EMPLOYEE REPORTED: HE AND A COWORKER WERE LOADING BELT STRUCTURE IN THE 16 LEFT BELT ENTRY, HE STEPPED ON A SLICK PIECE OF ROCK, LOSING BALANCE AND FELL ON HIS BACK. SINCE THE DATE OF THE INJU RY, HE HAS EXPERIENCED INTERNAL PAIN TO HIS BACK, LEFT KNEE AND RIGHT HIP. BECAME A LOST TIME INJURY ON 9/14/02. (BECAME REPORTABLE 9/14/02.)