Brittany Patterson Published

MarkWest Agrees to Pay Millions in Federal Settlement Over 'Pig' Emissions


A natural gas energy processor has agreed to pay a $610,000 civil penalty and install millions of dollars worth of equipment to reduce harmful emissions at hundreds of facilities across western Pennsylvania and eastern Ohio.

In a federal settlement filed this week in the U.S. District Court for the Western District of Pennsylvania, Ohio-based MarkWest agreed to pay the civil penalty and install $2.6 million worth of equipment at more than 300 compressor stations, pig launchers and pig receivers.

In addition, the company will install and operate ambient air monitoring systems near compressor stations in Ohio and Pennsylvania and participate in other supplemental environmental projects, totaling $2.4 million.  

The federal settlement is the first to acknowledge that the use of a maintenance technique called “pigging,” is a major source of harmful emissions in wet gas shale plays like the Marcellus and Utica.

Devices called “pigs” are used to remove debris and liquids inside pipelines. Often, before the pigs are inserted, pipelines are depressurized, which releases gas into the atmosphere

The settlement between the U.S. Department of Justice, Environmental Protection Agency and Pennsylvania Department of Environmental Protection and two MarkWest subsidiaries — MarkWest Liberty Midstream Resources, LLC and Ohio Gathering Company, LLC — alleges the company failed to apply for or comply with air pollution permits. As a result, the company unlawfully vented hundreds of tons of natural gas and volatile organic compounds, or VOCs.  

VOCs include chemicals that cause smog, or ozone pollution, and can cause serious health impacts, including headaches, nausea and damage to internal organs.

Patrick McDonnell, secretary of the Pennsylvania DEP said in a press release the new air monitoring data MarkWest must submit will help the agency improve oversight and reduce air pollution.

“The new methodology to measure emissions from pigging developed through this case will help us work with all operators in Pennsylvania to reduce emissions,” he said.

MarkWest is the largest processor and separator of natural gas in the Appalachian Basin and has operations across the northeast and near the Gulf of Mexico. The company operates two processing facilities in West Virginia, one in Kenova and the Cobb Processing Facility in Clendenin. A spokesman for MarkWest said the settlement will only apply to the operations outlined in the documents.

EPA says the technology installed under the settlement will prevent more than 700 tons of VOC emissions from being released annually.

The settlement is subject to a 30-day public comment period and final court approval.