2008-12-03_HYDROLOGY - M1997058 - Laserfiche WebLink

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Mr. Andy Rodriguez, P.E. December 2, 2008 Page 2 Depletions Currently 7.6 acres of ground water surface is exposed at the Baseline Resource pit (WDID 0203017) (7.18 acres in the settling ponds and 0.42 acres in dewatering trench). Consumptive use from the operation of this site consists of 11.19 acre-feet of water lost in product (4% moisture of 380,250 tons of raw material), 1.66 acre-feet for on-site dust control, 11.29 acre-feet used in the production of 92,000 tons of concrete and 22.38 acre-feet of evaporation from the 7.6 acres of exposed lake surface. The total consumption at this site from mining operations is 46.52 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 & 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 Bestway Concrete Well No. 1 (permit no. 67418-F), 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. Additional information regarding the well is shown below: Well Field WDID None Well Field Name None Relevant Water Right Case Number None Well WDID 0210166