Laserfiche WebLink
<br />!e <br /> <br />. <br /> <br />. <br /> <br />~,' <br /> <br />that all of the identified sites and any other competitive sites are to be evaluated as part of the <br />feasibility study. <br /> <br />Geologic conditions appear to be fairly consistent at the dam sites. The valley walls appear to <br />consist primarily of relatively fme-grained sedimentary rock types such as shale and mudstones with <br />sandstone caprock visible in many locations. The shale and mudstone strata appear to be <br />susceptible locally to relatively shallow slope movement, probably in response to elevated moisture <br />content. Regional geologic maps indicate that these strata are part of the Mesa Verde Formation <br />of Cretaceous Age. The valley floor contains variable and unknown amounts of alluvial and/or <br />colluvial fill materials over bedrock. <br /> <br />Topographic conditions at the dam sites are generally similar as well. The sites are located in a <br />relatively narrow, deep valley with an average flow-line grade of approximately 4.5 percent and <br />sidewall slopes ranging from 25 to 40 percent. <br /> <br />To attain the desired minimum storage of 500 acre-feet we anticipate an embankment height in <br />excess of 50 feet and less than 80 feet. Therefore, the dam will be classified as intermediate in size. <br />The classification of the dam in terms of hazard level is not certain and must be evaluated as part <br />of the study in order to determine the appropriate inflow design flood. Previous work by Armstrong <br />and Associates, Inc. indicates that the structure may be Class I, requiring use of the probable <br />maximum precipitation (PMP) to develop the design flood. SRK has assumed that a detailed dam <br />break study or incremental damage analysis (IDA) will not be necessary and that the dam can be <br />classified based on available in formation and earlier studies. <br /> <br />1.4 General DIscussIon <br /> <br />Based on the information presented by the MCRC and our site trip observations, we believe that <br />a number of options are available to develop a new dam and reservoir to replace and/or <br />supplement the existing facilities. In addition to a number of potential dam sites, there are a <br />number of potential embankment types including: <br /> <br />. Earthfill; <br />· Earthfill/rockfill; <br /> <br />· Roller compacted concrete (RCC); and <br />. Concrete. <br /> <br />A range of outlet work and spillway options are available as well including: <br /> <br />2 <br />