Motiva Enterprises began routine maintenance at its Port Arthur refinery Monday, the company’s spokesperson in Houston confirmed.

“We schedule our maintenance programs in advance, and communicate with our neighbors as to what they should expect during this time,” Motiva’s media desk said in response to the Port Arthur News’ submitted questions. “Today, we began maintenance activities at our Port Arthur Refinery.

The Port Arthur refinery is the largest refinery in the U.S., producing some 630,000 barrels of refined crude oil per day.

Reuters news service reported Monday that Motiva had begun a one-month overhaul on its key crude oil processing unit, which produces 325,000 barrels per day. The news service also reported Motiva took down its coking unit, which would remain down through mid-March.

Refineries typically do maintenance in February, between producing winter-grade and summer-grade gasoline.

“Motiva routinely plans maintenance on equipment,” Motiva said in its issued response. “Routine maintenance helps ensure our units continue to operate in a safe and reliable manner.”

Citing “commercial confidentiality,” Motiva did not respond to questions about how the maintenance shutdown would affect the workforce of some 1,500 at the Motiva site. Nor would it respond specifically to what units would be involved or how long maintenance would take.

Motiva’s new president and CEO, Brian Coffman, spoke optimistically about growth opportunities for the company in Port Arthur, where refining has taken place on the Motiva site for more than a century. Coffman was speaking at the Greater Port Arthur Chamber of Commerce’s annual banquet.