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<br />SeCTION I <br /> <br />d. Flood Danage Analysis <br /> <br />L\TRODlJCTIO~ <br /> <br />The expected eccnomic flood damage for t);r: vanOllS <br />storm fret;uencie~ has been calculated and cOTl'H'r~ed <br />in to an avt:: rage ~il\nual daf.lage associ" tod wi th <br />floocing. <br /> <br />The drainage wIst"r pLannir:g of Slaughterh0usl.' Gulch was undcr- <br />tab,r; in 1J7.' by tlw City of I.i ttl"ton in u:lopeT:ltion with the <br />Dom'?r Regional Council of Governments and the Departilwnt of <br />~l?USlng a~d Urban ~:evelopment (fWD). The project is being coor- <br />dln"-ted duectl;; h'lth the City. The engineering firm of Fra,;icr <br />t; Gingerr, ,Inc. l,as .retained to carry out the necessary planning <br />iJ-nd j1Tdllun;J,ry deSIgn efforts needed to identify and resolve <br />the putential flood haza,ds associated '~'ith Slaughterhouse Gulch. <br />Ftanning included the study evaluation ;Iud recommencation of <br />solutions to the identifiable drainage problems on thr gulch. <br />Th~ s~ope of. services completed t~us far in the project, arc in <br />accorcance wIth the contract reqUIrements and are listed bC'low: <br /> <br />e. Alternative::. <br /> <br />Tl;rce reasonable alternatives have been developed <br />together with appToximate costs and benefits to be <br />derived from each alternative. These alternatives, <br />as presented, are schematic in nature \,ith only <br />sufficient information presented to allow for com. <br />parison between alternatives. <br /> <br />a. Base MappinR <br />!lase l:'aps have been prepared at a seal.., of 1" ~ SO' <br />horizontal with a 1 foot v('Tticol contour inton'al <br />. <br />utilizing aerial photography I'lethodo;. The maps are <br />of sufficien~ accuracy and adoquate scale to serve <br />as hase maps for the llw,;ter dninageway planr.ing <br />'Iud ,.my fut\lre el'l~iJleer ing and cons truction drah'ings <br />for lmprovement~. TI", ITI;!PS hav'> teen used for tIle <br />fl?oc. plain and damage :",alysi~ and are pr"sently <br />celng scrined for final preliminary design. <br />b. Hydrolen <br />^ complete ~ydrolegic~l ~tudy of the tot;!l dT;!i~age <br />hasin has heen complct(,O;: to <!etermine the probable <br />flood magnitudes for !t.e 2, 5, 10 and 10(1-yo:l"[ storm <br />froquer.cies. The hydrologh: ~>valuation ha'; been <br />completo.! for an ultimate land use condition within <br />the basin Teflcctir.g betr. exis~ing and future channel <br />ccnuit.\ons. <br /> <br />',1'1 th the completion of this scope of services and the selecti(}n <br />of three alternatives, tJ:iJ> interim report has been prepared <br />and submitted. to the City. After due consideration ;J,nd review <br />of the alternatives, by the City and various other r('vi"", gro"ps, <br />a single alternative or approach will be selected for pore <br />detailed analysis and study. <br />This rep"rt rep1:esC'llts the completion of the in.i tLll phase of <br />this contract. In this report we have attempted to cever only <br />the basic and necessary inforI:latio:1 which is required for <br />sE'lection of an altern,1tc to be pursued in tb, fin"l p1-a~;e nf <br />the <.:ontTact. <br /> <br />c. Flood Plain Definition <br /> <br />The flood plain limits on both the f.lllin tlrllinClgel,ay <br />Cll'.l~ the South Tributary haye ~een detcrminetl for <br />each of the fOllr storm frequencies to illustrate the <br />extent of floouLng amI als~' fC'r a means of determin- <br />i r.f. appTOX jl~a t e f lClod dalCilf:e s . <br /> <br />,1' <br /> <br />-1, <br />