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DEPARTMENT OF NATURAL RESOURCES <br />DIVISION OF WATER RESOURCES <br />May 20, 2011 <br />Mr. Jacob Bauer <br />}?O Martin and Wood Water Consultants, Inc. <br />538 Commons Drive <br />Golden, CO 80401 <br />Re: St. Barbara Sand and Gravel Mine, Substitute Water Supply Plan <br />DRMS File No.W1-2004-013 <br />Section 1, T21S, R63W, and Section 6, T21S, R62W, 6th P.M. <br />Water Division 2, Water District 14 <br />Approval Period: January 1, 2011 - December 31, 2012 <br />Dear Mr. Bauer: <br />ccS <br />John W. Hickenlooper <br />Governor <br />Mike King <br />Executive Director <br />Dick Wolfe, P.E. <br />Director/State Engineer <br />REC°F1V' 'F7k <br />Divisiar, 0b sraIlul?, <br />mining and Safety <br />We have rece ved your November 8, 2010 letter requesting the renewal of a substitute <br />water supply plan`SWSP) for a sand and gravel pit to be operated by the applicant, Trans <br />Colorado Concrete (a division of Pete Lien & Sons, Inc.). Updated engineering has been <br />provided in support of this request. The mine is permitted with the Division of Reclamation, <br />Mining, and Safety under File No. M-2004-013. The $257 renewal fee has been accepted with <br />receipt no. 3647958. <br />PLAN OPERATION <br />Mining at the St. Barbara Sand and Gravel Mine is projected to continue for <br />approximately 25 years. However, at this time it is uncertain whether mining at the site will occur <br />over the approval period. Therefore, two scenarios were considered; Scenario A assumes that <br />mining will occur over the approval period and Scenario B assumes that mining will not occur <br />over the approval period. <br />Under Scenario A, there will be one four-to-five acre cell to be mined during the months <br />of June and July only. The cell will be dewatered via a dewatering trench when the cell is being <br />actively mined. Operational losses will occur due to water retained in the mined product and <br />water used for dust suppression. Total estimated annual aggregate production is 25,000 tons <br />per year. The total annual water consumption for dust suppression is estimated at 0.56 acre- <br />feet for both 2011 and 2012. Evaporation will occur from exposure of a total of 7.46 acres of <br />water in four settling and wash ponds and in the mined cell for the ten months when it is not <br />actively being mined. For the two months when the cell is actively being mined, evaporation will <br />occur from a total of 6.52 acres of water in the four settling and wash ponds and a dewatering <br />trench. The settling and wash ponds are 1.34, 1.80, 2.04, and 0.90 acres in size. The pond <br />formed in the mined cell while it is not dewatered is 1.38 acres in size. The dewatering trench is <br />3,800 feet in length with an average width of 5 feet for a total exposed water surface area of 0.44 <br />acres. Your attached Table 1A shows the site net evaporation calculations (25.23 acre-feet) and <br />water consumed by site operations (1.30 acre-feet). Effective precipitation credit was applied to <br />this plan. <br />Office of the St4 <br />ate Engineer <br />1313 Sherman Street, Suite 818 • Denver, CO 80203 • Phone: 303-866-3581 • Fax: 303-866-3589 <br />www. water. state. co.us