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5.0 INSURANCE APPLICATION To establish actuarial insurance rates" data from the engineering study must be transformed into flood insuran~e criteria. This process includes the determination of reaches, Flood Ha!zard Factors, and flood insurance zone designations for each flooding so~rce studied in detail affecting the Town of Rangely. . 5.1 Reach Determinations Reaches are defined as sections pf flood plain that have relatively the same flood hazard, based on ,the average weighted difference in water-surface elevations between! the 10- and lOa-year floods. This difference may not have a varia~ion greater than that indicated in the following table for more thar 20 percent of the reach: I Average Difference Between 10- and lOa-Year Floods Variation Less than 2 feet 2 to 7 feet 7.1 to 12 feet More than 12 feet 0.5 foot 1.0 foot 2.0 feet 3.0 feet The locations of the reaches determined for the flooding sources of Rangely are shown on the FloQd Profiles (Exhibit 1) and summarized in Table 3. 5.2 Flood Hazard Factors The Flood Hazard Factor (FHF) i~ used to establish relationships between depth and frequency of ~looding in any reach. This rela- tionship is then used with depth-damage relationships for various classes of structures to establ~sh actuarial insurance rate tables. The FHF for a reach is the average weighted difference between the 10- and lOa-year flood water-surface elevations rounded to the nearest one-half foot, multipli~d by 10, and shown as a three- digit code. For example, if th~ difference between water-surface elevations of the 10- and lOa-year floods is 0.7 foot, the FHF is I 005; if the difference is 1.4 f~et, the FHF is 015; if the differ- ence is 5.0 feet, the FHF is 05q. When the difference between the 10- and lOa-year flood water-su~face elevations is greater than 10.0 feet, it is rounded to the ,nearest whole foot. 5.3 Flood Insurance Zones Flood insurance zones and zone ~umbers are assigned based on the type of flood hazard and the FHF, respectively. A unique zone number is associated with each Possible FHF, and varies from 1 for a FHF of 005 to a maximum of 30lfor a FHF of 200 or greater. ]6