EE WAS CARRYING A BELT ROLLER THROUGH A MANDOOR TO THE BELT ENTRY. AS HE STEPPED THROUGH THE MANDOOR HIS FOOTING SLIPPED AND HE TWISTED HIS BACK. HIS BOOTS WERE MUDDY FROM WALKING THROUGH A WE T MUDDY AREA ALONG BELTLINE. THERE WAS NO DAMAGETO ANY EQUIPMENT OR IMPAIRMENT TO THE OPERATION.NO OTHER FACTORS WERE INVOLVED.