Abstract: On March 8, 1989, Employee #1 and a supervisor were in a barricaded area on the mezzanine level of number 1 acid reclaim. Employee #1 had walked north by a floor opening 31 inches wide by 88 inches long, which was a section of metal grating they had removed. Employee #1 was walking south looking through the grating showing a supervisor of a sub-contractor a section of abandoned condensation line which needed to be removed. This was located on the level below them. Employee #1 was looking back north and walking south when he stepped into the opening and fell 9 foot 9 inches to a plywood floor. Employee #1 was hospitalized with the following injuries; cracked ribs, a dislocated shoulder, and a broken nose.