EE WAS WATER BLASTING MATERIAL BUILDUP OUT OF THE 3RD FLOOR PREHEAT TOWER RISER DUCT WHEN A BIG CHUNK BROKE LOOSE & HIT THE WATER BLASTER WAND TIP. THE SEESAW EFFECT THREW THE EE AGAINS THE ADJACENT HANDRAIL CAUSING AN IMPACT TO HIS LEFT SHOULDER & UPPER BACK. THE CHUNKS THAT FALL INSIDE THE DUCT CAN NOT BEEN SEEN THRU THE 8"" PORTHOLES THAT THE WATER BLASTER WAND IN INSTEREDT THR