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these computations are tabulated at selected cross sections for each stream segment for which a floodway is computed (Table 2). As shown on the Flood Boundary and Floodway Map (Exhibit 2), the floodway boundaries were determined at cross sections; between cross sections, the boundaries were interpolated. In cases where the floodway and IOO-year flood boundaries are close together, only the floodway boundary has been shown, The area between the floodway and the boundary of the 100-year flood is termed the floodway fringe. TIle floodway fringe thus encompasses the portion of the flood plain that could be completely obstructed without increasing the water-surface elevation of the 100-year flood more than 1.0 foot at any point. Typical relationships between the floodway and the floodway fringe and their significance to flood plain development are shown in Figure 2. I- 1QQ.YEAR FLOOD PLAtN -I FLOODWAY FRINGE FLOODWAY FLOODWAY FRINGE FLOOD ELEVATION WHEN CONFINEO WITHIN FLOODWAY STREAM 1 CHANNEL I i AREA OF FLOOD PLAIN THAT COULD BE USED FOR DEVELOPMENT BY RAISIN-G GROUND LINE AB IS THE FL1')("I 'I "; L EVATION BEFORE ENCROACHMENT. LINE CD IS THE F LEVATION AFTER ENCROACHMENT. "SURCHARGE IS EXCEED 1.0 FOOT (FIA REaUIREMENT) OR LESSER AMOUNT IF SPECIFIED BY STATE. Figure 2. Floodway Schematic 5.0 INSURANCE APPLICATION In order to establish actuarial insurance rates, the Federal Insurance Administration has developed a process to transform the data from the engineering study into flood insurance criteria. This process includes the determination of reaches, Flood Hazard Factors, and flood insurance zone designations for each flooding source studied in detail affecting the Town of Firestone. 7