Laserfiche WebLink
EXHIBIT 15 <br />MEMORANDUM <br />TO: Corey Hoffmann <br />FROM: Jon Ford <br />FILE: 1182BLH01 <br />DATE: November 10, 2005 <br />RE: Ground Water Inflow, Ground Water Depletion and Injury to Senior Water Rights, and <br />Ground Water in Storage -Proposed MMRR Quarry <br />Annual Ground Water Inflow to Proposed Quarry <br />The Lyman Henn, Inc. August 19, 2005 report states that ground water will likely be encountered in the <br />quarry, but in very small quantities. Therefore, we have estimated the average annual ground water <br />inflow to the proposed MMRR quarry (]0-year plan) using Darcy's equation, as follows: <br />Q = K•I•A <br />Where Q = inflow <br />K = average hydraulic conductivity <br />I = gradient of the water table <br />A = effective cross sectional area of pit face normal to [he water table <br />gradient below the water table <br />For our estimate, we used the following: <br />K = 10-5 cm/sec (0.3 ft/day) from Lyman Henn, Inc. report dated August 19, <br />2005 <br />I = .24 ft/ft from our Cross Section A-A' (from Exhibit 14) <br />A = width of 1150 feet from mine plan multiplied by an average saturated <br />thickness of 230 ft estimated from the mine plan and the cross section <br />Using these values, we conclude that the average inflow will be on the order of 16 acre-feet per year. <br />Based upon our experience in the area, we conclude that the Lyman Henn estimate of hydraulic <br />conductivity could be low. In that case, the estimate of ground water inflow would also be low. <br />Ground Water Depletion and Injury to Senior Water Rights <br />The August 19 Lyman Henn, ]nc. report indicates that the ground water inflow will be fully consumed. <br />Therefore, there will be a reduction in the amount of ground water equal to the consumed inflow (16 <br />of/yr) available to meet the Black Hawk/Central City Sanitation District (BHCCSD) well (Permit No. <br />59840-F) at the Waste Water Treatment Plant (W WTP) demand of 24.2 of/yr. Unless this ground water is <br />replaced up gradient of the BHCCSD well, there would likely be a significant injury (reduction in well <br />yield) to the BHCCSD well. <br />Senior City of Black Hawk water rights in the vicinity of the Proposed MMRR Quarry site are as follows: <br />• Black Hawk Effluent Diversion, Case No. 93CW055, 5 cfs, at the location of the W WTP effluent <br />discharge. <br />• Black Hawk exchange, Case No. 92CW059, 14 cfs, along North Cleaz Creek from the confluence <br />with Clear Creek up to the vicinity of Black Hawk, runs past the Quarry site. <br />LEONARD RICE ENGINEERS, INC. <br />2000 Cur STREer, SUITE 300, DENVER, COLORADO 8021 7-51 19 • PHONE (303) 455-9589 • Fnx (303) 455-01 1 5 <br />