2013-01-02_HYDROLOGY - M1985112 - Laserfiche WebLink

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Mr. Jared Dains, E.I. Loloff SWSP December 31, 2012 Page 2 of 5 renewed until documentation has been provided to this office that shows Loloff is complying with either the February 2, 2012 DRMS letter or an alternative plan approved by DRMS. This office is in receipt of a September 7, 2012 letter from DRMS to Loloff documenting the exposed groundwater compliance process. This letter provided the option of Loloff purchasing and committing water shares to the State Engineer's Office or the possibility of reducing the final size of the pond to reduce the overall augmentation requirement and the required bond. These proposals will be evaluated by the Loloff's and a revised plan will be submitted to DRMS for their review. To allow replacements to be made while Loloff works on obtaining exposed groundwater compliance, this SWSP will be renewed for 2013. Future SWSPs will not be renewed unless Loloff can show a good faith effort in obtaining compliance and document the steps taken and result of this effort. Depletions Depletions at the site during this plan period will consist of evaporative losses and operational losses. In 2011, the amount of exposed ground water at the Loloff Pit increased from 10.5 acres to 17.2 acres and remained at 17.2 acres for 2012. It is anticipated that with mining operations in 2013 that the exposed ground water will further increase from 17.2 acres to 20.2 acres. Net evaporative depletions were calculated using a gross annual evaporation of 45 inches from the exposed water surface, with a credit of 9.97 inches for effective precipitation. No credit was claimed for ice cover periods. The net depletion of ground water due to evaporation of exposed ground water surface was calculated to be 54.36 acre -feet for this plan year. The Applicant projects mining a total of 55,000 tons of aggregate production in 2013. This material will be wet mined below the ground water table and thus assessed a water loss equal to 4% by weight of the material mined, or 1.62 acre -feet. Additionally, there will be an intermittent fill of the pit as material is removed. Using a specific weight of 125 pounds per cubic foot and a porosity of 30% for the sand and gravel, the intermittent fill volume is estimated to be 12.52 acre -feet for 2013. Finally, the Applicant has estimated that a total of 1.00 acre -foot of water will be used for dust control purposes during this plan period. The total evaporative and operational losses during 2013 are 69.5 acre -feet as shown on Table 1. Depletions at the Loloff Pit do not instantaneously accrue to the Cache La Poudre River, but instead result in a lagged depletion. A stream depletion model based on the Stream Depletion Factor (SDF) technique was used to calculate the lagged depletions to the Cache La Poudre River. An SDF of 60 days was used for the Loloff Pit site. The total lagged depletions for this plan period due to both projected and past consumptive use at the site are estimated to be 57.60 acre -feet, as shown on Table 1. Replacement Sources Two replacement sources are proposed to replace depletions from the Loloff Pit. A lease of augmentation water from the City of Aurora will provide replacement water during the non - irrigation season and a lease of augmentation water from the Graham Drainage Ditch Company will supply replacement water during the 2013 irrigation season. A lease of 21.1 acre -feet of fully consumable water provided by the City of Aurora ( "Aurora ") will be used to make replacements during the non - irrigation season of January through March, and November through December 2013. The releases will be made from the Metro Waste Water Reclamation Facility (WDID 0200700) located in Denver on the South Platte River approximately 66 miles upstream from the Cache la Poudre confluence. Therefore a 16.5%