2009-09-21_REVISION - C1981010

• Permit No: C1981010
• IBM Index Class Name: REVISION
• Doc Date: 9/21/2009
• Doc Name: Proposed Decision and Findings
• From: DRMS
• To: Trapper Mining, Inc
• Type & Sequence: PR6
• Email Name: JDM
• Media Type: D
• Archive: No

VI. Use of Explosives
The blasting plan, as well as other items related to blasting, is discussed in Section 3.4 of
Vol. III of the permit application.
1. The Division has previously approved blasting at times other than those described in
the blasting schedule due to unavoidable hazardous situations. These situations
include elimination of misfires, adverse weather, equipment failure, and safety related
reasons. (4.08.3(2)(b)(v) and (4.08.4(2)).
VII. Disposal of Excess Spoil
Section 3.5.3 of Vol. III of the permit application discusses the disposal of excess spoil.
Trapper proposes to remove approximately 29.3 million cubic yards of overburden spoil
material in the K-Pit and place the material in two permanent fills, the K-Pit Buttress Fill
and the Horse Gulch Fill. Much of this material is located within the landslide that
occurred in the K-Pit in October 2006. Appendix T of the permit application contains
engineering designs for the K-Pit Buttress Fill and the Horse Gulch Fill
The K-Pit Buttress Fill will be constructed at the toe of the landslide that occurred in
October 2006 using spoil removed from the K-Pit area. This fill will be constructed in
horizontal lifts placed on the existing topography. Lifts will not exceed 100 feet thick
and will typically be 25 to 50 feet thick. A truck/loader fleet will place each lift
beginning on the outer perimeter of the fill and then advancing inward toward the center
of the fill. As conditions require, a dozer will be utilized to push the material to the edge
of the lift in the center of the fill. The slopes of the fill are planned to be 3H:1 V and will
be contoured to blend with the existing topography.
The Horse Gulch Fill will be constructed utilizing dragline spoil from the K Ridge Pit
and truck/loader spoil from K-Pit. The dragline portion will first be constructed through
typical dragline spoiling. The truck/loader portion of the fill will be constructed in
horizontal lifts placed on the floor of Horse Gulch. Lifts will not be more than 100 feet
thick and will typically be 25 to 50 feet thick. The west face of the fill will have an
overall slope not to exceed 3H:1 V. A 30-foot wide bench will be constructed every 100
vertical feet.
The K-Pit Buttress Fill and the Horse Gulch Fill will be inspected in accordance with
4.09.1(11). A certified report will be submitted to the Division within 2 weeks after each
inspection to certify that the fills have been constructed as specified in the design
approved by the Division.
The K-Pit Buttress Fill and the Horse Gulch Fill will be re-topsoiled, and seeded in
permanent vegetation compatible with the planned post mining land use of Rangeland
and Wildlife Habitat.
As discussed below, the Division proposes to approve placement of the landslide material
into the K-Pit Buttress Fill and the Horse Gulch Fill.
Trapper Mine 30 September 21, 2009