The provisions of § 210-149A shall not apply to restrict the height of a church spire, tower or belfry or a monument, flagpole, water cooling tank and/or tower, elevator, bulkhead, stage tower, or in the case of a power plant in an Industrial B Zoning District noise attenuation walls, or exhaust stacks, provided, nevertheless, that in all events, in the case of exhaust stacks the height shall be limited to 195 feet and, in the case of noise attenuation walls, the height shall be limited to 45 feet.