After a series of sinkholes made the ground in a Philadelphia suburb feel like a waterbed, the Pennsylvania Public Utility Commission granted an emergency order Wednesday to stop the flow of natural gas liquids on the Mariner East 1 pipeline.
The agency believes that Sunoco’s construction of two sister pipelines, Mariner East 2 and 2X, is to blame and that keeping the 87-year-old Mariner East 1 pipeline active while Sunoco and regulators assess its integrity creates a serious public safety hazard.
“Permitting the continued flow of hazardous liquid through the (active) pipeline without the proper steps to ensure the integrity of the pipeline could have catastrophic results impacting the public near or adjacent to the path of (the pipelines),” the agency’s inspectors wrote in a petition for an emergency order on Wednesday.
Sunoco will be required to perform a series of tests on a two-mile portion of the line and submit the results to the PUC. It is expected to stay off-line for up to two weeks, the agency said, and cannot be restarted without the PUC’s approval.
In the past week, three sinkholes had formed along 550 feet in West Whitehead Township, a densely populated area in Chester County.
For months, Sunoco has been boring a tunnel under the neighborhood. Using a method called horizontal directional drilling, the company planned to thread its pipeline through the tunnel, which stretches under Amtrak railroad tracks.
According to the PUC, the first sinkhole — 8 feet wide and 3 feet deep — was discovered in December, although local residents said it was a month earlier.
The second sinkhole materialized last week and was five times deeper.
One house was evacuated as the third sinkhole developed just 10 feet from the home’s foundation wall. This third hole was 15 feet wide and 20 feet deep, deep enough to leave exposed portions of Mariner East 1 — the existing 8-inch pipeline buried about 4 feet to 8 feet underground.
Sunoco spokesperson Vicki Granado said in a statement on Monday that Sunoco “did take immediate action Saturday to successfully stabilize and mitigate three areas along our right-of -way.” She said the company injected an “approved liquid concrete mix” into the sinkholes and assured that “all areas have been secured.”
Ms. Granado did not respond to a further request for an interview. Calls to Sunoco on Wednesday were not returned.
According to the PUC, Sunoco did not notify authorities about the sinkholes and the company’s own compliance group “was also unaware of these events until March 3.”
On Monday, the PUC and officials for the federal Pipeline and Hazardous Materials Safety Administration, along with a geologist from the Pennsylvania Department of Environmental Protection, were at the scene and identified other sinkholes developing south of the known ones.
Amtrak officials were also seen on the tracks a few hundred feet from the sinkholes. Spokeswoman Beth Toll said, “No change to the track structure has been observed.”
All about the karst
“We predicted this,” said Lynda Farrell, executive director of the Chester County-based Pipeline Safety Coalition. The nonprofit, which has advocated against building high pressure pipelines in urban areas, hired a hydrologist in 2015 to study karst topography in Chester County.
Karst forms when soft rocks like limestone or dolomite dissolve under the surface and form gaps, fractures, tunnels and even caves.
“Our study essentially said, this is an accident waiting to happen,” Ms. Farrell said.
As part of the company’s permit application with the Department of Environmental Protection, Sunoco submitted a 158-page “Void Mitigation Plan for Karst Terrain and Underground Mining,” prepared by Pittsburgh-based Tetra Tech Inc.
The plan mapped sections of the pipeline where it was supposed to go deep underground using horizontal directional drilling techniques and where it would encounter areas of limestone or mining — both a risk for subsidence.
The map for West Whiteland Township where the sinkholes developed looks like no other in the pack. It shows more than a dozen known sinkholes, at least a hundred “surface depressions,” a thick layer of limestone and a sprinkling of surface mines in the vicinity.
In its analysis, Tetra Tech designated the area as having a low risk for running into large voids. Along the entire path of the pipeline, its risk ratings ranged from low to very low.
Tetra Tech declined to answer questions about the study, instead saying it was instructed to refer queries to Sunoco.
In its original permit application, Sunoco had said even if its drilling met a large void underground, “as long as the drilling fluid isn’t surfacing, we will continue to drill and pump water into the void.”
A revision in August deleted that protocol and said instead that drilling would stop and the company would reassess its options if a large void was discovered.
Can it happen here?
Karst topography caused by eroding limestone is more prevalent in central and eastern Pennsylvania, but it can happen in southwestern areas of the state as well, explained Bill Kochanov, a senior geologist with the Pennsylvania Geological Survey who literally wrote the book on sinkholes in the state.
It can develop through subsidence from underground mining, by water flowing through an area of soft rock like limestone, or where things buried underground decompose in a way that leave gaps — like septic tanks, or old logs abandoned in the backyard.
When someone calls Mr. Kochanov about a sinkhole, his first question is what the address and is there limestone below it?
While there is limestone close to Pittsburgh, it isn’t very thick.
For example, the thickness of the limestone in West Whiteland, according to Tetra Tech’s analysis, is 2,000 feet. Around here, it’s usually thinner than 100 feet, Mr. Kochanov said, and in many areas just a few feet thick.
Tetra Tech’s maps show areas of the Mariner East 2 pipeline in southwestern Pennsylvania where the pipeline travels through abandoned and active mines and limestone.
Other pipelines, including the Rover Pipeline, also being built by Energy Transfer Partners, of which Sunoco is a subsidiary, and the Falcon ethane pipeline being developed by Shell Pipeline Co. have karst analyses as part of their permits.
The Rover pipeline just peeks into Washington County, which has four caves, according to Tetra Tech’s analysis, but none in the path of the pipeline.
Trouble following the pipeline
The Mariner East 2 pipeline projects — intended to deliver natural gas liquids from southwestern Pennsylvania, Ohio and West Virginia to a processing terminal in the Philadelphia area — have been rocky from the start.
From Sunoco suing landowners for the right to access their land through eminent domain to townships mounting considerable fights against it to spills reported throughout the state.
The Department of Environmental Protection has documented dozens of spills of drilling fluid along the 350-mile path.
In the summer, an Environmental Hearing Board judge ordered that Sunoco stop its horizontal directional drilling activities — where the company bores tunnels to bury the pipeline deeper below sensitive areas — because they were impacting drinking water supplies.
In January, the DEP ordered all construction on the project cease, calling Sunoco’s pattern of violations and failure to disclose them to authorities “egregious and willful.” A month later, the DEP fined Sunoco $12.6 million and said work could proceed.
The stops and starts have cost Energy Transfer Partners millions of dollars. During a call with analysts last month, a company executive said delays on Rover and Mariner East 2 added $750 million to the budget. He also said he’s confident Mariner East 2 will be put into operation by the end of the second quarter, while Mariner East 2X, will be ready by the middle of next year.
Anya Litvak: alitvak@post-gazette.com or 412-263-1455.
First Published: March 7, 2018, 5:23 p.m.
