The embattled Mariner East 2 pipeline set the stage for an “obscene” war of words between a Chester County resident and a pipeline worker, county District Attorney Thomas P. Hogan said Wednesday.

Hogan railed against the out-of-town worker in a statement, calling his use of a demeaning word and a sexist epithet in a social media exchange “inappropriate and unprofessional.”

“We will not allow our citizens to be bullied," Hogan said, adding that he had discussed the incident with Sunoco Pipeline LP, the pipeline’s operator, and Pipeliners Local 798, the union representing the worker.

Hogan’s statement came weeks after he initiated a criminal investigation into Sunoco, which started pumping natural gas liquids through the pipeline last Dec. 29.

The incident in December unfolded on Instagram, when the worker posted the slurs in a comment on a post from an outspoken critic of Mariner East 2.

She responded by raising concern about welds along the pipeline, specifically mentioning “manipulated data” and the integrity of the pipes used.

The worker sent a second message assuring her his welds “were fine.”

“But if my weld was bad, I hope it’s in your backyard so I can watch your house burn down on the news,” he added, apparently referring to when a similar pipeline exploded in Beaver County, Pa., last year.

The woman, who spoke with the Inquirer and Daily News on the condition of anonymity because she said she feared retaliation, said this was the second time a pipeline worker had sent her harassing messages, after a similar incident last summer on Twitter.

“These are the very same workers whom the safety of my family and my community relies on,” said the woman, who lives with her children near the pipeline. “This type of behavior is unacceptable. These are also the workers whose jobs are being given a priority over our safety and our environment.”

Local 798 Business Manager Danny Hendrix said the pipeline worker had been “admonished and called in by his peers." He said he hoped such “trash talk” would not be seen again.

“We’re a professional organization here, and we don’t act that way,” Hendrix said from Oklahoma, where he oversees 8,200 members of his union in 42 states.

“It’s not operable for us to talk to the opposition that way. We’re trying to educate people about what we do, and bashing them doesn’t help anyone.”

Late last month, Hogan took the unprecedented step of opening a criminal investigation into Energy Transfer Partners and the Mariner East Project. He appointed Seth Weber, a former assistant U.S. attorney in Philadelphia, to lead the investigation as special prosecutor.

In announcing the probe, Hogan accused Gov. Tom Wolf and state agencies of failing to hold Sunoco Pipeline accountable for numerous delays, construction errors, and environmental violations. He has yet to outline which laws he believes Sunoco and its affiliates violated.

Sunoco has bristled at the investigation, with a spokesperson promising to aggressively defend against Hogan’s “baseless accusations.”