2018-12-24_REVISION - C1981010 - Laserfiche WebLink

Home Browse Search

Please recalculate the sedcad runs to reflect conditions addressing the anticipated effects of disturbance for: 15. Middle Pyeatt 16. East Pyeatt systems Trapper Response to Comments 15-17: The two drainages have been modeled with current topographical boundaries and projected future disturbances to look at planned future conditions, versus those that existed when the "worst case" scenarios were developed for these two drainages. Enclosed with these comments are the Engineering Certifications and site drawings for both East Pyeatt and Middle Pyeatt Drainages. The Engineering Certifications testify to the fact that both drainages and series of ponds project that the 24 hour average settleable solids concentration released from the lower most ponds in each drainage is 0.0 ml/1, well below the 0.5 ml/l settleable solids standard and that all ponds have in excess of 1.0 feet of freeboard for a 25year/24 hour rainfall event as required. 24 December DRMS: Trapper's response is adequate. 18. Please discuss to what extend extent if any, the No Name Pond system may be affected by the changes in topography proposed at the D Pit? Trapper Response: No impacts are anticipated to occur to the No -Name Pond system as the post mining topography has not changed from the previous submittal of map M12 with PR -07. 24 December DRMS: Trapper's response is adequate. 19. Will there be any water routing structures to construct or modify? Trapper Response: There are no plans to construct or modify any water routing structures with this revision. 24 December DRMS: Trapper's response is adequate. When comparing the pre (M3, PR7) and post mining (M12, PR9) topography for the drainage cross sections proposed in Map M15 DRMS found the contour interval in the M3 series is incorrectly called out at 10', it appears to be 20' in reality making the M3 series maps incorrect. 20. Please resubmit corrected M3 series maps drawn at a contour interval of 10 feet so that DRMS can accurately compare pre and post mining topography in the drainage ways. Trapper Response: The legend included on M3 series maps is standardized on all of Trapper's 400 scale maps. The reference to 10' contours was in error on our part. The M3 map series has been corrected to reflect the actua120' contours present on the maps. Due to the M3 series maps depicting the pre -mining topography of the mine -site, 10' interval contours are not available. The topography used on M3 map is derived from the USGS quadrangles drawn in 1966. The revised maps are included in this response. 24 December DRMS: Trapper's response is adequate. Rule: 2.05.3(6) The above rule addresses the requirements for spoil and associated disposal structures. A description of the proposed N Pit was included in Section 3.1.4.1 as well as Map Trapper PR9 2"`' Adequacy Prepared by: R. Reilley, LISP, M.S. Page 9 Date: December 2018