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<br />TOPOGRAPHIC SUR\~YS <br /> <br />A. Existing Topographic Surveys <br /> <br />Topographic maps of the project area are published and <br />available from the United States Geological Survey. These <br />reaps are at a scale of I inch equals 2000 feet. <br /> <br />Topographic maps for the Sheephorn Reservoir and Darn <br />Site were prepared in 1973, by Falcon Air Maps for the <br />Applicant. The contour interval is 5 feet at a scale of <br />1 inch equals 400 feet. Aerial photography was taken and <br />horizontal ground control was established by instrument <br />survey on the site. Photogrammetric methods were then used <br />to prepare the final topographic maps of the site. The ele- <br />vations were tied to existing bench marks established by the <br />U.S.G.S. <br /> <br />B. Surveys and Mapping <br /> <br />1) General <br /> <br />The proposed mapping includes large scale topographic <br />mapping (1"=100', 5 foot contour interval) at the specific <br />sites to be developed. There will also be included the lo- <br />cation of control baselines at each of the dam sites. <br /> <br />2) Topographic Mapping <br /> <br />Air markers will be located at existing USGS control <br />points and flight markers as required for photogrammetric <br />control. Photo control panels will be constructed of fabric <br />or similar material, and will be left in the field only as <br />long as required for the survey flight. Upon completion of <br />the flight, all panels, flagging, and other evidence of the <br />survey will be removed from the site, with the exception of <br />the monlliuents at the end of the baselines as discussed below. <br /> <br />3) Control Surveys <br /> <br />A control baseline will be located at each dam site, <br />powerhouse, pump station, pipeline and tunnel. 'This work <br />will be carried out by ground survey methods. A permanent <br />reference point will be established by setting steel monu- <br />ments placed in a small volumn of concrete in a secure lo- <br />cation. These monuments will be similar to those routinely <br />used by USGS. The exact location of these monuments is de- <br />pendent upon the interpoint visibility from the air since <br />photo control points will be located at each one of them. <br /> <br />The baseline between the monuments on each abutment of <br />the cams will require clearing a sufficient width (4 or 5 <br />feet) so that the entire length of the baseline can be sur- <br />veyed and referenced staked at 100 foot intervals. This will <br />require clearing of brush along the line of sight, but removal <br />of trees would be kept to a minimum. <br /> <br />-6- <br />