The West Virginia Department of Environmental Protection (WVDEP) has negotiated a voluntary remediation agreement (VRA) with an affiliate of MarkWest Energy Partners LP to continue restoring the site of its Mobley Processing Facility, where more than 200 gallons of heat transfer oil was spilled in 2016.

The state’s VRA program encourages voluntary cleanups of contaminated sites, under-utilized properties and the redevelopment of abandoned ones. The WVDEP said it has accepted a VRA application from MarkWest, a subsidiary of MPLX LP.

Under the agreement, MarkWest Liberty Midstream & Resources LLC would work with the agency to “identify human health and ecological risks associated with current and potential future uses” of the seven-acre site in Wetzel County, where the 920 MMcf/d processing facility is located. The company must also establish additional remediation standards and ensure those standards are maintained. WVDEP said that once the steps are completed, the company would submit a final report for review and approval.

The heat transfer fluid Dowtherm MX escaped a faulty valve at a processing train that was under construction in February 2016. About 260 gallons was released, making its way into a storm drain, out of the facility’s stormwater retention system and into the tributary of a creek. The water supply in the nearby town of Pine Grove was temporarily interrupted. The release also impacted the surrounding surface area.

During the initial cleanup, Impacted soils and sediments were excavated and removed from the site. Dams were built within the tributary and creek to remove residual Dowtherm from the surface water. Instrumentation controls have also been installed to help stop the flow of water off-site should a future release occur.