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April 26, 2023 C-1980-007/West Elk Mine LDS <br /> raise material higher than a single excavator could alone. The pile was within the footprint of the un-reclaimed <br /> area on the top of the LRP. Some material had sloughed off the north side of the temporary pile but had been <br /> caught by the berm. Aerial images of the area were collected with a drone and processed to produce a 3- <br /> dimensional digital model,using Pix4D Mapper. The volume of the temporary stockpile was estimated,using the <br /> same software. The software calculates the difference between the Digital Surface Model (DSM) and a base <br /> surface that is created by interpolating between the vertices of a user-created polygon. There are several methods <br /> that the software can use to create the base surface,but all give similar results. Using the default method <br /> (triangulation),the estimated net volume of the pile at the time of the inspection was 26,315 m3 (+/-402 m3). The <br /> currently approved PAP allows for the temporary stockpiling of 150,000 cubic yards of compacted refuse and/or <br /> coal on the RPE and LRP (Page 2.05-46). As discussed below,the volume of the temporary waste pile on the RPE <br /> at the time of the inspection was 36,732 m3 (+/- 918 m3);the total volume of temporarily stockpiled material is <br /> estimated at around 82,500 cubic yards. <br /> The Division finds that the configuration of the temporary fines pile is not out of compliance with either <br /> the Rules or the approved mine plan,however it is a large stockpile that does not have an approved design. The <br /> stockpile should not grow any larger, and should be reduced in size as soon as possible. Future permitting work <br /> will be necessary to clarify language in section 2.05.3 of the PAP discussing the configuration of temporary <br /> stockpiles, and to remove inconsistencies between pages 2.05-44 and 2.05-46. <br /> PROCESSING WASTE/COAL MINE WASTE PILES—Rule 4.10 and 4.11 <br /> Drainage Control; Surface Stabilization; Placement: <br /> At the time of the inspection ground conditions were still too wet to allow transportation of waste to the <br /> RPEE, so waste was continuing to be temporarily stockpiled on the RPE. The volume of the temporary stockpile <br /> was estimated at 36,732 m3 (+/- 918 m3), and the material remained within the footprint of the un-reclaimed area <br /> on the top of the RPE. <br /> ROADS—Rule 4.03 <br /> Construction 4.03.1(3)/4.03.2(3), Drainage 4.03.1(4)/4.03.2(4), Surfacing and Maintenance4.03.1(5) and <br /> (6)/4.03.2(5)and (6), Reclamation 4.03.1(7)/4.03.2(7): <br /> Wells Excavating had done work on the RPEE haul road to improve the surface and to clean the ditch in <br /> preparation for the transportation of waste to the RPEE,however continuing wet weather had led to several <br /> rockfalls and slumps in the days preceding the inspection that had partially blocked the road, and more work was <br /> necessary for it to be passable. <br /> SLIDES and DAMAGE-Rule 4.12: <br /> Surface slides and rockfall were evident around the wider area, as well as within the permit area(for <br /> example, on the haul road to the RPEE). Mine staff reported that the MSB slump had been moving again <br /> following the wet winter and spring, and Barr Engineering were being consulted on a mitigation plan. Drone <br /> imagery of the MSB was collected at 400' above the bench,which gave a ground sampling distance of <br /> approximately 2"per pixel. The raw images clearly show the cracks on the outslope of the bench. The images <br /> were processed to produce a DSM, and contours were generated at 2' intervals. The contours show how the <br /> surface has deformed. <br /> Number of Partial Inspection this Fiscal Year: 7 <br /> Number of Complete Inspections this Fiscal Year: 3 <br /> Page 3 of 14 <br />