EE WAS LOSENING BOLTS ON THE LID OF PRIMARY CRUSHER TO DO MAINTANCE INSIDE WHEN THE WRENCH HE WAS USING SLIPED OFF CAUSING EE TO LOSE HIS BALANCE AND FELL BACKWARDS APPROX. 3 FT LANDING ON A S UPPORT TOWER FOR THE CRUSHER LID WHICH INJURED HIS LEG HE CAUGHT HIS FINGER TRYING TO STOP HIS FALL.