All vent pipes in outdoor locations shall be located at least ten (10) feet from an adjoining property line and shall extend at least ten (10) feet above ground level. All vent pipes shall be supported by at least the equivalent of a four (4) inch by four (4) inch nominal dimension redwood post securely anchored in the ground. One-piece galvanized iron vent pipes may be self-supporting if securely anchored at their base in concrete at least twelve (12) inches in depth and extending a minimum four (4) inches out from the pipe.