refinery is once again “putting our community in harm’s way.”
Minor-Brown’s district includes Delaware City Refining Company.
What will happen, and how will the public be informed, according to DNREC:
The use of the secondary pollution control process will result in increased sulfur dioxide being released from the facility’s “stack” high in the air, so that it disperses into the atmosphere. Any concern for public health impact would occur if conditions caused the sulfur dioxide to be increased at ground level. A facility can have increased emissions and exceed its permit and still have ambient air readings at ground level remain in the green, or good, range.
DNREC and the public can monitor sulfur dioxide readings at ground level at two DNREC-maintained air monitoring stations in the Delaware City area located east of the refinery on Route 9 and west of the refinery near Lums Pond. That data, updated hourly, is continuously available at de.gov/airdata. Those two stations are part of a statewide network of 11 air monitoring stations for various pollutants.
The U.S. Environmental Protection Agency health standard for sulfur dioxide is 75 parts per billion in the ground level air, when people with asthma or other breathing related issues are advised to limit time outdoors or wear masks to reduce exposure. During the May-June 2025 refinery increased emissions, the highest hourly measurement at DNREC’s Delaware City monitor during the incident was 29.6 parts per billion, and most hourly values over the 17 days were 2 parts per billion or less.
As a result of a DNREC order from a previous incident finalized this week, the refinery has acquired fenceline sensors to measure air quality on the edges of the refinery property and to make that data publicly available. The refinery has indicated four of those sensors are being immediately put into place to begin operations and provide air quality readings; however, the publicly accessible website for those readings has not been completed. DNREC is urging the refinery to complete that website as soon as possible to share information during this period, and until the website is available, also to publicly report out the results on a regular basis until it does.
Speaker Melissa Minor-Brown additionally said in a statement:
“It is so incredibly disappointing – and extremely unacceptable – that the Delaware City refinery has once again put our community in harm’s way. By many accounts, this was not an unavoidable accident, but instead the result of decisions made by the refinery, including the decision to delay necessary maintenance despite clear warnings and opportunities to act sooner.
“I’m looking at this situation not only as a lawmaker, but as a parent raising my children just a few miles away. Families in our community deserve to feel safe in their homes and confident that their health and safety are being protected – period, end of story.
“Last year, the state implemented measures to help reduce any negative impacts on nearby residents, including mandating that the refinery have air monitors surrounding the facility. But that is only one piece of the puzzle. To that end, I appreciate all of the work DNREC and Secretary Greg Patterson have done to address this situation and their willingness to hold the refinery accountable.
“I sincerely hope the refinery takes these actions seriously and that this is the last time I have to issue a statement like this, because we should not have to continue dealing with preventable environmental and public health risks.”
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