DELAWARE CITY, Del. (AP)- Drivers and residents near Valero Energy's Delaware City refinery are warned to expect fiery waste-gas burnoffs and odors over the next few days as the company works to permanently shut down the plant.

Delaware natural resources officials say the pollution release will begin early Friday and continue into the weekend. The refinery often sends up clouds of gasses during shutdowns and startups of its major systems.

The burning of waste gases can still generate tons of sulfur dioxide gas as a byproduct.

Valero announced last week that it would close the plant, citing losses of $1 million a day since January. About 500 full-time employees and hundreds of contractors will lose their jobs.