Abstract: A knock-out plug having sections held together by a hinge along the top side. The knock-out plug can bend or fold along a crease in the bottom side when force is applied to the top side, or hinge side, of the plug. Conversely, force applied to the bottom side and peripheral wall of the knock-out plug tends to hold the sections together. When placed into the opening in an HSA, the edge of the opening and force of the soil against the bottom side during drilling keeps the plug in place and the sections intact. When desired, the knock-out plug can be hit or pounded on the top side, through the HSA channel which causes the plug to fold or bend and be released easily from the opening.

Abstract: The problem of removing a plug from a hollow stem auger (HSA) opening after drilling a subsurface hole is solved by a knock-out plug having sections held together by a hinge along the top side. The knock-out plug can bend or fold along a crease in the bottom side when force is applied to the top side, or hinge side, of the plug. Conversely, force applied to the bottom side and peripheral wall of the knock-out plug tends to hold the sections together. When placed into the opening in an HSA, the edge of the opening and force of the soil against the bottom side during drilling keeps the plug in place and the sections intact. When desired, the knock-out plug can be hit or pounded on the top side, through the HSA channel which causes the plug to fold or bend and be released easily from the opening.