2009-01-23_HYDROLOGY - M1999120 - Laserfiche WebLink

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Mr. Brian Leavesley Page 2 January 21, 2009 Dewatering at the Ft. Lupton Mine commenced in 1999. Dewatering will continue through 2009 and all dewatered water will be discharged directly back to the South Platte River. The applicant's accounting specifies the depletions and accretions from the dewatering operation. DEPLETIONS Currently 5.17 acres of ground water surface is exposed at the Ft: Lupton Mine, including 0.72 acres of dewatering trenches and 4.45 acres of silt ponds. Consumptive use from the operation of this site consists of 11.77 acre-feet of water lost in product (2% moisture of 800,000 tons of raw material), 1 acre-feet for on-site dust control and 14.89 acre-feet of evaporation from the 5.17 acres of exposed lake surface. The total consumption at this site from mining operations is 27.66 acre-feet. The depletions from evaporation and water lost in mined product were lagged to the stream using a Glover analysis and assuming a distance to the stream of 1,853 feet, distance to the impermeable boundary of 7,996 feet, transmissivity of 83,195 gal/day/ft and specific yield of 0.2. The depletions from well no. 57957-F (dust suppression) were also lagged to the stream using a Glover analysis and assuming a distance to the stream of 690 feet, distance to the impermeable boundary of 7,996 feet, transmissivity of 100,000 gpd/ft and specific yield of 0.2. Attached Table 4 shows the total lagged depletions determined to accrue to the steam system during this plan period. REPLACEMENTS The 0.52 shares of the Lupton Bottom Ditch are part of 2.25 shares that were historically used to irrigate 95 acres of corn and small vegetables. The land historically irrigated by the 2.25 shares is the same land that is currently being mined at the Ft. Lupton mine. Assuming a 10% ditch loss and a 55% irrigation efficiency, the dry-year consumptive use of the 2.25 shares was determined to be 138 acre-feet. The prorated consumptive use and return flows for the 0.52 shares is shown in attached Table 4. The Lupton Bottom shares will be delivered back to the South Platte River at either the augmentation station located just north of WCR 14.5 or the Petrocco Augmentation station located just east of the pit. The nontributary Laramie-Fox Hills aquifer water will be withdrawn by existing wells pursuant to permit nos. 66271-F, 66273-F and 66274-F, which are further described in Table 1 below. The wells are currently permitted for industrial, irrigation, commercial and augmentation and are allowed a combined average annual withdrawal of 73.1 acre-feet and a maximum pumping rate of 150 gpm. The Applicant's accounting includes the 2% relinquishment requirement for the nontributary Laramie-Fox Hills water. Tnhla 1 Well Field WDID 0204101 0204101 0204101 Well Field Name EVERIST LFH WL FLD EVERIST LFH WL FLD EVERIST LFH WL FLD Relevant Case # N/A N/A N/A Well WDID 0210211 0210212 0210213 Well Name EVERIST LFH WELL 66271-F EVERIST LFH WELL. 66273-F EVERIST LFH WELL 66274-F Relevant Well Permit 66271-F 66273-F 66274-F WeIkLocation, Aquifer SW, NE SEC 30,2N, 66W LAR/FOX HILLS NW, NW SEC 24, 1S 65W LAR/FOX HILLS NW, NW SEC 30,2N, 66W LAR/FOX HILLS Allowable AF Amount 73.1 ACRE FEET COMBINED