PITTSBURGH (TNS) — On Thursday night, Equitrans Midstream Corp. said its contractors had successfully flooded the troubled Cambria County storage well that had been leaking gas since Nov. 6, stopping the flow of gas to the surface. But in the early hours of Friday morning, it appeared the effort had failed and venting resumed.

The roaring noise and powerful odor of gas were back, residents of Jackson Township reported.

It’s still not known what caused the well to lose pressure and start venting an estimated 100 million cubic feet of natural gas per day. That estimate was preliminary.

The venting was stopped at 12:15 p.m. Thursday when specialized emergency responders pumped enough heavy liquid into the wellbore to counteract the gas flow. When that later proved insufficient, the Canonsburg-based company began preparations for another approach.

Equitrans reiterated in a statement that “crews will work 24/7 to monitor the well and prepare the site for plugging activities, which could extend into the weekend.”

Once the well is plugged with cement, Equitrans will conduct an investigation into the cause of the leak and an environmental assessment of the Rager Mountain Storage facility and areas nearby, according to a company update.

“Equitrans is committed to conducting a comprehensive fit-for-service analysis on all wells at the Rager Mountain storage facility prior to returning to full service,” the company said.

The storage field has 10 wells, four of which are currently being used to relieve pressure and deliver product to customers. There are also two observation wells that are used to monitor conditions underground.

The Department of Environmental Protection has asked to company to monitor for gas leaking in the subsurface, as a precaution because the cause of the leak and the health of the wellbore is unknown, the DEP said.