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to avoid potential anthropogenic effects to groundwater quality, which could be <br />caused by blasting, mine ventilation or other factors. <br />Intermediate Monitoring Wells <br />The Sunday Mines Group may potentially affect groundwater quality in close <br />proximity to underground workings because oxidation caused by mine ventilation <br />could influence the solubility of uranium and other trace constituents. However, <br />based on the data discussed in Section 8, any increase in oxidation of groundwater <br />near the underground mine workings is expected to be local in extent. As this <br />groundwater migrates away from the underground mine workings, it is expected to <br />be reduced to background redox conditions through interaction with trace organic <br />matter present in the Top Rim sandstone. Reduction of groundwater along the flow <br />path reduces the solubility of uranium and vanadium, and results in precipitation of <br />those elements into insoluble mineral forms. This geochemical process of uranium <br />precipitation caused by reduction of groundwater is a well- understood mechanism <br />for formation of uranium ore deposits (Guilbert and Park 1986). These ore - forming <br />processes can be used as a natural analog to understand the fate of uranium and <br />associated naturally occurring elements such as arsenic, molybdenum, and selenium <br />in the groundwater system (Langmuir 1999). <br />Two intermediate monitoring wells recommended by DRMS will be installed as <br />shown on Figure 11 -1. These wells will evaluate water quality at an intermediate <br />location between the existing mine workings and the compliance wells. The purpose <br />of these monitoring wells is to provide early indications of any potential groundwater <br />quality issues prior to effects at the compliance wells. <br />The intermediate monitoring wells are located in areas expected to be mined during <br />the life of the Sunday Mines Group; mining is planned to progress from current <br />mining areas towards the south. Therefore, these wells will be abandoned when <br />active mining approaches the monitoring well locations. However, these wells will <br />provide for additional environmental protection at the Sunday Mines Group during <br />the period when they are operational, and early warning of potential groundwater <br />issues prior to effects at the compliance wells. The intermediate monitoring wells will <br />not themselves be compliance wells. <br />Compliance Wells <br />Two groundwater compliance wells are proposed to be located south of the existing <br />mine area at the mine permit boundary. The permit boundary encompasses all areas <br />that are planned to be mined in the future. The purpose of the compliance wells is to <br />measure compliance of the mining operation with respect to applicable groundwater <br />quality standards. <br />Topaz Mine DRA Monitoring Well <br />One monitoring well will be installed at the Topaz Mine DRA. This well was <br />requested by BLM to further assess the potential for leachate generation from the <br />Sunday Mines Group DRAs. This well will be a shallow monitoring well installed <br />within colluvial sediments located near the base of the Topaz Mine DRA. <br />C \Users \cwoodwardiDesktop\Sundays \FINAL - Environmental Protection Plan Sunday Mines Revised January 2012 docx <br />1 1 -3 <br />