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<br />To supplelrrent the Dis(:hart:<O Probability CUT'.'es, plotted <br />hyurographs ~ave been cnclos,.,rl to show the hydrogr<lphs <br />based on proJectod development at a selected rlesign <br />point. Flood hydrographs for the 2, 5, ]0 ar.d 100.ye;<r <br />StOn:l frequencies at the confluence with the SOllth Platte <br />River, are shown on Figure 3. <br /> <br />SECTIOr.; IV <br />HOeD pl.An' ANALYSIS <br /> <br />Once the ":esig~ hydrographs \-Iere calcul,ltod [or the varieus <br />freque:lcics, it ",as possible to cvaluat<: the cllannel rela- <br />tive to the flood plain for each storrr. frcquency and the area <br />of inundation resultir,g from oach flood. The flood plain <br />evaluation ,,'a~ corr:pleted with the use of the Corps of fngincers' <br />P.EC-2, "Water S\lrface Profiles" conputcr program. This pro- <br />gram l;3S developed by the Corps of Fngir.eers at the Hydrologic <br />Engineering Center in Davis, California, and h:J.s been accepted <br />as one of the most thorough and cooprehensivc co~puter pro. <br />grams for calculating water surface profile:; in natural and <br />urban channels. This program has also been us<,d in other <br />studies of this type in the nenver Metropolitan area. for the <br />Urban Drainage a.nd Flood Control District. <br />To evaluatc Slaughterhouse Gulch, 42 channel cross sections <br />,;ere taken from the 1" " SO' :;calc rr.apping available for the <br />project. The South Tributary was evaluated with 7 CrO$S <br />sections taken from the mapping. <br /> <br />The Mannings' roughness factors, used in the computatior: of <br />the ,\'ater surface profile, varied fror.l 0.02 to 0.05 in the <br />channel and 0.04 to 0.07 in the overbank areas. <br /> <br />Flood profiles \,ere run on both the strcams fOT the four <br />st(lrm frcqlle:1cic~. CQncurrent with the charnel evalllat i')n, <br />structures sJong the channel "'fro also ;;m'lyz<.;d. St.rcct-chanr.cl <br />cros.si"l( structure capacities "ere cO::lputcd aleng with ratir.~ <br /><.;urV0S Ier each crossing by means of the ll'ate-: Surfacc Profi les <br />computer program. In addition, three ~tructuros in th~ study <br />area "ere evaluated longhand due to their complexity. The <br />structures evaluated by hand ~ere the cenduit under Prince <br />Stroet ~nd Santa Fe Drive, the storm se"'er from Poworg Park <br />to Winder~ere Street and the storm se~er on the South Tribu- <br />tary. <br /> <br />The conduit under SOInta Fe Drive and Prin,",,, Street \,'as <br />In~tallec in segments. The sizes ran,:e from a 48 -inch con- <br />crete pipe at the inlot to oti-inch concrete pipe ,,"'hi,-il th"ll <br />eJ~pties into a 10' x 10' box culvert. The conduit system <br />'~a5 analyzed .1s~uming inlet control at tho 4H-illCil pipe. <br />The I:!axi~um capacity before overtopping was calculated to be <br />approximately 130 cfs. <br /> <br />The ~tori:l sewor from ',\'1 r.d,- rll"....re St re',' t t(l P~"'t'r$ Pu rk \'<lr i es <br />in sizo froTa t"o 3D-inch m..tal pipes to a 42-il:cll concrete <br />pipe, to a 36- inch con<.:ret<: pipe, just recently il,stalled in <br />Dorry Circle, anu a 3('-incr. pcL'l1 pi.pe U\\,-let flom POh'ers p"rk. <br />Thi~ se..er systo~ 1>115 anal)'zod usi:1,Q the Ilernoulli Equ"tio~ and <br />computing the m<lximum allowable hydr"ulic: grade liue and J.is- <br />charge through the system "ithcut surcharging any inlets. The <br /> <br />-11- <br /> <br />- 1 2 - <br />