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"?E+ ll]•i+9 1b:23 E '~G~ 4f~5 ~•g4? 5F'i. LE <br />L'A,i~i MOUNTAIN RESOURCES, SAN LUIS PROJECT <br />CMIRD nDEQUACy LETTER RESPONSES <br />Paye 13 of 28 <br />22. Section H-H' on Figure C-10 shows the 4B-inch culvert downdrain to <br />be buried. Nhat will be the minimum and maximum fill depths placed <br />on the pipe? Are anti-seep collars considered necessary for this <br />culvert? <br />.'.ES;'ONSE~ The pipeline will be below grade at the inlet structure and wa.' <br />sealed into :he concrete head wall. The pipeline will be maintail~~~. <br />at a relatively Constant grade from the inlet to the outlet and will <br />require some regarding of the natural topography along its alignment. <br />The pipe line will, therefore, he daylighted downstream of the inlet <br />and subject to the regrading will either be on surface tr be in cut. <br />No seepage collars are considered necessary for the pipeline. <br />27. The text an page D-42 states that figure D.6-2 shows the freeboard <br />required to contain PMF inflows as a function of the elevation of <br />the tailings. Figure D.6-2 1s titled "Borrow Map", Please provide <br />the missing reference on PMF elevations. <br />'t~~~~J;'SE: the incorrect figure was referenced on page D-42. The correct figure, <br />providing freeboard required to contain PMF flows as a function of <br />elevation, is included here as Figure D.6-15. The text will be <br />changed to cite the correct reference. <br />Please commit to reporting of hydroloe;~ data to the Division as <br />required in the approved permit. <br />_~._. Hydrologic data will be reported to the Division as reglired in the <br />approved permit. <br />". Pseudostatic factors of safety of less than 1.25 are t~nacceptabie <br />far embankment slopes. Please provide further design speciftcations <br />which would provide far a minimum factor of safety of 1.25 under <br />p.seud~static conditicns. The minimum acceptable factor of safety of <br />1,25 for embankment ;'apes is recommended because this would help <br />ensure a more stable condition during the life of the fe~ei]ity. The <br />U.S. Bureau of Mines and Canmet guidelines for tailings disposal <br />foci 1 ity designs both indicate that 1.25 is a prudent des.'gn criteria <br />fur pseudostatic conditions. <br />RESrC>~SE: Ir. order to select suitable seismic design criteria for the tailings <br />embankment and provide stable conditions durfng and after operation <br />of the facility, SRK adopted the following ap roach. <br />6c <br />