OPERATOR WAS REMOVING ICICLES FROM A CABLE TRAY TO PREVENT A FALLING OBJECT HAZARD. AS OPERATOR WAS CLEANING UP THE ICE CHUNCKS FROM OFF THE GRATING HE STEPPED ON A SMALL PIECE OF ICE AND ROLL ED HIS ANKLE. OPERATOR FELT SLIGHT PAIN BUT IT DID NOT SEEM BAD ENOUGHT TO SEEK MEDICAL ATTENTION. OPERATOR HAS BEEN WORKING ALL OF HIS SHIFT UP TO 1-21-02. ON 1-22-02 OPERATOR WAS GOING FOR