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Mr: Paul Bruss, E. I. <br />March 18, 2015 <br />Page 2 of 5 <br />In accordance with the letter dated April 30, 2010 from the Colorado Division of Reclamation, <br />Mining, and Safety ( "DRMS "), attached, all sand and gravel mining operators must comply <br />with the requirements of the Colorado Reclamation Act and the Mineral Rules and Regulations <br />for the protection of water resources. The April 30, 2010 letter from DRMS requires that you <br />provide information to DRMS to demonstrate you can replace long term injurious stream <br />depletions that result from mining related exposure of ground water. A November 20, 2013 <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, it is this office's <br />interpretation that the memo itself does not provide evidence of compliance with the April <br />30, 2010 letter. Therefore, please provide an explanation and /or documentation with the <br />next SWSP request which explicitly identifies how the operator plans to mitigate injurious <br />stream depletions that result from mining- related exposure of post -1981 ground water, in <br />accordance with the April 30, 2010 letter from DRMS. <br />DEPLETIONS <br />The Rocky Ford East pit is in the process of reclamation. This SWSP renewal is to cover <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: 2975 ft <br />Distance from alluvial boundary: 7675 ft <br />Transmissivity: 71,000 gpd /ft <br />Specific yield: 0.2 <br />You have calculated the total lagged depletions to be 153.10 acre -feet for the period April 1, <br />2014 - July 31, 2015 (see attached Table 1). <br />REPLACEMENTS <br />Valco will continue to utilize a combination of leased water and historical ditch credits to <br />make replacements to the river. A one -year lease dated August 1, 2014 was obtained to <br />provide replacement supplies during this approval period for 86 acre -feet from the Upper <br />Arkansas Water Conservancy District ( "UAWCD "). Additionally, Valco owns 2 shares in the <br />Rocky Ford Ditch, which have been determined to yield 25.72 acre -feet per year of <br />consumptive use for the purposes of this plan and will be used to off -set depletions at this <br />pit. Lastly, Valco owns 26 shares of Canon City and Oil Creek ( "CC&OC ") Ditch, which have <br />been determined to yield 38.34 acre -feet per year of consumptive use for the purposes of this <br />oF"co� <br />1313 Sherman Street, Room 821, Denver, CO 80203 P 303.866.3581 F 303.866.3589 www.water.state.co.us I y� " - - 01 <br />* 1p, * 41 - <br />1876 �% <br />