Pennsylvania environmental regulators on March 16 issued another notice of violation to Energy Transfer Partners LP’s (NYSE: ETP) Sunoco Mariner East 2 NGL pipeline for releasing drilling fluids into a stream.

The company told the Pennsylvania Department of Environmental Protection (DEP) it released about 50 gallons of fluid into the Snitz Creek on March 15 while drilling under the steam in West Cornwall Township in Lebanon County, about 30 miles east of the state capital Harrisburg.

It was ETP’s third inadvertent release into the Snitz Creek, following spills in August and September 2017. It was also the project’s 40th Notice of Violations and 107th inadvertent release since May, according data from the DEP.

“Drilling was immediately stopped, the mud was contained and removed, and the DEP was notified,” ETP spokesman Jeff Shields said in an email.

The DEP said it must give its approval before ETP can resume drilling at the site.

The latest spill comes about a week after Pennsylvania utility regulators suspended operations of ETP’s Sunoco Mariner East 1 liquids pipeline after sinkholes were discovered near the project.

“Regarding Mariner East 1, we are focused on performing the required work and preparing to share our information with regulators so we can safely return (the pipeline) to service,” Shields said.

Mariner East 1 transports up to 70,000 barrels per day (bbl/d) of propane and ethane from the Marcellus and Utica shale formations in western Pennsylvania to customers in Pennsylvania and elsewhere, including ETP’s Marcus Hook industrial complex near Philadelphia.

The sinkholes were near the area where construction is underway for the $2.5 billion Mariner East 2. The order stopping flows on Mariner East 1 did not affect work on Mariner East 2.

Construction of Mariner East 2, which started in early 2017, was originally expected to be completed in third-quarter 2017 but has been delayed by a couple of work stoppages by Pennsylvania regulators, among other things.

ETP currently expects to complete Mariner East 2 by the end of the second quarter.

Once complete, Mariner East 2 will expand the total capacity of the Mariner East project to 345,000 bbl/d.

ETP’s other projects include the Dakota Access crude line from North Dakota to Illinois and the Rover natural gas pipe from Pennsylvania to Michigan, which have also come under intense regulatory scrutiny over the past year or so.