Construction of the Mariner East Pipeline system crossing Pennsylvania was completed several months ago, but the contentious Energy Transfer LP project continues to rack up legal penalties.

The Pennsylvania Public Utility Commission on Thursday imposed a $51,000 fine against Energy Transfer’s subsidiary Sunoco Pipeline LP for violations related to construction of the pipeline through an apartment complex in Middletown Township, Delaware County.

The PUC by a 3-0 vote adopted a recommended decision by an administrative law judge that partly upheld a complaint from Glen Riddle Station LP, the owner of a 124-unit apartment complex that was bisected for eight months by a massive trench and 30-foot high sound walls that were as close as five feet from some buildings.

The March 8 recommended decision by Administrative Law Judge Joel H. Cheskis said Sunoco created a fire hazard during construction, made excessive noise, and failed to adequately communicate with residents of Glen Riddle Station Apartments.

But the judge also dismissed Glen Riddle Station’s complaints that Sunoco created traffic hazards, caused a water main leak, and improperly used a dangerous product, Calciment, on its property. The judge said that Glen Riddle had failed to demonstrate that Sunoco misapplied Calciment, a lime material used as a drying agent that can cause harm if inhaled or ingested.

Sunoco’s exceptions to the judge’s recommendation were “entirely without merit,” the PUC said in its order.

David La Torre, a spokesman for Glen Riddle Station, said the apartment owners were pleased the PUC validated its objections related to Sunoco’s “reckless behavior.” The most important part of the decision, La Torre said, was a requirement that Sunoco stop its “dangerous conduct” since it remains active in the township.

Energy Transfer LP, which can appeal the decision, did not respond to a request for comment.

The PUC’s decision, if it stands, would close one short chapter in the epic saga of the Mariner East project, which has drawn $24 million in fines from Pennsylvania regulators during construction, according to a tally by the PA Environment Digest blog.

The apartment complex is waging a separate legal battle seeking communications between municipal officials and Sunoco Pipeline to shed light on what it says is a cozy relationship between the township and the energy company. “We renew our call for the township to be transparent and release its emails with Sunoco, which were paid for by taxpayers,” La Torre said. “It’s time to drop the secrecy.”

The Mariner East project, which transports gas liquids such as propane and ethane from shale-gas producing regions in Appalachia to an export terminal southwest of Philadelphia, encountered numerous trouble spots during construction of its 350-mile path across Pennsylvania, particularly where it threaded its way through densely populated areas near Philadelphia, such as the Glen Riddle section of Middletown.

Sunoco attempted to horizontally bore a 3,500-foot underground pathway for its two new pipelines under the apartment complex. But leaks of drilling fluid during construction spilled into streams, and groundwater gushed out of the bored hole. Sunoco abandoned the effort, filled the unfinished bore with grout, and switched its construction methods to a conventional open trench.