WASHINGTON, Kan., Dec 10 (Reuters) - Residents near the site of the worst U.S. oil pipeline leak in a decade took the commotion and smell in stride as cleanup crews labored in near-freezing temperatures, and investigators searched for clues to what caused the spill.A heavy odor of oil hung in the air as tractor trailers ferried generators, lighting and ground mats to a muddy site on the outskirts of this farming community, where a breach in the Keystone pipeline discovered on Wednesday spewed 14,000 barrels of oil.TC Energy did not provide details of the breach or say when a restart on the broken segment could begin.OIL FLOWS TO CREEKEnvironmental specialists from as far away as Mississippi were helping with the cleanup and federal investigators combed the site to determine what caused the 36-inch (91-cm) pipeline to break.Emergency workers installed booms to contain oil that flowed into a creek and that sprayed onto a hillside near a livestock pasture, said Hubbard."