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� � <br />Water User's Association (GVWtJA), Palisade Irrigation District (PID), Mesa <br />Countv Irrigation District (MCID), Grand Valley Irrigation Company (GVIC), <br />Southern Pacific Railroad (SPRR); various utility departments' personnel and <br />other individuals or agencies identified by ENGINEER, COtTNTY or LOCAL <br />SPONSORS �vho have pertinent lrnowledge and an interest in the area under <br />consideration. <br />2.A.3. ENGINEER shall utilize the storm drainage criteria of COUNTY, <br />LOCAL SPONSORS, Colorado Water Conservation Board, Staxe Engineer, and <br />FEMA where appropriate and applicable. <br />2.A.4. ENGINEER shall define the watershed and sub-watershed boundaries in <br />sufficient detail so that existing and potential stormwater control facilities and <br />their effectiveness can be evaluated. Hydrologic siudies shall be performed to <br />determine: 1) runoff hydrographs for each individual sub-watershed using the <br />HEGHMS, HEC-1, or TR-20 rainfall-runoff modeling program; and 2) runoff <br />hydro�graph at each hydrologic point, defined by ENGINEER and approved by <br />COUNfY, by routing and combining individual hydrographs using a computer <br />model routing program such as SWMM or other accepted model, all wori: to be <br />performed in a manner accepta.ble to COUNIY. This hydrologic information <br />will be compiled for the �-, 10-, 2�-, and 100-year retum periods for both <br />existing watershed conditions and for future watershed conditions, as projected <br />from planning and zoning maps compiled with the assistance of LOCAL <br />SPONSORS. The �00- year retum period can be computed by a straight line <br />projection from the �-, 10-, 2�-, and 100- year analyses. <br />Potential effects of possible Drain�eway improvements shall be considered in <br />the development of the hydrographs for the future watershed condition to <br />preliminarily approximate changes in stormwater routing that will occur as the <br />increased runoff due to urbanization creates and amplifies erosion gullies. � <br />Potential effects of existing and proposed publicly owned and maintained <br />detention facilities will be clea.rly identified for each watershed development <br />condition. The peak flows and volumes shall be evaluated for reasona.bleness. <br />Hydrology calculations shall be presented to COUNTY for review and approval <br />before proceeding with the hydraulic calculations. <br />All flows and volumes for the existing and future land use conditions shall be <br />evaluated for reasonableness. Hydrology ca.lculations for the existing and future <br />