Over the weekend, investigative work on the Poplar Pipeline crossing under the Yellowstone River in northeast Montana, where a leak occurred a week earlier, uncovered exposure of the 60-year-old pipeline in an area in which it had originally been buried eight feet below the riverbed.
The state Department of Environmental Quality (DEQ) reported that a pipeline sonar survey divulged exposure of a 50-foot stretch of the pipeline under the riverbed where the leak occurred. The new data should assist investigators in the ongoing search for a cause of the spill, according to the DEQ.
Air quality monitoring since the spill have turned up no unhealthful situations, according to DEQ, which said over the weekend that local residents "should feel comfortable with their normal outdoor activities."
Water supplies affected by the Jan. 17 crude oil spill of nearly 40,000 gallons along the river were deemed to be meeting federal safe drinking water standards as of last Friday, the DEQ said (see Shale Daily, Jan. 23). In an updated report Monday, DEQ said local residents now can use water as normal.
Privately held Bridger Pipeline Co. owns and operates a 123-mile pipeline with two river crossings in Montana. The original pipe dates back to the 1950s, and the river crossing where the leak occurred was built in the late 1960s, according to DEQ.
Texas-based Bridger's pipeline has a 42,000 b/d capacity, and the company last inspected the river crossing in 2012 with "no unusual findings," according to DEQ officials. At that time, Bridger estimated the pipeline to be eight feet below the river bed.
"At one point, the bottom of the river bed is [now] one foot below the pipeline," DEQ said. "The sonar survey did not identify a cause of the pipeline breach, but this data will assist investigators in determining the cause of the spill."
State officials on Friday said that the water treatment plant for the town of Glendive, MT, about seven miles downstream from the spill (see Shale Daily, Jan. 20), was "decontaminated and the main distribution lines flushed through the city's fire hydrants."
DEQ said on Monday that 24 surface water samples have been taken on the river, including the spill site, and all of them have been within safe standards. Water was tested for volatile organic compounds, benzene and other components of crude oil.
DEQ also confirmed Friday that the 12-inch diameter pipeline was carrying primarily Bakken crude oil at the time of the release.
It was the first significant spill in Montana since an ExxonMobil Corp. pipeline broke in south-central Montana near Laurel in July 2011, releasing 63,000 gallons of crude along an 85-mile stretch of the Yellowstone River. ExxonMobil is facing several millions of dollars in state and federal fines related to that spill.