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<br />n erva on oar <br />Animas River Floodplain, Silverton, Colorado <br /> <br />PROJECT EXECUTION <br /> <br />Ground Control Survey <br /> <br />We propose to perform the ground control survey,fop.tl\is'pToject with at <br />least 2 survey crews. All control points shown on our layout plan, (attachment <br />4-1) including the permanent monuments as approved, would be set and paneled <br />prior to aerial photography. <br /> <br />Elevation would then be established on each and every control point by <br />closed circuit leveling method based on available Bench Marks from U.S.C. & <br />G.S. & U.S.G.S. lines. We anticipate no problem achieving high third-order <br />circuits for this project, as there are various third-order U.S.G.S. Bench <br />Marks and first and second-order U.S.C. & G.S. Bench Marks available to the <br />proj ect. <br /> <br />Horizontal control would be performed utilizing one second theodolites <br />for angles and H-P 3800 Distance Meters measuring thousandths of feet. The <br />entire horizontal network would be tied directly to available U.S.C. & G.S. <br />& U.S.G.S. triangulation stations to obtain Coiorad6Grid.C~ordina~es on all <br />horizontal control points (attachment 4-Z). Stations. "VT"" .1'KENuA:Ll. NO.. Z", <br />and "ARROW ET", which are existing third~arder monuments, shonrd be available <br />to this project. By using these stations we shouldh~ve.no problem obtaining <br />- . . , .~ , <br />at leas t high third-order Co-ordinates. .; <br /> <br />All field data would then be entered into our.in~qoY8e Wang computer for <br />closure checks and balancing prior to use as base cont~l for mapping' compilation. <br /> <br />Topographic Mapping <br /> <br />The aeiral photography used for the mapping would be flown with a 6" focal <br />length camera at a flight height of 3000' above mean ground elevation. The flight <br />lines would follow the outline on attachment 4-1. The scale of the photography <br />would be approximately 1" = 500" wi th 60% forward overlap and 30% :!; 10% side lap. <br /> <br />The maps would be compiled on our Ke1sh plotters at the scale of 1" = 100' <br />in pencil on mylar and photographicallynreduced to the scale of 1" = ZOO' for <br />final drafting using the scribing method. <br /> <br />Bell Surveying, Engineering & Mapping Compa~ies <br /> <br />