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• Utilizing strict pH monitoring of the process waste stream, there are reasonable assurances to prevent impounding <br />waste containing tin-removed acid forming constituents (in this case sulfide minerals and heavy metals). Despite <br />this, the DRMS has determined that practice based ground water protection be applied to this operation through the <br />implementation of a composite liner system. This is further elaborated in Exhibit C. <br />None of the chemicals added as part of the process (refer to Exhibit C, 6.3.3(2)(a)) are listed as Designated <br />Chemicals and the source water for the process is municipal drinking water. The condition of the newly processed <br />tailings can only be bettered by this process when compared to their initial, pre-existing state. <br />6.4.20(1)(c)(iii) <br />same as 6.4.20(1)(e)(ii) <br />6.4.20(1)(c)(iv) <br />There will be no newly placed waste rock piles as part of the proposed operations. <br />There is, however, pre-existing abandoned waste rock (amounting to approx. 8,000 tons) located in the area of the <br />proposed Tailings Impoundment. As described above, this operation will be processing this material to extract the <br />acid forming constituents. <br />6.4.20(1)(c)(v) <br />There will be a temporary daily stockpile located at the Mobile Mill Site. The Crusher Feed Pile will hold a <br />multiple day's stockpile of feedstock for the mobile crushing plant. A maximum of 200 tons of material can be <br />contained in this area for any period of time. The surface of this area is to be concrete paved and sheltered with a <br />roof to prevent any acidic run-off and potential seepage. Additionally, the surface slopes '/4" - 1' towards the rear <br />where a 10" wide x 48" high concrete wall provides a berm to contain any residual moisture or sedimentation. The <br />opened face of this stricture shall be protected with a heavy canvas curtain that can be closed during a rain/snow <br />• event. The surrounding grade will be sloped to ensure run-off will not enter the structure. <br />Constriction and grading details can be found in Exhibit E, drawing E15. <br />6.4.20(1)(c)(vi) <br />There will be no other application of material at other land sites. <br />6.4.20(2) <br />Refer to the maps within Exhibit A and E for locations of pre-existing acid-forming materials and the earlier <br />mentioned Crusher Feed Pile. <br />6.4.20(3) <br />The only other known requirement for environmental protection measures from other jurisdictions at this location <br />pertain to CO Water Quality Control Division's stormwater management provisions. Refer to Exhibit C for <br />specifics regarding the Stonnwater Management Plan and SWMP permit requirements. <br />The groundwater generated from drainage of this area is hydraulically connected to the Big Five Tunnel, which lies <br />directly beneath the Tailings Impoundment. The EPA currently is doing extensive monitoring of this groundwater. <br />The Big Five Tunnel drainage is monitored, collected, and pumped to the Argo Tunnel Treatment Facility located in <br />Idaho Springs. The proposed operation will NOT adversely affect this monitoring and as time goes forward they <br />should begin to see an improvement in qualily because we are removing some point sources of acid runoff. <br />6.4.20(4)(a) <br />There are no other known pennits or local licenses needed in order to proceed with operations concerning the <br />handling of potentially acid-forming, pre-existing waste rock. Again, no designated chemicals are being used as part. <br />of operations. <br />• <br />Page 2 of 31