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<br />I. I~TRODlfCTlOi'l'
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<br />A.
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<br />AuthOlri/lltioll
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<br />The Urlxm Drainage und Flood Conlrol District (UDFeD) and the Town ofEt;c, Co!or<ldo. in response
<br />to rapid development in the Eli", Planning Arc<< cast ofth<: Boulder/Weld County line near the Tov.n of
<br />Erie. sponsored an Omlill! System, Alternate Evaluation Study of lands within alid adja,,;cm to the Erie
<br />Planning Area.
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<br />This study was performed under the direction of the Project Sponsors (roDFeD and the Town of Eric).
<br />The tirm of Love & As>\wja(cs, foc. is re~)Xlnsibk for the study content. Input was obtained from the
<br />Advioory Board, woose mcm~rs included representatives of UDFeD, Town of Eric, Boulder County,
<br />Colorado Department of Transportation (CDOT). and Union Pacific Railroad (UPM). The study Wf\';
<br />prepared undeT UDFeD Agreement No. 99-04.09.
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<br />B. l'urpllseand SClIpe
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<br />Thepurpl\,eoftheoutfullsystem,planning"udyis to identify alternate m ethodstoconveystonn\.\.ater
<br />within the ~1Udy arca to cnhancc public h.;:alth and safcty and minimi?.c property damagc. The
<br />h~idro logic ,tlldy, undertakcn a, a part 0 f this project. provides publ ic and private entities a
<br />comprehensive analysis of e"isting and proposed percent imperviousn~"Ss within the study area fot
<br />catchments of approximately 100 acres. ]t identifies critical arcas of "ormwater managemcll! and
<br />provides ~tn analysis of altcrnat~'S which m:::}' Ix u,ed a:; a gtlidcline for addre~,ing water ~tlality
<br />uegradalionllltJ no"J peak It><.:r<msesresultillg jj-omclIrrem"nJ future devcloPlHem allticipated within
<br />the stud> area.
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<br />Theoulfull systems planning swd} emailed:
<br />
<br />. compiling data on existing stormwatet management f<leilit;.:,s. ,oib. exi,ting and prO!X1>ed land Llses.
<br />prnpcrtyov,ncrship.v,etlan.Js.am.llltilities.
<br />. identify'ing prob.1blc !low paths and cmchments (00 gre~lter than 130 acres in area) under current
<br />landuscusing19'i9aerialtopography.
<br />. devI'klping baw hydrologic ptediction nl<,d<.'l;; fur <.'xisting and ptujeded fUlUre percent
<br />impernousm:ss for the average storm lOA-inch). 2. 5, 10. 50, ilIld IOO-ycar storm events.
<br />. identifying exi;;ling stomlwatet management facilities and the ade'quacy of their hydraulic operation
<br />under I'xisting and proposed pcrc",nt impcr\'i"'.l~ne~~.
<br />. defming critical areas requiring stormwatcr management. exdus;"" arcas, and IOrWs (,I' !apid
<br />dewl('pment,
<br />. de,cribing mcthod~ of stllrmwater management and production of general management
<br />recommendati"ns for ,atiouscatchmetlts in the stL,J: area. and,
<br />. recommending stormwmcr management altemati\'e~ for eomideratioll by the I'roject S!"-'l1wrs. the
<br />Achi,ory Clllllmiuce. and public' and priv'l1e entities
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<br />I he prdil1lin"r~ de~igl1 "I' th\.' attemale sekclcd tl\ II1\.' I'mkc.t "r<\lI"'r., i, addressed in " s\lr.,eq\JCnl
<br />report.
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<br />C Ila~djnelnformatioll
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<br />Illtormationuscd for the outfall sluJyindude,;:
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<br />. Topographic mapping from aerial photography tlown durmg J\.larch. 1999 with a 2-1<.\ot contour
<br />interval and dectr(lfJically filed on AlItoCAD Versivll 14 (ACAD-14) (ALtee Con,ultants. Ioc..
<br />19(9),
<br />. Land u>e maps f(lr the Town ofEri~ (Town of Fri\:, 19(9) and Cil~' of Lafayene (C;t~ of Lafayette.
<br />19(7),
<br />. NRCS wils maps for BOllldcr (SCS, 1975) and "Veld Cotmties, Colorado (SCS, 1982).
<br />. Ditches and reservoirs holding water rights on file with tbe State Engineer's Oflke (SEO) and with
<br />Boulder COllnty (Boulder County Transportation Department, 1999),
<br />. Flood Insurance Studies (FlS) and Flllod Insurance Rate Maps (FIRM) for BOlllder and ('..oal Creeks
<br />updated in 1995 (FEM'!", 1995; USDA SCS. 1976; and WRC Engineering, [ne.. 19(6)
<br />. FrS (Draft) for Bullhead Gulch (Taggart Engineering Associates, Inc.. 1998), and,
<br />. Various drainage rcport~ (Eric Drainage Reports. 1995-1999) lor existing and proposed
<br />developments and master plans within the sllldy area provwkd by tm: Town of Erie.
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<br />I), ne~lgD Procedures
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<br />Design procedures and parameters u>ed in the study tollow recommenililtions in UDFeD Urhun Srm'm
<br />n",inaw' Crila!a Man/wi (lIDFCD. 19(9) and Bml/"er COlI'lIy .\wrmw(l[er Manage"'!'''' Ham",j
<br />(Rvulder County, 19.'\4). COlllpllter models uwd in the ~tudy indude CUHPF (UDFeD, 199.'\).
<br />U)S\l,"~1\\'1N (lmSWM) (lJ1JFCD. 199.'\b), and IlY-8 (Federd! Highway A<lministration. 1966).
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<br />The flcwdplain of Bould~'r Cr~>ek and Coal Creek is r..gulated by the F<::deral Emergency Managem<::l1t
<br />Agency (FE7\.IA) under the :--<iltional Flood Ill,urance Ptogram. A Flood Insurance Study (F1S) has lx.>ell
<br />prepared for portions of Bullhead Gulch and Prince Tribut,,,y (T"ggart Engineering As,ociate" !nc..
<br />19(8)alldiscurrenl1>ullderre\'iewhyFE~1A
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