2017-12-07_HYDROLOGY - M1997054 - Laserfiche WebLink

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Mr. Stephen Buechner, P.E. December 7, 2017 Page 3 of 6 The IDS Alluvial Water Accounting System (“AWAS”) stream depletion model was used to determine the lagged depletions from dewatering, evaporation and operational losses to the Arkansas River. The aquifer characteristics used in the model are: transmissivity (T) = 55,000 gallons per day per foot and specific yield (SY) = 0.2, the distance of the exposed ground water to the stream = 1,400 feet (measured from the centroid of the exposed ground water surface), and the location of the parallel impermeable boundary was estimated to be 2,650 feet from the stream. During this plan approval period, no ground water will be used for reclamation, concrete batching, or any other purpose. As shown on Table 3, attached, the total consumptive use was calculated to be 44.45 acre-feet and lagged stream depletions were calculated to total 42.6 acre-feet during this SWSP period. SITE DEWATERING The Applicant began dewatering the Parkdale Pit in 2012 to assist in the mining of material below the groundwater table. The water is removed from the ground and placed into a series of dewatering trenches. This water will be eventually piped and then discharged on the north side of the property boundary into Currant Creek which is a tributary to the Arkansas River. All water pumped from the pit reaches Arkansas River within the same month it is pumped. The Applicant will monitor the dewatering operations and include the data in their monthly accounting submittals to the State Engineer’s Office. REPLACEMENTS The proposed sources of replacement water for this pit include a five-year lease of 50 acre- feet per year of fully consumable water from the Board of Water Works of Pueblo (“PBWW”), valid April 1, 2016 through March 31, 2021 (attached), an additional one-time lease of 18 acre-feet of fully consumable water from PBWW, valid March 1, 2017 through March 31, 2018 (see attached letter from PBWW dated February 27, 2017), and the applicant’s ownership of 5 shares of Twin Lakes Reservoir and Canal Company stock, which yield approximately 3.5 acre- feet/year of water. The PBWW water will be provided at the City of Pueblo wastewater treatment plant located east of Pueblo when adequate exchange potential exists to make that replacement water available at the Parkdale Project site. When there is insufficient exchange potential to utilize reusable effluent, the PBWW will release water from upstream storage at Twin Lakes Reservoir. Upstream reservoir releases will be subject to a 0.07 percent per mile river transit loss, which equates to approximately 6.55 percent from Twin Lakes to Parkdale. Front Range Aggregates has an additional backup supply for this project from a 50 acre-foot lease with Cañon City Water Department, which will only be used in the event that the other sources become inadequate. The Cañon City lease, a copy of which was provided to this office on September 12, 2008, is valid until January 2035. CONDITIONS OF APPROVAL I hereby approve the proposed SWSP in accordance with §37-90-137(11), C.R.S., subject to the following conditions: