2013-01-29_PERMIT FILE - C1981022A (3)

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Section - 2.05.6 times as well as by some compaction of pond bases during construction, and accumulations of fine suspended solids which will tend to further limit overall base permeability. Both TSS and various chemical constituents tend to accumulate in the sediment in the bottom of sedimentation ponds due to natural settling. Regular periodic removal of sediment accumulations from the sedimentation ponds unl eliminate a pnten tial anttrrr of rnnrentra trrl rnnarihirnrc minimizing chemical buildup. OMLLC will monitor sedimentation pond dischazge in order to detect any significant changes in surface water quality. If significant changes are noted, OMLLC may, with consultation from the DMG, develop and implement appropriate water treatment plans, Upon completion of mining, all mine disturbance areas will be reclaimed. Reclamation and establishment of effective vegetative cover will minimize disturbed area runoff to the sedimentation ponds, limiting potential effects of surface leaching and evaporation. Reclamation will also result in restoration of natural drainage and direct discharge to the receiving drainages once the sedimentation ponds are removed at the end of the extended liability period. Given this consideration, any potential ground water impacts will be both limited in scope and of a temporary nature. Protection of Water Rights and Use - As previously noted under Protection of Surface Water Quantity and Quality (Mine Water Supply Withdrawals), OMLLC's water supply withdrawals will not exceed their water rights. In addition, mine drainage will have little or no impact on water rights or use since only ground water will be directly impacted and beneficial ground water use in the area is very limited. There is some potential that subsidence effects may impact surface seeps and springs in the azea which axe non-adjudicated water sources used on an informal and occasional (when flowing during part of the year) basis by livestock. OMLLC is committed to working with azea landowners to restore, replace, or provide reasonable compensation for any significant livestock watering sources that are adversely impacted. Mitigation could include repairs to suxficial tension cracks in stock ponds and ditches, construction of additional stock ponds, cleaning of existing stock ponds, and providing additional supplies of water through augmentation of existing OMLLC water rights. Mapping of Hydrologic Protection Information -Information presented on the regional and facilities azea maps which addresses hydrologic protection issues includes: • Water supply intakes • Receiving surface water drainages • Diversion, collection, treatment, storage, and discharge facihdes and structures • Water monitoring locations and elevations • Existing and proposed sedimentation ponds, impoundments, and mine development waste pIles • Cross-sections for sedimentation ponds, impoundments, and mine development waste piles Evaluation of Probable Hydrologic Consecjuences In order to assess the probable hydrologic consequences of the planned mining and related activities OMI has reviewed and evaluated all available information on baseline hydrologic conditions in Section 2.04.7, Hydrology Description, which characterizes the existing surface and ground water environments. Within the context of the existing hydrologic conditions, OMI then considered all potential hydrologic impacts, both positive and negative, which could occur as a result of the current and planned mining and related activities based on the plans presented in Sections 2.05.2 and 2.05.3, Operation Plan, and Section 2.05.4, Reclamation Plan. Both direct and indirect mining-related impacts were identified and evaluated and the effectiveness of operational protection and control PROS 2.05-88 Revised November 2002