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<br />22 <br /> <br />22 <br /> <br />Table 7. Summary of Residential Flood Damages - Town of Ha~tun, Colorado. <br /> <br />by flows cdgi oating in the offsite areas is non~exi stent, excepting a singu- <br />lareventin the early 1960's. In fact, in recent years. no recOllection of <br />flood water entering the Town from basins 1 and 2 is known. This is most <br />likely the result of the cultivatIon practices used in these agricultural <br />areas, the high infiltration rHeof the Haxtun lOdrlfl sands whiCh predOlllinate <br />within these basins, severdl County roadcrossiogs which prevent runoff from <br />moving downstream, and the existence of depression areas with no outlets <br />throughout the upstream cultivated areas. <br /> <br /> Depth of Flooding <br /> No. of Residences (ftl Estimated <br />Location 'II/Basement '0110 Basement lO-Year IOO-Year Yijl11e <br />logijnAvenlle, <br />BrYijntoChijse Sts. 9 1 1.5 2.1 $ 586,000 <br />LogijnAvenlle, <br />Fletcher St. toRR 1 2 0.6 0.8 $ 152,000 <br />Intersection, Fletcher <br />ijnd Washington Aves. 4 0 0.8 1.0 $ 240,000 <br />Joe Avenue "d <br />Fletcher St. 1 0.8 1.0 $ 46,000 <br />Utijh Avenue, <br />Fletcher St. to RR 2 1 0.5 0.8 $ 166,000 <br />TOTAL 16 5 $1,190,000 <br /> <br />Basis of Design <br />The hydraulic analysis of the existing systems and eventual alternatives <br />combined the HEC-2 analysis with nonnal-depthcalculationsforpro posedstonn <br />sewer systems. The anijlysis enabled the planning of improved channel sec- <br />ttons,stonnsewers, and crossings for later cost estimation. <br />Basic design crtterla contained in the Urban Orainage and FloOd Co ntrol <br />Oistrict"StonnOrainageCriteriaManual"werefollowedwhendesigningstreet <br />and drainage fijcilities for the alternative evaluation process. All local <br />facilities wtlre designed to flow full. The channel draining the Town was <br />designed to convey the fllll IOO-yearfl0w. RoUghnessvijlllesforthehydrilUlic <br />CalClllijtions ranged from .025 for natural stream bedding to .045 in areijS <br />where natuNl chijnnels Vlere deemed to be overgrown. <br />The following design criteria were followed in the analysis of existing <br />and proposed systems: <br /> <br />1. Minimum roughness values. <br /> <br />a. Concretepipe,channelliningsandcu1verts, .013. <br /> <br />b. Corrllgatedmetalplpe(CMP), .024. <br /> <br />c. Corrugatedmetalplpe,11ned, .013. <br />d. Natural streambeds, .035. <br /> <br />e. Matntijined grasslined channels, .030. <br />f. Street sections, .015. <br /> <br />2. Design velocities for grassHnedchanllels were limited toftve feet per <br />second,with'maxtmumsideslopesoffourhorizontal to one vertical. <br />