Water control gate abutment air vent

An apparatus for delivering ventilation air at atmospheric pressure to a space that, when a nappe is overtopping a hinged, water control gate panel in raised position, is:

• below said hinged, water control gate panel;
• upstream of said nappe;
• and above a tailwater level that is below said nappe and said hinged, water control gate panel, said apparatus comprising:
• an abutment sealing surface on a side of a dam abutment, said side of said dam abutment facing towards said hinged, water control gate panel;
• an abutment seal attached to said hinged, water control gate panel and in contact with said abutment sealing surface,
• at least one vent inlet that is at said atmospheric pressure;
• at least two vent outlets established through said abutment sealing surface;
• and
• vent piping passing through said dam abutment, from said at least one vent inlet to said at least two vent outlets,
• wherein said at least two vent outlets are at at least two different elevations so that, during flow of said nappe overtopping said hinged, water control gate panel in raised position, said vent piping delivers said ventilation air at said atmospheric pressure to said space through at least one of said at least two vent outlets,
• wherein each said at least two vent outlets has a respective vent outlet hole height and said abutment seal has a seal-to-abutment sealing surface contact height, and
• wherein said seal-to-abutment sealing surface contact height is greater than each of said respective vent outlet hole heights.