2012-04-02_INSPECTION - C1981008

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March 15, 2012 C- 1981- 008/New Horizon Mine MLT BACKFILL and GRADING — Rule 4.14 Contemporaneous Reclamation 4.14.1; Approximate Original Contour 4.14.2; Highwall Elimination 4.14.1(2)(f); Steep Slopes 4.14.2, 4.27; Handling of Acid and Toxic Materials 4.14.3; Stabilization of Rills and Gullies 4.14.6: • In the New Horizon Mine permit application package, details on backfilling and grading, including post- mining topography (PMT) are found in Section 2.05.4(2)(c). A detailed table showing Overburden and Backfill Balance calculations for the final series of cuts (85 thru 111 and 95B thru 99B) is provided as Attachment 2.05.4(2)(c) -7. Map 2.05.4 -1 -2 illustrates the mining cut sequence and the PMT for the western portion of the permit area. One of the complaints raised by Turner - Morgan relates to the elevation (comparatively high) of Bench 2 backfill (spoil) being placed on the Morgan property and the potential reduction in thickness of Bench 1 (surface spoil) that could be placed on top of the spoil. As prescribed on permit page 2.05.4(2)(d) -12, a minimum of 3.0 feet of Bench 1 material is to be placed beneath the Lift B subsoil. The text goes on to state that, "All Bench 1 material stripped after June 2010 on the Morgan property will be salvaged and restored to the Morgan property." The large Morgan Bench 1 stockpile ( "OB 1 "), and a smaller OB I pile, continue to occupy backfilled areas behind the pit. This stockpiled material is to be replaced only on the Morgan property, on top of Bench 2 spoil and beneath Lift B subsoil. During the inspection, I viewed the active pit on the Morgan property from numerous vantage points and directions. Bench 2 spoil placed as backfill on the trailing (east) side of the pit appears to have been placed to an elevation somewhat higher than the top of the Bench 2 surface exposed in advance of the pit. This difference in elevation was especially visible when viewed from the north end of the pit (Photo 1). The thickness of Bench 1 Surface Spoil now in place on top of the Bench 2 spoil did appear to be somewhat thinner than what has been observed on previous inspections, but was easily in compliance with the minimum thickness required by the permit. Within the backfill exposed at the southern end of the Morgan pit, I observed an area where a layer of large -slab Bench 1 material had been distributed at a level that appears to be at or below the top elevation of Bench 2 spoil placed immediately to north (Photo 2). It would be undesirable to place rocks of this size within the upper portions of Bench 1 Surface Spoil, and depositing this very rocky material at a greater depth within the backfill is a reasonable alternative. The source of the large -slab material is a layer of well - cemented material in the middle of the in -situ Bench 1 overburden. This layer is resistant enough that the shovel is unable to dig it, unaided. Therefore, the mine has been drilling and shooting this layer to facilitate its removal. • On the Morgan property, between the large OB1 stockpile and the pit (Photo 3), a layer of Bench 1 Surface Spoil has been spread (possibly live - hauled) atop the area Bench 2 spoil backfill that was in the process of being placed at the time of the Division's Aerial Inspection on February 29, 2012. At the close of the inspection, I discussed the subject of backfilling and grading with mine personnel. Replacement of Bench 1 Surface Spoil is to be no less than the minimum thickness (3.0 feet) required by the permit. Topsoil and subsoil replacement thicknesses will be as described in Section 2.05.4(2)(d) of the permit. PMT for the Morgan (and WFC) parcel is expected to match that shown on the various permit maps, including Map 2.05.4 -1 -2. Number of Partial Inspection this Fiscal Year: 8 Number of Complete Inspections this Fiscal Year: 3 Page 4 of 12