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<br />the floodway and 100-yelJr floodplain boundaries are either close <br />together or collinear, oQly the floodway boundary has been shown. <br /> <br />., <br /> <br />No floodway has been computed for Boulder Creek, Arapahoe Avenue <br />Overflow, and Dry Creek. However, the City of Boulder and the <br />Urban Drainage and Flood Control District (UDFCD) regulate a <br />floodway which is more restrictive than the floodway required by <br />FEMA. Contact the City of Boulder or UDFCD for this Hoodway <br />information. Because Twomile Creek has been designated as an area <br />of shallow flooding, a Hoodway is inappropriate; therefore, no <br />floodway has been shown in this study. <br /> <br />:, <br /> <br />The area between the Hoodway and 100-year floodplain boundaries <br />1S termed the Hoodway fringe. The Hoodway fringe encompasses <br />the portion of the floodplain that could be completely obstructed <br />without increasing the water-surface elevation of the 100-year <br />flood by more than 1.0 foot at any point. Typical relationships <br />between the floodway and the floodway fringe and their <br />significance to floodplain development are shown in Figure 6. <br /> <br />Ie <br /> <br />- 100.YEAR FLOOD PLAIN <br /> <br />-I <br /> <br />FLOODWAY <br />FRINGE <br /> <br /> <br />FLOODWAY <br /> <br />FLOODWAY <br />FRINGE <br /> <br />STREAM <br />CHANNEL <br /> <br /> <br />FLOOD ELEVATION WHEN <br />CONFINED WITHIN FLOODWAY <br /> <br />ENCRO~MENT ~ <br /> <br />........... :. .... .:.. -1'.. -. ~.. <br /> <br />-.. - <br /> <br />..-_.. ..- <br />I <br /> <br />. <br /> <br /> <br />ENCROACHMENT <br />-r <br /> <br />_.- <br /> <br />.....L <br />AREA OF FLOOD PLAIN TI-lAT COULD <br />BE USED FOR DEVELOPMENT SY <br />RAISING GROUND <br /> <br />LINE AS IS THE FLOOD ELEVATION BEFORE ENCROACHMENT. <br />LINE CD IS THE FLOOD ELEVATION AFTER ENCROACHMENT. <br />.SURCHARGE IS NOTTO EXCEED 1.0 FOOT (FEMA REQUIREMENT) OR LESSER AMOUNT IF SPECIFIED B.( STATE. <br /> <br />Figure 6. Floodway Schematic <br /> <br />\ <br /> <br />17 <br />