Horizontal drilling can resume at 16 locations in Pennsylvania along Sunoco Pipeline LP's Mariner East 2 gas and liquids pipeline route to a terminal outside Philadelphia, a state environmental judge ruled Aug. 3, but a ban remains in place at 39 other locations.

State Environmental Hearing Board Judge Bernard Labuskes granted an emergency appeal by Sunoco to continue activities at the 16 locations to prevent boreholes from collapsing and to retrieve equipment still down the hole. A hearing covering all of the drilling locations is scheduled for Aug. 9 in Harrisburg.

The order came after the judge met with attorneys for Sunoco and a consortium of environmental groups opposed to the new line, which roughly parallels the existing Mariner East 1 pipeline from the wet gas area of the Marcellus Shale below Pittsburgh east to the Marcus Hook terminal.

While the judge rejected the environmental groups' moves to block Sunoco's permitting by the Department of Environmental Protection in February, he ordered a drilling halt at 55 locations statewide in July after repeated spills of drilling mud and the alleged contamination of 14 private water wells in Chester County.

Sunoco has already signed a consent order acknowledging that it contaminated the wells and is providing water while it hooks the 14 households to a public water supply. Sunoco had hoped to have the 275,000-barrel-per-day gas liquids pipeline open in the first half of 2017, with later plans to expand to 450,000 bbl/d.

Mariner East 2 is the latest in a series of pipelines being developed by Energy Transfer Partners LP or affiliated businesses to run into construction difficulties. Sunoco Pipeline's parent, Sunoco Logistics Partners LP, completed a merger with Energy Transfer Partners in April, making ETP a subsidiary of Sunoco Logistics.