TransCanada's Keystone Pipeline spill cleanup on schedule

This aerial photo shows spills from TransCanada Corp.'s Keystone pipeline, Friday, Nov. 17, 2017, that leaked an estimated 210,000 gallons of oil onto agricultural land in northeastern South Dakota, near Amherst, S.D. (DroneBase via AP)

AMHERST, S.D. -- TransCanada Corp. says cleanup of a massive on-shore oil spill from Keystone Pipeline in South Dakota is halfway finished.

Last November, the pipeline leaked 210,000 gallons of crude oil onto agricultural land in Marshall County, one of the largest on-shore oil spills in the U.S. since 2010.

TransCanada spokeswoman Robynn Tysver told Aberdeen American News that the work has transitioned from excavation of the Amherst site to its remediation to original condition.

"All of the excavation work at the site has been completed, and most of the impacted soil has been removed," Tysver said. "We are now working to replace the top soil, with plans to seed later in the spring."

The pipeline moves oil from eastern Alberta, Canada to Oklahoma and Illinois.

TransCanada said the cleanup is on track with its schedule. The company also has agreed to restore the roads used by trucks transporting equipment and soil.

Last month, a half-ton of contaminated soil was spilled as the result of a truck rollover. The soil has been cleaned up and the truck's driver was charged with careless driving. A case is still open about an unknown truck driver dumping contaminated soil southwest of the leak site, according to the State Department of Environment and Natural Resources' leak database.

A spill and activity report on the agency's website shows that TransCanada has installed groundwater monitoring systems, which haven't yet detected any contamination.

An investigation into the cause of the leak is ongoing.