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I I I I I I I I I I I I I I I I I I I 39 4. Twenty percent engineering, contingency, and utility relocation cost con- sidered for each alternative. 5. Forty year design life, and ten percent interest assumed to calculate annual costs. 6. Offsite channel construction not considered in cost estimate for each alternate. Discussion of Alternatives The results of the alternative evaluation have been summarized on Table 12. Meetings were held with the Town and State to di scuss the general con- siderations to be followed in preparing a selected plan. The project corespondence reflects that a pipe/channel diversion concept was favored within the Planning Area. The major advantages to the diversion concept are: :A 1. Limited need to expand existing right-of-ways. 2. Existing box culvert at City Park would not have to be modified. 3. Involvement with railroad right-of-way limited to box culvert proposed for the Eastern Flow Path (i.e., over the Town of Ordway Ditch). 4. Future development is provided with outfall drainage facilities within a reasonable distance offsite. 5. Smaller diameter storm sewers (less than 48 inches) are constructable by Town forces. It was also di scussed wi th the Town that a fi ve-year frequency be uti- 1ized for design and implemented. Overf1ow channel sections along the major outfall 1 i nes can be used to address the potenti al fl oodi ng in a di vers i on system, as well as for providing for 100-year conveyance to the major draina- geways. In areas where a five-year storm sewer is constructed, it is recom- mended that street improvements be considered to insure the proper functioning of inlets. An example of this would be along Otero, Lincoln, Colorado, and Main Streets from Second Street to Railroad Avenue.