Sunoco Pipeline LP has reached a settlement with Pennsylvania regulators to address corrosion control problems on Mariner East (ME) 1 that would require the company to conduct a rare “remaining life study” of the system.

Sunoco would also pay a civil penalty of $200,000 in a settlement it reached with the Pennsylvania Public Utility Commission’s Bureau of Investigation and Enforcement (I&E). The agreement stems from a complaint filed late last year by the I&E, following a year-long investigation of ME 1 after a 20 bbl leak of an ethane/propane mixture in Berks County in 2017.

I&E said its investigation revealed that Sunoco’s corrosion controls were deficient at the time of the leak, failed to monitor corrosion with regular tests and failed to demonstrate adequate cathodic protection, a method used to control the corrosion of metal surfaces. The bureau’s complaint recommended a $225,000 fine and the study.

A joint petition was filed earlier this month by Sunoco and I&E requesting that the PUC approve the settlement, which the parties said was reached after extensive discussions. If approved, it would require Sunoco to retain an independent expert to conduct a study of how much longer  ME 1 can remain in service.

The parties have agreed that the study would, among other things, include an assessment of ME 1’s corrosion growth rate; a schedule identifying portions of the pipeline to be replaced or repaired over the next five years; a summary of the highest risks to the system; and remaining life calculations by segment, age, coating type and soil conditions.

Moreover, as long as the system continues transporting highly volatile liquids, Sunoco would be required to submit an annual assessment of its efforts to maintain the pipeline’s integrity.

PUC spokesman Nils Hagen-Frederiksen said there is no timeline for commissioners to review and consider the proposed settlement.

ME 1 is an old refined products pipeline that was built in the 1930s and converted by Sunoco in 2013 to move 70,000 b/d of ethane and propane. The pipeline has been offline since January, when a sinkhole formed near it in Chester County. It wasn’t the first time service on the line has been suspended. The pipeline, along with ME 2 and 2X, which are under construction, have repeatedly confronted legal and regulatory issues related to fouled well water, multiple sinkholes that formed near the right-of-way, historic fines for construction violations and leaks.

The I&E’s request last year that Energy Transfer LP subsidiary Sunoco conduct a remaining life study was “really unheard of in this industry,” said PUC Senior Prosecutor Stephanie Wimer in a filing to support the settlement. But she added that “the public outcry regarding ME 1 warranted, in I&E’s view, this extraordinary relief on the part of the company.

Without the settlement, Wimer wrote, it was unlikely that Sunoco would have been required to conduct such a study if the matter was fully litigated. State law and regulations don’t require it. With the settlement, Sunoco has not admitted to all of the allegations included in I&E’s complaint. Some of those issues have since been resolved.