2013-10-22_HYDROLOGY - M2000082 - Laserfiche WebLink

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East 8" Street Pit SWSP October 18, 2013 Page 2 of 5 The Applicant projects using 1.38 acre -feet of water per year from the pit for dust control purposes. The site will be continuously dewatered during this SWSP period, and all such water will be discharged to the Cache la Poudre River. As long as the pit is continuously dewatered and all water is discharged to the Cache la Poudre River, the accretions to the stream system should be sufficient to replace the lagged dewatering depletions. The total consumptive use of ground water at the East 8th Street Pit (including evaporative and operational losses) is estimated to be 8.37 acre -feet for this plan period The IDS Alluvial Water Accounting System (AWAS) analytical stream depletion model, which uses the Glover method, was used to calculate the lagged depletions to the Cache la Poudre River. The following parameters were used in the model: transmissivity (T) = 120,000 gallons per day per foot, specific yield (SY) = 0.2, the distance from the river to the edge of the alluvium = 11,000 feet, and the distance from the centroid of the exposed surface water areas to the river = 600 feet. The total lagged depletions were determined to be 8.56 acre -feet for this plan period. This amount includes lagged depletions resulting from past consumptive use at the site that are projected to impact the river during this plan period. The attached Table 1 shows the monthly breakdown of evaporative, operational, and lagged depletions. Replacements Pursuant to a mining lease agreement between Superior and the City of Greeley ( "Greeley "), Greeley will provide the required augmentation water for the East 8th Street Pit. A copy of the mining lease has previously been provided to this office. An August 23, 2013 letter from Greeley confirming the monthly replacement schedule was provided with this SWSP request and is attached. For this plan period, Greeley will provide a total of 12.8 acre -feet of fully consumable water that has been changed for augmentation use. The replacement water will be delivered to the Cache la Poudre River at Greeley's wastewater treatment plant (WDID 0302312) located approximately '/2 mile upstream of the East 8th Street Pit. The delivery schedule incorporates a transit loss of 0.13% based on the currently assessed rate of 0.25% per mile. Any releases by Greeley at a location other than its WWTP must be coordinated with the water commissioner to insure the proper transit losses are applied and that no intervening water rights are injured. In addition, if a different transit loss is determined by the division engineer or water commissioner, the Applicant must modify their accounting and replacements as necessary to be consistent with the determined transit loss. Long Term Augmentation 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 number 1, Superior has submitted a financial warranty in the amount of $270,000 for the East 8th Street operation, which the Mined Land Reclamation Board has determined equals the estimated costs of reclamation. It is noted that per the mining lease agreement with the City of Greeley (landowner), Greeley has the long term augmentation responsibility at this site.