TransCanada's Keystone Pipeline has received the green light from the U.S. Pipeline and Hazardous Materials and Safety Administration (PHMSA) to resume operations at reduced pressure, after a discovered leak nearly two weeks ago forced the company to shut the pipeline down.

In yet another case where automatic leak detection systems failed, this particular leak was first spotted by a local landowner in Hutchinson County, South Dakota, who reported it to the company. An estimated 65,000 gallons of oil spilled onto neighboring farmland.

The Keystone pipeline, which ships about 500,000 barrels of oil per day between Hardisty, Alberta and Cushing, Oklahoma, has been operating since June 2010. It was supposed to be the first phase of a major expansion, Keystone XL, to link Alberta oil producers to refineries in Texas. But the Keystone XL project was rejected last November by U.S. President Barack Obama.