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GVest Elk Aline <br />if subsidence in the area of SOD wetlands creates a chango in the gradient that would result in a <br />lo~~~ering of wetland water table, modifications to the sh•eam channel to stabilize the water table <br />may be necessary. The mitigation efforts may include the construction of rock dales or weirs <br />that ~~-ould act as impediments to stream flow and result in the re-establislunent of the ~a~etland <br />water table levels. The Best Currently Available Technology will be used to restore the water <br />levels of the wetlands if necessary and only implemented after obtaining approval. <br />Additional mitigation of mitwlg impacts may be necessary if loss or dig-•ersion of~ f~lo«~ or a <br />significant change in the stream profile will significal,tly impact vegetation. Efforts evil) be <br />made to re-establish riparian vegetation in areas negatively impacted by changes in flow <br />locations. These re-establishment L'ff01'tS nla)' include, but not be limited to, planting of new <br />seedlings or reseeding wish appropriate species. The appropriate permits and approvals of plant <br />or seed mixes will be obtained prior to performins,~ nlltlgatloll actlVltleS. <br />[t is a17tIClp2lted that little or no impacts to wildlife and domestic livestock uses, and their <br />respective habitat ~~-111 OCCLII' aS ~ C0115egllenl'e Oi illllllllg-induced subsidence on the permit area. <br />In the unlikely event that subsidence effects adversely impact wildlife or domestic livestock uses <br />associated mitigation measures will focus on returned disturbed areas to a capability and land <br />use(s) ~~rhich existed prior to mining. These mitigation measures may include, but not be limited <br />to, repairs of surface cracks that are deemed dangerous to human, wildlife, or livestock. The <br />repairs of the cracks may include liackfilling with available native soils, gavels, concrete block, <br />etc. Livestock fences damaged by mining related activities will be repaired as soon as possible. <br />MCC has entered into an agreement with the Minnesota Canal and Reservoir Company to <br />obtain the appropriate approvals, pel-traits, and implement a preventative measures <br />construction project to modify and improve the Monument Uam (Exhibit 76). MCC <br />recognizes that any dam I170d1f1CatlonS pCOposec{ t0 zlncl Cal'1'led OLIt by the Minnesota <br />Reservoir and Ditch Company will require the activities be consistent with the reservoir <br />company's existing Forest-issued Special-Use Permit or will require a modification. to the <br />pei-lnit. Implementation of this project will prevent damage to the dam/reservoir from the <br />potential ofmining-induced microseismicity, strengthen the clam a;_~ainst damage due to <br />Ilattll'aliy OCCLll11n~? seismicity, and control damage clue to past and future periodic <br />movement ofthe landslide located on the left (south) abuhnent of the dam. Exhibit 72, <br />Prevention Measures, contains the general design of the measures to be implemented that <br />will allow the dam to reach a static safety factor of 1.5 and will safely withstand any <br />mine-induced microseismic event. The plans include the construction on the downstream <br />face of the dam of a sand chimney drain covered by stability berm. Additionally, a <br />buttress constructed of erosion resistant Till ~ti-ill he placed at the too of the danl. 1'he <br />purpose ofthe berm and buttress is to increase the stability ofthe danl till itself and to <br />impede ftu•ther movement of the landslide located in the lcI•t abuhllent. Other <br />preventative measures to increase dam and landslide stability may include the slip-lining <br />of the existin~~ outlet conduit with !-[DPE pipe to eliminate tho pe~ssibility of further <br />dama~~e l0 the el']stlllg cast iron pipe, replacement of tho inlet structure to outlet coruluit <br />to eliminate leakage around the existing structure, and construction ofdewatering treL1CI1 <br />to further stabilize a portion of the landslide. The detiniti~ms of affected area and disturbed <br />area. in CDRMS Rule I.0-1 do not apply to the preventati~~e measures Cur Moruunent Uam brcautie <br />the measures area '`reinforcement of asensitive sh•ucture•' as described in C[7RMS Rule <br />2.05-171 Re~•isedJune20051'!2l0. lter. Alarch100G:.1lnr100(, PR10. ~\'or. 300<,7R107..4ugrrsl2007!'RIOs <br />