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VI-2 ALTERNATIVES INVESTIGATED The following alternatives, except fOe the optimum combination alter- natives, emphasize a particular approach to major drainage problem solutions. The approximate cost range of the alternatives was iden- tified on a lOa-year frequency design basis. An evaluation of this and other parameters leads to the identification of three reasonable alternatives. The costs used are presented in Table VII-I of the following section. These three alternatives are illustrated on map5, copies of which are fi led with the Urban Drainage and Flood Control District. Unimproved Flood Plain. This alternative is to floodplain zone the existing flood plain areas, preventin9 any fur-ther development in the flood plain. Flooding would sti I I occur in the presently developed areas. However, a non-structural progr'am \-lOuld be implemented to gradually reduce damages and remove structures in the flood plain. This program would consist of identifying all the existing structures in the flood plain as non-conforming uses. and eventually clearing those structures In the flood plain areas. For example, once a trai ler had been damaged or moved by flooding, no more trai lers would be allowed to take its place. Recurrent trouble areas or hazard-causing structures would be more quickly removed. The Red Barn in Wheat Ridge is an example of such a structure. The Federal Insurance program would be a strong force in helping to remove structures onc.e damaged, and to assist in keeping new hazards from developing. The expected annual average damages for ~'na Gulch is $749,000 for this alternative under future development conditions. The present worth of the probable damages or costs for the next 40-year period would be 10 million dollars. Some channel maintenance would be nec- essary to remove debris blockages in the urbanized areas. Secondary and intangible benefits would result with adoption of this alternative. On a 40-year basis, about 20 perce~t of the damages could be eliminated by the removal of recurrently flooded structures and other hazards, and by various flood-proofing measures. This would lower the damage cost figure to 8 mi 11 ion dollars for a 4Ci-year basis or an annual cost of 0.6 million dollars. The total cost, including the immediate re- moval of highest hazards, would be appro>,imately 8.2 million dollars.