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iUiu4i ut, .t,E 15:18 F.is 503 383 4613 valmont MICROFLECT Adrian Schottroff Qwest Wireless, LLC 426 North Fairview Ave. St. Paul, MN 55104 Ph: (651) 643 -2073 Fx: (651) 642 -4719 VALKUN1 ill! tturl...1 October 3, 2000 DEC 1 1 2000 CJTE'O` LINO L- A6CE"1 Subject: Failure Modes for Tapered Monopoles and mounting appurtenances. Communication Monopoles Designed for the State of Minnesota Dear Mr. Schottroff, We understand that there may be some concern on the part of local building officials regarding the potential for failure of proposed tapered monopoles we will be quoting for Qwest Wireless project sites located in Minnesota. To address this concern we offer the following: Communications monopole structures designed by Valmont/Microflect are typically sized in accordance with the latest revision of the EIA/TIA 222 Standard entitled "Structural Standards for Steel Antenna Towers and Antenna Supporting Structures." This standard has been approved by ANSI, who has generated the standard for "Minimum Design Loads for Buildings and Other Structures ". The standard, which is the basis for design loading for practically every building code and standard in the country, has dealt with the design of antenna support structures for over 40 years. '.The ELA. standard, based on provisions of this nationally known specification, bas a long history of reliability. At its core philosophy is it's first and foremost priority to safeguard and maintain the health and welfare of the public. The EIA standard dictates minimum wind loading (the predominant loading on a monopole structure) for each county in the United States. It is Valmont/Microileet's policy to use the wind loading listed in the latest ETA standard as a minimum loading unless the customer specifies a larger value. Statistically, the wind speed listed in the EIA standard has been determined to be that wind which has an average reoccurrence of 50 years (i.e. the magnitude has a 2% chance of occurring in any one year). T'nis wind is the "fastest mile" wind at 33 ft. above ground. By definition, the "fastest mile" wind is the average velocity of a mile of wind passing a fixed point. This "fastest mile" wind is customized with height, exposure, and gust factors that apply to a particular installation which, in effect, increases the wind velocity. Page 1 of 3 10 -03 -00 17:21 =_1uU1 Cnmmunieonons 0;';, ValmontIndu :tries, Inc 3.75 25th Street SE Salem, Cregon 973C2.1123 USA 503.383.9207 fax 503.303.460 www.valmont,com TO:US WEST WIRELESS FROM:503 363 4613 p01