2008-01-22_HYDROLOGY - M2001085 - Laserfiche WebLink

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Ms. Michelle Cunico Johnson January 17, 2008 Page 2 Laramie-Fox Hills aquifer water pumped from well no. 64401-F. The well is limited to an average annual withdrawal of 15.6 acre-feet per year and is permitted for industrial, commercial, augmentation, dust control, residential and domestic uses. Depletions The annual depletion resulting from evaporation from the 2 acres of exposed ground water is 5.7 acre-feet. During the remainder of the mining period (November 1, 2007 through September 30, 2008) the water lost in mined product will be 5.66 acre-feet from 360,000 tons of mined product. That depletion assumes that the liner will be approved by May 31, 2008 at which time the applicant would no longer need to replace depletions resulting from water lost in mined product. Stream depletions were calculated by using the Alluvial Water Accounting System ("AWAS") model with the "Alluvial Aquifer" boundary condition option. The following table shows the input data. Xft Wft T d/ft S ecific Yield 2,295 3, 836 63, 000 0.2 To determine the timing of stream depletions resulting from the pumping of tributary groundwater by the wells, the AWAS model was used with the alluvial aquifer boundary condition option. The AWAS -alluvial aquifer model uses four aquifer input parameters for each well 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 location of the stream depletion is assumed to be perpendicular to the river. Based on the AWAS analysis, there will be 0.15 acre-feet of lagged depletions that will impact the South Platte River after January 31, 2010. Those lagged depletions were wrapped into the depletions in the prior months. Therefore, for purposes of the SWSP, it will be assumed that all lagged depletions impact the South Platte River by January 31, 2010. Replacements The replacements sources for this plan are nontributary Laramie-Fox Hills water withdrawn by well no. 64401-F and 2.87 acre-feet of fully consumable water leased from the City of Brighton. The delivery of fully consumable Fulton Ditch water will be made to the South Platte River from Brighton's Midland augmentation station from May through October and from one of Brighton's storage facilities; 1241 Avenue or Ken Mitchell Lake in November and December. The nontributary Laramie-Fox Hills water will either be discharged into the Ski Lake and recharged back to the river or discharged directly to the river via Brighton's 124th Avenue Pipeline. If the water is discharged into the Ski Lake, the accretions will be lagged to the river using the Alluvial Water Accounting System ("AWAS") model with the "Alluvial Aquifer" boundary condition option. The following table shows the input data. Xft Wft T d/ft S ecific Yield 1,808 5,300 61,600 0.2