The Pennsylvania Department of Environmental Protection (DEP) has responded to several reports of fluid discharges at construction sites for the Mariner East pipeline system in Chester County, including a confirmed spill at a state park.

Mariner East Pipeline Project

The agency said Sunoco Pipeline LP reported an inadvertent return on Monday in Marsh Creek State Park in Upper Uwchlan Township, where an “unconfirmed amount” of drilling fluid (mud and water) spilled into wetlands and  Marsh Creek Lake. Mitigation efforts were ongoing at the site, a DEP spokesperson said Thursday, adding that Sunoco had been working to bring in additional vacuum trucks. 

“We recognize the importance of this waterbody and are committed to allocating all necessary resources to fully remediate and restore the area,” said spokesperson Lisa Coleman of Sunoco parent Energy Transfer LP. “Critical resources have been mobilized including environmental specialists, professional geologists, operations and construction specialists, along with cleanup machinery such as pumps, vac trucks, tanker trucks, boats, sandbags and turbidity curtains.”  

She added that those efforts will be ongoing as the company conducts assessments and cleans and restores the impacted area. Coleman also said no public drinking water has been impacted. 

State regulators also received reports of discharges in a marshy area and an apartment complex in West Whiteland Township earlier this month (Aug. 8-9), where Mariner East has had various construction issues over the years. DEP is investigating what may have occurred.

Work at the horizontal directional drill sites in Upper Uwchlan and West Whiteland has been stopped for now. The incidents are the latest in a long line of problems that the project has encountered.  

While inadvertent returns are a common occurrence during directional drilling, Sunoco has had repeated issues throughout Pennsylvania during work to complete Mariner East. Multiple drilling fluid spills, impacts to local water supplies and other violations during construction of the system have resulted in more than $13 million in fines.

The system, which consists of three pipelines in various stages of development and service, has faced constant regulatory and legal challenges that have led to delays and operational problems. It moves natural gas liquids from processing facilities in Ohio, Pennsylvania and West Virginia to the Marcus Hook Industrial Complex near Philadelphia.