2010-04-06_INSPECTION - M1986061

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(Page 2) MINE ID # OR PROSPECTING ID # M-1986-061 INSPECTION DATE 3/22/10 INSPECTOR'S INITIALS RCO OBSERVATIONS This was a pre-operation inspection of the areas proposed by the operator to be added to the permit under Amendment AM-2, as well as a monitoring inspection of the existing 112c permitted area, performed by the Division. The operator was contacted about the scheduled inspection. The operator's representative named on page one was present during the inspection. Except for loading stockpiled material and hauling away by trucks, the site was not active during this inspection. The permit boundary ID sign was observed at the entrance to the site. Most of the permit boundaries run along existing fencelines, and it was observed that existing disturbances are within the boundaries. After the amendment is approved the operator must ensure that new boundaries of the expanded affected area, are adequately marked. Corner markers should be made more visible, and please ensure that they are durable. The bond is adequate at this time, but it will be completely recalculated as part of this amendment. No new figures are included with this report, since the amendment review is not completed. The northern part of the permitted area, Mining Area 1, has been almost fully mined. It will be expanded to the west, into an additional area called Mining Area 3. The highwall along the west sideof this mining area is vertical through a 25-ft section of aggregate, and the 10 ft of overburden has been sloped at about 2:1. The operator proposes to continue this type of highwall across the amended areas also. The pit floor in this area contains 2 large stockpiles of overburden and a topsoil pile. There is also a large topsoil pile above the western highwall. Highwall reduction, at the conclusion of mining in this northern area, will include backfilling deep fills of overburden to attain a surface of 1-:1 gradient, then topsoil and revegetation to irrigated pasture. The asphalt plant remains set up where it has been for a few years, in the southern part of Mining Area 1. It is clean and orderly, and all fluids are adequately stored with impermeable secondary containment. Not far south of the plant is a small area where the landowner stores his agricultural equipment (this was approved under a past revision). This pit floor elevation will not be mined down further. All earthmoving and processing equipment as well as agricultural equipment will eventually be removed so that the area can be reclaimed. The pit floor is fairly level. Recent snow melt has produced a muddy floor with a few areas of ponded water. A perimeter berm along the east side helps contain this water on the pad. However, there is one location along the eastern edge of the pad (pit floor) of Mining Area 1, where ponded stormwater has breached the containment berm and washed soil and rock down the slope. There is a buried culvert in this area whose inlet sits well above the height of the water level of the puddle (estimated surface is 20 ft x 100 ft). The location of the wash out is where the pad was extended sometime in the past by filling the gulch. Whether the failure was due to poorly compacted fill material or another reason, it was incompetent and failed when it was saturated and weighted by impounded water.. Removal of the buttressing material by gullying and/or deep wetting from spring snowmelt has also created several stress cracks along the edge of the pad, indicating further instability. Damage has occurred, and more damage appears possible. All eroded materials were transported a short distance down the slope, but appeared to be retained near the toe of the slope,, within the permitted area and above the confluence with Cottonwood Creek. This situation is noted as a problem on page one, under the topics of "erosion/sedimentation" and "stormwater management plan." The corrective action is that the operator must develop and implement a prompt and long term remedy to this unstable feature, and report such to this office. Please see the last page for the correction date. At the toe of the entrance ramp road is the water fill station. This station will remain in this location during future phases of mining. Farther south in Mining Area 2 are several gas well features that are well-marked and protected. Mining Area 4 will be added to the west of these structures, and pit expansion activity will include avoiding the gas well structures but rerouting a section of buried pipeline, under agreement with the well owner. In Mining Area 2, there is a grass-lined channel with culverted crossings for mining equipment, near Valley Fill #1 (which has been fully backfilled and is now used as stockpile area). A second large gulch, in the south end of Mining Area 2, will be similarly filled up to the future grade of the pit floor, and will be designated Valley Fill #2 and will include its own grass- lined channel. The south end of the current active mining in this area consists of another steep highwall, stormwater retention pond, pitrun and overburden stockpiles. Mining has extended southward nearly to the gulch that will be backfilled. It appears that some of the overburden that was stripped and placed along the top of the gulch slope has