2020-08-10_PERMIT FILE - M1984041

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� � �� l� _n.~a WATER MANAGEMENT 4~1 Relationship to Surface Water and Groundwater There are no rivers Or streams within the proposed disturbance area; however,there are dry creek beds that flow during major 8tOnns.vvhiCh8ner8naetUleK4ine. [}uhngnorm8| precpitabonevanta. the majority Of runoff infiltrates into dry soils or geologic fractures. These dry creek beds nsna|y flow with appreciable water. Storrnvvoter from the Mine and proposed disturbance area is not anticipated to report directly to the Eagle River without first passing through a sediment control structure. The depth to groundwater at the Mine is not known; however, water has not been encountered in the Lower Pit or Upper Pit development to date. Also, previous drilling campaigns in the Upper Pit and East pit area explored depths ranging fponn 10 to 250feet below ground surface without encountering groundwater.As outlined in Section 2.0, additional drilling may be performed (within Upper Pb and East Pit disturbance \irnita) to further define the depth and extent of gypsum and depth to groundwater. Drilling permits (including drill hole plugging and reclamation) Would be obtained prior to drilling and drill holes would be plugged in o manner appropriate 0o vvetar conditions encountered during drilling, |f groundwater is encountered during dri||ing, the u|dnnote pit depths (Upper Pit and East Pit) may be veducedfronn what is described herein and shown on the Drawings to avoid impacting groundwater.There is no source of surface or groundwater within the area of mining activity, so the operation would not affect either surface or groundwater. 4.2 Water Use Water required for dust suppression on haul roads would be acquired from the wallboard plant water supply system as per the current mining operation procedure. No other water use is anticipated for the proposed mining activities described herein, 4.3 Surface Water Management 4.3-1 Existing Sediment Ponds Existing sediment ponds W1501 and yN6(]1 will be used to temporarily store stornnvvater runoff and sediment from the Upper Pit Access Road and East Pit Access Road. M501 was constructed in 2004 (previously pond P4) and M801 was constructed in 2008 (previously pond P5). Three other ponds (M201, M301, and M401)were constructed in 2004 to temporarily store stormwater runoff and sediment from the haul road. Constructed pond |ooaUVnS and crest elevations differ slightly from the information provided toC(] DFlIVISinTFl-OO and TR-07. AC{u8| disturbance areas for the ponds, Spi||xv@ya, outlet atructuneo, and access roads were accounted for and additional cultural resources surveys were completed in July 2019.