Canadian company TC Energy will temporarily divert a north-central Kansas stream to isolate a four-mile stretch fouled by its busted Keystone oil pipeline.
Last month’s spill primarily polluted that stretch of Mill Creek, though benzene and other chemicals turned up farther downstream in levels that could ultimately harm wildlife — but that remain too low to pose concerns for public drinking water. (No towns or cities draw their water from the immediate area.)
TC Energy and its contractor will use giant bladders filled with water to block off the four-mile stretch from the rest of creek — both upstream and downstream — and then bypass that section by pumping the clean water upstream of the spill through a 1.2-mile-long above-ground hose that empties back into the creek bed farther downstream.
This could mean carrying upward of 5,000 gallons of water per minute. (Streamflow varies seasonally and depending on the weather, TC Energy says.)
“We are committed to diverting the full flow of the creek and we’re able to add additional pumps and equipment as necessary,” the company wrote in an email.
Federal and state regulators overseeing the spill site say that diverting the Washington County creek will help.
“This will reduce the possibility of chemicals moving downstream and enhance oil recovery efforts,” the state health department said in an email. “Additionally, reducing the flow will allow the teams on-site to determine if the oil has sunk to the bottom of the creek.”
Searching for sunken oil is critical to a thorough cleanup because the Dec. 7 Keystone accident in Washington County — estimated by TC Energy at nearly 600,000 gallons — was the second-largest spill of dilbit oil on U.S. soil.
Dilbit, or diluted bitumen, comes from Canadian tar sands and doesn’t behave like conventional crude oil. Top scientists warned nearly a decade ago that the federal government should pass special regulations to prepare for the particular difficulties of cleaning dilbit spills.
When dilbit pours into a river or stream, it soon starts sinking — flummoxing traditional cleanup methods that focus on containing and recovering floating oil.
This raised a risk that dilbit could flow through large, underwater holes in the two emergency dams that were set up to stop the huge slick of floating crude oil in Mill Creek from moving downstream.
A National Academies of Sciences study found little in the way of reliable options to detect dilbit once it begins moving below the water’s surface. The weathering process that causes the stuff to sink can start within a matter of days. The spill occurred nearly one month ago.
TC Energy hasn’t offered specifics on what methods it is using to check for sunken dilbit, but the EPA says it has heavy crude oil experts offering technical guidance and that “efforts to identify and contain submerged oil are being conducted.”
A scientist who worked on the 2016 National Academies study and advised the Environmental Protection Agency on a major dilbit spill in Michigan suggested crews in Kansas could run tests for sunken dilbit in Mill Creek by placing fine meshes over the underwater holes for short periods of time in search of the stuff.
“But estimating the amount is much harder unless and until (sunken dilbit) settles out in some kind of slack water area and can be measured in sediment cores,” Steve Hamilton, a Michigan State University professor of ecology & biogeochemistry, wrote in an email.
Eventually, he said, crews searched successfully for sunken oil in the Kalamazoo River by disturbing the riverbed with special poles to release globules and sheen that floated to the surface.
“(This) turned out to be the most practical indicator,” he said. “But it may take awhile for the (sunken) oil to produce a sheen. We do not understand what makes it more prone to float up at a later time.”
Hamilton suspects sunken dilbit may bind to organic matter that only frees globules once it decomposes, but that theory remains untested. If it proves true, he said, that could mean dilbit that sinks now and attaches to organic matter in Mill Creek wouldn’t shake free and reveal a sheen until the creek water warms up months from now.
TC Energy and environmental regulators haven’t publicly estimated how long the Mill Creek cleanup will take or how long they will divert the creek with pumps and an above-ground hose.
“Once the remediation work is completed and the area has been tested,” the company said by email, “the creek and water will return to (their) normal flow route prior to the incident.”
The U.S. Environmental Protection Agency said in an email that the timeline for restoring normal flow would depend on water and sediment samples and work to rehabilitate the streambanks.
State environment officials signaled weeks ago in an update to the Kansas Water Authority that diverting the stream could help prevent further environmental damage.
“It’ll really help the stream quality further down(stream) on Mill Creek,” said Erich Glave, who directs the Bureau of Environmental Field Services at the Kansas Department of Health and Environment. “So we’re really hoping all that process gets done.”
The U.S. Army Corps of Engineers confirmed that it knows about the plan and will help with permits as needed.
“We are communicating with the (Kansas Department of Health and Environment) and EPA on whether regulatory support is needed in the form of any additional permits,” it said in an email.
About 740 workers are on site in Washington County.
Cold weather complicated the cleanup, requiring crews to apply indirect heat to prevent ice buildup.
The EPA says more than 800,000 gallons of liquid have been pulled from the four-mile stretch of the contaminated creek so far — that includes water and oil.
TC Energy finished pipeline repairs last week, putting the Keystone system back in service to all its delivery points. The Keystone transports oil from the Canadian tar sands in Alberta to facilities in the Midwest and as far as Houston, Texas.
A federal order requires the pipeline to operate for now at a lower pressure than it did prior to the spill.
Read more about the Keystone spill in Kansas:
- The Keystone pipeline is back in business while the Kansas oil spill cleanup continues
- Pipeline company says Kansas oil spill contained, but chemicals found downstream
- Not just any oil spill. The Keystone pipeline dumped notoriously hard-to-clean 'dilbit' in Kansas
- Keystone Pipeline has history of spills, warnings and fines. This Kansas spill is the largest yet