2013-05-22_INSPECTION - M1979097

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Mr. Jared Dains May 17, 2011 Middle Poudre Combined Plan — Lafarge West, Inc. Page 4 of 9 A stream depletion model using the Glover method was used to calculate the lagged depletions to the Cache La Poudre River. The alluvial aquifer model uses four aquifer input parameters for each site as follows: 1) X- distance from well to river, 2) W- distance from the aquifer boundary through the well to the river channel, 3) T- transmissivity of the alluvial aquifer (in gallons per foot/day) between the well and the river, and 4) S- specific yield - 0.2 was used for all wells. The following parameters for each site listed in the table below were used in the model: Site Name T X W S East Rigden Pit 55,000 250 5,800 0.2 Three Bells Pit 45,000 500 4,800 0.2 Weitzel Pit 50,000 2,900 5,300 0.2 Kyger Pit 45,000 250 5,200 0.2 Port of Entry Pit 55,000 250 5,800 0.2 Shields Mine 55,000 4,530 8,000 0.2 According to the Applicant, the distance from the surface of the exposed ground water area for each site to the Cache La Poudre River was measured based on the down gradient extent of the exposed ground water surface (nearest point). For purposes of this SWSP, the method used to measure the distance to estimate the lagged depletions will be accepted, however any future SWSP must measure the distance from the exposed ground water surface area for each site to the Cache La Poudre River based on the centroid of the exposed ground water surface. The total lagged mining depletions for all seven sites is 365.11 acre -feet. Real time depletions were used for all six sites. Replacements Replacement water for this combined plan will come from the following sources: accretion credits from recharge of 8.5 shares of the Box Elder Ditch, accretion credits from dewatering at the Three Bells Pit, a lease from the City of Greeley ( "Greeley ") for fully consumable effluent, and a lease of augmentation water provided by the Lake Canal Reservoir Company ( "LCRC "). Lafarge owns 8.5 shares in the Box Elder Ditch and will use all of the shares in this combined plan. The shares will be diverted into a recharge pit (WDID 0302002) through an existing lateral from the ditch. The recharge pit was constructed on the un -mined portion of the Three Bells Pit site and it was excavated to only the upper portion of the gravel deposit and will not expose additional ground water. The estimated recharge pit size is one acre. For the purposes of this plan, evaporation from open water was assumed for the entire surface area of the recharge pit for the number of days water was diverted into the recharge pit. Based on this approach, the proportion of days with water diverted into the recharge pit to the number of days per month was applied to the monthly gross evaporation rate, resulting in an evaporative consumptive use from the recharge pit of approximately 2.04 acre -feet. Lafarge owns 5.5 shares of the 6.0 shares of the Box Elder Ditch that were historically utilized for the irrigation of the Three Bells property (344.3 acres). The dry-up acreage claimed for Lafarge's 5.5 shares would be 305.6 acres of the 344.3 historically irrigated acres on the Three Bells property. The historical consumptive use credit of the 5.5 Box Elder Ditch shares associated with the Three Bells property was determined to be 281.4 acre -feet, based on a historical consumptive use analysis that was completed in support of an application for an augmentation plan pending in case no. 2002CW205.