2008-01-15_HYDROLOGY - M1997058 - Laserfiche WebLink

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Mr. Andy Rodriguez, P.E. January 14, 2008 Page 2 Depletions Currently 7.6 acres of ground water surface is exposed at the Baseline Resource pit. Consumptive use from the operation of this site consists of 24.86 acre-feet of water lost in product (4% moisture of 845,000 tons of raw material), 3.31 acre-feet for on-site dust control, 17.8 acre-feet used in the production of 145,000 tons of concrete and 22.38 acre-feet of evaporation from the 7.6 acres of lake surface exposed after December 31, 1980. The total consumption at this site from mining operations is 68.35 acre-feet. The depletions from the mining operation were lagged to the stream using the SDF method. The construction of the slurry wall affects the timing of the lagged impacts on the South Platte River. The applicant previously prepared a numeric model to account for this affect. According to the model, the SDF for the Batch Plant production well (concrete production and dust suppression) was estimated to be 176 days and the SDF for the evaporation loss and water lost in product was estimated to be 205 days. Replacements The proposed source of replacement for this pit is fully consumable effluent leased from the City of Aurora and nontributary ground water pumped from an existing Laramie-Fox Hills aquifer well. The applicant has entered into a long term lease agreement with the City of Aurora ("Aurora") whereby Aurora will deliver up to 49 acre-feet of fully consumable water to the South Platte River at the confluence of the South Platte River 8~ Sand Creek, just north of Metro Wastewater Treatment Plant. The confluence is located approximately 20 miles upstream of the Baseline Resource Pit. A 0.25 percent per mile transit loss for November through March (5.0 percent overall loss) and a 0.5 percent per mile transit loss for April through October (10.0 percent overall loss) has been accounted for in the replacement schedule. In addition to replacing depletions resulting from this mining operation, the City of Aurora effluent will also be used by the Applicant to replace 20.9 acre-feet of depletions resulting from operation of the well no. 14007-R, in accordance with the C.R.S. 37-92-308(4) SWSP approved for Bestway Concrete. Since the City of Aurora effluent is being used as a replacement source for both plans, the applicant's accounting for each SWSP must specify the total amount of effluent released and the amount associated with each SWSP. The nontributary Laramie-Fox Hills aquifer water will be withdrawn by an existing well pursuant to permit no. 64750-F. The well is currently permitted for industrial, commercial and augmentation use and is allowed an average annual withdrawal of 43.5 acre-feet and a pumping rate of 100 gpm. The Applicant's accounting includes the 2% relinquishment requirement for the nontributary Laramie-Fox Hills water. A monthly breakdown of depletions and replacements is shown in attached Table 1-Rev1.