A portion of Interstate 16 was closed Thursday morning after a tractor-trailer hauling kaolin overturned. A second collision between two semis on the detour route was minor, according to reports.The two accidents combined to make the early morning commute in the area difficult.Georgia State Patrol Sr. Trooper Tommy Strickland reported that a truck hauling kaolin, traveling eastbound on I-16 around 3 a.m., left the road and went into the median.When the driver, Valgie Mumford, 35, of Clars Avenue in Savannah, tried to regain control and re-enter the roadway, his big rig flipped, coming to rest across both eastbound lanes, blocking them, Strickland stated in reports.Mumford was taken to East Georgia Regional Medical Center by Bulloch County EMS, where he was treated for facial injuries, according to reports. He was not charged in the accident.Traffic was rerouted for about four hours, said Sgt. Brad Mosher, the GSP Post 45 commander.