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<br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />'I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />The condition with ice is believed to be somewhat conservative as the Poudre River is <br />normally very low throughout the winter. It is doubtful that the ice thickness would develop <br />to produce a load of 10,000 pounds per linear foot as is typically used on dams. <br /> <br />An analysis of the pier to base slab joint was also conducted to determine the potential for <br />movement of the piers under the NORMAL LOADING CONDITION indicated above. The <br />analysis was based on a sliding friction type of analysis rather than the concrete shear strength <br />concept due to the erosion of the joints. Based on this analysis and assuming 25 percent loss <br />of contact at the joints, the factor of safety against sliding was determined to be 1.25. Of <br />course, there is more than just friction holding the pier to the apron. Therefore, the factor of <br />safety is conservative. For concrete dams, a factor of safety of 3.0 would be required for <br />sliding between components. <br /> <br />Based on our analysis, it would appear the SU1lcture is stable under most conditions. This <br />analysis, however, is based on various assumptions; and more specific physical information <br />would be required to conduct a more in-depth analysis of the structure. The concrete strength <br />and whether the piers make good contact with the base slab and whether the base makes good <br />contact with the rock foundation would have to be determined to make a final prediction of <br />the structure's stability. There are areas where the concrete is deteriorated and does not meet <br />the strength criteria used in the analysis . We know the concrete to rock interface is lacking in <br />some areas. These items would have to be addressed and repaired to ensure the long-term <br />stability of the structure. <br /> <br />2. Proposed New Structure - Stability. One alternative examined as outlined in Section A.S <br />below is to replace the existing structure wim a new structure. This structure would be <br />composed of a concrete base slab and seepage cutoff, an overflow wall section, and a control <br />gate in the same area as the existing sand gate. This alternative is described more thoroughly <br />below in Section A.S. <br /> <br />The stability of this section was determined using the same conditions as outlined above for <br />the existing structure: USUAL, UNUSUAL, arid EXTREME. <br /> <br />PAGE8.CbapcerV <br />