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• sweeping slopes, moderate contour furrows will be established to mitigate any fWtre <br />sheet flow aad loss of the topsoil resource. Efforts will be made to establish reclamation <br />blocks along the contour of slopes in order to eliminate the loss of the topsoil resource <br />onto spoil areas. All other areas targeted for the grazingland land use will generally be <br />on slopes greater than 10% and depending on the size of each reclamation unit will need <br />to be chisel plowed (or ripped with a dozer) at a minimum if topsoil laydown activities do <br />not produce sufficient surface roughness to limit the excessive formation of rills on first <br />and second year reclamation blocks by "normal" seasonal runoff events. Contour <br />furrows will be created with regular frequency on slopes greater than 20% and less <br />frequently on areas between 10% and 20% slopes depending on the length of the slope <br />and the size of individual reclamation blocks as determined by topsoil laydown <br />progression in any given year or series of years. Past reclamation efforts undertaken in <br />the East Pit provide a general context to the likely construction frequency of contour <br />furrows in the West Pit and Section 16 reclamation areas. The steeper slopes in the South <br />Taylor area will likely require the construction of contour furrows at a greater frequency <br />than previously mined areas. As indicated under "Mulching Techniques" in Section <br />2.05.4, use of mulch would be considered a last resort, but is certainly an erosion control <br />metric that may be utilized (where deemed necessary) for long south - facing slopes such <br />as in South Taylor. Spoil will be graded to minimize long, uninterrupted slopes. <br />Replacement of topsoil will be followed by chisel plowing and contour furrowing (when <br />necessary). <br />The use of these soil stabilizing practices on areas currently undergoing reclamation at <br />• Colowyo has been very effective in controlling surface runoff, thereby preventing surface <br />erosion and gullies. The efficacy of these mechanical techniques will continue to be <br />closely monitored as changes to the reclamation program are initiated. <br />4.15.5 Grazing <br />All the lands reclaimed by Colowyo will not be grazed by livestock for a period of at <br />least three years after seeding or planting and will be managed to promote the postmining <br />land use. <br />Grazing by livestock will not commence until Colowyo has demonstrated to the <br />satisfaction of the Division that the vegetation on the reclaimed surface is adequately <br />established and can be expected to withstand grazing pressures. Any grazing studies <br />undertaken by Colowyo will not preclude or interfere with postmining vegetation <br />sampling as required in section 4.15.8. <br />4.15.6 Field Trials <br />In 1975 Colowyo funded a revegetation study that was initiated on the Colowyo property <br />by the Department of Agronomy at the Colorado State University and the Colorado State <br />University Experiment Station. The study was designed and the work was monitored <br />mostly to determinf the suitability of using native species at the mine site. Test plots <br />were used to' simulate the disturbance that would result from surface mining- <br />4.15-4 Revision Date: 6/21/11 <br />Revision No.: TR -84 <br />