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Hennepin County � _, <br /> AET Project No. OS-06764 ��� -;�, ��-�.,� ��,,� ������ <br /> May 24, 2016 <br /> Page 2 of 5 <br /> Analvsis Results <br /> Review of Tower Support S, s� <br /> A review of the guy wire tower support system was performed based on a design wind of I 10 <br /> miles per hour. As noted above, we assume the County will follow the installation instructions <br /> included in the Campbell Scientific Instruction Manual for UT30 Tower-based Weather Stations <br /> with the listed exceptions. The design of the tower structure and guy wire assembly (i.e. <br /> materials, connections, etc.) has been engineered by Campbell and was not included in our scope <br /> of services. <br /> Based on the requirements of ASCE-7 and the 2015 Minnesota Building Code, we estimate the <br /> maximum tension in the guy wires with a 110 mile per hour wind will be approximately 990 <br /> pounds. Our analysis took into account ice formation on the tower. Refer to the Helical Anchor <br /> Analysis section below for our opinion on the adequacy of the proposed screw anchor to resist <br /> this load. <br /> If concrete deadmen are used to anchor the tower and guy wires,the Campbell design installation <br /> procedures are appropriate with the exception of the size of the guy wire deadman. We <br /> recommend the concrete deadmen for the guy wire anchor be at least 27" x 27" x 27". Refer to <br /> the Deadman Anchor Analysis section below for our recommendations regarding uplift <br /> resistance and backfilling of the deadmen. <br /> Site Soils <br /> We completed a hand auger soil boring at each of the tower locations. Subsurface Boring Logs <br /> for each of the five locations are attached in the appendix. A summary of the soils encountered at <br /> each of the five locations is provided beiow: <br /> • 6 Mile Creek Road <br /> The soil boring encountered approximately 1 '/2 feet of dark brown silt topsoil. Fine <br /> alluvial lean clay with sand was encountered beneath the topsoil and extended to a depth <br /> of approximately 6 feet. The underlying soil consisted of a thin layer of coarse sand over <br /> clayey sand that extended to the boring termination depth of approximately 7 feet. <br /> • Rolling Hills Drive <br /> The soil boring encountered approximately 1 foot of dark brown lean clay topsoil over <br /> fine alluvial lean clay with sand extending to a depth of approximately 2 %2 feet, and then <br /> clayey sand extending to the boring termination depth of approximately 7 feet. <br /> • Electric Drive <br /> The soil boring encountered approximately 1 foot of dark brown lean clay topsoil over <br /> lean clay with sand extending to the boring termination depth of approximately 7 feet. <br /> • Crow Hassen Park Reserve <br /> The soil boring encountered approximately 3 inches of dark brown silty sand topsoil over <br /> silty sand extending to a depth of approximately 6 feet and then lean clay to the boring <br /> termination depth of 7 feet. <br />