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Mr. Paul Bruss <br />October 28, 2015 <br />Page 2 of 6 <br />memo was previously provided to summarize the impacts of the proposed dewatering <br />operation that will be utilized to safely backfill each pond; however, Condition of Approval <br />No. 3 of the SWSP approval dated March 18, 2015 required that additional explanation and/or <br />documentation be provided with any renewal request which explicitly identifies how the <br />Operator plans to mitigate injurious stream depletions that result from mining -related <br />exposure of post -1981 ground water in accordance with the April 30, 2010 letter from DRMS. <br />According to the renewal request, Valco is currently in negotiations with a potential buyer for <br />the portion of the Rocky Ford East Pit property west of County Road 22 ("West Property"), <br />which includes Ponds 1 and 2 as shown on the attached Figure 1. It is the understanding of <br />Valco that the potential buyer is seeking a new DRMS permit to continue mining operations on <br />the West Property and will be making application for a permanent plan for augmentation once <br />mining operations are completed. Valco plans to retain the portion of the Rocky Ford East pit <br />property east of County Road 22 ("East Property"), which includes Ponds 3 and 4 as shown on <br />the attached Figure 1, and intends to backfill the remaining ponds on the East Property. <br />The information contained in this renewal request does not satisfy the requirements <br />referenced in the April 30, 2010 letter from DRMS; therefore, any future renewal request <br />must include evidence and/or documentation that on-going progress has been made to <br />come into compliance with the April 30, 2010 letter from DRMS. Please note that any <br />future renewal may not be approved without this information. <br />DEPLETIONS <br />The Rocky Ford East pit is in the process of reclamation. This SWSP renewal is to replace <br />depletions resulting from evaporation from the ponds and from the water contained in the <br />previously mined product. During the reclamation, dewatering will occur from one pond to <br />another within the mining boundary, since three of the four ponds will be completely <br />backfilled and the fourth reduced in size. <br />Evaporative depletions have been calculated using the maximum surface area of the pit, <br />which is 29.9 acres of post -1981 exposed ground water surface area. <br />Depletions have been lagged back to the Arkansas River using a Glover analysis with the <br />following inputs: <br />Distance from river: <br />Distance from alluvial boundary: <br />Transmissivity: <br />Specific yield: <br />2975 ft <br />7675 ft <br />71,000 gpd/ft <br />0.2 <br />You have calculated the total lagged depletions to be 115.66 acre-feet for the period August <br />1, 2015 - July 31, 2016 (see attached Table 2A). <br />1313 Sherman Street, Room 821, Denver, CO 80203 P 303.866.3581 F 303.866.3589 www.water.state.co.us <br />