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<br />was not modeled separately. Water surface elevations from the left <br />bank were taken from the failed bank condition used for floodway <br />delineation. <br /> <br />Above Taft Hill Road, a spill occurred on the right bank between <br />sections 243330 and 244850 for the 500-year event. This spill was <br />computed using a split flow routine in file UPPER500. The right bank <br />spill flow path was rrodeled with the file OVNDV500, which returns to <br />the river downstream of section 240020. Farther upstream of Taft Hill <br />Road, the OVNDV500 flow path received more flow from spills across the <br />railroad embankment paralleling the river. These flows were computed <br />with a separate split flow routine. At section 250470 flow spilled on <br />the right bank into a large gravel pit and returned to the channel <br />between sections 247610 and 248490. The amount of this spill was <br />computed with a weir equation at the edge of the gravel pit. The <br />spill flow path was not modeled. <br /> <br />Channel roughness factors (Manning's "n") from the 1989 study were <br />used without change. A roughness value of 0.035 was used for the <br />Cache La Poudre River channel. The roughness values for the overbank <br />areas were modified to reflect current conditions. OVerbank roughness <br />values were furnished by the study sponsors and were used in the <br />revised models. The overbank "n" values used in this study ranged <br />from 0.04 to 0.104. In areas where flows were separated from the <br />channel, roughness factors used were in the range for overbank areas. <br /> <br />The starting water surface elevations for the main channel of the <br />Cache La Poudre River at the downstream study limit for the LCWER and <br />LOWER500 models were taken from those developed for the new 1992 Flood <br />Insurance Study for Larimer County where that study terminates just <br />downstream of Horsetooth Road. These water surface elevations were <br /> <br />9 <br />