The driver of the 18-wheeler that slammed into the back of a school bus this week faces O-W-I charges.  Forty-two-year-old Wayne Murphy of Indianapolis is being held in the Columbia County Jail.  A 15-year-old Milwaukee girl who was sitting in the back of the bus, Alexis Jenkins, is at Children’s Hospital in Madison listed in critical condition.  A second student is in good condition.  Twenty people on the bus from Hope Christian School were injured while they were on a field trip to the Wisconsin Dells.  The bus was parked on the shoulder of Interstate 39 near DeForest when it was hit.