EMPLOYEE WAS SUPERVISING THE COMPLETION OF THE RETAINING WALL AT THE PRIMARY CRUSHER. HE WAS AT THE TOP OVERSEEING THE PLACEMENT OF PRECAST CONCRETE PANELS (STACKING) USING AN EXCAVATOR TO SET THEM. THE MACHINE WAS SETTING ONE DOWN, WHEN IT CAME FORWARD TOO FAST CAUSING SLACK IN THE LIME. IT HIT (THE SHACKLE) HIS FOREHEAD, CAUSING THE LACERATION.