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<br />Avenue. Flowing eastward, much of the spill overtopped the Lincoln <br />Avenue roadway and flowed directly south back to the river. Any water <br />which remained north of Lincoln Avenue flowed east into the Dry Creek <br />drainage. The aroount of the spill from the river was computed using <br />split flow routines in the UPPER and UPPER500 files. The file LINC9l <br />modeled the spill flow path and ccrnputed the spill from this path back <br />to the river. <br /> <br />At section 228800, the upstream side of the Burlington Northern <br />bridge, flows from the 500-year flood spilled east along Vine Drive. <br />The amount of flow which spilled was determined from a rating curve <br />for normal depth flow over the control section at this location and <br />was subtracted manually from the UPPER500 discharge. The spill along <br />Vine Drive flowed into the Dry Creek drainage and returned to the <br />LOWER500 model via Dry Creek. <br /> <br />Downstream from Taft Hill Road there were large excavations on <br />both sides of the river. Oonditions were also ccrnplicated by the <br />presence of two diversion structures (for Larimer and Weld Canal and <br />Arthur Ditch) with significant backwater effects. Due to the <br />elevation of protective berms, during the l00-year and lesser events, <br />most of the effective flow was on the left bank. For several hundred <br />feet downstream from the Taft Hill Road bridge, a high sand bank <br />separated flow between the river channel and the left overbank. To <br />account .for this division, the aroount of the weir flow over the left <br />road approach to the bridge was subtracted from the total flow within <br />this short reach. The remaining flow was confined within the banks to <br />below the Arthur Ditch Diversion, where the division ended. Because <br />of the short distance involved in the left bank split flow path, it <br /> <br />8 <br />