At approximately 12:50 p.m. on 5/02/2018, an employee was operating a remote control crane in the rolling mill. He and three other mill employees were changing out a mill stand. He had the remote control box for the crane hanging from a strap around his neck. When the stand is slid out of position for removal, an opening to the flume approximately 2' x 5' is exposed until the stands are swapped and a new stand slides into position. While positioning the crane to pick up the entry box, the employee stepped within about 2' of the opening onto a pile of mill scale. Under his weight, the mill scale gave way, causing his feet to slide out from under him. Subsequently, he slid feet first into the flume. He landed on the scale in the flume, a drop of approximately 10", sustaining broken ribs and a broken shoulder.