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<br />JI'. <br />~-'-,. . <br /> <br />n,_ <br /> <br />00091..6 <br /> <br />3.17 <br /> <br />.~ <br /> <br />,.( <br />~ <br /> <br />~~ gnaurveyed sections <br />~~ aurveyed section <br /> <br />from available topographic mapping show the <br />to be steeper, ranging from 15 to 18 <br /> <br />. ~ .".... <br /> <br />:t.....~':. <br /> <br />for the Portland Flume survey are based on the USGS bench mark <br />t: ~'"t-ion.o <br /> <br />., '\.~ ~t.!':-ate8t corner <br />1..1 C~ A poi~t of known <br />.:.-ti"" ot 100 feet at <br /> <br />of the Beaumont Hotel. The Cascade survey was not <br /> <br /> <br />elevation. The datum for it is based on an assumed <br /> <br />the intersection between the vertical walls and flume <br /> <br />_~" north side of the downstream end of the flume. <br />Oo>o.C- .,.. ..... <br />~ portland profile is very uniform with a range of slopes of 7.85 per- <br />~. La 9.67 percent. There are areas of local variations beyond this range, <br /> <br />_c <br /> <br />...id4lnt at the Highway 550 box culvert. <br /> <br />The slopes in this area vary <br /> <br />t.- 12.8 percent at the approach to 5.3 percent just downstream of the box <br /> <br /> <br />~:"..n. The Cascade E'lume has a much greater variation in slopes. In <br /> <br /> <br />..~o<.l it gets steeper in the upstream direction. It starts at a slope of <br /> <br />~.~) percent at the Uncompahgre River and increases to a slope of 12.94 per- <br /> <br />c.~t at the last surveyed reach. Above the survey limits, it is estimated <br /> <br />chAc the flwne slope ranges up to 18 percent. There is a large local varia- <br /> <br />Uor. L~ slope of .the Cascade Flume at the Highway 550 box culvert. Here the <br /> <br /> <br />el~ rangc~ from 3.84 percent to 22.77 percent. The large decrease in slope <br /> <br />in ~~e downstream direction on Cascade Creek makes it much more likely that <br /> <br />~hi. flume will experience problems with debris blockage. The last 500 feet <br /> <br />of the cascade Flume is the critical area with a slope of one-half to one- <br /> <br /> <br />~~ird of that upstream. <br /> <br />3.3.3 Flume Condition <br /> <br />Currently, both flumes are in poor condition. This can be attributed to <br /> <br />their age and the back-to-back flood years of 1981 and 1982. The major <br /> <br />problems .are: <br /> <br />,. <br /> <br />A general deterioration of <br />flow and impact of rockS. <br />length of both flumes. <br /> <br />the flume' s channel bottom due <br />This is evidenced along nearly <br /> <br />to =ntinuous <br />the entire <br /> <br />2. A weathering of the flumes' side walls. This has been caused by climate <br />conditions and accelerated by the fact that there are no expansion joints <br />in the flumes. It also appears that the original concrete is not rein- <br />forced with steel. some of the repair work does contain steel reinfor- <br />cement. <br /> <br />~..~.,"-O,. _--:-_"",:"""=,,-,,,~!.~__=~. <br /> <br />-~-- __ ,...." ~-""'" __....-..~,,~. _ ._~""""_-I""".4"""'..__ ~ ., .J~~~".''''~. :....:.:.._:~..;.:--.-:. ~-. <br /> <br />.-, ..::.. <br /> <br />- ~-=--"- <br />