The Mariner East (ME) 1 pipeline remains offline more than a week after service was stopped in response to yet another sinkhole that formed in southeast Pennsylvania, compounding problems for the system as the state oversees additional geophysical tests and the public outcries grow louder.

The Pennsylvania Public Utility Commission (PUC) and its consultants are monitoring detailed geological surveys around the sinkhole that formed Jan. 20 on Lisa Drive in Chester County’s West Whiteland Township. The sinkhole exposed Sunoco Pipeline LP’s ME 1. Sinkholes formed in the same neighborhood early last year, prompting regulators to shut down the line. The commission said late last week that the surveys are expected to take “several days” to complete.

Lisa Dillinger, spokesperson for Sunoco parent Energy Transfer LP, said the sinkhole was filled with specialized grouting to ensure it remains stable. “We will continue to work alongside the PUC’s Bureau of Investigation and Enforcement and its consultants to conduct geophysical testing to determine if additional work is necessary,” she added.

ME 2 and 2X were also recently under construction in the same right-of-way nearby, but it remains unclear if those pipelines are in the area exposed by the latest sinkhole. Partial service recently started on ME 2, but Sunoco was forced to repurpose a short stretch of 12-inch diameter pipeline that once carried refined products to bypass two areas in West Whiteland where construction is on hold over other regulatory issues.

PUC spokesman Nils Hagen-Frederiksen was working on Tuesday to confirm their location in relation to the sinkhole and whether ME 2 is in service in that area, but said the “pipeline team have their hands full right now.”

Meanwhile, freshman Democratic state Rep. Kristine Howard called on state Attorney General Josh Shapiro and Auditor General Eugene DePasquale to open a criminal investigation into the ME system.

“Both Sunoco and the PUC were quick to claim there was no danger to the neighborhood,” Howard said. “But the stark fact remains — this is not the first time this issue has occurred — nor the second, nor the third. Something needs to change, and that is why I have called on the attorney general and the auditor general to provide greater scrutiny and accountability for this major public safety concern.”

The Chester County Commissioners also sent a letter to PUC Chairwoman Gladys Brown with a series of pointed questions about last week’s incident. The latest outcry came after the Chester County District Attorney’s office opened a criminal investigation into construction of the ME projects.

Howard joined Democratic state Sen. Andrew Dinniman in speculating that the area’s limestone geology is a “large factor” in the appearance of sinkholes in the area. ME operations were shut down for the second time last year after Dinniman filed an emergency order to stop work and a formal complaint with the PUC. He questioned the safety of the entire system after the first group of sinkholes formed near it. The Jan. 20 incident marked the third time ME 1 operations have been halted in less than a year.

The PUC eventually lifted the second stoppage without addressing a number of conditions proposed by an administrative law judge, including requirements for additional geophysical and geotechnical testing. Those kinds of tests had been conducted after the initial shutdown when the first sinkholes formed.

Indeed, the ME project has been confronted by subsidence issues from western to eastern Pennsylvania in areas of heavy coal mining or karst geological formations. According to the Pennsylvania Department of Conservation and Natural Resources (DCNR), only certain parts of the state experience sinkholes. Large areas of central and eastern Pennsylvania are underlain by the kind of bedrock that naturally erodes such as limestone, dolomite and marble.

Sunoco noted in its permit application filed with the state Department of Environmental Protection that it did not conduct thorough geotechnical tests in areas without known karst formations. As sinkholes emerged along the route, DEP urged it not to limit tests to those areas alone. The company has already conducted geotechnical analysis in the Lisa Drive area as a result of all the regulatory issues it has faced.

The PUC said results from the latest tests would be analyzed by its engineers and consultants to determine the next steps at the Lisa Drive site. Regulators and Sunoco are also monitoring stormwater flow around the incident site. Sunoco won’t be able to bring ME 1 back online until it has permission from the state.

As the service outage continues, producers are again left to find workarounds for their natural gas liquids (NGL). The regulatory issues knocked out service for nearly three months last year, forcing operators to utilize more costly rail and truck for their propane and find other arrangements for ethane, which must move by pipeline because of its high vapor pressure or be rejected into the gas stream.

ME 1’s anchor shipper, Range Resources Corp., which has 20,000 b/d of ethane capacity and 20,000 b/d of propane capacity on the system told investors last week that the net impact to cash flow from the latest outage is expected to be minimal.

“Range is utilizing available capacity on the recently commissioned Mariner East 2 pipeline to continue moving its propane to the Marcus Hook terminal,” said investor relations chief Laith Sando, vice president. “For ethane, Range has multiple options for marketing its production, including the ability to sell ethane as natural gas.”

The 70,000 b/d ME 1 entered service in the 1930s to move refined products, but was repurposed and began moving NGLs about three years ago. ME 2 and 2X, which is expected to come online later this year, run parallel along roughly the same path as ME 1 for about 350 miles to move liquids from processing facilities in Ohio, Pennsylvania and West Virginia to the Marcus Hook Industrial Complex near Philadelphia.