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Mr. Forrest Luke <br />Page 3 of 4 <br />September 2020 <br />Rule 4.09.1(7): Disposal of Excess Spoil <br />DRMS August 2020 <br />The Division of Reclamation, Mining and Safety (DRMS), has reviewed Evaluation ofI and J <br />Pit Spoil Pile Stability Report by Aga Associates. Inc. dated May 26, 2019 for the Trapper <br />Mine Permit Revision PR-10. <br />4. In the Conclusion and Recommendations section of the report, the Operator states the spoil <br />piles will be constructed in small lifts (20-40 feet) to allow for better compaction of the spoil <br />particles. Pursuant to Rule 4.09.1(7), please explain how the spoil piles will be concurrently <br />compacted to ensure mass stability and prevent mass movement. <br />5. Please provide the Rockscience Inc. slope stability analysis data for the Agapito Associates, <br />Inc. geotechnical evaluation of the I and J Pits Spoil Piles to allow the Division to duplicate <br />the analysis with Clover Technology's Galena software for verification purposes. Please <br />include the profile geometries and the material properties used in the stability analysis, <br />preferably in paper and electronic forms. <br />Trapper Response to Comment 4: <br />The spoil piles will be dumped in 20-foot lifts for the most part with the large overburden trucks <br />providing the required compaction for the layers of fill. To sort the rock required for the underdrain, <br />taller dump faces, up to 40 feet tall, will be utilized to collect the rock. Even allowing for this taller <br />face, the compaction provided during this process allows for safety factors above 1.75 at the worst <br />case, exceeding the 1.5 criterion. <br />DRMS October 2020 <br />Trapper's response is adequate. <br />Trapper Response to Comment 5: <br />The profile geometries are included separately as DXF files so that they may be opened as digital files <br />and measurements taken from them. They are called A Section through D Section and their <br />material properties are included in Table 1, Summary Numerical Model Input Parameters, Page 4 of <br />Agapito Associates, Inc. report `Re: Evaluation of I and J Pit Spoil Pile Stability, Trapper Mine. <br />DRMS October 2020 <br />Trapper's response is adequate with the exception of: <br />5a. Please export the x,y coordinates from the DXF file crossections A-D into an excel file <br />and submit the excel file to DRMS. <br />Rule 4.23.2 Auger Mining <br />DRMS August 2020 <br />DRMS notes that as per the above referenced rule, auger mining shall maximize coal <br />recoverability of remaining reserves after completion of mining. DRMS finds that there may be <br />areas of undisturbed coal left in unmined sections that are in excess of 2500 feet apart. Given <br />that the ownership is the State of Colorado with a Trapper Lease, please demonstrate: <br />