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9.2 Remediation Work Plan <br /> CDPHE (2002)presents an evaluation of 10 alternatives for remediation of the IXURoyal <br /> Tiger site. The alternatives evaluated by CDPHE (2002)included no action as well as a <br /> variety of active remediation efforts. The proposed remediation of source materials <br /> associated with the IXURoyal Tiger site is based upon the recommendations outlined in <br /> the Targeted Brownfields Assessment(CDPHE,2002)Alternative 4A with some <br /> refinements. The plan elements include: <br /> 1. Improve the conveyance of adit flow around fine grained tailings; <br /> 2. Create additional wetlands in the south side of the Swan River valley immediately <br /> adjacent to the IXURoyal Tiger site; <br /> 3. Divert Swan River flows upstream of the site to the north channel; <br /> 4. Improve the fine-grained tailings cover below the former mill area; <br /> 5. Cover stream-side tailings in place;and <br /> 6. Place institutional controls to minimize contact with waste rock. <br /> The locations of the various plan elements are shown on Figure 3. Completion of these <br /> tasks will meet the objectives outlined above,and will be protective of human health and <br /> the environment for those occasional users who will visit the site for recreational <br /> purposes. The following paragraphs describe the remediation plan in more detail. <br /> 9.2.1 Improve Adit Conveyance <br /> AN discharges currently flow along an unlined channel down the slope of the waste- <br /> rock pile,around the perimeter of the covered Tine-grained tailings below the former mill <br /> area,and into a wetlands area. The unlined channel is currently eroded into a relatively <br /> steep face of the waste rock,affording the potential to erode these materials as well as <br /> increasing the saturation of the waste-rock pile. The charnel currently flows at a lesser <br /> grade along the uphill side of the covered fine-grained tailings,where add discharges <br /> may infiltrate into the subsurface and potentially leach metals from the fine-grained <br /> tailings. <br /> The channel leading from the adit to the wetlands will be re-routed and lined to minimize <br /> or eliminate these sources of metals into the environment. Approximately 550 feet of <br /> lined surface-water diversion ditch will be constructed upslope of the waste-rock dump, <br /> conveying the adit discharge around the waste rock rather than across the face of the <br /> pile. A culvert will be constructed to convey flow underneath an existing access road on <br /> the west side of the waste-rock pile, if it is determined that this road will remain in use. <br /> The new channel will be placed further away from the covered fine-grained tailings and <br /> discharge into the existing wetlands area. <br /> The improved channel will be lined with concrete specified to be compatible with the <br /> chemical and physical characteristics of the adit discharge. The channel will be sized to <br /> convey the expected flows based on previous measurements collected by ABC and <br /> CDPHE. <br /> Benefits of the improved adit oonveyance will include removing a potential source of <br /> saturation of the waste-rock pile.reducing the amount of erosion of waste-rock <br /> materials,and removing a potential source of infiltration into the fine-grained tailings <br /> below the former mill area. <br /> IXl/Royal Tiger VCtlP Application -- -_ .._., Page 23 of 33 <br />