The only earth movement that Jeff and Michelle Seaman have noticed is the large gash dug by excavators and pipeliners in their backyard 50 feet from the pool where Ms. Seaman likes to float.
On the hillside behind their Finleyville home, trees have given way to a 100-foot-wide path of dirt where Sunoco Pipeline L.P. has been trying to string its Mariner East 2 pipelines.
But it's the shifts of the earth below the Seamans' home that are responsible for the 18-month-and-counting mess that they're seeing on the surface.
The pipeline was supposed to travel under the couple's house, and under Froman Run and Route 88 through a nearly half-mile-long tunnel launched from a property over the hill and completed at another beyond a wall of trees.
It was supposed to be out of sight and out of mind, but turned out to be neither.
The Seamans blame Sunoco. Sunoco blames subsidence.
A disturbance under the earth
In this part of Pennsylvania, subsidence is commonly associated with coal mining: When coal is removed from the earth, it leaves voids in its wake.
Some collapse right away, sinking the surface above. Some take time to yield the space to other rocks. The movement underground can crack foundations on the surface, damage roads and, yes, break pipelines.
Landslides are another category of subsidence that can wreak the same havoc.
With a soaking spring and summer, Western Pennsylvania has had its share of them in recent months, including the Sept. 10 slip that ruptured a newly activated natural gas pipeline in Beaver County. The pipeline was built by Energy Transfer Partners.
The resulting explosion burned down a home and brought a new level of alarm to residents near the yet-unfinished Mariner East 2 pipeline — a path that stretches 303 miles across picturesque hills underlain by hundreds of miles of old mines.
Before construction began, Sunoco, which merged with Texas-based Energy Transfer Partners last year, told Pennsylvania regulators that the chances of its drills running into voids was either "low" or "very low."
It's not that the company didn't know about the honeycomb of old mines under the state, but it didn't think they would impede the pipeline's progress.
The schematic for the horizontal drilling planned to go under the Seamans' home shows the entire area sits on top of the old Pittsburgh Coal Co.'s Cincinnati Mine.
Opened in 1835, the mine was notorious for one of the worst explosions in the history of the industry, which killed 96 miners and one rescuer in 1913.
Sunoco's drilling work near the couple's Washington County home began May 27, 2017. The first signs of trouble showed up within the first week.
Drilling mud came out of the ground in three unexpected places: two near a travel-trailer sales parking lot and one just outside the Seamans' home, flowing into a culvert that emptied into the high-quality stream known as Froman Run.
Sunoco stopped drilling, placed filter socks and straw bales around the spills then carried on.
On June 10, about 40 gallons of drilling mud oozed out of the ground outside Mingo Presbyterian Church, a 187-year-old building with a bright red roof next to the Seamans' place. A pumper truck was called in to vacuum the spill.
The next day, some 100 gallons of muddy water showed up in an old pump house behind the Seamans' home.
Sunoco dispatched vacuum trucks and stationed someone from the company to sit outside the couple's kitchen window 24 hours a day for weeks, monitoring the old water well to ensure a quick response to subsequent mud spills.
Deep underground coal mining
In its initial report to the state Department of Environmental Protection, Sunoco said the spills were likely related to conditions below the surface caused by "historic deep underground coal mining in the area."
When Tetra Tech, the same contractor that had prepared the original spill response plan, was asked to reevaluate the design of drills in the area, it determined the risk of further spills was inherent to drilling in that spot. It was bound to happen.
"In response to a better understanding of the subsurface geology and degree of fracturing," Sunoco said, it decided to abandon attempts to install the pipeline through horizontal directional drilling — a method of tunneling under obstacles — and to instead use a combination of trenches and shallower, shorter bores.
That's when Sunoco cut down the trees on the steep slope in the Seamans' backyard and dug a trench that has remained empty since this summer, save for a large hole filled with muddy water.
The homeowners, meanwhile, wondered: If a pipeline is ever laid there, will it be vulnerable to landslides?
Rethinking pipeline failures
So far, spills and mishaps at Sunoco's horizontal drilling sites for the Mariner East 2 pipeline have been examined by regulators from an environmental perspective — Did the spill pollute a creek? Did it foul drinking water or cause erosion?
Those things draw fines and require the company to rethink its processes.
