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<br />and future conditions. On-stream detention was included in the analysis at Taft
<br />l'ill Road, at the Colorado & Southern Railroad upstream of South Co llegeAvenue,
<br />at the Colorado" Southern Railroad near Timberline Road and at Timberline Road.
<br />
<br />Table 3
<br />
<br />Impervious Percentages
<br />
<br />Land Use
<br />
<br />Percent Impervious
<br />
<br />Agricu1tur<'!
<br />
<br />1
<br />
<br />5
<br />
<br />Open Space
<br />Low Density Residential
<br />Normal Residential
<br />
<br />Resu1tsof the analysis arepresente<i in Table 5 for existing condi tionsandin
<br />Table 6 for fully developed conditions including canal importation.
<br />
<br />5
<br />
<br />Hobilellomes
<br />
<br />30
<br />40
<br />50
<br />
<br />Table 5
<br />
<br />Location
<br />
<br />Flood Discharges: Existinq Basin Conditions
<br />
<br />IOO-year
<br />
<br />CO!l'Ji1ercial
<br />
<br />95
<br />
<br />2-year lO-year 25-year
<br />
<br />Table 4
<br />
<br />Confluence with
<br />PoudreRiver
<br />
<br />430
<br />
<br />Rainfall Depths
<br />
<br />LeMay Avenue
<br />
<br />850
<br />
<br />Two-hour Duration Stonn
<br />
<br />2-year
<br />
<br />50~year
<br />
<br />500-year*
<br />3.58
<br />
<br />South College Avenue
<br />Colorado & Southern
<br />Rllilroad(Upstream
<br />of College Avenue)
<br />Shields Avenue
<br />
<br />310
<br />70
<br />
<br />340
<br />
<br />10-year
<br />
<br />25-year
<br />
<br />Loo-:i!:.a..!.
<br />
<br />1.04
<br />
<br />1.74
<br />
<br />2.47
<br />
<br />2.89
<br />
<br />2.13
<br />
<br />* Extrapolated from NOAA Atlas (Reference 19).
<br />
<br />Rainfa111ossesto infi1tration <Vld depression storage are also input pdrdmeter,
<br />to the SWMl1model. Infiltration rates wereass\.lll1ed equal to permeability rates
<br />
<br />I!rq""~"1 5~udy Limit
<br />
<br />1':(1
<br />
<br />presented in Larimer County soil surveys conducted by the Soil Conservation Ser-
<br />vice (Reference 20). This is consistent wi th the inforITldtion used in th~ Dry
<br />Creek study and by the U. S. Army Corps of Engineers for Fossi1 Creek. Depres-
<br />
<br />1.100
<br />
<br />1,400
<br />1,250
<br />1,WO
<br />
<br />50-year
<br />
<br />1,700
<br />1,600
<br />1,450
<br />
<br />1,600
<br />050
<br />
<br />,"
<br />
<br />2,150
<br />1,740
<br />1,650
<br />
<br />2,250
<br />1,000
<br />
<br />,co
<br />
<br />500-year
<br />
<br />2,600
<br />
<br />2,250
<br />
<br />2,000
<br />
<br />3,200
<br />
<br />1,720
<br />
<br />"0
<br />
<br />Flood Discharges: Fully Developed Basin Conditions (with Canal Importation)
<br />
<br />LOCdtion 2-yeal"
<br />
<br />Ca~fluef!ce wi th
<br />POlldreRiver 680
<br />
<br />sion ~tora'JP of 0.1 ind"~ for pt'rvio!Js areas and 0.1 inches for impervious
<br />
<br />areas were also values obtained fron!theCorpsofEngineersas ty pical values
<br />along the frollt range of Colorado.
<br />
<br />LeKayAvenue 570
<br />
<br />South College Avenue 540
<br />Colorado & Southern
<br />RailrOdd(Upstream
<br />ofColleqeAvenue) 520
<br />
<br />HydroloqicResults
<br />The hydrologic model Wd, run to tJeter'lline the frequencydischarg esforthe2-
<br />year, 10-year, 25-year. 50-year. lOO-year and 500.year events for both e~isting
<br />
<br />Shie1d~ Avenue 175
<br />
<br />Up5treamStudyLimit 250
<br />
<br />-15-
<br />
<br />900
<br />820
<br />
<br />820
<br />200
<br />
<br />1,200
<br />310
<br />
<br />>0"
<br />
<br />?f.f1
<br />
<br />Table 6
<br />
<br />10-year 26-year 50-yen 100-year
<br />
<br />1.340 1,730 2,000 2,300
<br />1,160 1,600 1,760 2,000
<br />\,080 1,4S0 1,680 1,90{J
<br />
<br />1,160 ;,640 2,100 3,000
<br />460 880 1 ,300 ~,OOO
<br />620 S30 1,110 1,560
<br />
<br />-16
<br />
<br />SOO-year
<br />
<br />2,850
<br />2,350
<br />
<br />~,2~U
<br />
<br />4,200
<br />
<br />3,100
<br />2,120
<br />
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