The Delaware Department of Natural Resources and Environmental Control (DNREC) has issued a Notice of Violation (NOV) to the Delaware City Refining Company (DCRC) for unpermitted emissions from DCRC’s Fluid Coking Unit that occurred between May 25 and June 11, 2025. DNREC’s NOV, which documents the Department’s findings and the calculated release quantities, is available at the dnrec.delaware.gov website.
Based on the Notice of Violation, DNREC’s investigation of the incident will now move to consideration of penalties to DCRC for the permit violations.
DNREC’s review found that when the unit’s primary carbon-monoxide boiler and wet-gas scrubber train went offline and required repairs, the facility routed flue gas for 18 days to a backup incinerator (BUI) and, during two periods in the timeframe, to a bypass stack. This event was not a leak, but the repair situation caused the refinery to use a backup system that does not control emissions of some air pollutants as they would be in its primary operation. As a result of using the backup system, there were substantial emissions throughout the event that were a violation of the refinery’s permits.
Specifically, DNREC’s review and calculations found that the use of the backup incinerator over the 18 days resulted in unpermitted emissions of 928,820 lbs. of sulfur dioxide (SO2) and 68,775 lbs. of nitrogen oxides (NOx). Additionally, during the two periods when there was discharge through the bypass stack instead of the backup incinerator, there were unpermitted emissions of 11,251 lbs. of SO2, 166,760 lbs. of carbon monoxide (CO), 970 lbs. of NOX, 5,976 lbs. of particulate matter (PM), along with other pollutant quantities described in the NOV. These excess emissions also resulted in an exceedance of the annual SO2 limit of 182.3 tons per year for the refinery’s Fluid Coking Unit, with total SO2 emissions from the event of 464.4 tons.
While the refinery had more emissions than permitted being dispersed into the air during the 18-day event, ambient air quality in the area at ground level remained in the green, or “good,” range for SO2, the primary pollutant discharged. The daily and hourly measurements at DNREC’s Route 9 monitoring station and other sites in the state network – designed to warn of impact to people’s health – stayed well below the federal 1-hour SO2 health standard. DNREC’s assessment indicates nearby residents were not exposed to concentrations known to cause health effects based on U.S. Environmental Protection Agency standards.
Even though the health standard for SO2 was not exceeded, permitted emission limits were exceeded throughout this event. Permit limits are set at levels that are intentionally lower than the health standard to ensure the standard will not be exceeded. Air quality monitoring is conducted near ground level and facilities utilize tall stacks to enhance dispersion of pollutants away from where people live, work and breathe.
DNREC will now evaluate DCRC’s corrective action plans and the facility’s records to determine the appropriate next steps under state law. Any enforcement orders and assessed penalties will be a matter of public record. DNREC also previously issued an NOV to the Delaware City Refinery for an 10-hour incident on March 13, 2025 that resulted in carbon monoxide, sulfur dioxide and smoke being released because of a shutdown of the Fluid Coking Unit’s carbon monoxide boiler.
An NOV is part of the multi-stage DNREC enforcement process where DNREC has the responsibility to collect evidence, act in relation to applicable state law and regulations, and provide due process where the Department defends its decisions. That process can include:
- An initial report or notice of environmental release, which for an industrial facility can mean emissions believed to be over reportable limits;
- An environmental investigation, including collection of emissions data and investigation into cause of the incident;
- A Notice of Violation, which documents DNREC’s understanding of the facts, background and a description of a violation;
- A Notice of Administrative Penalty Assessment, proposing a monetary penalty based on the severity and duration of the violation;
- A Notice of Conciliation, prescribing specific actions a facility has agreed to take to return to compliance;
- A DNREC Secretary’s Order, requiring corrective measures to be completed by a set deadline;
- A possible appeal by a facility of DNREC’s penalties or Secretary’s Orders, which by law can go to the Environmental Appeals Board and to state court.
In this case, DNREC published the initial reports of the incident on the Delaware Environmental Release Notification System (DERNS), available at the de.gov/derns webpage. DNREC has completed its data collection and technical review and has now issued the NOV.
By statute, a portion of penalties collected is directed to the Community Environmental Project Fund (CEPF), which awards competitive grants to nonprofit organizations in affected communities near where violations occur. A history of CEPF-funded projects is at the de.gov/cepf webpage.
About DNREC
The Delaware Department of Natural Resources and Environmental Control protects and manages the state’s natural resources, protects public health, provides outdoor recreational opportunities and educates Delawareans about the environment. The DNREC Division of Air Quality monitors and regulates all emissions to the air. For more information, visit the website and connect with @DelawareDNREC on Facebook, Instagram, X (formerly known as Twitter), Bluesky, LinkedIn or YouTube.
Media Contacts: Nikki Lavoie, nikki.lavoie@delaware.gov; Michael Globetti, michael.globetti@delaware.gov