About 75 ConocoPhillips workers are monitoring a 6-mile stretch of the Yellowstone Pipeline along the North Fork of the Coeur d’Alene River after the pressure in the pipeline mysteriously dropped last weekend.
No leaks have been detected in the 10-inch pipeline, which transports unleaded gasoline and diesel fuel between Thompson Falls, Mont., and Spokane, said Jeff Callender, a ConocoPhillips spokesman.
However, company officials still don’t know what caused the pressure to drop. They expected to start acoustic testing in the pipeline Thursday night to learn more precisely where the drop in pressure occurred. In the meantime, the Yellowstone Pipeline remains closed between Cataldo and Enaville.
Callender described the company’s actions as “proactive” and “precautionary.” He said the gradual drop in pressure could have been caused by a variety of factors other than a leak, including a sudden temperature change.
ConocoPhillips has crews walking the buried pipeline daily and also conducted aerial flights to check for possible fuel leaks. The round-the-clock monitoring includes shining lights on the river at night to check for oil sheens, he said. As a part of its emergency response plan, the company has installed fuel containment booms on the river at the Cataldo Mission and Kingston. ConocoPhillips also has set up a command center at Silver Mountain Resort in Kellogg.
The Yellowstone Pipeline follows the North Fork of the Coeur d’Alene River, a renowned fly-fishing stream, and tunnels under the riverbed in places. ConocoPhillips is the pipeline’s majority owner and operator.
Pipelines along scenic waterways have attracted national attention recently, after a pipeline operated by ExxonMobil Corp. spilled tens of thousands of gallons of crude oil into Montana’s Yellowstone River on July 1. That cleanup is expected to cost more than $40 million.
The Yellowstone Pipeline was built in 1954 to transport fuel from Montana oil refineries to distribution terminals in Spokane.
ConocoPhillips has been in touch daily with Idaho Department of Environmental Quality, the Department of Homeland Security, local counties and other agencies as it searches for the reason behind the pressure drop, Callender said. Though there was gasoline in the line when the drop in pressure occurred, the fuel wasn’t being pumped through the pipeline.
Marc Kalbaugh, a DEQ remediation manager, said that ConocoPhillips may have preliminary results from the acoustic testing as early as this afternoon.
Spills from the Yellowstone Pipeline have been a concern in the past. In 1983, a contractor struck the pipeline, releasing nearly 25,000 gallons of fuel into Wolf Lodge Creek, a tributary of Lake Coeur d’Alene. The spill destroyed habitat for west slope cutthroat trout.
Ten years ago, the Yellowstone Pipeline’s owners completed a number of repairs to reduce the risk of environmental contamination, including reducing crossings of the Coeur d’Alene River.