2017-03-22_HYDROLOGY - M2001005 - Laserfiche WebLink

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Mr. Paul Bruss March 22, 2017 Page 2 of 7 A monthly breakdown of these amounts for both plan years is shown in Table 1, attached. Total depletions from mining activities are estimated to be 147.57 acre-feet for the 2017 plan year and 147.57 acre-feet for the 2018 plan year. Dewatering at this site will produce delayed depletions to the stream system. As long as the pit is continuously dewatered, the water returned to the stream system should be adequate to offset the depletions. However, once dewatering at the site ceases, the delayed depletions must be addressed. Accordingly, dewatering is required to continue during the term of this plan. At least three years prior to completion of mining, a plan must be submitted that specifies how the post pumping dewatering depletions (including refilling of the pit with ground water) will be replaced in time, place and amount. The Applicant is hereby notified that if dewatering ceases, then depletions to the stream as a result of refilling of the pit must be addressed as outlined by Guideline 14 of the April 1, 2011 General Guidelines for Substitute Water Supply Plans for Sand and Gravel Pits. LAGGED DEPLETIONS The renewal request has included lagged depletions associated with evaporation, dust control, and water removed with the mined material. Evaporative depletions were lagged individually from each pond based on the exposed ground water area, dust control depletions were lagged from the fresh water supply pond, and depletions from water removed with the mined material were lagged from the centroid of the Phase 2 mining area. The depletions were lagged through use of IDS- AWAS, which utilized the Glover Method with the following parameters: Glover Method Input Parameters Location T S X W Phase 1 40,000 0.087 934 1,489 Supply Pond 40,000 0.087 551 1,018 Phase 2 40,000 0.087 541 1,252 T = Transmissivity of aquifer (gallons per day per foot) S = Specific yield of aquifer X = Distance between the centroid of the pond or mining area and the Arkansas River (feet) W = Distance between the Arkansas River and the alluvial boundary (feet) The cumulative lagged depletions are 147.39 acre-feet for the 2017 plan year and 147.57 acre-feet for the 2018 plan year, and may be found in Table 1, attached. REPLACEMENTS The main source of replacement water is based on the 55.2 acres that is now removed from agricultural production by the mining operation out of the total pro rata share of 89.47 acres of alfalfa and silage corn historically irrigated with Lester-Attebery Ditch water. A ditch wide analysis has been completed and the calculated historical consumptive use for the Grisenti parcel was 220.8 acre-feet per year (2.47 acre-feet per acre). The historical irrigation summary is attached as Table 2. The proposed dry-up of 55.2 acres of historically irrigated land provide a historical consumptive use credit of 136.39 acre-feet (150.28 acre-feet credit during April through October and a return flow obligation of 13.89 acre-feet during winter months). 60 shares of Twin Lakes Reservoir water