2017-01-09_HYDROLOGY - M1977572 - Laserfiche WebLink

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Daniel J. Gillham, P.E. Page 3 of 6 January 6, 2017 the post-1981 exposed water surface in order to claim the exemption. The calculated evaporation requiring augmentation is 106.33 acre-feet (see Table 2, attached). Welt Permit WDID Total Pre-1981 Exposure Post-1981 Exposure No. Exposure (acres) (acres) 52184-F 6706363 30.2 7.0 25.87 In accordance with the letter dated April 30, 2010 from the Colorado Division of Reclamation, Mining, and Safety ("DRMS"), all sand and gravel mining operators must comply with the requirements of the Colorado Reclamation Act 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. 2, a portion of the ongoing depletions from exposed groundwater from the North Gateway Park Ponds are replaced by the plan for augmentation decreed in case no. 13CW3060 on September 28, 2016. According to the applicant, the remaining portion of depletions will be replaced with additional replacement water available by agreement with CPW from their water portfolio with LAWMA. It is our understanding this additional replacement water is to be added to the existing augmentation plan (13CW3060) in early 2017. DEPLETIONS The three ponds are located at an average distance of 76.7 feet from the Arkansas River. You have performed a Glover analysis using the following parameters: Transmissivity 200,000 gpd/ft Specific yield 0.2 Distance 76.7 feet from the river You have enclosed the results of your analysis, which indicate that 95.8% of the depletions to the river occur within the first month. Therefore you have made the assumption that all depletions may be considered to occur within the same month for accounting purposes. The total depletion to the Arkansas during the plan period of this SWSP is 106.33 acre-feet. This office's standard way of calculating lagged depletions for gravel pits is to use a Glover analysis for which the distance from the river is determined based on the centroid of the pit; the analysis for this SWSP uses the edge of the pit instead of the centroid of the pit. Though this office does not generally support this approach, it will be accepted for the purposes of this SWSP since the decree in case no. 13CW3060 also relies on a Glover analysis that uses the distance from the edge of the pit. REPLACEMENTS Replacement water is to be provided through an agreement with CPW from their water portfolio with LAWMA. Copies of the March 29, 2016 Temporary Special Use Agreement between Lamar and CPW and the August 2, 2000 Water Management Agreement between CPW and LAWMA, are attached. According to the agreements, 53.165 acre-feet of fully consumable replacement water will be provided to Lamar for the plan period from June 1, 2016 through May 31, 2017.