2014-11-25_HYDROLOGY - M1977098 - Laserfiche WebLink

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Sievers Pit SWSP Page 2 of 7 November 24, 2014 and the Mineral Rules and Regulations for the protection of water resources. The April 30, 2010 letter from DRMS requires that you provide information to DRMS to demonstrate you can replace long term injurious stream depletions that result from mining related exposure of ground water. In accordance with approach no. 1, you have indicated that a bond has been obtained for $295,172 through the 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 gravel pit. In addition, the Sievers Pit will be backfilled and reclaimed as irrigated land once mining is complete, thus eliminating any long -term injurious stream depletions related to exposure of groundwater. Depletions The anticipated consumptive use at the Sievers Pit mining operation is 51.12 acre -feet with 48.10 acre -feet depleting the stream during the SWSP period. The Sievers Pit is decreed for 2.6 acre -feet for sand screen operation, 9.5 acre -feet for dust control of roads and crusher, 3.6 acre -feet for concrete production, 5.1 acre -feet for asphalt production, 0.2 acre -feet for domestic use, and 5.1 acre -feet of pond evaporation. However, the uses covered by the decree in Case No. 83CW65 during the SWSP approval period include only the 9.5 acre -feet for dust control of roads and crusher and the 5.1 acre -feet for asphalt production, as shown on the attached Table 2. This SWSP anticipates that a total of 6.0 acres of water surface will be exposed at the site in the dewatering trench and ponds. During the SWSP period, the total evaporation loss from the 6.0 acres of exposed groundwater is estimated to be 15.5 acre -feet. Groundwater will also be consumed during the process of mining aggregate. Previously the aggregate production at Sievers Pit occurred above the ground water table; therefore, the decree in case no. 83CW65 did not account for the amount of water lost with the mined product since there was no ground water diversion. For the purpose of this SWSP, Lafarge anticipates mining below the ground water table a maximum of 400,000 tons of aggregate per year resulting in a water loss of 5.9 acre -feet, assuming 2 percent water weight due to the dewatered state of the mine. The maximum amount of water used for dust control is anticipated to be 15.0 acre -feet, which is a 5.5 acre -feet increase from the decree. Therefore, depletions that will be covered by the SWSP will be evaporation from the exposed ground water in the dewatering trenches and ponds, the water lost with the mined product and the increased amount of water used for dust control. The other uses will remain within the limits as described in the decree in case no. 83CW65. The Applicant proposes to divert surface water from the Crystal River and deliver it to the pit via the Kaiser - Sievers Ditch for temporary storage into a one acre storage pond before the water is used in an aggregate wash plant at the site. The one acre storage pond does not expose groundwater. A lateral on the Kaiser - Sievers Ditch which runs along the eastern boundary of the pit will be used to deliver the water. The Applicant estimates that approximately 9 acre -feet was required to initially fill the one -acre pond. The initial fill was conducted during a free river period when un- appropriated water existed in the Crystal River during the previous plan period. Additional water will be delivered as needed to replace water consumed during the washing process or evaporated from the pond. The total gross evaporation loss from the one - acre storage pond is estimated to be 3.75 acre -feet during the SWSP approval period. Water 1313 Sherman Street, Room 821, Denver, CO 80203 P 303.866.3581 F 303.866.2223 www.water.state,CO.us n �, `f8 76 '