WEST MIDDLETOWN, Pa. — While a legal battle continues over Sunoco's Mariner East 2 project, construction of the controversial Marcellus Shale pipeline has begun in far Western Pennsylvania, where crews are working feverishly to install the pipe in a deep trench cut across the landscape.

More than two dozen workers in a slow-moving caravan of heavy equipment last week worked their way up a hillside in Hopewell Township, Washington County, welding sections of 20-inch-diameter coated-steel pipe before the conduit was lowered into place and buried.

It's a messy business, involving lots of earth-moving machinery and mud, and it presages the disruption that could take place this year in Delaware and Chester Counties, when Sunoco Logistics Partners LP plans to build the other end of the 350-mile pipeline connecting the Marcellus and Utica Shale production areas with Sunoco's terminal on the Delaware River in Marcus Hook.

Sunoco and the state's political and business leaders have endorsed this $2.5 billion project, which will provide a needed market outlet for producers to send propane and other liquid fuels extracted from the shale fields, potentially fueling new industries.

"It's really been welcomed here and in southeast Ohio," said Jeff Shields, spokesman for Sunoco Logistics, whose headquarters are in Newtown Square. Most of the fuel that will be sent to Marcus Hook is set for export to European petrochemical producers, but Sunoco also hopes to develop new local industries to buy the materials.

When the pipeline work is done, Sunoco says, it will restore the landscape with the original topsoil and add new seed and mulch, leaving a cleared 50-foot-wide pathway through forests and across pastures.

But Sunoco also will leave behind hard feelings among some landowners who did not willingly agree to the project, and whom Sunoco took to court to take pipeline easements by eminent domain.

"We're going to have to live with this every day of our lives," said Patricia Yevins, 61, whose 50-acre farm near West Middletown will be bisected by the pipeline after she lost her eminent-domain case. She objected to the way Sunoco's agents "bullied" her and said that they demanded the right to come back within three years and build an adjoining pipeline without additional compensation.

"They say the chance of an explosion is remote, and that may be true," said Yevins, whose husband died two years ago. "But guess what? I've never had the best luck in the world."

Yevins and three neighbors in Hopewell Township who lost eminent-domain actions still await a decision by a mediator to determine how much compensation Sunoco must pay to cross their land, though the company has already cleared the rights of way and dug the trench.

"It's very demoralizing," said Robin Rohrer, whose 38-acre farm also will be crossed. "You realize how few rights you have as a citizen. This gas and oil business – they're brutal people."

Unlike in the Philadelphia suburbs, where some residents who object to the pipeline have little connection to natural-resource extraction, this rural part of Appalachia has ties going back more than a century to the coal and gas industry. "Nobody was against the pipeline completely," Yevins said. "But they should be required to play fair."

Shields says the company has acquired rights of way on more than 2,600 tracts, "the vast majority of those being negotiated easements that did not involve any court action."

The section of the Mariner East 2 project that is under construction here starts in Scio, Ohio, and terminates in Washington County near the village of Houston. The pipeline will interconnect with the Mariner East 1 project, a 300-mile pipeline to Marcus Hook that Sunoco began operating a year ago.

The Pennsylvania Department of Environmental Protection last week approved a package of water-crossing and sedimentation permits allowing Sunoco to complete the Mariner East 2 project by adding a new 20-inch-diameter pipeline from Washington County to Marcus Hook, which would quintuple the capacity of Mariner East from 70,000 barrels a day to 345,000 barrels.

Sunoco plans to complete the project by the third quarter of this year. The company is considering plans to add a third pipeline to the route. All together, the pipelines could carry up to 675,000 barrels a day.

Three environmental groups opposing the project have asked a state Environmental Hearing Board judge to reconsider his decision on Friday to allow construction to proceed on the Pennsylvania segment pending a March 13 hearing on their appeal of the permits. The Clean Air Council, the Delaware Riverkeeper Network, and the Mountain Watershed Association argue that the DEP's review process for the cross-state pipeline was flawed.

In emergency briefs filed Friday, the activists argued that the pipeline project will do "unprecedented irreparable harm" to the environment if it proceeds.

Sunoco says it needs to move forward to prepare the pipeline route before April 1, when the U.S. Fish and Wildlife Service restricts tree-clearing for seven months in areas that serve as the habitat for the Indiana bat, a threatened species.

Sunoco completed its tree-clearing in Washington County earlier this winter, and positioned its equipment and pipe segments to prepare for the massive job of welding the 60-foot sections into a pipeline. Engineers recently bent individual pipe segments to conform to the contours of the landscape.

On Thursday, a crew from Welded Construction LP of Perrysburg, Ohio, the contractor laying the pipeline, slowly moved its way along the route. Two welders worked on opposite sides of the pipe beneath an awning suspended from the side of a Caterpillar "tack rig," sealing the pipe ends in a spray of sparks.

Across the rough terrain, they were accompanied by a team of assistants and support vehicles, including a towed school bus that provides the unionized welders with shelter, required under their labor contract, and a small trailer bearing a portable toilet.

All told, more than 500 people are working on the pipeline segment, including 29 inspectors. On a good day, they complete about a half-mile of pipeline.