EE WAS LIFTING STEEL PLATE DECKING PIECES (2' X 5' X 3/8"") THAT COVERED HYDRAULIC PIPING LOCATEDIN A MOAT AROUND A CONCRETE FOUNDATION. A FELLOWWORKER WAS HELPING HIM, USING A PINCH BAR AND BE NDING OVER TO GRASP THE EDGES OF EACH PIECE THEYWERE LIFTING AND MOVING THE PIECES A SHORT DISTANCE. INJURED ALLEDGES THAT HIS BACK STARTED HURTING AFTER MOVING 6 OR 7 PIECES DUE TO TWISTING.