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© RtsOOnse Ltrer <br />1.i 9/98 <br />Page a <br />. (eJ 73te application describes "diverting" surface runoff during drilling. Please be more <br />specific as to how this wtll be accomplished. The Divuton a concerned with the <br />proposed diversion labeled "D-S" in that we believe this could contribute to slope <br />saturation and instability. Please provide plans and drawings for the diversions to be <br />used in conjunction with this ,VOI. <br />Response -Your concern relative [o Diversion D-5, shown on [he original Exhibit <br />A-1, is acknowledged. This diversion is proposed as an operational component <br />under Technical Revision TR-32 and will be reviewed and addressed as a Technical <br />Adequacy issue under the TR. No long-term diversions are proposed in conjunction <br />with the exploration activities as reflected by the revised Exhibit A-1 which <br />accompanies these responses (also refer to the previous response to Comment 3c). <br />r 1 <br />LJ <br />Under the sub-heading of "Drilling and Related Activities", it is stated that, "During <br />drilling, OMI will control dust from drilling and related activities, divert and control <br />both natural runoff from disturbed areas and fluid loss from drilling, and will clean- <br />up any trash or debris". The reference to drainage diversion and control reflects <br />temporary site-specific control measures that may include berms or small temporary <br />ditches on the upslope edge of drill pads to intercept and divert any drainage azound <br />these areas and berms, straw bales, silt fencing, or other measures on the downslope <br />side of the pads to capture and control runoff and sediment from the pad areas. <br />Since each drill pad will only be disturbed for a period of approximately two weeks <br />during the relatively dry early winter period, construction/application of drainage <br />control measures will be limited and will be on an as-needed basis. As noted in the <br />NOI, drilling fluids will be contained by portable pits and/or excavated pits. Any <br />excess natural ground water flows from the drillholes during drilling and pumped <br />discharge resulting from well development or initial aquifer testing will be controlled <br />by pits and then discharged through either temporary pipelines or an installed <br />discharge line to Elk Creek. <br />A maximum discharge rate of 200 co 300 gpm (0.4 co 0.7 cfs) is anticipated during <br />pump testing of the large diameter dewatering wells. Oxbow has applied to the <br />Colorado Department of Public Health and Environment -Water Quality Control <br />Division for modification of existing CDPS Permit CO.0000132 to reflect discharge <br />from the dewacering wells. Given normal processing time for a CDPS Permit <br />modification, OMI has talked with WQCD about a construction dischazge permit <br />for the well testing activities and anticipates a response shortly. Applications have <br />also been filed with the Colorado Division of Water Resources for construction of <br />the proposed monitoring and mine dewatering wells and the required CDWR <br />acknowledgements have been received. Copies of the noted applications and <br />acknowledgements accompany these responses for your reference. <br />I• <br />