2009-06-12_HYDROLOGY - M2001017 - Laserfiche WebLink

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Mr. Brian Leavesley June 9, 2009 Depletions Page 2 Currently 5.01 acres of ground water surface is exposed at the Lohmann Pit, including 0.93 acres of dewatering trenches and 4.08 acres of silt ponds. Consumptive use from the operation of this site consists of 5.88 acre-feet of water lost in product (4% moisture of 200,000 tons of raw material), 1 acre-foot for on-site dust control and 14.43 acre-feet of evaporation from the 5.01 acres of exposed lake surface. The total consumption at this site from mining operations is 21.32 acre-feet. The depletions from mining operations were lagged to the St. Vrain River using a Glover analysis and assuming a distance to the River of 2,000 feet, distance to the impermeable boundary of 4,176 feet, transmissivity of 50,000 gal/day/ft and specific yield of 0.2. Attached Table 4 shows the total lagged depletions determined to accrue to the stream system-during-this-ptarrperFod. -- Replacements The 0.25 shares of the Rural Ditch is part of 7.4 shares that were historically used to irrigate 215 acres of pasture grass, corn and alfalfa. The land historically irrigated by the 7.4 shares is the same land that is currently being mined at the Rinn Valley Pit. Assuming a 10% ditch loss and a 55% irrigation efficiency, the dry-year consumptive use of the 7.4 shares was determined to be 337 acre-feet. The prorated consumptive use for the 0.25 shares is 11.4 acre- feet. In order to claim credit for the! Rural Ditch water for augmentation use under this plan the applicant must have a method, agreed upon by the water commissioner, to measure the augmentation water back to the St. Vrain River. The nontributary Laramie-Fox Hills aquifer water will be withdrawn by existing wells pursuant to permit nos. 66271-F, 66273-F and 66274-F. The wells are currently permitted for industrial, commercial and augmentation use and are allowed a combined average annual withdrawal of 73.1 acre-feet and a pumping rate of 150 gpm. The wells are further described in Table 1 below. The Applicant's accounting includes the 2% relinquishment requirement for the nontributary Laramie-Fox Hills water. Table 1 Well Field WDID 0204101 0204101 0204101 Well Field Name EVERIST LFH WL EVERIST LFH WL EVERIST LFH WL FLD FLD FLD Relevant Water Right N/A N/A N/A Case Number Well WDID 0210211 0210212 0210213 Well Name EVERIST LFH WELL EVERIST LFH WELL EVERIST LFH WELL 66271-F 66273-F 66274-F Relevant Well Permit 66271-IF 66273-F 66274-F Well Location SW, NE SEC 30, 2N, NW, NW SEC 24, 1S NW, NW SEC 30, 2N, 66W 65W 66W Aquifer LAR/FOX HILLS LAR/FOX HILLS LAR/FOX HILLS Allowable AF Amount 73.1 ACRE FEET COMBIN ED