1998-10-05_REVISION - M1984099 - Laserfiche WebLink

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HALL IRWIN COMPANIES* PAGE 2 BAILEY PIT - TECHNICAL REVISION SEPTEMBER 23, 1998 tables and cross sections in that letter show how much material they think has to be removed to reconstruct the slopes damaged by highwater in 1997 & 1998. Each numbered typical cross section corresponds with a matching number shown on the map. The line weights on the map depict the slope widths on the cross section. A trenching and cut/fill method is the best way to complete the minor amount of work needed to correct the slopes. Tectonic Construction CO. will be doing the excavation and rough grading with a Cat 225 excavator or equivalent. This activity will not change the reclamation plan as approved, or increase the distur- bance in the mine area. It will improve the slopes along the river and reduce the chances of further erosion on these banks . 2 ) ARMORING OF BANKS - As part of the ACOE permit Tectonic placed inert material along the banks as armoring. This material consisted of dry concrete rubble placed on cut banks along the inner river banks . The areas and volumes are show in the attached 404 permit. The rubble used is consistent with the Colorado Department of Health and Environment regula- tions for inert material. During the reconstruction of the river banks parts of the setback areas were reconstructed using this material as fill and armoring material. Once the banks have been laid back to 3h to lv some of this material will remain visible along the cutbank areas . During late winter and early spring Tectonic is required to plant 350 willow stakes and 350 cottonwood stakes along the river. For them to be release from the ACOE permit they have to have nearly a 100% survival rate. 3 ) CHANGE OF WOODY SPECIES(RUSSIAN OLIVES) - Per your recommendation we are removing the Russian Olive trees from the approved plan. As we understand it, the Division of Wildlife and NRCS are trying to stop introduction of this tree species in the state after recommending it highly in their review comments during the 1970 's and 80 's. The approved plan called for planting approximately 500 Russian Olive trees along the north, east and south perimeters of the mine to act as a screen into the reclaimed area. The intent was to create a visual barrier with the Russian Olives and provide food for wildlife species expected to use the site.