VIDEO: Crews now know the source of a leak which spilled diesel fuel into Boneyard Creek. It came from an underground fuel storage tank at a construction site in Champaign. Construction workers were digging at the site and ran into an abandoned tank underground. The fuel leaked for at least two hours. Dozens of gallons were spilled. The water in the Boneyard Creek flows to the Sanitary District treatment plant in Urbana. Firefighters say they don't think there will be any major consequences. The plant should be able to filter it all out.