EMPLOYEE WAS CLEANING TUB PLUGGED WITH SOLIDS, HE LOST HIS BALANCE & FELL ONTO CHANNEL ON LEFT RIB CAGE, KNOCKING THE BREATH OUT OF HIM. HE LOST HIS GRIP & CONTINUED TO FALL, HITTING HIS BACK TWICE ON STEEL THEN LANDING ON THE 8TH FLOOR. PAIN IN HIS LEFT SIDE AND LOWER LEFT BACK, HE FELL 6'.