2009-02-23_GENERAL DOCUMENTS - C1981020

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The majority of the reclaimed areas of the mine site were stable with adequate surface water runoff control. Observations were made throughout the inspection with regard to the erosional stability of the reclaimed landscape. The most significant challenge associated with the reclamation. at the Munger Canyon Mine was the construction of stable backfill slopes at grades of up to 2H:1V in the portal area and along the portal access road. To ensure that the reclamation of the mine site and road would be stable, analysis of stability was performed on three areas on the road and two on the mine site. The stability analysis is described on pages 3-8 through 3-11 of the PAP. The reclaimed configuration is shown on Figure 3.1-5 through 3.1-7. Reclamation stability cross-sections are provided in the PAP on Figures 3.1-8A, 3.1-9, and 3.1-9A. As shown in Figure 3.1-9A at Station 49+25 the backfilled area west of the portals was reclaimed to an overall, approximate 3:1 slope. This was verified with field measurements using an inclinometer at two locations west of the portals where an average slope of 42% or slope ratio of 2.4:1 was measured. Slopes along the former portal access road and in the area of the mine portal backfill were extensively roughened by track hoe gouging. A quick growing annual cover crop ("Quickguard" sterile hybrid) was hand broadcast immediately following completion of grading and surface roughening. Permanent seeding was done by hand broadcast followed by mulching in November 2007. Overall the reclamation project has been very successful and there has been minimal erosion to date. The graded backfill slopes in the portal area blend in well and conform to the original topography. The portal access road reclamation generally blends into the adjacent steep slope and outcrop topography. There are segments of steep road cut exposed along portions of the reclaimed road but these are approved in the reclamation plan based on backfill stability considerations. A portion of the backfilled slope in the vicinity of the portals is shown in Photograph No. 1 and a portion of the backfilled and graded portal access road is shown in Photograph No. 2. Post-mining slopes and landform configuration are similar to the pre-mining conditions identified in figure 1.1-2, and existing conditions shown in Figure 2.2-1 of the PAP. Because the disturbed area associated with the operation is of limited area and is located primarily in a draw with steep slopes and existing rock outcrops, post-mining topographic configuration is not unlike the pre-mining conditions. All highwalls were removed and there were no variances from approximate original contour (AOC) requirements allowed in the permit. There are some minor settling cracks in the immediate vicinity of the portal backfill. As seen in attached Photo No. 3 there is a significant settlement crack along the base of where three portals were backfilled. This is expected to heal with time and will continue to be monitored. A bigger concern is a small area of sloughing (Photograph No. 4) in the location of what appears to be the site of the former ventilation portal. This will require some remedial work to ensure that the portal remains properly sealed and stable. Since there is no vehicle access to this location it is recommended that the area of slumping be hand-worked with a shovel by tamping down and roughening to the extent possible. The area should then be reseeded. The sloughing at the ventilation portal is a maintenance issue that will not preclude Phase I bond release. The Division will continue to monitor this location on a routine basis. Access to Munger Canyon is from Colorado State Highway 139. The waste disposal haul road began at SH139 and ended east of the waste disposal area. The lower section of this road from SH139 7