EMPLOYEE WAS USING A WHEEL WRENCH TO CLOSE A WHEEL VALVE. THE WRENCH SLIPPED OFF OF THE WHEEL AND HIS RIGHT HAND STRUCK A VALVE THAT WAS LOCATEDBELOW THE VALVE HE WAS CLOSING. THE RESULT WAS A LACERATION TO HIS RIGHT THUMB THAT REQUIRED FIVE SUTURES TO CLOSE. NO LOST TIME, RESTRICTED DUTY ONLY.