(Updates throughout, adds quotes from DEP and ETP and background)
Jan 3 (Reuters) - Environmental regulators in Pennsylvania on Wednesday ordered Energy Transfer Partners LP's (ETP) Sunoco Pipeline unit to stop work again on its Mariner East 2 natural gas liquids pipeline after numerous violations of its construction permits.
The Pennsylvania Department of Environmental Protection (DEP) said the $2.5 billion project's permits will be suspended until Sunoco addresses concerns outlined in the order.
“Until Sunoco can demonstrate that the permit conditions can and will be followed, DEP has no alternative but to suspend the permits,” DEP Secretary Patrick McDonnell said in a statement.
Those conditions include addressing all impacts on private water wells in Silver Spring Township in Cumberland County near Harrisburg, the state capital, identifying all in-progress or upcoming construction activities and submitting a detailed operations plan.
Jeff Shields, a spokesman for the Mariner East project, said in an email that ETP intends to "expeditiously submit" the reports the DEP is seeking and noted the company was "confident that we will be reauthorized to commence work on this project promptly."
Shields could not say whether the latest order to stop work would affect the project's already delayed completion schedule.
Before the DEP's order on Wednesday, ETP had expected to complete the project in the second quarter of 2018.
That was delayed from the third quarter of 2017 before the DEP last ordered the company to stop some work on the project in July following fluid spills from horizontal directional drilling activities that adversely affected some drinking water supplies, among other things.
Energy companies use horizontal drilling to cross under obstacles like roads and rivers.
After reaching an agreement with the state to restart work on the pipeline, the company said in August it expected to complete the project during the fourth quarter of 2017.
Mariner East 2 is just one of ETP's projects, which include the Dakota Access crude line from North Dakota to Illinois and the Rover natural gas pipe from Pennsylvania to Michigan, that has come under intense regulatory scrutiny for environmental reasons over the past year.
Once complete, Mariner East 2 will expand the total takeaway capacity of the Mariner East project to 345,000 barrels per day to move propane, ethane and butane from the Marcellus and Utica shale formations in Pennsylvania, Ohio and West Virginia to customers in Pennsylvania and elsewhere, including ETP's Marcus Hook industrial complex near Philadelphia, according to ETP's website. (Reporting by Scott DiSavino in New York and Swati Verma in Bangaluru; Editing by Steve Orlofsky)