Sunoco Logistic Partners LP is holding a binding open season for a third Mariner East pipeline to deliver Appalachian natural gas liquids (NGL) to its Marcus Hook Industrial Complex on the Delaware River south of Philadelphia.

In its announcement, Sunoco said shippers have expressed interest in expanding Mariner East to provide more NGL takeaway capacity from points in eastern Ohio, western Pennsylvania and West Virginia for delivery to Marcus Hook — a former oil refinery that’s being repurposed for NGL storage, processing and distribution to local, domestic and international markets (see Shale Daily, Dec. 5, 2013). Sunoco launched the open season on Sept. 10, but no closing date has been announced, said spokesman Jeff Shields.

He added that while the open season would ultimately determine how much additional capacity the third pipeline would offer, it would likely be designed for up to 250,000 b/d. Sunoco revealed in June that it was considering constructing a third Mariner East pipeline (see Shale Daily, June 4). It would likely follow the 300-mile path of the company’s existing Mariner East 1, which runs from Western Pennsylvania to Marcus Hook.

In June, Shields said the third pipeline would likely be built at the same time as Mariner East 2, which is slated to begin next year. Propane deliveries have already started on Mariner East 1 and Shields said ethane deliveries are expected to begin in the fourth quarter. Combined, Mariner East 1 and 2 would provide up to 345,000 b/d of NGL takeaway capacity. A successful open season for Mariner East 2 was completed last November (see Daily GPI, Nov. 6, 2014).

Shields said Mariner East 2 could eventually be expanded by 175,000 b/d, bringing the total possible capacity available on all three pipelines to 770,000 b/d.

The third pipeline would provide ethane, propane, butane, natural gas and condensate transportation. Sunoco said it would consider moving refined products if there is sufficient customer interest. The expansion is expected to enter partial service by 2017, Sunoco said, with condensate service anticipated between 2017 and 2018.