But the earth's reaction to the pipeline can also be considered from the lens of safety: If the underground rock and soil shifted easily when prodded, will they do so again when a pipeline is installed, pressurized and filled with a highly volatile liquid?
These concerns have been articulated most forcefully by residents in a Philadelphia suburb in Chester County, where attempts to bore underground opened up sinkholes in people's backyards.
What if the ground moves again, they asked Sunoco when its officials were put on the stand at an administrative hearing earlier this year.
State Sen. Andy Dinniman, a Democrat from Chester County who has been the leading political voice against Sunoco, suggested that laying pipelines in karst geology — which exists where limestone has eroded underground and left voids behind — could be unsafe.
John Zurcher, a pipeline safety expert hired by Sunoco to testify at the May 10 hearing, disagreed.
Of all the thousands of miles of transmission lines in Pennsylvania, he said, "I know of no incidents that any one of those pipeline companies have had with subsidence or anything else due to these formations."
Zurcher said he even consulted a database of pipeline incidents maintained by the Pipeline & Hazardous Materials Safety Administration before making his claim.
"There's never been a failure of a pipeline in one of these areas caused by geology or a sinkhole or even mining subsidence that we have here in Pennsylvania."
Checking the records
The PHMSA records, which date back several decades, show more than a dozen such incidents across the country, including in Pennsylvania.
Appalachian states — including Kentucky, West Virginia and Ohio, which are known for coal mining and scenic, steep hillsides — had the bulk of them.
In 2009, a Columbia Gas Transmission pipeline broke apart in Pike County, Ky., at a site where the slope of the ground changed over a mine area.
The official cause was subsidence.
Three years before that, another Columbia pipeline ruptured in West Virginia, pulling apart a threaded joint. The cause: ground movement.
In January in Ohio, a landslide moved a relatively new part of the Rockies Express pipeline more than 10 feet, causing it to break and catch on fire.
And in Pennsylvania in 1990, a Buckeye Partners pipeline in Armstrong County leaked liquid fuel when it was damaged by a landslide.
Two years later, a small natural gas transmission pipeline exploded on the border of Greene and Washington counties in the town of West Finley.
An explosive shift
At the time, in 1992, Cecil-based Consol Energy was mining near — but not under — a house owned by Ira and Francis Mayhle.
Their grandson was resting on a couch when an explosion set the home on fire. The young man, visiting during a cross-country trek to college, narrowly escaped through the back door.
"Subsidence was not expected," a federal safety report stated, because the mining was taking place 1,000 feet away from the house.
The earth shifted enough to break the Columbia Gas Transmission pipeline. The gas migrated 26 feet to the house, finding a source of ignition and burning the place down.
In the same testimony in which he said that subsidence has never broken a pipeline in this region, Zurcher, who worked as a safety manager at Columbia Gas Transmission from 1997 until 2003, noted seven protective measures that Sunoco had included in its permit to mitigate the risk of earth movement on Mariner East 2.
For example, for areas where there is a risk of subsidence from karst or mining activity, Sunoco's experts suggested keeping the pipe somewhat loose in the bore — not cementing it tightly against the hole.
Mines for miles
Mine-related subsidence has foiled Sunoco's Mariner East 2 drilling plans in several other sites in Western Pennsylvania.
In Murrysville, Sunoco determined that drilling slurry overfilled an underground void — a remnant of previous mining activity — sending the fluid to the surface and into Turtle Creek in September 2017. The spill resulted in an 8-foot to 10-foot sinkhole.
In Penn Borough, a series of unsuccessful attempts to drill under a Norfolk Southern railroad track veered into at least one large underground void, resulting in spills and a deviation of the drill path in the summer of 2017. Sunoco's consultant said there were mines all around the site but not immediately underneath.
Closeby, a horizontal directional drill procedure planned to travel under Gombach Road in Penn Township escaped that fate by changing course.
With similar geology but no activity at the site yet begun, the company proposed to instead lay the pipeline by trenching and drilling a shallower bore that would use air instead of pressurized fluids to break up the rock. This would prevent spills, the company said.
No karst, no problem
Sunoco's permit application — which detailed what the company weighed when coming up with its pipeline design — revealed that if there was none of the suspected limestone erosion known as karst, the company did not delve deeply into geotechnical analysis.
