EE DROVE THE YARD MAIL TRUCK TO THE LIMESTONE QUARRY AND PARKED NEXT TO THE PRIMARY CRUSHER CONTROL ROOM TO DELIVER MAIL. WHEN THE EE STEPPED OUT OF DRIVER'S SIDE HE SLIPPED ON THE SNOW AND IC E CAUSING HIS RIGHT KNEE TO TWIST. THE EE BEGAN LOSING TIME FROM WORK ON 3-7-03. RIGHT KNEE REQUIRED SURGERY.