MarkWest Energy Partners LP said this week that a month-long effort to clean up a spill of heat transfer oil from its Mobley Processing Facility in Wetzel County, WV, has been completed.

The fluid, Dowtherm MX, was released on Feb. 20 through a faulty valve at a new processing train under construction (see Shale Daily, Feb. 23). It's unclear what caused the valve to fail, but the fluid entered a storm drain and was released from the facility's storm water retention system and made its way into the tributary of a creek.

Shortly after the spill, MarkWest said the oil did reach the inlet of the nearby town of Pine Grove's fresh water treatment facility, but did not enter the public drinking water. The company said Tuesday that it has since collected 50 drinking water samples from homes and businesses in the area that were analyzed by a state-certified laboratory. MarkWest said the results showed "conclusively" that no oil released during the spill reached water wells or the water distribution system in the community.

About 260 gallons of the fluid was released (see Shale Daily, Feb. 29). Federal, state and local officials responded to the cleanup efforts, which involved vacuum trucks and booms. MarkWest dispatched dozens of employees and contractors to help with the spill response, distribute bottled water and help with door-to-door notification of residents after the spill.

Pine Grove was able to switch over to an alternate water source throughout the cleanup. MarkWest said the Pine Grove Water Works resumed normal operations over the weekend after the tests and a cleaning of the water treatment facility.

The valve at the 200 MMcf/d processing plant under construction has since been replaced. Since the train was not yet commissioned, there was no downtime at the facility as a result of the leak, the company said. MarkWest is now a subsidiary of Marathon Petroleum Corp.'s master limited partnership MPLX LP (see Shale Daily, Dec. 1, 2015). Not including the train under construction, the Mobley complex is a 520 MMcf/d cryogenic processing facility.