2013-05-29_HYDROLOGY - M1985112 - Laserfiche WebLink

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Mr. Jared Dains, E.I. Loloff SWSP —Amendment #1 May 28, 2013 Page 2of6 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. The Loloff Pit is not in compliance with this requirement. On February 2, 2012 DRMS sent a letter to Loloff Construction outlining two options to bring the pit into compliance through raising the bond amount over a three year period. The 2012 SWSP provided that 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. 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 and associated dewatering operation in 2013 that the exposed ground water will decrease from 17.2 acres to 2.0 acres by August 1, 2013. 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 32.90 acre -feet for this plan year. Dewatering will occur at the site to allow for dry mining. Ground water pumped for dewatering purposes will be discharged to a drainage ditch that runs along the west border of the site. This drainage ditch generally runs southeast, crosses under Balsam Ave and then under Highway 263, where it turns east and empties into the Ogilvy Ditch. The Applicant is required to ensure and show the dewatering water is released to the Poudre River through the Ogilvy return structure. This SWSP does not authorize the use of any of these conveyance structures; it is the Applicants responsibility to obtain the legal right to use such conveyances and return structures and to provide documentation their water returned to the river. The operator does not have an end date for the dewatering operation but anticipates the operation will be continuous for at least 5 years. As the pit will refill with ground water once dewatering ceases, this will create a large depletion that must be replaced by the operator. Until the operator has a plan to cover post - pumping depletions, dewatering operations must continue to keep the pit in a dewatered state. As long as the pit is continuously dewatered, the accretions to the stream are assumed to sufficiently offset the lagged depletions from dewatering. However, to properly account for post - pumping depletions all dewatering operations must be equipped with a totalizing flow meter to monitor the monthly dewatering volumes from the site, with the monthly meter reads reported on accounting submittals. 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. Finally, the Applicant has