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<br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />Future planning concepts by the City of Northglenn include an Automated Rapid <br /> <br /> <br />Transit system {ARD. The proposed alignment of the system will run through the Par 3 <br /> <br /> <br />golf course below 104th Avenue and west of 1-25, which is part of the major drainagewoy. <br /> <br /> <br />The system, however, will hove minimol impact on the major drainage, since the present <br /> <br /> <br />alignment only partially infringes on the flood plain. <br /> <br />CHAPTER III <br />HYDROLOGIC ANAL Y51S <br /> <br />A. General <br /> <br /> <br />The purpose of the hydrologic analysis In a major drainageway planning study is to <br /> <br /> <br />define the storm runoff peak flows, hydrographs, and volumes for various recurrence <br /> <br /> <br />interval storms at critical locations within the basin. This information is subsequently <br /> <br /> <br />used to assess the existing drainage facilities, potential flood damages, and possible <br /> <br /> <br />drainage improvements. .The overall study area was broken down into sufficient number of <br /> <br /> <br />sub-basins to adequately define the runoff peak flows and volumes using the current U.D. <br /> <br /> <br />and F.C.D. procedures. This chapter presents the details of the analysis to define the <br /> <br /> <br />required hydrologic data. <br /> <br /> <br />B. Major Sub-basins <br /> <br /> <br />The basin boundaries, as previously defined in the Project Reuse Report, were used <br /> <br /> <br />in the contract for preliminary basin delineation. A detailed investigation of the drainage <br /> <br /> <br />patterns of the area, using Northglenn, Adams County, ond Thornton maps, and numerous <br /> <br /> <br />field inspections, showed that the original basin boundaries have been modified slightly by <br /> <br /> <br />the development patterns, major thoroughfares, and irrigation canals. The most <br /> <br /> <br />significant area of change is in the vicinity of Federal Blvd. and 104th Avenue where the <br /> <br /> <br />major street (Federal Blvd.) and an abandoned irrigation canal (Niver Canal) have altered <br /> <br /> <br />the historic drainage patterns. This area (Sub-basins G-I, G-2 and G-22) is currently <br /> <br /> <br />tributary to the Niver Canal, which transports a portion of the storm runoff into the <br /> <br /> <br />Grange Hall Creek basin, and, therefore, the sub-bosins were included in the study area <br /> <br /> <br />and were analyzed accordingly. Other minor boundary changes occurred in the northern <br /> <br /> <br />portion of Northglenn, ond adjocent to the Platte River. The street patterns in these <br /> <br /> <br />areas have added some orea to the basin and removed other areas with a negligible net <br /> <br /> <br />change. <br /> <br />7 <br />