2014-02-28_HYDROLOGY - M1977522 - Laserfiche WebLink

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Mr. Rick Parsons, P.E. L.G. Everist Combined SWSP Page 4 of 10 February 27, 2014 The net evaporation for the Firestone Pit includes a credit of 0.60 acre -feet of consumptive use of ground water associated with the partial subirrigation of the historically irrigated acreage. No other phreatophyte credit was applied to the other sites. Computation of evaporation under this plan was reduced during the ice covered periods. You have assumed the ice covered period to occur during the months of December, January and February, based on average monthly temperatures less than 32 °F taken from the Longmont 2ESE weather station for the Saint Vrain Pits and Fort Lupton 2SE station for the South Platte Pits, and for December and January for the Cache La Poudre site based on the monthly temperatures taken from the Greeley UNC weather station. However, for the purpose of this SWSP, the Applicant shall replace the net evaporation depletions from the exposed ground water surface area that may occur during the assumed ice covered period (the months of January, February and December) for any time that the pits are not completely covered by ice. Computation of the net evaporation during any time that the pits are not completely covered by ice shall be determined as the pro -rata amount of the monthly gross evaporation rate distribution amount identified in the State Engineer's General Guidelines for Substitute Supply Plans for Sand and Gravel Pits, subtracting the pro -rata amount of the effective precipitation for that period. The material excavated from the gravel pit areas will be washed on site. The consumptive use of water associated with excavated material is dependent on the location of the material with respect to the water table. According to the "General Guidelines for Substitute water Supply Plans for Sand and Gravel Pits" the product moisture loss is calculated as four percent by weight of mine material excavated below the ground water table and two percent by weight for the mined material excavated above water table. The Applicant anticipates 2014 mining production at the Carbon Valley Resource, Rinn Valley Pit, Firestone Pit and Fort Lupton Sand and Gravel to be 150,000 tons, 580,000 tons, 200,000 tons and 1,650,000 tons respectively. For 2015, production at these same sites are anticipated to increase to 200,000 tons, 580,000 tons, 450,000 and 1,800,000 tons, respectively. Water used for dust control at Carbon Valley Pit, Rinn Valley Pit, Firestone Pit and Star Water Resources will come from water originally pumped from the pits for dewatering. Water used for dust control at the Fort Lupton Sand and Gravel was previously used from an existing alluvial well, permit no. 57957 -F (WDID 0205018 DI TIRRO WELL 2), located outside of the approved slurry wall on the Fort Lupton Pit site. Well permit no. 57957 -F is no longer being used for dust control, as Everist has a re- circulating water system at the site where reusable water is pumped from lined cells to wash material and for dust control. Continuous dewatering operations at Carbon Valley Pit, Rinn Valley Pit, and Firestone Pit are occurring in order to facilitate dry mining conditions. This water is used for dust control at these pits, and is used for concrete production at the Rinn Valley pit. All other water pumped for dewatering is returned immediately to the river system. The applicant has performed a lagged water balance for these operations and account for the lagged depletions which is offset by monthly net accretions. Totalizing flow meters have been installed and monthly meter readings showing dewatering volumes were reported on the 2012 -2013 submitted accounting. A stream depletion model using the Glover method was used to calculate the lagged depletions to the River. The alluvial aquifer model uses four aquifer input parameters for each site as follows: 1) X- distance from centroid of the well to the 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. The following parameters for each site listed in the table below were used in the model: TABLE E — AQUIFER CHARACTERISTICS Site Name T X W S Carbon Valle Pit 50,000 2,000 4,173 0.2