Philly.com (http://bit.ly/2lOogYJ ) says CEO Michael Hennigan broke the news to industry analysts during a conference call about the company's quarterly earnings on Wednesday.
Environmental advocacy groups had tried to halt construction of the $2.5 billion Mariner East 2 project, claiming it would unleash massive and irreparable damage to the state's environment and residents.
The pipelines will connect Marcellus and Utica Shale wells in Ohio, West Virginia and Pennsylvania to a Sunoco terminal in Marcus Hook, near Philadelphia.
A 16-inch pipeline will be built alongside the 20-inch pipeline already under construction.
The permitting process had always allowed a second pipeline, but Sunoco didn't formally commit to that until Wednesday.