Laserfiche WebLink
<br />. <br /> <br />. <br /> <br />. <br /> <br />A one-foot floodway was developed for the main chmmel. A one-foot floodway <br />was not developed for the VINE, LINC, and LEMA YDS Divided Flow Paths. <br />On the VINE DFP: <br />o Only the 500-year event was determined to spill down this flow path, <br />o The 500-year discharge of 1,100 cfs was determined using an offline rating <br />curve. <br />o On the effective condition workmaps the 500-year floodplain was not <br />delineated east of Linden Street. <br />On the LINC DFP: <br />o Spills occur to the LINC DFP from the Cache la Poudre River main chmmel <br />between Cross Sections 228637 and 227437 during the 100- and 500-year <br />events. A small amount of flow (less than 7 cfs) may be leaving the main <br />chmmel during the 50-year event. <br />o The majority of the LINC DFP flows return to the main chmmel by spilling <br />over Lincoln Avenue between the Cache la Poudre River Bridge and Lemay <br />Avenue. <br />o A residual amount of LINC DFP flows are conveyed east across Lemay <br />Avenue. <br />o The 100- and 500-year floodplains were delineated on the effective condition <br />workmaps. Some differences were noted between the floodplain delineations <br />on the workmaps and the FIRM. <br />On the LEMAYDS DFP: <br />o The 100-year discharge utilized to delineate the LEMA YDS floodplain <br />assumed the Lemay Avenue embankment fails. The 100-year embankment <br />failure scenario was simulated in a separate Cache la Poudre River model <br />(LEMA Y.DAT). The LEMA Y.DAT model was not utilized in the current <br />study. <br />o The 500-year split flow discharges were computed for the LEMAYDS spill <br />over Lemay Avenue north of Mulberry Street in the 500-year Cache la Poudre <br />River Main Chmmel model (UPPER500.DA T). <br />o The 500-year floodplain was not delineated along the LEMA YDS flow path <br />on the effective condition workmap. <br /> <br />. <br /> <br />. <br /> <br />. <br /> <br />The input/output HEC-2 reports for the effective floodplain and floodway models are <br />provided in Appendix G. A digital copy of the effective HEC-2 models utilized for the current <br />study is provided on the disk included with this report. <br /> <br />. <br /> <br />3.6 <br /> <br />ANdERSON CONsulTiNG ENGiNEERS, INC. <br /> <br />COFC2003-10 Oxbow FINAL LOMR.doc <br />