EE WAS REPAIRING ""BECK"" ON TOP OF BAGHOUSE.THEY WERE FINISHED AND WERE CLEANING UP AND PACKING UP THIER TOOLS. THE TOOLS WERE PLACED IN A 5 GALLON BUCKET AND AN AIR CHISEL WAS STICKING OUT 13"". EE TRIPPED ON WALKWAY THAT WAS LIFTED FOR THE WORK AND FELL ONTO THE BUCKET AND CHISEL. STOMACH AREA WAS SORE AND TENDER.