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a iiii~iiiiiiiiiiiiiii 999 t~~~ environmental scientists & engineers 1409 lorim¢r square February 22, 1982 • d¢nver, coloredo 80202 JOJ-571-10Ci0 FHB 2 21982 Mr. Jay Lucas Reclamation Specialist Mined Land Reclamation Division Room 423, Centennial Building 1313 Sherman Street Denver, Colorado 80203 RE: Jenkins Mine Amendment, MLR File #77-393 Deaz Mr. Lucas: RECE11i/ED MINED LAND REGLAMATI~ Cole. Dept. of Natnraf Resources In response to your adequacy letter of Februazy 5, 1982 to Mr. Vazra, we would respond as follows to the questions raised: Mining Plan (1.) Both clay and aggregate aze to be mined at the site with the aggregate spanning the entire mazket from borrow material to classified crushed rock. Mining Plan (2.) With regard to water control on site, the "minor diversions" aze small lateral ditches approximately one foot deep or small lateral berms approximately one foot high at forty-five or so degrees to the normal drainage to prevent the flow of water during natural runoff into the working pit. These would be placed "upstream" of the working pit areas to keep them relatively dry during runoff. The "working sump" is a depression in one end of the working pit which will accumulate the natural runoff from water which finds its way to the working pit. The size of the sump will vazy, but will be adequate to contain runoff from a relatively significant storm.t~The method of removal of water from the working sump will be evaporation. Initial plans call for the installation of a gravel wash plant in the neaz- to mid- term. The gravel wash plant will require a sedimentation basin so that water can be recycled through the plant once the fines have settled out of the dirty wash water. Normally, the sedimentation basin is in close proximity to the wash plant and is built on a mildly sloping portion of the site in a horseshoe shape. Dischazges will be made into one leg of the horseshoe and recycle water drawn from the other. Sedimentation basins of this type aze normally about one acre in size with a water surface azea of approximately one-third of an acre. When the sedimentation basin is implemented, more detailed information will be forwazded to theJ Mined Land Reclamation Division relative to its design. Exhibit E -Reclamation (l.) As your site visit indicated, there is relatively little undisturbed topsoil in this 40-acre phase of the project. Topsoil will be spread as available; however, it may only be available in sufficient quantities to cover those azeas most likely to establish a good stand of vegetation. Therefore, there may be :;ome azeas