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The outer surface, as shown on sheets 15 to 18, 20 to 23, 27 to 29, 36 and 37 of the zoning plan, is an imaginary surface located at a constant elevation of 45 m above the airport reference point but at 9 m above the surface of the ground when that elevation would place the outer surface at less than 9 m above the surface of the ground.
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