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Waste rock is placed on the waste rock pile as described in the mining plan. Waste rock <br />is also gobbed underground to reduce the volume of the external waste rock pile. The <br />waste rock proposed for gobbing underground will not be differentiated from waste rock <br />disposed in the surface facilities. Therefore, the geochemical characterization of waste <br />rock provided above and in section (14) Geochemical Data and Analysis is applicable to <br />waste rock that may be placed underground. In addition, the underground workings are <br />historically dry, the water table occurs below the contact of the ore zone and although <br />drilling has identified a few perched aquifers in the area, none reach the underground <br />workings (see below in section (8) Groundwater Information). After mining is finished, <br />the waste rock pile will be reclaimed as described in Exhibit E - Reclamation Plan. <br />6.1.3 Prevention of Adverse Offsite Impacts <br />6.1.3.1 Stormwater <br />Stormwater will be diverted away from the waste rock pile and ore pad via berms and <br />ditches. Diversion structures will be constructed and maintained and left in -place after <br />reclamation in order to discourage runoff from coming in contact with either the waste <br />rock pile or the ore pad area. Cotter understands the importance of constructing and <br />maintaining all stormwater control structures regardless of any other activities onsite. <br />6.1.3.2 Cross Contamination <br />Cross contamination of the waste rock and ore underground is minimal due to the nature <br />of the "split shooting" method used in mining. During the "split shooting" mining <br />method, the test boring are drilled and probed to determine where the break between ore <br />and waste material is, and then the waste material is blasted and removed. Once the <br />waste material is removed, the ore material is blasted and removed to the ore stockpile <br />area. <br />Cross contamination between the waste rock pile and ore on the surface is unlikely as the <br />ore pad is located downhill and in a separate area from the waste rock pile. Upon <br />reclamation, the toe of the waste rock pile may extend to the ore pad area but runoff from <br />the waste rock pile will be captured and retained in the runoff basin located south of and <br />beneath the ore pad (See Drainage Design Plan maps). <br />6.1.3.3 Groundwater <br />There is no significant groundwater at the LP -21 mine area, and migration rates for water <br />infiltrating through the waste rock piles have been calculated for similar mines in the area <br />and do not pose a threat (see Contamination Migration Report found in Appendix II). <br />For a full discussion of the potential effect to the groundwater see below in <br />(8) Groundwater Information. <br />6.1.3.4 Re- vegetation <br />The waste rock pile and ore pad will be capped with fine waste material and any available <br />soil, and then reseeded after mining is completed. Evaporation from the surface and <br />shallow subsurface limits infiltration through the waste rock pile. After re- vegetation is <br />O'Connor Design Group Inc. U - 7 <br />