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<br /> TABLE XIII <br />BENEFIT,COST, REACH C <br />t,lternative II B:C ratio . 0.40 <br />Alternative i2 B:C ratio . 0.40 <br />Alternative i2 B:C ratio . 0.17 <br />Alternative #4 B,C ratio . 0.34 <br />Alternative 15 B:C ratio . 0.40 <br /> <br />. <br /> <br />of increased drainage flows from this developing area will <br />significantly increase the damage potcnti~l in the Valley <br />Airpark area. <br /> <br />. <br /> <br />. <br /> <br />for these reasons, Alternative ~4 far reaches A and B is not <br />a suitable improvement plan for the Dry Creek drainageway. <br /> <br />Since the outlet of future dr...inagc flows through the Valley <br />Airpark as upstream development proceeds is critical to the <br />overall drainage plan for this basin, improvements should be <br />considered in this reach for any of the alternatives, even <br />though the benefit'cost ratio for the isolated reach is not <br />greater than 1. These improvements should be consistent with <br />typical drainage criteria for the City of Fort Collins or <br />Larimer County. This criteria would generally require a <br />drainage system to contain the 100-year event. <br /> <br />* l\.lternativcs #1, 112 and *5 are identical. <br /> <br />Interpretation <br />A strict interpretation of the benefit:cost analysis indicates that <br />hlternative ~4 fer reaches ~ an~ n is by far the most economically <br />feasible imorovement plan with substantial net benefits of $3.0 million. <br />No alternative for reach C is eco~omically acceptable. <br /> <br />l',lternative ~4, while very effective in reducing damages in <br />the trailer park north of the Larimer-Weld Canal and in the resi- <br />dcntial and co~~ercial areas near College Avenue, leaves many <br />flood plain and drainage problems along Dry Creek unsolved. <br /> <br />First of all, because of the very wide, flat flood plain area <br />along Dry Creek and because of the large difference in flood <br />magnitude for a IO-year event versus a 100-year ever.t (720-cfs <br />Vf'!nms 2, 700-cfs), an extensive lOO-year flood pl..in ',/Quld <br />remaln. Secondly, discharges exceeding the lO-year capacity <br />would flow directly into the Larimer-Weld C~n^l. Overflow of the canal <br />during liJnjer ev€n;;s j,w?ardizos an extensivc dcveloped area below the <br />canal, and the failure of the canal embankment could cause <br />SeVere Jdmdg€ in localizcd areas. Fin3lly, with no iMprovements <br />in Reach C, future drainage improvements in presently undeveloped <br />areas between College Avenue and the Valley Airpark will have <br />:10 Guitablc oCltl",t to the Poudr.. r<i.,fer. The conccntra':.ion <br /> <br />The importance of developing an overall drainage pla~ for <br />ultimate development within this basin suggests that the <br />entire study length be treated as one r~ach for purposes <br />of establishing an improvement plan. The reduction in damages <br />or the benefits of the project may still be separated into <br />reaches so that appropriate funding decisions may be made <br />between the local governments. <br /> <br />Eliminating Alternative .4 as a plan <br />*1, ~2, *3 and t5 are evaluated from <br />dr~i~ageway planning in Table XIV. <br />benefits and costs for re<lche~ A, B <br /> <br />of improvenent, Alternatives <br />a standpoint of total <br />That is, thE' total project <br />and C are co~bi:1cd. <br /> <br />-38- <br /> <br />-39- <br />