A leak from the existing Keystone oil pipeline running from Canadian oil fields shows why an expansion shouldn’t be built, environmental groups said. Pipeline company TransCanada said it took about 15 minutes to isolate a section of a pipeline in Marshall County, S.D., after a pressure drop was detected on the system Thursday morning. The drop in pressure was indicative of a leak and the company said about 5,000 barrels of oil were spilled. The release came before Monday’s decision from Nebraska regulars on whether or not the company can go ahead with its plans for an extension, the Keystone XL oil pipeline. Kelly Martin, a campaign director with the Sierra Club, said TransCanada’s […]