Sunoco Logistics Partners LP said Friday afternoon that it had begun building the contested Mariner East 2 pipeline, after a Pennsylvania Environmental Hearing Board judge earlier in the day rejected a request to block key state permits allowing its construction.

"Work has already started in several areas," Sunoco spokesman Jeff Shields said by email Friday.

Judge Bernard A. Labuskes Jr. on Friday turned down a request by three environmental groups to block permits issued Monday by the state Department of Environmental Protection that would allow Philadelphia-based Sunoco Logistics to start construction of a 306-mile underground segment of the pipeline to deliver Marcellus Shale propane to Marcus Hook.

Labuskes set a March 1 date to hear the appeal of the permits sought by the Clean Air Council, the Delaware Riverkeeper Network, and the Mountain Watershed Association, which argue that the DEP's review process for the cross-state pipeline was flawed.

On Friday afternoon, the environmental groups filed a motion with the Environmental Hearing Board to reconsider the decision.

The groups are appealing the DEP's approval of water-crossing and sedimentation permits for the $2.5 billion pipeline, which would transport propane and other natural-gas liquids across Pennsylvania to a terminal in Marcus Hook. The permits were the final regulatory hurdle for Sunoco.

In a filing Tuesday with the hearing board, DEP stated that it had waived a seven-day notice requirement, and that Sunoco was cleared to begin construction of a section of the pipeline to be horizontally drilled under Raystown Lake in Huntingdon County.

DEP also stated that Sunoco planned to hold preconstruction conferences on Wednesday for four sections of the pipeline that would be horizontally drilled in Delaware County, and that work could begin immediately after.

Those sections would bore under parts of Middletown Township, Aston Township, Brookhaven, Chester Township, and Upper Chichester Township.

To reduce disruptions in some neighborhoods and beneath busy roadways, Sunoco said it planned to install much of the pipeline using horizontal drilling methods instead of the more traditional technique of installing the pipeline in a trench.

The Mariner East 2 pipeline would run 350 miles from shale-gas producers in western Pennsylvania, West Virginia, and Ohio to Sunoco's Marcus Hook Industrial Complex, a former refinery site on the Delaware River in Delaware County. Much of the material transported through the pipes will be exported by ships to petrochemical plants in Europe.

The project's first phase, using an existing underground pipeline repurposed to deliver up to 70,000 barrels of natural-gas liquids a day, is already operating.

Sunoco wants to build one or two new adjacent pipelines as part of the Mariner East 2 project. Altogether, the pipelines could carry up to 675,000 barrels a day.

The western part of the pipeline, which runs from Houston, Pa., to West Virginia and Ohio, is already under construction after the DEP granted the necessary permits.

In a related matter, West Goshen Township, Chester County, filed a formal complaint against Sunoco on Friday with the state Public Utility Commission, contending that the company had breached the terms of a 2015 settlement agreement regarding the Mariner East project.

West Goshen, where residents were among the most fiercely opposed to the project, said Sunoco has installed only one of two remotely operated valves at locations on the Mariner East 1 pipeline that it had agreed to under the settlement, which had been approved by the PUC.

The township also said that it had recently learned that Sunoco planned to install a remote valve on the Mariner East 2 pipeline near Greenhill and Boot Roads in West Goshen, despite a promise from Sunoco that it would first notify the township of any such plans.

"Sunoco Logistics did not live up to their commitments," said David Brooman, West Goshen's special counsel. He called the alleged violation "surprising" and "disappointing."

Shields, the Sunoco Logistics spokesman, said in a statement Friday night that the company was disappointed West Goshen filed the complaint, and that it was "in full compliance with the settlement agreement, and intends to meet its obligations."