Laserfiche WebLink
<br />are necessary to control runoff from the face of the contour <br />depression fill area. The upper diversion created by the <br />access road would appear to handle runoff from above the <br />disposal area, however it does not appear that any specific <br />provisions have been made for ensuring that possible <br />contaminated storm runoff and snowmelt from the face of the <br />disposal area will not discharge off site. It would seem <br />appropriate to include some provision for containing runoff <br />from the face of the disposal area at the base of the pile, <br />such as a collection ditch/berm and settling basin or pond <br />installed immediately below the disposal area. The Division <br />feels that, based on actual experience and observations of <br />thunderstorm intensity and heavy snow accumulations in the <br />area of the mine, the inclusion of specific stormwater control <br />measures is warranted. <br />The Division should also point out that the existing approved <br />permit contains requirements for the installation of specific <br />drainage control structures, such as an upper diversion ditch <br />associated with the open cut surface mining areas and a <br />provision ~or culverting runoff from the inside edge of the <br />access roads to a riprapped discharge point along the outside <br />edge of the access road. The Division recommends that the <br />applicant review the correspondence contained in the file for <br />this operation and incorporate required drainage control <br />structures into the amended operation. Additionally, all <br />drainage control structures presently approved or proposed to <br />be incorporated into the amended operation need to be shown on <br />the mine plan map and, if any are to be left as permanent <br />reclamation features, should also be shown on the reclamation <br />plan map. <br />It appears that the original position of the approved open pit <br />cut upper diversion ditch will need to be relocated from it's <br />presently approved position. The ditch is presently approved <br />to be contained within the original access road which is no <br />longer used, has already been partially inundated by the pit <br />progression, and will be completely mined through under the <br />current proposal. If the applicant wishes to eliminate this <br />ditch and allow upgradient runoff to drain into the pit for <br />subsequent use in the processing operation, information should <br />be provided which clearly demonstrates that the proposed below <br />grade design of the pit will at all times have sufficient <br />capacity to contain both the maximum anticipated volume of <br />water that would be stored in the pit prior to pumping for <br />future use, plus the additional anticipated volume of water <br />that would be generated by storm events and/or snowmelt. This <br />demonstration also applies to the cut and fill tailings <br />disposal areas referenced in the amendment application. The <br />response references a minimum of 1 ft. of freeboard for the <br />pits, however no information was provided demonstrating that <br />this design parameter will ensure adequate containment. <br />8 <br />