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The outer surface, shown on Department of Public Works Plan S-352 dated July 20, 1977 and prepared for the Department of Transport, is an imaginary surface located at a common plane established at a constant elevation of 150 feet above the assigned elevation of the airport reference point, except where that common plane is less than 30 feet above the surface of the ground, the imaginary surface is located at 30 feet above the surface of the ground.
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