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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 />II <br />I <br />I <br /> <br />flow to that crossing Foothills and Arapahoe. The value for <br />Manning's "n" used across the UCBRP was ,040 to reflect <br />shallow flow through dryland vegetation, Results of this <br />analysis are tabulated below: <br /> <br />TABLE 4 <br /> <br />COMPARISON OF FHAD VS, ENGINEER'S STUDY <br />PRE-CONSTRUCTION 100 YEAR FLOOD LEVELS <br /> <br />Sect:.ion <br /> <br />FRAD <br /> <br />16.1 <br />17 <br />19 <br />20 <br />20,1 <br />21 <br />22 <br /> <br />5243.04 <br />5246.69 <br />5248.46 <br />5253.15 <br />5256.47 <br />5258,79 <br />5262.46 <br /> <br />Boulder Crk. <br /> <br />Research Park* <br /> <br />5243.25 <br />5248.53 <br />5251.33 <br />5254.73 <br />5257.95 <br />5260.13 <br />5262.32 <br /> <br />5243.25 <br />5244.38 <br />5246.67 <br />5251. 78 <br />5254.02 <br /> <br />* Before construction of wetlands. <br /> <br />3,2,5 Re~earch Park: A~-Bnilt Condition~ <br />IAS-BUILT-Aooendix 2dl <br /> <br />Again, in an effort to maintain consistency, key sections <br />were laid out so that they align with those used in previous <br />models. Due to the nature of the grading modifications, some <br />sections were bent or moved to more accurately reflect flow <br />conditions. <br /> <br />Generally, the grading modifications consisted of lowering <br />areas adjacent to the creek south of the existing concrete <br />bike path. The material excavated was used to form building <br />pOds above the published FHAD 100 Year flood profile (Fig. <br />7) , It is worth repeating here that the actual building <br />envelopes were constructed above flood elevations published <br />in the FHAD, The EXIST model showed that the hydraulically <br />disconnected flows were actually up to two feet lower than <br />the FHAD profile across the UCBRP. The construction of the <br />wetlands lowered the UCBRP flood profile still further (Fig. <br />4a,b) resulting in excess freeboard for structures on the <br />UCBRP (Fig, 7). <br /> <br />The construction of the wetlands greatly reduces the width of <br />the floodplain, confining flows to the area shown on the <br />accompanying construction drawings. Generally, this would <br />cause an increase in flood velocities. By providing <br />sufficient dense vegetation for added roughness, velocities <br /> <br />Love &. Associates. Inc. <br /> <br />Page 10 <br />