AN AIRSLIDE CONNECTED TO THE DISCHARGE OF A SILO BECAME PLUGGED WITH MATERIAL. EE OPENED AIRSLIDE & REMOVED CHUNKS OF MATERIAL & THREW THEM DOWN ONTO THE ADJACENT WALKWAY. AFTER CLOSING AIRSLIDE THE EE STEPPED DOWN ONTO THE ADJACENT WALKWAY & STEPPED ON ONE OF THE MATERIAL CHUNKS. THE CHUNK ROLLED & HIS ANKLE TURNED.