Federal and state regulators have reached a settlement with MPLX LP to pay nearly $7 million in fines and other measures aimed at strengthening air pollution controls at natural gas processing plants in six states.

The agreement resolves alleged violations of clean air laws governing the control of emissions from equipment leaks, pressure relief devices, storage tanks, truck and railcar loading, combustion devices and process heaters.

The Environmental Protection Agency (EPA), the Department of Justice, the states of Oklahoma and West Virginia, and the Pennsylvania Department of Environmental Protection announced the agreement to strengthen pollution controls at 20 gas processing plants in Pennsylvania, Ohio, West Virginia, Kentucky, Texas and Oklahoma that would help reduce volatile organic compound (VOC) emissions by 1,500 tons/year. 

As part of the settlement, MPLX is required to complete supplemental environmental projects and pay a $925,000 penalty. The company would pay $2.78 million to install and operate new technologies as well as improve and expand existing control techniques that minimize VOC emissions at its natural gas processing plants.

MPLX is also required to mitigate VOCs at two gas compressor stations in Pennsylvania and Ohio with new technology to capture and control emissions during truck loading operations, which is expected to cost at least $700,000, EPA said. Another project involves the $2.5 million installation of ambient air monitoring stations near four processing plants in Pennsylvania, West Virginia, Kentucky and Texas. The company would also spend $75,000 to study the effectiveness of computer modeling of fugitive leaks as a potential emission reduction tool.

The consent decree has been filed in the U.S. District Court for the Northern District of Ohio and is subject to a 30-day public comment period before it is finalized.

MPLX, the midstream master limited partnership of Marathon Petroleum Corp., completed a merger with MarkWest Energy Partners LP three years ago, giving it substantial gas processing assets across the country.  The latest consent decree comes after another earlier this year in which MPLX and its affiliates were required to perform a trio of environmental projects and pay a $610,000 civil penalty for similar air emission violations at facilities in eastern Ohio and western Pennsylvania.