2015-02-09_HYDROLOGY - M1984043 - Laserfiche WebLink

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Jesse Lee SWSP Pit February 5, 2015 Page 2 In accordance with approach nos. 1 and 3, you have indicated that a bond has been obtained for $32,000 through the Division of Reclamation, Mining, and Safety ( "DRMS ") to assure that depletions from groundwater evaporation do not occur in the unforeseen event, or events, that would lead to the abandonment of the Pit. Depletions The anticipated net depletions for this SWSP are 2.32 acre -feet per year. The currently exposed groundwater at the site totals 0.40 acres, within the existing ponds (0.38 acres) and a drainage ditch (0.02 acres). The drainage ditch is approximately 350 feet long and approximately two feet wide and gravity drains water to the existing ponds. Gross annual evaporation at the gravel pit location is estimated to be 39.0 inches per year. Using the climate data from the Buena Vista weather station the net evaporation for the 0.40 acres exposed at the site is estimated to be 1.06 acre -feet. You have provided a monthly breakdown of the annual depletions made up of 1.06 acre -feet of net evaporative loss, 0.26 acre -feet of water lost with the mined product (which represents 9,000 tons of mined product), and 1.00 acre -foot of water used for dust control. These depletions have been tagged to the Arkansas River. The aquifer parameters used in the stream depletions model are as follows: 1) X =250 feet (distance from the centroid of the exposed surface area to the river), 2) W =2,300 feet (distance from the aquifer impermeable boundary to the river channel), 3) T= 50,000 gal /day /foot (transmissivity of the alluvial aquifer), and 4) S =0.2 (specific yield). According to the General Guidelines for SWSPs for Sand and Gravel Pits water consumption by mining operation shall also include water removed from the tributary stream system by the "first fill" or an "intermittent fill" of the gravel pit. The "first fill" or an "intermittent fill" is the water that fills an unlined gravel pit and occupies the volume previously occupied by the removed sand, gravel, or other solid material. For "wet mined" pits such as the Jesse Lee Pit the "first fill" occurs continuously during mining. The first fill for any administration period shall be calculated as: Vfif = Vmm(1- porosity) -Vlp, where: Vfif = Volume of water in the first fill Vmm = the net increase in the volume of "mined material" below the water table that has been filled with ground water Porosity = the ratio of the pore volume to the total volume of the mined material Vlp = Volume of water calculated as lost in the product For the Jesse Lee Pit, the "first fill" may be estimated based on the 9,000 tons of aggregate production multiplied by the percentage gravel matrix (65% assuming a porosity of 35% and a density of the material of 1.69 tons /cubic -yard) and then subtracting the volume of water lost with the mined product. Based on the 9,000 tons of aggregate production, the water removed by the "first fill" was determined to be 1.88 acre -feet. This is just an example; the Applicant shalt calculate the water removed by the first fill based on the actual porosity and density of the mined material at this site.