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<br />~ <br /> <br />2909 Wesl 71h Avenue <br />Denver. Colorado 80204 <br />303-573-7882 <br /> <br />Woodward.Clyde Consultants <br /> <br />. <br /> <br />09',' l~. <br /> <br />February 16, 1978 <br /> <br />. <br /> <br />I <br /> <br />Colorado Water Conservation Board <br />Centennial Building <br />1313 Sherman Street <br />Denver, Colorado 80202 <br /> <br />Attention: Mr. Felix Sparks, Director <br /> <br />Re: Geotechnical Consultation, Narrows Dam, <br />Morgan County, Colorado, State of Colorado <br />Department of Natural Resources <br />Contract No. C153205 <br />Job No. 19140-7354 <br /> <br />Gentlemen: <br /> <br />. <br /> <br />. <br /> <br />We have completed our independent review of the data and studies <br />developed by the u.S. Bureau of Reclamation for the feasibility <br />stage design of Narrows Dam. Our conclusions and recommendations <br />are summarized in the following paragraphs. <br /> <br />The Narrows dam site is located on the South Platte River <br />upstream approximately 7 miles from the city of Ft. Morgan. <br />A zoned earth dam with downstream filter drains is planned <br />as shown by the Bureau's feasibility design drawings, <br />Figures 3 and 4. The maximum section has an approximate <br />height of 147 feet above streambed. The total crest length <br />is about 22,500 feet which includes a considerable length <br />of low abutment dikes for flood storage purposes. The <br />bedrock at the site is the Pierre formation consisting of <br />shaley siltstone and claystone. The generally pervious over- <br />burden soils are relatively shallow on the left abutment, <br />across the stream channel and partially up the right channel <br />slope, but become deep onfue right abutment. The current <br />Bureau feasibility stage design contemplates a complete <br />cutoff trench to bedrock from the left abutment to about <br />Station 278 onthe right abutment. From this location <br /> <br />. <br /> <br />Consulting Engineers. Geologists <br />and Environmental SClsnlisls <br /> <br />II <br /> <br />Olllces In Olher PTlnClpa\ CItIes <br />