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of neutralizing capacity in the geologic system. As stated above, in the unexpected event <br /> that infiltration reduces to the point where it would create a lowering of the water table in <br /> the diatreme, exposing more sulfide for oxidation, the water level in the diatreme can be <br /> easily raised back to or above the current level by emplacing a plug in the Carlton Tunnel <br /> and raising the exit elevation to any desired level. <br /> ATTACHMENT 3—DEEP CARBONATE GEOCHEMISTRY EVALUATION/ADRIAN <br /> BROWN <br /> Memorandum by Schlumberger Water Services/Task 3 Cripple Creek Deep Carbonate Study <br /> Geochemical Modeling Results <br /> 2—Mass-Balance Geochemical Model <br /> • Page 2: The text states"The average flow through the system is about 1,660 gpm.No net <br /> increase in flow from the Carlton Tunnel is expected as a result of changing surface <br /> disturbance patterns in the future."However,according to the Hydrogeochemistry <br /> Evaluation provided by Adrian Brown, dated December 15, 2015,there will be an <br /> estimated 25%increase in Carlton Tunnel flow during the AM- 11 operations. Please <br /> explain this discrepancy. <br /> RESPONSE.Please see response to 3.6.1 above. <br /> 2—Mass-Balance Geochemical Model <br /> • Page 2: The text states"Prior to the currently ongoing Deep Carbonate (DC)project <br /> investigation, water levels in the northern eruptive center were unknown. These have now <br /> been measured to be anywhere from 670 to 1,480 feet higher than the elevation of Carlton <br /> Tunnel,indicating that the Northern Diatreme is not as well drained by the main diatreme <br /> mass(as previously assumed) and that a hydraulic gradient exists from the Northern <br /> Diatreme towards the Carlton Tunnel." Considering this information, is the current <br /> mining plan for the North Cresson Pit(and possibly the underground mine) adequate <br /> with regard to potentially elevated water levels in this slower draining portion of the <br /> diatreme? <br /> RESPONSE.No. The diatremal water level will still be well below the mining proposed in <br /> Amendment 11 and prior amendments. <br /> 2—Mass-Balance Geochemical Model <br /> • Page 5: the text states"Once sufficient HCT data become available as part of the ongoing <br /> DC project,these will be more representative of sulfide oxidation rates for model Cell 2. <br /> At that time,the geochemical model should be updated accordingly." Do you intend to <br /> provide this updated information to the Division when it is available? <br /> RESPONSE. Yes. The testing has been in progress for approximately 52 weeks to date, <br /> with the result that there is still available sulfide to oxidize, and available carbonate to <br /> neutralize the products of oxidation. Accordingly, we propose to continue the testing for <br /> the balance of 2016, after selective burn-out of the neutralization, to determine the <br /> kinetics of the sulfide oxidation post-burnout of the neutralizing capacity. The results to <br /> date are included herein as Attachment 3. <br /> ATTACHMENT 4—GROUNDWATER FLOW MODEL/PREPARED: FEBRUARY 27, <br /> 2012 /ADRIAN BROWN <br /> Page 13 of 28 <br />