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<br />Jrea,hav"o""nSel.x:t,,_ tor this stUJy.
<br />
<br />uti I Fl"'U for grazing, ~j H, fhe ;n.rerspersing of SCl'1la hay lands. On
<br />t~e main stem uDstrean of th" South Fork confluence, residential
<br />development has fully utilized thGflood plain. Along South Fork
<br />from East IO<:thAvenuetotheupstreilmstudy Ilmits,foursmall
<br />detention dams and reservoirs located On the stroom are oncouraging
<br />th~ urbanization of this area. Immediately u?stream 01 tho study
<br />raac:honthaSouthFork,lfighlandMemoryG.;.rdensCematerystraddles
<br />tc,estrearl,andagolfcourselsstlll furtherupstrea'1. ihespread
<br />01 urbanlz~tion is expected to continue downstream WiTh the eastward
<br />exp"nsion of Northg lenn and Thorntof1. Va Iley widths increa~e pro-
<br />gressively in the downstream direction, ter~if1ating in a broad llood
<br />plain near the mouth. AsareSu!tof this valley topography, tre-
<br />qu~nt flooding of the valloy floor may be expected. These factors
<br />would increase the potential for flood damages as development con-
<br />tinues downstreaM toward the moYth. Tho stream profiles and cross
<br />sections presonted in this report should be useful guides and refer-
<br />ences forpl"nning future developments and pointing outh(lzardou s
<br />f lood ~ones.
<br />
<br />Flood Contro I I ITIproveme~ts
<br />Sioee tne study "r~~ is presortly undeveioped, no major
<br />Ilood control projects have ~oen cc"structcc. Loc~ I '~ilter stora9P.
<br />"'J~erv:li rs haVE! been COnS tructed i n the ~ppor bas i n as a re5u I.,. of
<br />uroan gro~th. Theso reservoirs general IV do not ir>::lude 5pecHic
<br />flOQ<1control stor"ge, and the only cootrol exerciS01 is through
<br />discharge lir1itation"ftheoutl'lts. There are no Corps of Engln'lers
<br />flood control projects in thO ~asjn.
<br />
<br />studv Reae:h
<br />
<br />ThcstudvreachbGginsattheSouthPiatteRiv'lrand
<br />tollo'l/5 Grilnge l1a II Creek upstrea'" to tho junctiOn wi th Sout~ For~,
<br />about 4 miles, aM On tho South Fork from its confluence wih the
<br />m"in stem upstream to Nort,~ 'bsnlngto1 Bouievard, at;o'Jt 1.3 ",iles.
<br />,'k> flOOd outlines are SMwn on ~iate 30 for t:", Grangi< liall ~reek
<br />reach from the lTIoJn to Riverd"le 110,,". Tile comt;inat;o1 ot ~tc('p
<br />S lo"es. sha i low 1100:: depths, ~nd I ir1i t('d <;hilnne I ca~ilcity for toi 0
<br />rood co,..,~in" ~o ':\<Jko the flood =tiinc ;n::eterC'in~t" witho~t additiooill
<br />extensive topogr~p_~lc 5urvuys. llowov,,~, to provido 'Ju I::ance in th<!
<br />Drop",r ,'50 ot t.~e flood ~ la i '", the extent of f! coJ i n!l ',,"s est i mat,~d
<br />".1J " ""te'r Sur I "~,, ~rofil<l co.vo IOP0ct lor th,) IOw()r rGclcl,. Tn i s
<br />prOf; I~ I 5 includ~G On plate 32. but an octuill t lood may di /fer from
<br />th"tshown.
<br />
<br />Bridges Across th~ StrGaC'
<br />Two h ighwaV bridges cross the ma i n ~tCM of Griln<)o !-fa II
<br />Creek in the st~dy reach. I n addition, the Union Pacl f ic Rai IrOild
<br />crosses th€streamon" hiqh "",bankm€ntwith d multi-plate pipe to
<br />e:onvey stre",'" f lows. No d~ta are .:!va i I"b Ie on the E~st I04th Avenue
<br />crossing of South Fork. Table 9 d;spl~ys pertinent elevations for
<br />th"s~ strue:tur~s and shows their r~lat;onshjp to the Int~rmodiate
<br />Region" I Flood. Theplansandprofiles,plates30through32
<br />i nd ie"Te tho f 100<1 poten-"idl at the ~~idges and tMei ~ ostimated
<br />offects On tho p~SSQg8 of the Intermediate RegionQI and Standard
<br />P,-ojee:tFioods. Crosssectionsonpiiltel7showthedep-rhanawiotn
<br />of the I ntermed ia-l-e Regional and Standard f'rojectFloods.
<br />The Union Pac; f ie: r\1l i IroaJ emban~-"'ent crossi ng the stream
<br />a bOut a th I rd Of " M I I e COWn5 tre"," f rom tho SOLl tl, For k j u net i on ~Ias
<br />
<br />Covelop~nts in tho Flood FI"in
<br />Urbanilation in thO 5tJdy reacn i> occurrin2 r~ '10
<br />~xtrom~ upstrea," portio~ with the rEl'"lcli nder st i II rur~ I in e:harae:Ter.
<br />
<br />Fr ()I.' dlt, jUfll.:i ,un ",f Gr<l",;" i~.j i I C, ,.,..i<. C"~ j-,,,., 30urh Pld!.;" :,i v,." io
<br />Riv<)rc~ Ie !,o"d, ~~" f l<:x1d r I ai n i " crcr lilnd wi~h alar,]" ;\octinn uno"r
<br />i rris"tion. UpstredOl trorr Hiverdale ,10dd ~o I rm~ Drive on t~., "",i n
<br />ste'" aN! East 104tl, Iw<)nJC <on Sou~" "ork. +", lar.ds i."" lor(J€ly
<br />
<br />f.',
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