EE WAS RIGGING SCAFFOLDING AT B-19 CLINKER RECLAIM HOPPER. HE WAS STANDING ON A BOARD WHEN HE WENT TO STEP INTO A ROPE LADDER. THE LADDER SWUNG FORWARD WHILE RIGHT FOOT REMAINED ON BOARD, CAUS ING STRAIN OF LOWER LEFT ABDOMINAL WALL. PHYSICIAN PLACED HIM ON LIGHT DUTY ON 10-9-01.