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<br /> <br />~ <br /> <br />2 <br /> <br />, . <br />~ <br /> <br />. <br /> <br />. <br /> <br />" <br /> <br />The appraisal-level e~gineering design will consist of <br />preparation of a large-scale topographic map showing <br />the preferred dam and spillway alignments; a cross <br />section along the centerline of the dam; cross sections <br />through the dam at the locations of the principal and <br />emergency spillways; ~nd a geologic map showing the dam <br />alignment, the reservoir high water line, and the <br />borrow areas. The qu~ntities of borrow materials <br />needed for the preferred design will be tabulated. A <br />computerized pseudost~tic stability analysis, using the <br />maximum horizontal seismic accelerations recommended by <br />Algermissen and Perkins (1976, U.S. Geological Survey <br />open-file report 76-416) and a standard Dames & Moore <br />engineering computer program, will be run for the <br />preferred design. <br /> <br />The appraisal-level design work will identify all major <br />facilities which will be impacted by dam construction. <br />preliminary design drawings will, show recommended <br />relocation for roadways, railroads, power transmission <br />lines and all other impacted facilities. <br /> <br />c. All major dam components including found~tion <br />preparation, embankment placement, spillways, coffer <br />dam and diversion works, irrigation diversion <br />facilities, hydroelectric machinery, powerhouse and <br />other structures, switchyards, access, trash racks, <br />site improvements and other identified ancillary <br />, facilities will be designed and quantified to the <br />appraisal level of detail. Full description of unit <br />sizing rationale and design parameters will be made. <br />Drawings showing plan, sectional and det~il views of <br />the major components will be prepared for the recom- <br />mended alternative and any other major components of <br />significant interest which may not be a part of that <br />plan. <br /> <br />d. It is anticipated that the primary criterion for <br />spillway design will be the peak and volume of the <br />"Probable Maximum Flood" (PMF). Previous studies of <br />the Narrows project PMf as prepared for the Bureau of <br />Reclamation and the CWeB will be reviewed, updated and <br />modified, as necessary, to adapt the PMF flood estimate <br />to the proposed Hardin Dam site. Other design floods <br />may be considered for spillway design depending upon <br />the outcome of discuss~ons with the Colorado State <br />Engineer's Office, the U.S. Corps of Engineers and the <br />ewcs. Flood design cr~teria will be reviewed with <br />these agencies to adopt a design approach that is <br />acceptable to the State. <br /> <br />-5- <br />