2012-01-20_HYDROLOGY - M2006003 - Laserfiche WebLink

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Mr. Andy Rodriguez, P.E. Page 2 of 5 Bestway's Brighton Combined SWSP January 11, 2012 2011, respectively. Water shall not be impounded in the reservoirs except pursuant to lawful diversions allowed by statute or decree. At all other times, all inflow of water into the reservoirs from any source, including precipitation and ground water inflows, shall be removed by the applicant. The water may be removed from within the lined area and returned to the stream system through surface flow or ground water recharge without need for replacement, so long as the operator does not put the water to beneficial use. The Applicant, through the Division of Mining Reclamation and Safety holds bonds amount of $974,000.00 for the Parker - Dersham Pit and $711,750.00 for the Baseline Pit which can be used to backfill or line the respective pits in the unforeseen event, or events, which would lead to the abandonment of the Pit. Depletions Approximately 2 acres of open water surface is present at the Baseline Pit and approximately 7.9 acres of open water surface at the Parker - Dersham Pit. Net evaporative depletions were calculated using a gross annual evaporation of 45.5 inches from the exposed water surface, with a credit of 10.19 inches for an effective precipitation amount of 35.32 inches per year. No phreatophyte credit has been applied to this plan. The net depletion of ground water due to evaporation from theses two pits are 29.15 acre -feet as shown on the attached Table 1 The Applicant anticipates that 425,000 tons of aggregate will be mined at the Parker - Dersham site and no mining will occur at the Baseline site during this plan period. The material to be mined falls within the limits of the Kirby - Dersham slurry wall liner approved on December 19, 2011. In accordance with the April 1, 2011 General Guidelines for Substitute Water Supply Plans for Sand and Gravel Pits which states in part "...the applicant must provide replacement for all native ground water remaining within the lined area that is put to beneficial use except for the water removed in product..." replacement water for water lost in product will not be provided by the applicant. An estimated 3.24 acre -feet of water from the Baseline Site plant well (permit no. 75087 -F, WDID 0210141) will be used at the combined pits for on -site dust control during this plan period. This well will also be used to support concrete production. It is estimated that 92,000 cubic yards of concrete batching will occur and that 40 gallons of water will be consumed per cubic yard of concrete production. This leads to 11.29 acre -feet of water to be used for concrete production at the combined pits. The evaporative and operational losses at this combined pit site will equal 43.68 acre - feet will occur at the combined pit site. The depletions from the mining operation were lagged to the stream using the SDF method. The construction of the slurry wall at the Baseline Resource site 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 evaporative loss was estimated to be 205 days and the SDF for the plant well is estimated to be 176 days. The total lagged depletions to be replace during 2012 are projected to be 43.68 acre - feet as shown on Table 1 Replacements The proposed source of replacement for this pit is nontributary ground water pumped from an existing Laramie -Fox Hills aquifer well and fully consumable effluent leased from the City of Aurora.