Amy Dalrymple, Forum News Service, Published October 17 2013
Tesoro crews work to recover oil from Tioga spill
Crews burned oil that had pooled in a wheat field following a pipeline leak near here but discovered more oil as they began digging to expose the pipe.
“That’s when I said, ‘I’ve got to go pack my bag,’ ” recalled Haugstad, who has years of experience responding to major oil spills.
Haugstad is director of contingency planning and response for Tesoro. He helped BP respond to the 2010 Deepwater Horizon oil spill in the Gulf of Mexico, and now is leading the immediate recovery effort north of Tioga, where an estimated 20,600 barrels of Bakken crude saturated the soil.
On Thursday, cleanup efforts focused on capturing as much free oil as possible while prepping the site for a North Dakota winter.
“We’ve got it contained. We’ve got it surrounded,” said Brian Sullivan, Tesoro’s vice president for corporate affairs. “So we just need to try to recover as much as we can.”
Meanwhile, workers conducted a pressure test Thursday for a new section of pipeline that will be routed away from the spill site. Tesoro Logistics is working with the Pipeline and Hazardous Materials Safety Administration on a plan to restart the pipeline.
The entire 35-mile section, including the repaired portion, will have leak detection and monitoring in place, the company said.
Gov. Jack Dalrymple met Thursday with Dan Romasko, Tesoro Logistics’ senior vice president of operations, and asked the company to take every precaution before resuming operations.
“We expect high standards from North Dakota’s energy industry, and I expect timely responses from Tesoro Logistics to the many unanswered questions that remain in order to prevent this from ever happening again,” Dalrymple said in a statement following their meeting.
At the cleanup site, about 40 crew members work during daylight hours, some excavating dirt to create low points for the oil to flow while other workers suck up the oily puddles with giant vacuum trucks.
Crews are working with 3,000 feet of trenches that have been dug at the site. The trenches are about 10 to 12 feet deep, the same depth as a layer of clay that is preventing the oil from seeping any deeper and contaminating water.
“By making openings down to the clay, you’re relieving the hydraulic pressure that allows oil to flow into the opening,” Haugstad said.
Crews recover about 290 barrels of oil per day, and have recovered at least 2,935 barrels so far. The recovered oil goes through a filtration system on site and then is trucked to Tesoro’s Tioga station.
“Instead of being disposed as a waste, we’re going to actually put it back in the system and send it either to the refinery or to market,” Haugstad said.
Oily water that is recovered is stored on site in a tank used for hydraulic fracturing. An environmental consultant is analyzing the water to determine how to dispose of it, Haugstad said.
The 7.3-acre site in farmer Steve Jensen’s field is now separated with berms to indicate hot, warm and cold zones.
The hot zone is where the spill occurred, the warm zone is where crews remove contamination from vehicles and equipment, and the cold zone is a staging area that has not been affected by the spill.
What is known as oleophillic material borders the hot zone to attract oil and prevent it from spreading, particularly when it rains. The material resembles white cheerleader pompoms.
Soil is most heavily stained in the area where the leak occurred. The faulty segment of pipe has been removed and sent to an independent lab for analysis.
Another area where crews have recovered the most oil is directly south of the leak, where the oil flowed down gradient and along the pipeline.
A third area most affected is a bit of an anomaly, Haugstad said. The oil also flowed directly east from the leak and heavily stained an area about 20 yards wide.
“There was something unique about the soil here that made it run pretty much east from the site,” Haugstad said.
During Haugstad’s first week on site, the effort focused on making sure oil did not affect water sources and determining the perimeter of the spill. Crews drilled four test wells around the site, and the environmental consultant takes weekly water samples to monitor for contamination. Officials are “highly confident” that water has not been contaminated, Haugstad said.
Crews also used a geoprobe to take a core sample down to the layer of clay every 50 feet to determine where the oil is. Haugstad said the spill estimate of 20,600 barrels is determined with a formula based on square footage, the thickness of the saturation zone and the porosity of the soil.
“It’s a fairly educated estimate,” he said.
Work is beginning to shift to an interim recovery phase that will continue through the winter. Haugstad said the plan is to use a French drain system that involves placing coarse rock in the bottom of the trenches, topped with a membrane to keep sediment out and then topped with soil. Pipes will be placed straight out of the ground so vacuum trucks can attach hoses to them and recover oil throughout the winter.
A St. Paul environmental consultant is developing a long-term plan to remediate the soil. The group is expected to present recommendations to the North Dakota Department of Health and the landowner soon, but the work would likely begin in the spring, Haugstad said.
Tesoro Logistics has said the expectation is to remediate the land to the same condition as before or better. A time frame has not been established because the consultant is still developing options.
“As unfortunate as it is, having it happen here in this type of soil is actually very beneficial with a clay layer and not hitting water,” Haugstad said. “If you hit water, whether it be groundwater or a river, it would have been much worse.”