By Joe Marusak From The Charlotte Observer RALEIGH, N.C.—Colonial Pipeline Co. faces a $200,000 a day fine if it fails to improve the way it detects leaks in its U.S. pipeline system, after a massive gasoline leak in Huntersville, according to a recent settlement in the case with the U.S. government. The agreement orders Colonial to find and use a better leak detection system across its entire network, citing several newly disclosed leaks over the years. Colonial, meanwhile, faces separate potential action by the state Department of Environmental Quality for the August 2020 leak in Mecklenburg County’s Oehler Nature Preserve, state Sen. Natasha Marcus, D-Huntersville, told The Charlotte Observer. Two teenage ATV riders chanced upon and reported the Huntersville leak in August. The spill was among the worst in the state, Michael Regan, then-NCDEQ secretary, said in September. Regan now heads the U.S. Environmental Protection Agency. The company eventually reported …