Maintenance at the Shell/Motiva manufacturing complex in St. Charles Parish caused significant flaring Wednesday, visible 25 miles away in New Orleans.

The flaring happened as the refinery restarted two of its units that had been shut down since last month for scheduled maintenance, said spokeswoman Rochelle Touchard. Elevated flaring is expected to continue until the units are completely restored, which may take several days, she said.

The Louisiana Department of Environmental Quality was sending someone to the Norco facility late Wednesday afternoon to conduct air monitoring, said spokeswoman Jean Kelly.

The refinery, located next to the Mississippi River, has over 600 full-time employees, including more than 160 contractors.