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<br />Also considered was a levee plan to provide protection to the agri- <br />cultural properties west of wild Horse Creek from flood flows ori6n- <br />ating on wild 1I0rse Creek. This plan, shown on Plate I, as Plan Ill, <br />comprises a levee located on the right bank of the Wil,l 1I0rse Creek <br />and assumes a 3-foot l,igher left bank levee in operation. An analysis <br />of this plan for degrees of protection up to 50 years witl, costs and <br />benefits reflecting only those associated with the right levee are <br />presented in Table 4. The analysis discloses that costs exceed benefits <br />at all scales of development considered and that 50 year protection <br />annual cas ts exceed the total poss ib Ie annual benefi ts. Therefore, thia <br />plan was dropped from further consideration. <br /> <br />TABLE 4 <br /> <br />PLAN III <br />RIGHT BANK PROTEGTION AGAINST FLOODS ON WILD HORSE CREFK <br /> <br /> Average Average <br /> Annual Annual Excess !llc <br />Frequency Benefi ts Costs* Benefits Ratio <br />10 500 6,100 -5,600 .('8 <br />25 3,100 12,600 -9,500 .25 <br />50 5,000 24,300 -23,800 .21 <br />* Includes eos t for operation and maintenance <br /> <br />From the foregoing, Plan II, providing protection against floods <br />originating on wild Horse Creek is the only economically feasible. plan <br />when considered on a first added basis. The optimum scale of develop- <br />ment for this plan, as presented in Table 3, is 100-year flood pro- <br />tection. However, since the proposed project is to protect an urban <br />area, and since standard project flood protection is economicslly feasible, <br />consideration was given only to providing standard project flood pro- <br />tection. As shown in Table 3, the excess benefits for this degree of <br />protection are $61,000 with an annual cost of $1,512,000. Providing <br />this degree of protection from Wild Horse Creek runoff incidentally <br />provides about laO-year protection against the Arkansas River and Two <br />Butte Creek flows. Additional protection against the Arkansas River. <br />and Two Butte Creek flows can be accomplished by incremently increasing <br />the levee height along the Arkansas River. As shown in Table 5, the <br />optimum second added increment is standard project flood protection <br />which develops $14,500 excess benefits and an annual cost of $232,000. <br /> <br />16 <br />