HYDRO22032 - Laserfiche WebLink

Home Browse Search

INSPECTION REPOR Site: National King Coal Mine, Hesperus, Colorado Inspected By: Don R. May, P.E., Project Engineer Inspection Date: Quarterly Inspection, April 5, 2001 ~II III'IIIII"~I'I'd,P~~.REG1,p~~7::... sss ~, r.. ~:, .:- T ~~'~ ~ „ a' PoF c . l~ ~~~ -- ~`~l ~l - - qf d5y_)IV.4L t":. Ponds: The east and west sedimentation ponds and their embankments and outlets appear in good condition. The west pond is shown in photograph 1. As mentioned in earlier reports, the ditch entering the pond is undergoing erosion and should be repaired. The east pond appears in good condition. Routine cleaning will be required sometime this spring. Drainage Ditches: The eastside and westside drainage channels appear in goad general condition. Photograph 2 shows the armored ditch that runs down the north side of the waste pile. Photograph 3 looks across the face of the waste pile from the south, where you can see the rock lined ditches on both sides of the pile. Both of these channels appear to have an adequate capacity and should resist erosion. Photograph 4 shows the clean water ditch that runs behind the mine office. All other ditches and structures were inspected and appear in good operating condition. Photograph 5 shows the mine yard and waste pile from a vantage point near the mine portal. As seen the yard is in good condition. There are no apparent drainage problems on the site. All drainage features have been constructed and are operating as stated in the drainage plan submitted to the Division of Minerals and Geology. Coal Waste Pile: There are no visible signs of structural instability on the waste pile. Photograph 6 looks down the new road that has been constructed above the north side of the pile to provide access to the upper valley as the pile grows. The toe of the waste pile face has been cut to a steep angle to make mare room for the coal truck while loading. This oversteepening of the face could result in instability. This area should be regraded the design slope of 3:1 and compacted to 90% proctor. It is important that the waste material be placed in lifts not to exceed 12" to 18° and that compaction results in the density stated in the design report. It is not possible to determine this by visual inspection and therefore the density should be periodically checked by measurement. Rill formation on the front face of the waste pile is unchanged from the last inspection. The highwall and other slopes at the site appear stable. It is recommended that the upstream end of the water pile u~~'~rd~=~~ `+_ ~~~^`?~! ^~-' --._L_.: ,~ ,~_ _.~_ _. .._ .. ._.. ,. ~..~w ,ILJ~C Ul, li., ~...~ A survey was completed to check the slope of the face of the waste pile. The reclamation design specified a slope not to exceed 3:1. The attached graphs show six cross sections taken on the face of the pile. The design slope is shown on each graph. As seen most areas are right or just slightly steeper than the design slope. The exception is cross section 1 and portions of 2. Section 1 is on the far side of the pile closest the high wall. In this area the slope is making a transition from very steep to the design slope. Care should be take, especially in this area, to assure that as the pile grows the slope of the face does not exceed the design slope.