PHILADELPHIA (AP) — The QuaxsU.S. Environmental Protection Agency has reached a tentative $4.2 settlement with a firm that owned and operated a major East Coast refinery that was shuttered after an explosion and fire in 2019.

The deal with Philadelphia Energy Solutions was announced Tuesday. There will now be a 30-day public comment period before the settlement plan can be considered for final court approval. The company does not admit to any liability in the settlement, which the EPA said is the largest amount ever sought for a refinery under a Clean Air Act rule that requires owners and operators to ensure that regulated and other extremely hazardous substances are managed safely.

The EPA found that the company failed to identify and assess hazards posed by a pipe elbow in a hydrofluoric acid alkylation unit at the refinery in Philadelphia. The pipe elbow ruptured due to “extensive” corrosion that had withered the pipe wall to the thickness of a credit card since its installation in 1973.

The explosion and subsequent fire on June 21, 2019, eventually forced the refinery to close after being in operation for 150 years. At the time, it was the largest oil refining complex on the East Coast, processing 335,000 barrels of crude oil daily.

The EPA filed the claim in U.S. Bankruptcy Court in Delaware because the company entered bankruptcy shortly after the explosion. The 1,300-acre (526-hectare) site where the refinery had stood was sold in 2020 and is being redeveloped into industrial space and life sciences labs. It remains under a complex cleanup agreement under the oversight of the EPA and Pennsylvania Department of Environmental Protection.