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<br />I <br />'. <br />, <br />'. <br />I <br />I, <br />I <br />I <br />. <br />. <br />I <br />I <br />I <br />I <br />I <br />I <br />II <br />I I <br />I <br />I <br /> <br />The 2-year event will impact all bridges, but once water is over the streambank, <br />velocities are reduced due to increased overbank conveyance. Grouted rock and buried <br />riprap in transition zones are shown for protection at each bridge (Drawing No.8). The <br />estimated cost for each bridge is about $21,530 each, with approximately $3,700 for <br />erosion protection, for a total of $100,920. <br /> <br />Therefore, the total capital construction costs associated with Big Dry Creek including <br />bridges is estimated at $413,190. The cost including a 25 percent contingency is <br />$516,600. The contingency is for construction contingency (10 percent) and for <br />engineering design fees and construction services (15 percent). The above stabilization <br />recommendations are a balanced approach between initial capital construction costs, <br />ongoing maintenance costs, and golf course landscape aesthetics. Larger rock sizes and <br />more extensive stabilization would cut ongoing maintenance costs but increase initial <br />capital construction costs and would not be aesthetically pleasing. <br /> <br />If no stabilization were provided, the stream would migrate because of lateral erosion at <br />the toe, resulting in near vertical banks and loss of fairways, greens, and wetlands. The <br />vertical banks would be unsafe for golfers and create a risk liability to the City. <br /> <br />Wetland vegetation will help stabilize banks (dependent on the type), but cannot <br />stabilize the toe because a significant root structure will not establish in the constant <br />zone of saturation. The plan described here is a balance, which should keep the stream <br />in the same alignment and be an attractive balance of varying slopes, vegetation, and <br />rock features. Grassed areas generally predominate along fairways, with other wetland <br />vegetation (brush and cattails) in other areas. The system, however, may require further <br />rock landscape and planting work from time to time, as is the inherent nature of soft <br />channel linings. <br /> <br />PREVIOUS AND CURRENT MODELING OF 1-25 <br />Urban Drainage and Flood Control District <br />The proposed golf course grading will not raise the 100-year water surface upstream of <br />1-25. It has been stated previously that a water surface of 168.1 feet (167.3 MSL) was <br />calculated for both existing and proposed conditions. <br /> <br />III-I0 <br />