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<br />program so that the cross sectiens were oriented left..J:,J.right hlcing downstream. Roughness <br />values and expansion and contraction coefficientsliOln the 19'J7 study were adjusted to follow <br />those us,d in the other study reaches. Encroachmmtsklr spoil banks levees were reviewed and <br />those encroachments where thc spoil banks were likely (0 farl were removed to reflect the so- <br />c2.lIed failed levee condition. All left and right bank encroachments using X3 records were <br />changed to ET records to facilitate the flood way computations. <br />During initial computations all flow at cross section 36840 was indicated to be in the <br />river chalme!. Comparing the geometry of the eross scetian with the topographic mapping found <br />that the overbank ekvations in ::he cross section input data werc significanly higher than shown <br />on the topographic mapping. S mce no reason for this codd be determined, cross section 36840 <br />was reme,ved from the hydraulic mode!. <br />At several bridges in the Reach 2 model, no weir now was computed \".hen the computed <br /> <br />water surface elevations were h'gher than the road ',~mbal1kments. This was based on a condition <br /> <br />when flow was contained by the spoil banle levees. Tel better model overbank flow conditions. <br />starting elevations for weir flow at these bridges were set to the elevations wherc water woule! <br />begin to overflow across the road when flow was in the overbanks. <br />C~oss section 37945 in tGe model was a duplicate .:Jf section 38295. The right overbank <br />elevation points in these cross sl~ctions were modified (0 more closely follow those shown on the <br />topographic mapping. <br /> <br />5.7 Split Flow Analyses <br /> <br />Comparing the initial re~;ults ofthe water surface profiles with the topography indicated <br />that split flows would occur in two locations. These chided flow areas are the result of part of <br />the flow of the Cache La Poudrc River spilling into separate flow paths apart from the main <br />ell1Imel flow. One split flow area was the result of floodwaters overtopping the U.S. Highwa\' <br />85 bypas~ in the vicinity of 8th Street in Greeley. Thi, over!1ow continues to the east along 8th <br />Street with the flow spilling back across 8th Street to the river between Ash A venue and the a <br />location j'lSt west of the airport. <br />Another split flow occur, on the right bank immediately upstream of the railroad bridge <br />northwest of Greeley between 35th and 59th Avenue,.. II-is split flow occurs where the main <br /> <br />" <br />-' <br />