The sprinkler system at Champion City Recovery did its job early Sunday morning, containing a fire at the transfer station before firefighters arrived. Fire officials responded to the scene at 138 Wilder St. at 2:23 a.m., discovering smoke and fire from a debris pile within the main building. There was minimal damage to the building, and no one was injured. The cause of the fire remains under investigation, fire officials said Sunday afternoon. The sprinkler system was already activated when firefighters arrived at the transfer and recycling station on the city’s north side, containing the fire to the debris (comprised mostly of construction materials). Firefighters used multiple hoses to douse the pile, and a heavy equipment operator from Champion City Recovery helped move the pile around for firefighters. The owner was on scene, the Fire Department said. Champion City Recovery is a rail-served transfer station managing construction and demolition waste. The fire was extinguished before 4 a.m. The city’s Building Department was called to survey any structural damage. The facility also had two fires in 2014: a smoky blaze within the building in June, then an excavator fire in November.