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PERMFILE100608
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PERMFILE100608
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Entry Properties
Last modified
8/24/2016 9:55:14 PM
Creation date
11/24/2007 7:14:35 AM
Metadata
Fields
Template:
DRMS Permit Index
Permit No
C1981026
IBM Index Class Name
Permit File
Doc Date
6/23/1981
Doc Name
MLRD PRELIMINARY ADEQUACY REVIEW & WYOMING FUEL CO. RESPONSE
From
MLR
To
WY FUEL CO
Section_Exhibit Name
ADDENDUM I
Media Type
D
Archive
No
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<br />ldyoming Fuels' Testing Results <br />Assumptions Produced by Other Operators <br />Waste Pile Spoils ' <br />Angle of Internal Friction 35 degrees 37 degrees <br />Cohesion 500 lbs./f t.2 100 lbs./f t.2 <br />Pit Wall Strength <br />Angle of Internal Friction 40 degrees 22 degrees <br />Cohesion 10,000 lbs./f t.2 4,000 lbs./ft.2 <br />Waste Pile Surcharge 10,000 lbs./f t.2 10,000 lbs./ft.2 <br />Based upon the obvious discrepancies between specific testing results developed <br />by other operators and the assumptions made by Wyoming Fuels, I would have to <br />disagree with the operator's contention that their assumed strength parameters <br />are conservative. Utilizing material input parameters similar to those developed <br />by other operators within the North Park coal province will probably result in <br />significantly reduced calculated factors of safety for both the waste pile <br />slopes and the pit wall slope. <br />On page 54 of their application (April version), Wyoming Fuels states that the <br />nomograph (incorrectly referenced as Figure 7; in actuality appears to be <br />• Figure 6) solution for the waste pile "stability number" was 41. Entering the <br />Figure 8 nomograph within input parameters for slope angle (i) equal 30 degrees <br />and ( ) equals 16.4, the correct nomograph solution for the stability number (N) <br />appears to be approximately 27. Utilizing this value results in a static slope <br />safety factor for the waste pile of 1.15, rather than the 1.8 reported within <br />the application A static slope safety factor of 1.15 will not satisfy the <br />requirements of Rule 4.09. <br />Utilizing Homographic solutions for stability analyses., is only appropriate in <br />relatively small, hazard-free overburden spoil fills. Considering the close <br />proximity of Wyoming Fuels' waste pile to its Pit No. 1 at the Canadian Strip <br />Paine and the potentially sub-standard factor of safety, I do not believe that a <br />Homographic technique is appropriate in this situation. I recommend that we <br />require the applicant to submit a thorough geotechnical and stability analysis <br />utilizing appropriate materials testing results and an "accurate" mathematical <br />technique such as the "modified Bishop's" method of analysis. <br />4.13 Contemporaneous Reclamation <br />As the present operations in Pit Ill will end soon, WF must explain why <br />reclamation cannot occur as soon as the initial cut in Pit Ill is completed. The <br />schedule of mining and reclamation operations concerns the Division for several <br />reasons. First, the length of time the topsoil stockpiled for Pit Ill reclamation <br />may seriously reduce its value as a plant growing medium. Secondly, any problems <br />which may exist in establishing the desired plant community will not be known <br />• until reclamation begins in Pit I12. Finally, the environmental problems caused <br />by the open pit and overburden stockpile will exist until 1987. <br />
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