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<br />Item 23 <br /> <br />It is true that using the theoretical approach to statistically <br />compute the 5 year runoff value for Montrose Arroyo within town yields <br />a value of 220 cfs. However, if that va 'I ue is plotted as shown, the <br />attached streamflow versus frequency curve (from which the 180 cfs <br />value was derived), the unreliability of that appr'o,ach is suggested. <br />The large inflection resulting is inconsistent. In addition, the <br />impact of this difference at the critica'J storm sewer location, by your <br />calculations, is only 20 cfs (220 cfs-200 cfs capacity), which is rela- <br />tively trivial in relation to city deriv,~d surface runoff, debris <br />blockage potential and other factors. Item 23 to be discussed at the <br />meet i ng. <br /> <br />Item 26 <br /> <br />To be discussed at meeti ng. Pl ease see attach,~d overflow com- <br />putat i on sheet for Cedar Creek (i nadvertant ly omittl~d from Hydraul ics <br />Addendum). As th i s sheet i ndi cates, at Hi 11 crest Dlri ve (nea r Gi bsons, <br />etc.), only approximately 40 cfs for the 100 year storm overtops the <br />street north of the rat i ng sect i on des i gnated "2" on the worksheet. <br />This 40 cfs quantity must fill the sump ,~rea northe,~st of Hillcrest <br />before spillage COlTillences. Resultant flooding, the'refore, will not be <br />as extreme as shown on the review maps, and through the parking lot <br />areas attained depths will only be a few 'inches. <br /> <br />Other Items <br /> <br />l <br /> <br />A. Format for fl oodp 1 ai n boundary des i gnat 'i on re 1 at i ve to area of <br />shallow and hydraulically disconnected flooding. <br /> <br />3 <br />