EMPLOYEE STATED HE WAS FIREBOSSING WALKING THE BELT SLOPE WHICH IS ON A 17 DEGREE INCLINE AND STEPPED ON AN PIECE OF LOOSE COAL/ROCK AND SLIPPED/TRIPPED CAUSING HIM TO STRAIN HIS LOWER BACK. E MPLOYEE HAS A HISTORY OF BACK RELATED PROBLEMS. HIS FIRST LOST WORK DAY DID NOT OCCUR UNTIL 7/16/03.