PLANT MGR WAS A PART OF IEEE CONFERENCE TOURING THE HOLCIM MIDLOTHIAN PLANT WHEN EE STRAYED FROM THE GROUP TO LOOK AT A FLY ASH FEEDER UNDER AN INTERSTICE SILO AND STEPPED OFF AN ELEVATED PLATFORM AND FELL APPROX 42"" TWISTING LEFT KNEE. SURGERY WILL BE REQUIRED & THERE IS CONCERN FOR A PRE-EXISTING BLOOD DISORDER