MarkWest Energy Partners LP said late last Friday that remediation efforts are still ongoing in Wetzel County, WV, nearly a week after the company discovered that chemicals had leaked from its Mobley Processing Facility (see Shale Daily, Feb. 23). Initially, the state said 3,000 gallons of heat transfer oil, identified as Dowtherm MX, had leaked from a failed valve at the plant. MarkWest confirmed Friday that 260 gallons of the fluid was released. The oil breached the facility's storm water retention system and made its way into the tributary of a creek, jeopardizing the town of Pine Grove's freshwater treatment facility. The town has since switched to an alternate water source and MarkWest said the cleanup effort is still ongoing. Water samples have shown that amounts of the fluid in the creek have rapidly declined, the company said. The Mobley facility is located in Smithfield, WV. It is a 520 MMcf/d cryogenic processing facility.