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U <br />III III III III IIII III <br />YAMPA MINING CO. <br />v.o. eox NN <br />NAYDEN, COLOMDO 81679 <br />January 6, 1985 <br />JAN 13 1°87 <br />Ms. Cathy Regej <br />Reclamation Specialist <br />Mined Land Reclamation Division <br />Colorado Department of Natural Resources <br />1313 Sherman Street, Room 423 <br />Denver, Colorado 80203 <br />Dear Cathy: <br /> <br />n.: ~?! : . ,.: a:. <br />r:C.~u i.'L 1(._ ~ ~~ 'i':~QiU <br />Enclosed are three cross-sections which compare as-built reclaimed <br />topography with the approved post mining design contours for the Hayden <br />Gulch Mine. The locations and number of cross-sections are those agreed <br />upon at our meeting at the Yampa Mining Company's office October 3, ].986. <br />As shown by the cross-sections, the as-built reclaimed topography very <br />closely depicts the approve3 post mining design with only minor <br />insignificant differences. <br />Also enclosed is Exhibit D, the approved post mining contour map. Exhibit <br />D identi.fiea the locations, as constructed, of the permanent drainage <br />ditches and the temporary terrace ditches. The existing ditch locations <br />vary slightly from the design Sue to haul road location, topsoil placement <br />considerations, and minor variations in the post mining topography. <br />As-Built cross-sections of ditch 1k1 and ditch !13 are included to <br />illustrate compliance with the design. <br />Also, you will find comments and brief calculation summaries submitted in <br />response to the questions you had concerning the lack of rip rap lining in <br />the last segment of Ditch 113. Include3 are the results of calculations <br />performed to determine the adequacy of the Swale located in watershed <br />number 31 in routing flood 3lscharge to ditch segment 32 without requiring <br />erosion control features. As can be seen from the tables, the existing <br />Swale will not be subjected to erosive velocities from the runoff of a 10 <br />year, 24-hour storn event and will, therefore, require no rip rap lining. <br />P c. <br /> <br />237.3h/1 <br />