2012-03-14_HYDROLOGY - M1985112 - Laserfiche WebLink

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Mr. Jared Dains, E.I. Loloff SWSP March 14, 2012 Page 2 of 6 amount over a three year period. Future SWSPs will not be 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. 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. It is anticipated that with mining operations in 2012 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 2012. This material will be wet mined below the ground water table and thus assessed a water Toss 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 2012. 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 2012 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 58.20 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 Platte River Power Authority will provide replacement water during the months of February, March, November, and December 2012 and a lease of augmentation water from the Graham Drainage Ditch Company will supply replacement water during the months of April through October 2012. Both sources will deliver replacements above the headgate of the Ogilvy Ditch, which is the first calling water right below the Loloff Pit point of depletion. A lease of 16.2 acre -feet of fully consumable water provided by the Platte River Power Authority ( "PRPA ") will be used to make replacements during the non - irrigation season (February, March, November, and December 2012). The lease (attached) was executed on November 9, 2011 and amended on January 27, 2012 to reflect a higher lease amount. Because January 2012 was free river the entire month, this month was not included on the amended lease. PRPA has an "Agreement for the Reuse of Water for Energy Generation ", dated August 10, 1978, with the City of Fort Collins ( "Fort Collins ") and Water Supply and Storage Company ( "WSSC ") that provides PRPA with the right to receive reusable water delivered by Fort Collins. PRPA, Fort Collins, and WSSC also obtained approval of a plan for augmentation including reuse of water in Division 1 Water Court Case no. W- 9332 -78. In case no. W- 9332 -78, the Court found that 4,200 acre -feet, or more per year, will be available from Fort Collins to the PRPA to be used primarily for cooling purposes in connection with its Rawhide Energy Facility. Pursuant to the decree in case no. W-