2009-06-24_PERMIT FILE - C1981019A (3)

Home Browse Search

sweeping slopes, moderate contour furrows will be established to mitigate any future sheet flow and loss of the topsoil resource. Efforts will be made to establish reclamation blocks along the contour of slopes in order to eliminate the loss of the topsoil resource onto spoil areas. All other areas targeted for the grazingland land use will generally be on slopes greater than 10% and depending on the size of each reclamation unit will need to be chisel plowed (or ripped with a dozer) at a minimum if topsoil laydown activities do not produce sufficient surface roughness to limit the excessive formation of rills on first and second year reclamation blocks by "normal" seasonal runoff events. Contour furrows will be created with regular frequency on slopes greater than 20% and less frequently on areas between 10% and 20% slopes depending on the length of the slope and the size of individual reclamation blocks as determined by topsoil laydown progression in any given year or series of years. Past reclamation efforts undertaken in the East Pit provide a general context to the likely construction frequency of contour furrows in the West Pit and Section 16 reclamation areas. The steeper slopes in the South Taylor area will likely require the construction of contour furrows at a greater frequency than previously mined areas. As indicated under "Mulching Techniques" in Section 2.05.4, use of mulch would be considered a last resort, but is certainly an erosion control metric that may be utilized (where deemed necessary) for long south-facing slopes such as in South Taylor. Spoil will be graded to minimize long, uninterrupted slopes. Replacement of topsoil will be followed by chisel plowing and contour furrowing (when necessary). The use of these soil stabilizing practices on areas currently undergoing reclamation at Colowyo has been very effective in controlling surface runoff, thereby preventing surface erosion and gullies. The efficacy of these mechanical techniques will continue to be closely monitored as changes to the reclamation program are initiated. 4.15.5 Grazing All the lands reclaimed by Colowyo will not be grazed by livestock for a period of at least three years after seeding or planting and will be managed to promote the postmining land use. Grazing by livestock will not commence until Colowyo has demonstrated to the satisfaction of the Division that the vegetation on the reclaimed surface is adequately established and can be expected to withstand grazing pressures. Any grazing studies undertaken by Colowyo will not preclude or interfere with postmining vegetation sampling as required in section 4.15.8. 4.15.6 Field Trials In 1975 Colowyo funded a revegetation study that was initiated on the Colowyo property by the Department of Agronomy at the Colorado State University and the Colorado State University Experiment Station. The study was designed and the work was monitored mostly to determine the suitability of using native species at the mine site. Test plots were used to simulate the disturbance that would result from surface mining. 4.15-4 Revision Date: 3/14/08 Revision No.: TR-72