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<br />arrival of the larger flood. <br /> <br />TABLE 3. <br />RISE TIMES BETWEEN LOWER AND UPPER FLOATS DURING FLOODS <br /> <br />GAGE <br /> <br />10-YEAR <br /> <br />50-YEAR <br /> <br />100-YEAR <br /> <br />500-YEAR <br /> <br />Hwy 52 (Upstrm) <br />Co. Rd (Dnstrm) <br /> <br />20 min <br />6hr,10min <br /> <br />15 min <br />5hr,30min <br /> <br />15 min <br />5hr,5min <br /> <br />15 min <br />lhr, 5min <br /> <br />3. FLOOD WARNING <br /> <br />3.1 Flood Warning Time <br />Flood warning time is defined as the time between the oc- <br />currence of an upper stage alarm and when water reaches the <br />invert elevaticm of the closure structure. The :Elood warning <br />times for Wiggins were calculated based on water reaching the <br />elevations defined in Table 4. <br />For example, the flood warning time from the downstream au- <br />tomated alarm 9age on the County road bridge to the Highway 6 <br />closure is thE! time from the activation of the upper float <br />alarm at elevat:ion 4613.0, to the t.ime that water reaches a <br />stage of 4545.1 at the Highway 6 closure West of Wiggins. <br /> <br />TARLE 4. <br />IMPORTANT FLOOD lNARNING ELEVATIONS <br /> <br />STATION TO STM?ION UPPER WARNING STAGE CLOSURE INVERT <br /> Elevation msl. Elevation msl. <br />HWY. 52 to Railroad Closure 4772.0 4550.8 <br />HWY. 52 to HWY. 6 Closure 4772.0 4545.1 <br />Co. Rd. to Railroad Closure 4613.0 4550.8 <br />Co. Rd. to HWY. 6 Closure 4613.0 4545.1 <br /> <br />Table 5 lists flood warning times provided <br />Burlington Northern Railroad closure structure. <br />lists flood warning times dev.aloped for the Highway 6 <br />structure. Note that additional flood warning time <br />obtained by reacting to the lower st.age alarm without <br />for the upper float transmission. <br /> <br />for the <br />Table 6 <br />closure <br />can be <br />waiting <br /> <br />TABLE 5. <br />FLOOD vTARNING TIMES FOR THE RAILROAD CLOSURE <br />(Times in Hours and Minutes) <br /> <br />Closure Invert Elevation <br />Discharge at Closure Invert = <br /> <br />= 4550.8 ft. msl. <br />33,000 cfs <br /> <br />GAGE <br />Hwy 52 (upstm.) <br />Co. Rd (dnstm.) <br /> <br />10-YEAR <br />12 hrs <br />5hrs,10min <br /> <br />50-YEAR <br />Hhr,30min <br />.2hr,45min <br /> <br />100-YEAR <br />7hr,35min <br />2hr,20min <br /> <br />500-YEAR <br />6hr,10min <br />Ihr,35min* <br /> <br />7 <br />