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<br />Wriaht Water Engineers, Inc. <br />1666 N. Main Avenue, Suite C www.wdghtwater.com <br />Durango, Colorado 81602 e-mail: pfoster@wdghtwater.com <br />(970) 259-7411 TEL <br />(970) 259-8758 FAX <br />November 13, 2008 <br />Via E-Mail <br />Peter Kearl <br />Resource and Environmental Manager <br />Four Corners Materials, Inc. <br />P.O. Box 1969 <br />Bayfield, CO 81122 <br />Re: Water Supply for the Simmons Gravel Facility <br />Dear Peter: <br />The proposed site for the Simmons Gravel Facility is located in Section 31, Township 36 N. <br />Range 13 West of the N.M.P.M. west of Mancos, CO. It is Wright Water Engineers, Inc's <br />(WWE's) understanding that the gravel facility will be a dry mining facility with water needs for <br />periodic material washing only. The amount of material washed is an estimated 120,000 tons <br />over 3 months or 40,000 tons per month. WWE understands that the washing facility is a <br />mobile facility and will be brought on the site intermittently to wash material. To provide the <br />water for gravel washing and settling, two ponds with a combined surface area of 0.22 acres is <br />anticipated. <br />Water Depletions <br />Water depletions for the gravel operation will be from pond evaporation and material washing. <br />Each component of water depletion is described more full below. <br />Evaporation <br />The calculated net evaporation rate for Mancos is 2.78 acre-feet per acre per year (AF/yr). <br />Based on a combined surface area of 0.22 AF, the calculated maximum annual depletion for <br />evaporation is 0.61 AF/yr (see Table 1). <br />Material Washing <br />Estimations of water depletions from the aggregate and sand washing are based on General <br />Guidelines for Substitute Water Supply Plans for Sand and Gravel Pits Submitted to the State <br />Engineer Pursuant to SB 89-120 and SB 93-260 (General Guidelines). As provided in the <br />General Guidelines, depletions from washing aggregate and sand are estimated to be 4 percent of <br />DENVER GLENWOOD SPRINGS <br />(303) 480-1700 TEL (303) 480-1020 FAX (970) 945-7755 TEL (970) 945-9210 FAX