EXPLAINER | Mariner East: A pipeline project plagued by mishaps and delays
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Mariner East: A pipeline project plagued by mishaps and delays

Jon Hurdle / StateImpact PA

A Mariner East 2 construction site in rural Pennsylvania. The Public Utility Commission lifted a ban on construction of a valve, removing one obstacle to completion of the troubled project.

Sunoco Logistics Mariner East pipeline project includes three lines — the Mariner East 1, the Mariner East 2, and the Mariner East 2X, all of which carry or will soon carry natural gas liquids (NGLs) from the Marcellus and Utica Shale plays in eastern Ohio and western Pennsylvania across the state to a processing and export terminal in Marcus Hook, Delaware County.

In 2014, Sunoco completed its conversion of a gasoline pipeline originally built in the 1930’s to ship gas from Philadelphia area refineries to rural Pennsylvania. Reversing the flow of the 8-inch line, Sunoco’s Mariner East 1 now carries NGLs across Pennsylvania to its suburban Philadelphia facility where it is shipped overseas to manufacture plastics.

The Mariner East 2 would expand capacity to 345,000 barrels of NGLs a day. The 20-inch diameter high pressure pipeline tunnels beneath 17 counties, cuts through 2,700 properties with a 50-foot right-of-way, and crosses more than 1,200 streams or wetlands. The company used eminent domain procedings to secure right-of-ways from reluctant landowners, including one family in Huntingdon County that sat in their trees to protest the pipeline construction. Dozens of landowners are still tied up in litigation with the company and the state Supreme Court could decide to hear the cases.

Construction on the $2.5 billion project began in February 2017, after the Department of Environmental Protection identified hundreds of deficiencies in its water-crossing and earth-moving permits. Since then the DEP has issued more than 60 violations to the company for polluting wetlands, waterways, and destroying about a dozen private water wells. In the summer of 2017, DEP, along with several environmental groups, agreed to a consent decree with Sunoco after dozens of drilling mud spills led to the pollution of high value wetlands and trout streams, and the loss of drinking water for residents of a Chester County community.

In April, 2017 Sunoco Logistics merged with Energy Transfer Partners, the builder of the controversial Dakota Access line. Completion of the line is now about 18 months behind its original schedule. The Mariner East 2X is a 16-inch NGL line that will run parallel to the ME2.

In March 2018 Pennsylvania’s Public Utility Commission ordered a temporary shutdown of the Mariner East 1, saying it could have a “catastrophic” effect on public safety if it leaks. The commission said the pipeline had been exposed by the appearance of sinkholes near the construction of the two other Mariner pipelines. On May 3, 2018 the PUC allowed NGL’s to flow through the pipeline after their inspectors reported the sink holes did not pose a threat to public safety.

Latest stories


Construction on the Mariner East 2 pipeline has faced myriad problems, including damaged water supplies and sinkholes in a residential neighborhood in Chester County.
Updated: December 11, 2018 | 4:11 pm

Judge denies emergency petition for Mariner East shutdown

Suit brought by seven residents fails on all four requirements
By Jon Hurdle

On a tour of the energy facilities in Salem Township, Forbes Road Volunteer Fire Department Chief Bob Rosatti stops at a Mariner East 2 construction site. The Slickville Volunteer Fire Department would have jurisdiction over an incident here, but the Forbes Road department -- just six miles south -- would provide mutual aid, Rosatti said.
Updated: December 11, 2018 | 9:36 am

Two hurt in construction accident along Mariner East 2 near Pittsburgh

Contractors were struck by equipment
By Reid Frazier

In this photo from May 2018, pipeline workers probe the ground on Lisa Drive in West Whiteland Township where sinkholes have developed as a result of the Mariner East 2 construction.

Delaware County study: Pipeline blast could be devastating, but risk is low

An independent consultant’s risk assessment said someone would be more likely to die from falling down stairs than in a pipeline explosion. Yet a leak would be more likely to ignite in a densely populated area because there are more ignition sources.

By Jon Hurdle

An aerial view of Mariner East 2 pipeline construction, adjacent to the Fairview Golf Course in Lebanon County August 24, 2018.

Mariner East pipelines: Judge reviews request for immediate shutdown

An administrative law judge for the state Public Utility Commission heard a second day of testimony Friday on whether to continue to allow operation of the controversial Mariner East pipelines while she reviews a request that the lines be permanently shut down. Several residents say Sunoco’s public awareness plan in the event of a leak is inadequate.

By Marie Cusick

Energy Transfer Partners, the parent company of Mariner East 2 pipeline builder, Sunoco, works at Snitz Creek in West Cornwall Township, Lebanon County after a drilling mud spill during the summer.

Residents urge PUC to halt Mariner East operation, hold hearing on emergency plans

Petition says Sunoco has not done enough to prepare communities for any leak of natural gas liquids
By Jon Hurdle

An environmental cleanup crew works to remove fuel from a spill in Darby Creek in Tinicum Township, Pennsylvania, near the Philadelphia International Airport. Sunoco plans to use this same line to ship natural gas liquids until construction along the Mariner East 2 is completed.

ME2 12-inch pipe passed safety inspections, PUC tells school superintendents

The line, built in the 1930s and upgraded in 2016, is among three that Sunoco plans to use as a substitute for Mariner East 2 while construction on that project is finished. Three school superintendents had asked PUC to help assess the line’s safety.

By Jon Hurdle

Mariner East 2 pipeline construction along Zinns Mill Road in Lebanon County August 24, 2018.
Updated: November 8, 2018 | 4:36 pm

Sunoco expects hybrid Mariner East 2 to start operating by year’s end

The company has joined three different lines to create a cross-state route for natural gas liquids. It says it will be able to fulfill customer orders.

By Jon Hurdle

Crews work to stabilize sinkholes in a West Whiteland Township, Chester County neighborhood on March 3. The sinkholes appeared  near a construction site for the Mariner East 2 pipeline.

Pipeline opponent wins Chester County seat in state House

Danielle Friel Otten says a pipeline being built yards from her back door motivated her to run
By Susan Phillips

Denise McCarthy told a Department of Environmental Protection hearing that the Mariner East pipelines would endanger her grand nephew, Jack, whose picture she held up as she spoke. DEP held the public meeting in May to hear comment on Sunoco's proposed permit modifications in West Whiteland Township, Chester County.

Full Mariner East pipeline risk assessment report released

Quest Consultants studied 'hundreds of unique potential hazardous material release scenarios'
By Scott Blanchard

Mariner East 2 pipeline construction crews work in the backyards of homes on Lisa Drive in West Whiteland Township, Chester County, on May 2. Sinkholes that opened in the area prompted the state's Public Utility Commission to order that an existing pipeline nearby, the Mariner East 1, be shut down until it could be determined that the sinkholes didn't threaten its safety. PUC on May 3 approved a re-start of Mariner East 1.
Updated: October 23, 2018 | 5:21 pm

Sunoco: Mariner East 2 delayed to 2020, so company will join three pipes as substitute

The cross-state natural gas liquids pipeline Mariner East 2 was supposed to begin operation by the end of September. Now, the company has come up with a workaround after acknowledging another lengthy delay in its pipeline project.

By Jon Hurdle
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