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<br />surveyed two channel and floodplain cross sections. From the field data, CWCB staff computed a <br />flood discharge from the July 9, 1996. flood event using the slop-area method. The estimated <br />discharges are 3,100 cfs and 3, 600 cfs respectively (See Attachment C-I and C-2). <br /> <br />Hydraulic characteristics for the Flood Insurance Study were computed using the Corp's HEC-2 <br />program. Flood profiles were drawn showing the computed water surface elevations for floods of <br />the selected recurrence intervals (See Attachment D). The water surface elevations and inundation <br />areas for the I DO-year flood event are shown on Attachment E. <br /> <br />Study Findings <br /> <br />The Board staff finds that the July 9, 1996 flood event was greater than the I DO-year flood event. <br />The roadway crossing of the stream immediately downstream of the Missouri-Pacific Railroad is a <br />concrete "ford," otherwise known as a "Texas Crossing." It appears that the stream crossing does <br />not have enough capacity to contain the I DO-year flood flow_ During the July 9,1996 flood, high <br />water overtopped the right overbank and flooded Booth Street, causing a flood condition in areas not <br />identified on the FEMA floodplain map (Attachment E). <br /> <br />Recommended Flood Mitigation Measures - Structural <br /> <br />The Board staffs flood mitigation recommendations are shown on Attachment F. The structural <br />flood mitigation measures are: <br /> <br />1) Construct a deflective jetty upstream of the county road on the right ban1e <br /> <br />2) Extend the "ford" (Texas Crossing) of the county roadway into the left overbank. <br /> <br />3) Add rip-rap material to the existing right bank rip-rap to lower the roughness and friction <br />coefficient, which would help create a smoother flow regime. <br /> <br />4) Widen the channel cross-section downstream of the Missouri-Pacific Railroad to a point 500 feet <br />downstream of the county road, <br /> <br />5) Add freeboard to the overall project design_ <br /> <br />Non-Structural Mitigation <br /> <br />Non-structural flood mitigation measures include: <br /> <br />I) Purchase of flood insurance by residents. <br /> <br />2) Implementation of flood-proofing measures by residents. <br /> <br />3) Relocation of residents in flood prone areas. <br /> <br />4) Informing the area residents that floods larger than the 1 DO-year event can and do occur, <br />