July 21 (Reuters) - U.S. energy company Energy Transfer LP said on Wednesday it plans to finish the final phase of its long-delayed Mariner East 2 natural gas liquids (NGL) pipeline expansion in Pennsylvania in the third quarter despite calls by county commissioners to shut some operating parts of the system.
Earlier this week, Chester County Commissioners asked the Pennsylvania Public Utility Commission (PUC) to shut the operating Mariner East 1 and a 12-inch (30-cm) "workaround" pipe being used by the Mariner East 2 expansion, according to local media.
The county commissioners said several sinkholes have developed this year near the Mariner East 2 construction site in West Whiteland Township in southeastern Pennsylvania about 30 miles (48 kilometers) west of Philadelphia.
Energy Transfer's Sunoco Pipeline unit used an existing 12-inch pipe - the so-called "workaround" pipe - to allow the 20-inch Mariner East 2 to enter service in December 2018 after numerous delays related to sinkholes and drilling fluid spills slowed the project's construction.
In regards to the Chester County request, a spokesperson at Energy Transfer said "there are no safety concerns regarding the ongoing operations of our active pipelines in this area, which have safely operated for years."
Mariner East transports liquids from the Marcellus/Utica shale in western Pennsylvania to customers in the state and elsewhere, including international exports from Energy Transfer's Marcus Hook complex near Philadelphia.
Sunoco started work on the $2.5 billion Mariner East expansion in February 2017 and planned to finish the 350-mile (563-km) pipeline in the third quarter of 2017.
Mariner East 2 did not enter service until December 2018 due primarily to several work stoppages by state agencies.
Since May 2017, Pennsylvania has issued 122 notices of violation to Mariner East, mostly for drilling fluid spills, including two in June.
(Reporting by Scott DiSavino Editing by Marguerita Choy)