FERC has authorized Transcontinental Gas Pipe Line Co. LLC (Transco) to proceed with construction of the 183-mile greenfield portion of the Atlantic Sunrise project.

The Friday letter authorizing construction comes after another earlier this month in which FERC gave the company permission to proceed with the new compressor facilities. Partial service has already started on a number of the project’s brownfield portions.

The authorization clears the 1.7 Bcf/d project to expand the Transco system a full path forward and keeps it on track for a mid-2018 in-service date. The greenfield portion of the project would cross 10 counties in Pennsylvania to unlock more natural gas from the northeast part of the state, where infrastructure is lacking.

FERC’s authorization comes just days after a coalition of environmental groups urged the Commission to deny it. Led by the Sierra Club, the groups argued it would be wrong to authorize construction given that a rehearing request is pending. FERC tolled the rehearing request earlier this year when it was without a quorum to give it more time to act. The groups accused the Commission of delaying a potential court challenge.

Sierra Club Pennsylvania Chapter Director Joanne Kilgour on Friday accused the Commission of pushing the project through and said the expansion’s opponents would “continue to fight and demand that their rights and the legally required process be upheld.”