EE WAS CUTTING A PIECE OF EXPANDED METAL OFF AT #4 BELT HEAD THAT WAS STICKING OUT IN WALKWAY. A SPLICE IN BELT CAME BY HIT EXPANDED METAL, EXPANDED METAL HIT EE'S RIGHT LEG ABOVE KNEE. EE ST EPPED BACK AND FELL OVER WATER LINE, MAY HAVE TWISTED RIGHT KNEE, IT WAS SWOLLEN A LITTLE.