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GENERAL35216
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Last modified
8/24/2016 7:56:18 PM
Creation date
11/23/2007 8:14:47 AM
Metadata
Fields
Template:
DRMS Permit Index
Permit No
C1981018
IBM Index Class Name
General Documents
Doc Date
6/4/1981
Doc Name
Proposed Decision and Findings of Compliance
Permit Index Doc Type
FINDINGS
Media Type
D
Archive
No
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occurrence,of sediment concentYations due to the installment of control measur- <br />es. Sediment contribution from underground mine dewatering should have little <br />impact on the surface water quality as this water will be stored in a holding <br />tank and treated for use in surface facilities (where it will be monitored) or <br />re-used in the mine. <br />Effects on the surface water system from the Refuse Disposal area should be <br />minimal. Analysis of the waste material does not indicate that toxic or acid- <br />forming characteristics are present, so the disposal areas will not be lined to <br />prevent percolation into the groundwater system unless future monitoring re- <br />sults indicate that this is necessary. The ~.vaste will be covered with four <br />feet of soil, thereby reducing infiltration of water into the pile and the <br />potential for contamination of surface waters. All run-off•from the disposal <br />areas will be routed through sedimentation ponds monitored for degradation of <br />quality before being released into the Red Wash t~,ibutary, and treated if <br />necessary. <br />Subsidence from underground mine workings could potentially impact both Red <br />Wash and Scullion Gulch. The effect on Red Wash is of greatest importance be- <br />cause it drains approximately 122 square miles at the location where mining <br />will extend beneath it. Although predictions indicate that maximum vertical <br />subsidence could approach six~feet after longwall mining under Red Wash, large <br />crevasses or collapse of the surface should not occur because there are 600 - <br />1,200 feet of overburden above the coal seain in that area. Furthermore, the <br />swelling of shales and overburden from the caved roof should effectively fill <br />the mine opening (p. III-1400 of the permit application). •An on-going monitor- <br />ing program will.be implemented to detect subsidence in the first longwall <br />panel and room and pillar panel during the' initial years of mining. Predic- <br />tions of probaDle'.disruption of the hydrologic regime from subsidence will be <br />based on an analysis of that data. Tension cracks may develop in formations <br />directly underlying Red Wash. It appears that these cracks may extend to a <br />depth of several tens of feet based on communication with experts in this field <br />(page IIC-106b of the permit application). These cracks will be of limited <br />extent, therefore, a minimal amount of surface water will be siphoned into <br />them. Furthermore, sediment accumulating in the cracks and clays in the over- <br />burden may ultimately seal them off from surface inflow. <br />33 <br />
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