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<br />As shown on the Flood Boundary and Floodway Map (Exhibit 2), the <br />floodway boundaries were determined at cross sections; between cross <br />sections, the boundaries were interpolated. In cases where the <br />floodway and IOO-year flood boundaries are close together, only the <br />floodway boundary has been shown. <br /> <br />The area between the floodway and the boundary of the IOO-year flood <br />is termed the floodway fringe. The floodway fringe thus encompasses <br />the portion of the flood plain that could be completely obstructed <br />without increasing the water-surface elevation of the IOO-year flood <br />more than 1.0 foot at any point. Typical relationships between the <br />floodway and the floodway fringe and their significance to flood <br />plain development are shown in Figure 2. <br /> <br />I. <br /> <br />100-YEAR FLOOD PLAIN <br /> <br />-, <br /> <br />FLOODWAY <br />FRINGE <br /> <br /> <br />FLOODWAY <br /> <br />FLOODWA Y <br />F RINGE <br /> <br />STREAM <br />CHANNEL <br /> <br />FLOOD ELEVATION WHEN <br />CONFINED WITHIN FLOODWAY <br /> <br /> <br />AREA OF FLOOD PLAIN THAT COULD <br />BE USED FOR DEVELOPMENT BY <br />RAISING GROUND <br /> <br />FLOOD ELEVATION <br />BEFORE ENCROACHMENT <br />ON FLOOD PLAIN <br /> <br />LINE AS IS THE FLOOD ELEVATION BEFORE ENCROACHMENT. <br />LINE CD IS THE FLOOD ELEVATION AFTER ENCROACHMENT. <br />"SURCHARGE IS NOT TO EXCEED 1.0 FOOT (FIA REQUIREMENT) OR LESSER AMOUNT IF SPECIFIED BY STATE. <br /> <br />Figure 2. <br /> <br />Floodway Schematic <br /> <br />5.0 INSURANCE APPLICATION <br /> <br />In order to establish actuarial insurance rates, the Federal Insurance <br />Administration has developed a process to transform the data from the <br />engineering study into flood insurance criteria. This process includes <br />the determination of reaches, Flood Hazard Factors, and flood insurance <br />zone designations for each flooding source studied in detail affecting <br />the Town of Pierce. <br /> <br />10 <br />