When problems with sinkholes began to surface, DEP program manager Domenic Rocco pushed back on that, writing to Sunoco that geotechnical studies should not be limited to sites with those issues. The data produced in such research might be valuable anyway, he said.
In August 2017, the DEP ordered construction to halt on Mariner East 2 and ordered Sunoco to reevaluate dozens of drilling designs — often requiring more detailed geophysical data to support the company's conclusions. The new information proved useful.
In its responses, Sunoco on several occasions referred to the new data to conclude that horizontal drilling at certain planned crossings was not a good option.
Pushing through the voids
Mine voids and eroded limestone don't automatically disqualify a site from hosting a pipeline.
Proof of that is the thousands of miles of pipelines that currently snake through southwestern Pennsylvania — a region pockmarked with mines — and through eastern Pennsylvania — an area known for its large pockets of fragile limestone.
In 2009, the Pipeline Research Council International published guidelines for building in areas prone to landslides or subsidence.
It warned that "avoiding potential geohazards is becoming increasingly difficult because of the inability to obtain landowner agreements, the lack of space in common utility corridors, environmental restrictions, incompatibility with existing land use, and/or public opposition."
The report's suggestions include using thicker pipe, using foam to cushion the pipeline in the borehole, and avoiding sharp elbows on pipeline joints.
___
Hundreds of miles of pipelines have been operating throughout Pennsylvania and the corresponding geology for years without issues from subsidences.
— Lisa Dillinger, Energy Transfer spokeswoman
___
Choosing the safe route
It is not the DEP's job to ensure that Sunoco has chosen a path where it's safe for the pipeline to operate or that it has designed its pipeline in a way that preserves structural integrity.
That responsibility falls on the licensed professional engineer hired by Sunoco to sign off on the plan, said Ramez Ziadeh, acting executive deputy secretary for programs.
DEP's authority is limited to ensuring that pipeline companies minimize erosion and impacts to waterways.
Only after construction begins does the state Public Utility Commission get involved, inspecting the progress to ensure it complies with federal pipeline safety rules.
Having spent 76 inspection days on Mariner East 2 last year, the PUC has taken note of how many times Sunoco's horizontal bores caused or encountered subsidence.
It has asked the company to voluntarily perform geophysical tests at all of its horizontal drilling sites, said spokesman Nils Hagen-Frederiksen. That will serve as a baseline, he said, against which future subsidence can be assessed.
Lisa Dillinger, a spokeswoman for Energy Transfer said Sunoco will monitor for subsidence by looking for surface depressions during flyover surveys, through ground patrol or by listening to local landowners.
As for instances already encountered, she said, "all subsidence areas have been sealed, grouted and fully restored. This is standard industry practice in these situations."
Not this family's plan
The Seamans bought their home in 2007, while eyeing the empty land next door for a pool.
In 2014, they finally talked the owner of the neighboring parcel into selling, but he insisted on keeping the subsurface rights in case Sunoco decided to build Mariner East 2.
The recently laid leg of Mariner East 1, which connects Houston to Delmont, had been installed without incident for the Seamans, so they figured it wouldn't disrupt their lives too much.
Anyway, there was nothing they could do about it, Mr. Seamans said.
Sunoco had the power of eminent domain. Even if he owned the minerals under his land, Sunoco — designated as a utility for this project — could simply take it.
When the spills started in the summer of 2017, the couple was taken aback. And not just by the mess.
They've taken videos of the work and streamed them on Facebook. Once, they drove down Route 88 to see how far the sound of the drill carries.
"You start going crazy," Ms. Seaman said. "You start hearing it in your sleep even when it's not going on."
No one was invited to a barbecue at their home this summer, although the pool deck looked festive enough with lights strung along a fence where a whale-shaped sign preaches: "Life's better on the beach."
Their older daughter calls to check if Sunoco is drilling before she decides if she'll come home from college for the weekend. The drilling shakes the house, Ms. Seaman explained.
They wonder what it will be like to live this close to a pipeline once it's actually done. Images of the explosion last month in Beaver County on a newly built pipeline are fresh in their minds.
"Our ultimate plan," Mr. Seaman said ...
"... is to get out of here," his wife continued.
