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Dewatering Rates <br />Oct -11 <br />Nov -11 <br />Dec -11 <br />Jan -12 <br />Feb -12 <br />Mar -12 <br />Apr -12 <br />May -12 <br />Jun -12 <br />Jul -12 <br />Total <br />Month <br />1 <br />2 <br />3 <br />4 <br />5 <br />6 <br />7 <br />8 <br />9 <br />10 <br />Cumulative Projected Decline <br />Advance(ft) <br />200 <br />400 <br />600 <br />800 <br />1000 <br />1200 <br />1400 <br />1600 <br />1800 <br />0 <br />Dewatering Rate (gpm) High <br />0 <br />5 <br />10 <br />10 <br />15 <br />20 <br />20 <br />30 <br />30 <br />10 <br />Dewatering Rate (gpm) Low <br />0 <br />0 <br />5 <br />5 <br />5 <br />10 <br />10 <br />15 <br />15 <br />5 <br />Dewatering Rate (gal /month) High <br />0 <br />223200 <br />446400 <br />446400 <br />669600 <br />892800 <br />892800 <br />1339200 <br />1339200 <br />446400 <br />6696000 <br />Dewatering Rate (gal /month) Low <br />0 <br />0 <br />223200 <br />223200 <br />223200 <br />446400 <br />446400 <br />669600 <br />669600 <br />223200 <br />3124800 <br />Dewatering Rate (AF /month) High <br />0.00 <br />0.68 <br />1.37 <br />1.37 <br />2.05 <br />2.74 <br />2.74 <br />4.11 <br />4.11 <br />1.37 <br />21 <br />Dewatering Rate (AF /month) Low <br />0.00 <br />0.00 <br />0.68 <br />0.68 <br />0.68 <br />1.37 <br />1.37 <br />2.05 <br />2.05 <br />0.68 <br />10 <br />Groundwater inflow rates are estimated to be on the order of 5 -10 gpm or less prior to <br />interception of the Creede - Campbell Mountain Formation contact. Overall average <br />groundwater flow rates are estimated to be on the order of 7 to 16 gpm throughout the <br />construction of the decline. Table 3.1 presents the estimated schedule of dewatering <br />rates. <br />Table 3.1 Estimated Dewatering Rates to the 9400 Level Decline <br />The development of dewatering rates was based on the conceptual model presented and the <br />following considerations: <br />1. Seasonality of groundwater flow in the Creede Formation. The decline construction schedule <br />proposes an October 2011 starting timeframe. For purposes of the dewatering <br />estimates the average decline advancement is estimated at 8 ft /day, 6 days per week, <br />which equates to roughly 200 ft /month for 1,800 feet total. The Creede - Campbell <br />Mountain Formation contact is anticipated to be approximately 1,200 feet from the 9400 <br />portal. The total construction duration requiring dewatering is estimated to be <br />approximately 225 days, between 9 and 10 months. Assuming the schedule presented in <br />Table 3.1, the majority of the decline construction will take place during the base flow <br />months, or the time of the year when groundwater yields would be the lowest. <br />2. Timing of the interception of the Creede- Campbell Mountain Formation contact. Based <br />on the assumptions used in the analysis with respect to monthly decline advance and the <br />projected location of the contact (approximately 1,200 feet from the surface) it is anticipated <br />that the contact will be encountered sometime during March 2012, prior to the spring melt <br />and suspected time period of increased flows along the contact. Higher flows are expected <br />to be encountered during the later stages of construction beyond the contact as the <br />benefits expected from grouting have not been considered in the estimates. <br />3. Groundwater elevation control at 9,382 ft msl. It is expected that <br />groundwater elevations in this area of the Creede Formation are controlled primarily by <br />the interception of the 9360 adit with the underground workings at elevation 9,382 ft msl. <br />It is expected that the 9400 decline will not intercept the local groundwater table within <br />the Creede Formation during construction with the exception of possibly during the later <br />stages of construction. <br />TR -18 Response to PAR LetterA&.S.doc 9 /26/2011 7 <br />