PUC pulls plug on Mariner East 1 - for now


Get used to hearing that word.

I'm pretty sure Sunoco Pipeline is already tired of hearing it.

Karst refers to a geologic formation where the ground is situated on old limestone formations that have been weakened by moisture over decades.

It turns out it's a pretty common occurrence in this area - particularly across a swath of Chester County.

Exactly in many of the same spots where Sunoco Pipeline is now running gases through its Mariner East 1 pipeline and is constructing Mariner East 2.

Mariner East 1 is Sunoco's old, original oil pipeline, which has been retrofitted and for the last couple of years has been delivering ethane, butane and propane from the state's Marcellus Shale regions to the company's old terminal site in Marcus Hook, where it is stored and then shipped to customers, many of them being overseas destinations.

Think of Mariner East 2 as Mariner East 1 on steroids. It's a much bigger pipe, capable of delivering several hundred thousands of barrels of gases every day. It is being constructed in basically the same areas as Mariner East 1.

That's where some of the problem is occurring.

These weakened karst areas are susceptible to sinkholes, fissures and other ground settling, in particular when the ground is disturbed, such as when drilling trenches for a new pipeline.

That's what happened last weekend when several sinkholes popped up in a neighborhood out in West Whiteland. The sinkholes are believed to have exposed the old Mariner East 1 pipe.

Yesterday, the state Public Utility Commission ordered Sunoco Pipeline to immediately shut down Mariner East 1 until the company can conduct tests on the line.

They didn't mince words, saying the sinkholes and exposed pipe could lead to a 'catastrophic' result.

You can get all the details here.

And read our editorial here.