FORWARD TWP — The single plume of black smoke coming from the site of a Marcellus Shale gas well was the exhaust from machinery.

That was the explanation on Friday from XTO Energy regarding the smoke seen early in the morning on Wednesday, Thursday, and Friday at the Hixon well site near the intersection of Leisie and Valencia roads.

Amy Dobkin, XTO’s director of community relations, said workers began completion operations on the Hixon pad on Wednesday.

“As with any industrial process, this is an expected occurrence and nothing out of the ordinary as engines start and stop,” Dobkin said.

She said all XTO operations are done in compliance with the state Department of Environmental Protection standards.

Gary Clark, spokesman for the DEP’s Northwest Region, said on Friday that the agency had not received any complaints about the smoke.