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-~)_ <br />Because the Soutih f"Io Cte is +>ver appr of>riatcri, eh~• use oP !+i t wn t,v !or ,!ust <br />suppression r,~ould have to Lo r'eplace,i by augmentation water. A.11 water' ::tared <br />in the pit or stored in clay-lined, ncndcwaten:e! ponds would also have to be <br />replaced by augmentation. Deco use of these concerns the following stipulation <br />is necessary: <br />WITHIN 60 DAYS OF PERMIT ISSUANCE THE APPLZCR lJT SHALL SUBI•fIT TO A!LRD AND <br />THE COLORADO ^TATE ENGINEERS OFFICE R MORE DETAILED BREAY.DOWN OF THE PRO- <br />POSED USES OF TRIBUTARY WATER ASSOCIATED WITH THE A1INE OPERATION AND A <br />DETAILED DESCRIPTIO(J OF A MITIGATION) PLA1J FOR DEPLETIOIJ TO TRIBUTARY 4/ATER <br />THAT ZS ACCEPTABLE TO T77E STATE EtiGIiJEERS OFFICE. MITIGATION MRY INCLUDE AN <br />AUGMENTATION PLAN OR MEMBERSJfIP I1T AN jrUGMENTATION PLAN APPROVED BY THE <br />STATE ENGINEERS OFFICE. <br />IX. Assessment of Probable Cumulative Impact <br />The purpose of this discussion is to provide an assessment of the cumulative <br />impacts 'of the proposed mine and any adjacent mines on the hydrologic balance <br />of the region. In this case there are no other mines located near the Xeenesburg <br />mine that could synergisticLf impacC the hydrologic balance above what is <br />predicted for the individual mine site. To the best of our knoraIedye, the only <br />additional mining expected to take place in the area will be continual mining <br />by Coors Energy Company of coal adjacent to the five year permit area. From <br />information supplied by Coors, it is anticipated that an additional area of 920 <br />acres will be mined adjacent to the 921 acre permit area. 2'h.is mining will <br />take place over the next 20 years within the area designated "Final Mining <br />Operations Boundary" on the tdine Plan trop in Appendix ,+f-2. nfininy in pits A <br />and B wiZ1 continue to proyress south into Section 36 and an additional pit <br />(Pit C) will be opened adjacent to Pit B. <br />The effects of mining additional coal adjacent to the five year permit area will <br />be to magnify the impacts predicted for the 5-year mine plan. Mining the adjacent <br />land will not affect any additional aquifers or surface water bodies, However, <br />the effects of mining on the drawdown of piezometzic surface of the Laramie <br />can be expected to increase. A model presented in Appendix I-1 fiaye 43 predicts <br />that drawdown wilt increase to 2,090 feet (0.9 miles) adjacent from the pit <br />compared to the current prediction of 1050 feet for the five year mine plan. <br />Impacts from this s.l.ight increase in drawdown w.i11 be. minimal since t'hcre arc <br />no users of this water in the vicinity of the mine. Since rnininy will tend to <br />move west away from Emris Draw and since the transmizsivities of the Laramie <br />make the drawdown curves very strop at the active />it, drawdown Went Ennis <br />Draw will be srrall duriny later years of mining. <br />Changes in ground water quality in the Laramie should not vary significantly <br />as the result of additional mining. The overburden chemistry does not change <br />very much in areas adjacent to the five year mine plan. If the applicant is <br />correct in his prediction of little change in ground water quality moving <br />through spoils, then Ennis Draw will not be greatly affected. However, if water <br />is greatly degraded as it moves through the spoils, the effects on Ennis Draw <br />