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<br />~ <br /> <br />MONTROSE FLOODPLAIN STUDY <br />COORDINATION MEETING OCTOBER 26, 1978 <br /> <br />AGENDA ITEI1~. <br /> <br />A. Presentation of Hydraulics Technical Addendum <br /> <br />1. Computer sUlll11ary printouts for all streams, photocopies of <br />Cedar Creek, Montrose Arroyo worksheet ~lpping and profile <br />contained in separate volume. Additiona'l' copies will be pre- <br />pared and sent, along with Dry Cedar Creek fl oodpl ai n mappi ng. <br />and profil e. <br /> <br />) <br /> <br />2. There are several computer rel'uns necessary due to initial iza- <br />tion revisions. These will bE! bound into the follow-up <br />copies of computer pri ntouts, and identified where I'evised. <br /> <br />3. Discrepancies between digitized data and mapping. S,ee sample <br />section plot. <br /> <br />4. HEC-2 Procedure: Backwater analysis was initialized at each <br />crossing, based on a rating of that crossing. Where that <br />elevation resulted in super cl'itical flOl~, depth was adjusted <br />to critical depth. <br /> <br />5. In preparing mapping and profi Ie, data was cross checked for <br />a consistent description of flooding. <br /> <br />6. Sixteen drainage problem area solutions, five year <br />floodpl ai n. <br /> <br />a. Indexing flood floWs to 5 year level results in a flow <br />of 175 cfs in Montrose Arroyo. This urban flooding <br />resultant from spilling from the Arroyo will not occur , <br />as all crossings are adequate. The 5 year floodp'lain then <br />is a result of only urban generated runoff . <br /> <br />Sixteen problem areas were ,analyzed considering il~dividual <br />drainage areas. Flows haVE' been defined for the !5 year <br />frequency. storm at each location, baSE!d 6n the Rational <br />Formula. The reason for thl~ problems generally i:; gutters <br />which do not drain; inadequate inlets to the storm sewer; <br />inadequate storm sewer; or 110 provision for drainage. <br />Recommended solutions involve handlin!1 the problems indi- <br />vidually, or where related ,as a system. <br /> <br />...n",',_)-_"_';'.,":';' <br />