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_GENERAL DOCUMENTS - C1981017 (283)
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_GENERAL DOCUMENTS - C1981017 (283)
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Last modified
11/2/2020 11:43:15 AM
Creation date
6/25/2012 1:42:53 PM
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Template:
DRMS Permit Index
Permit No
C1981017
IBM Index Class Name
GENERAL DOCUMENTS
Doc Name
Bid Documents (IMP)
Media Type
D
Archive
No
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DRMS Re-OCR
Description:
Signifies Re-OCR Process Performed
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-31- <br /> The major regional bedrock aquifers in the general area of the mines are <br /> the Cozette sandstone, Rollins sandstone, the Middle sandstone, and the <br /> Upper sandstone members of the Mesaverde Group; and the Wasatch <br /> Formation-Ohio Creek Conglomerate. <br /> The regional sandstone aquifers of the Mesaverde Group are thick, fine to <br /> medium-grained, calcium carbonate cemented, quartzitic sandstones. As <br /> Aquifers, they have low to moderate permeabilities and transmissivities. <br /> At the North Thompson Creek Mines, the only regional sandstone to have <br /> aquifer tests performed on it was the Upper sandstone member, which <br /> yielded a transmissivity value of 17UO gpd/ft. This value may be high <br /> due to fracture permeability. The Rollins, Cozette, and Middle <br /> sandstones, where fractured, should have similar transmissivities. The <br /> water quality analyses of the Upper sandstone member yield values for pH <br /> of 7.5 to 8.0, and TUS of 1262 mg/l . <br /> No wells are drawing water from the sandstones of the Mesaverde Group in <br /> the general area. However, ground water mine inflows from the Williams <br /> Fork Formation are utilized by the mines. This water is used within the <br /> North Thompson Creek Mines, and used outside of the mine for a sanitary <br /> supply, for dust suppression, for equipment washdown and in the <br /> 1 � washplant. This mine inflow water is tributary to both North and Middle <br /> 1 j Thompson Creeks. A small percentage of the inflow waters within the <br /> Sunlight and Coal Basin mines are used within the mines. The majority of <br /> the mine waters from these two mines are discharged to the surface. <br /> The coal seams of the Williams Fork Formation are not aquifers, since the <br /> coals are tight and have insufficient primary porosity to transmit <br /> water. Ground water movement within the brittle coals is dependent on <br /> secondary porosity and is localized in fracture and fault zones. The <br /> highest occurrence of ground water in the coal seams is found in areas <br /> adjacent to and/or under streams. This occurrence is due to the <br /> combination of a good source of recharge water and a well developed <br /> fracture system associated with stream valleys in the area. <br /> � 4 <br /> The main streams and tributaries to Fourmile Creek, North Thompson Creek, <br /> Middle Thompson Creek, and Coal Creek cut across the Iles Formation and <br /> the coal-bearing strata of the Williams Fork Formation at right angles to <br /> strike. This suggests that the resistant Upper, Middle and Rollins S <br /> sandstone members have been breached by the streams along fracture or r v <br /> fault zones. The existence of fracture controlled stream valleys is Q W <br /> supported by mine inflow data. The occurrence of inflows into the three <br /> mines are greatest adjacent to and under stream valleys. The inflow f <br /> rates also mimic the flow characteristics of the adjacent stream <br /> Perennial inflows are associated with perennial streams, and ephemeral �Y` <br /> inflows are associated with ephemeral drainages. The increased inflows <br /> associated with the stream system are a function of the higher vertical <br /> permeability of the strata resulting from secondary fracture porosity in <br /> the stream valleys. The quantities of mine inflows and of the associated <br /> stream depletion are functions of 1 ) the area. of mine workings adjacent <br /> to the streams, 2) the thickness of strata overlying the mine, 3) of the JJJ ! <br /> lithology of the overlying and underlying strata, a) of the stream flow <br /> characteristics, and 5) the mining methods in the area of the streams. <br />
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