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2023-09-12_REVISION - M2003001
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2023-09-12_REVISION - M2003001
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Last modified
9/13/2023 8:45:30 PM
Creation date
9/13/2023 9:33:12 AM
Metadata
Fields
Template:
DRMS Permit Index
Permit No
M2003001
IBM Index Class Name
Revision
Doc Date
9/12/2023
Doc Name
Request For Succession Of Operator
From
Burnco Colorado, LLC
To
DRMS
Type & Sequence
SO3
Email Name
ECS
MAC
AWA
SMS
Media Type
D
Archive
No
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TETRA TECH RMC <br /> Mr.Jeff Gregg <br /> March 21,2003 <br /> Page 4 <br /> Stability analyses were run on 400 randomly generated circles generated at the mine excavation and <br /> highwall,as well as the nearby permanent structure. The Simplified Bishop Method was used to <br /> estimate the factor of safety on the most critical surface. The modeling of the residual strength <br /> bedrock is conservative,thus the DMG considers a Factor of Safety of one or greater to be sufficient. <br /> Input files and graphic profiles of each analyses are attached. <br /> Following are the four scenarios modeled and the resulting factors of safety: <br /> ► Scenario 1: This scenario was modeled to simulate conditions along the mine perimeter. <br /> The mine highwall was modeled as described above with the slurry wall 55 feet from the top <br /> of the mine slope and the Plumb Ditch another 20 feet beyond the slurry wall. The ground <br /> surface elevation rose beyond the ditch based on the site topographic survey. The resulting <br /> Factor of Safety at the ditch was 1.24. <br /> ► Scenario 2: This scenario was identical to Scenario 1 with the exception that the surcharge <br /> load simulating a stockpile was added 10 feet from the perimeter of the mine. The resulting <br /> load was on the resisting side of the failure circle resulting in a Factor of Safety at the ditch <br /> of 1.37. <br /> ► Scenario 3: This scenario was modeled to simulate conditions on the interior berms of the <br /> mine where gas wells,pipelines,tank batteries,and access roads will be present. In this <br /> scenario,no slurry wall was modeled and the failure surfaces were run from structures <br /> located 55 feet away from the mine highwall. The resultant Factor of Safety was 1.05. <br /> ► Scenario 4: This scenario was identical to Scenario 3 with the exception that a surcharge <br /> load was added to the analysis to simulate a stockpile 10 feet from the top of the highwall. <br /> Again the resultant load was on the resisting side of the failure circle and the resulting Factor <br /> of Safety at the structure was 1.16. <br /> The mine plan incorporates minimum setbacks accounted for in our stability analysis. Based on our <br /> analysis,mining should not pose a hazard to nearby permanent structures. <br /> LIMIATIONS <br /> Our review is based on regional geologic mapping,present mining plans,bore hole data,and stability <br /> analyses using typical strength parameters for the various strata in the critical section. Should the <br /> mining plans change or subsurface conditions vary from those portrayed in this letter,we should be <br /> contacted in order to re-evaluate the potential affects on permanent man-made structures. Stability <br /> analyses were run at the structure in question and were not run on failure surfaces closer to the <br /> highwall. Factors of Safety at and closer to the highwall will be less than those calculated at the <br /> permanent man made structures. <br /> Please call with any questions or comments. <br />
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