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<br />14 <br /> <br />25 <br /> <br />3. <br /> <br />Minimum freeboard depth of one foot for dl1 improved channels and ponds. <br /> <br />IV. DEVELOPMENTOFALTERNATlVES <br />Using the hydrologic andhydraul1c data discussed in theprevlous sec- <br />tions, three conceptual alternat1vedrdiMge plans were developed. Theintenl <br />of each plan was to solve the Town's recurrent flooding problems, and to <br />narrow the list of most feasible drdina~e plans to evaluate further. Three <br />conceptual a1ternatives were developed and presented to the project sponsor s <br />forthelrconslderatlon. The three conceptual plans are discussed fUrther. <br />In order to be clearer in the presentation and analysis of the conceptual <br />alternatives, the Town was divided into four reaches sImilar to the drainage <br />baslndellneatlonsshownonFigure2. TIleseare: <br /> <br />ReachA Northeastern quadrant of Town, drained by theWalkerStreetCha nnel. <br /> <br />Reach B Southern and eastern portions of Town, drained by Fletcher Street. <br /> <br />Basis of Damdge Assessment <br />In order to assess to level of flood protection economically just 1fiable, <br />calculations of the dollar loss associated with the ID- and lOa-year flood <br />events were carried out. Todothis,severalassumptionsweremadetofaci1i_ <br />tate the calculations. TIl€ major assumpttonsw€re: <br /> <br />1. loss of wages ~ Total hours lost ~ S6.50/hour. <br /> <br />2. Loss of workdays: 10-yearevent,3days <br />100-year€vent, 5 days <br /> <br />3. <br />4. <br /> <br />Loss of business was assum€d equal to loss of wages. <br />Average single family house and content value: <br /> <br />,. <br />b. <br /> <br />With basement ~ $60,000 <br />Without basement ~ $46,000 <br /> <br />ReachC <br /> <br />Southwestern portion of the Town, drained by the channel adjacent to <br />the Burlington Rai1road,andoutfalllng Into Fletcher Street, <br />Northwestern portion of the Town, drained by Logan Avenue, Colorado <br />Avenue, Chase Street, and Strohm Street, outfalling into Fletcher <br />Street. <br /> <br />5. <br /> <br />Contents are defined as carpeting, <br />belongings, plus maintenance associat€d <br />and basements. <br /> <br />furniture, draperies, personal <br />withthecleanupofflrstfloors <br /> <br />Reach 0- <br /> <br />6. <br /> <br />Average depth in the business district was 1.5 feet and 2,0 feet, for the <br />la-and lOa-year frequencies. respectively, <br /> <br />Alternative 1 ~ Full Flow Through System <br />This plan would place all flow in clos<,dconduits and channels and route <br />the offs1te and in-town peak flows to tl1e channel draining the Town. FrOO1 <br />chis point, a lOa-year channel woulo convey tne flow from the inlet, past the <br />sewage treatment lagoons, to an improved lOa-year culvert crossing under <br />County Road 7. The flow through.systemwashydrau1ically analyzed for both <br />the la-and lOa-year recurrence intervals. This plan is presented on Figure <br />6. <br /> <br />AI~ernative 11 - Oiverted Flow ThrO~~~1.st~n <br />Tl1is plan would again place all flO\'ls in channelS and close conduits, <br />however, the historic flow paths would be diverted around thedowntown4reas <br />in an attempt to alleviate flooding pressure on the street flow net system. <br />TI11s alternative was analyzed for the 10- and 100~year recurrence intenals, <br />andO/ould inclUde the lOa-year channel outside of Town as inA1ternatlve 1. <br />This plan is presented on Figure 7. <br />