2009-10-16_PERMIT FILE - M2009082 (9)

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Consumptive Water Use The Parsons Mine includes the following consumptive uses during the life of the mining operation. The consumptive uses include evaporative losses, water used for dust control, and water consumed in the mined material removed from the site. Evaporative Losses The NOAA Technical Report NWS 33, Evaporation Atlas for the Contiguous 48 United States (U.S. Department of Commerce) determined gross evaporation. For this location, the annual evaporation is 45 inches or 3.8 feet. Monthly evaporation percentages established by the State Engineer's Office (SEO) for elevations below 6,500 feet were used to calculate the monthly evaporation. Colorado Climate Summaries data from the Western Regional Climate Center Website (w-,w.wrcc.dri.edu/cgi-bin/cliMAIN.pl?co3553) provided annual precipitation information at this site. The nearest station is the Greeley UNC Weather Station with a mean precipitation of approximately 14 inches for the years 1967 to 2009. Effective precipitation is 70 percent of total precipitation. Net evaporation is the difference between gross evaporation and effective precipitation. Net evaporation at the site is 2.93 feet. Water use at the Parsons Mine will include evaporation from exposed groundwater within the dewatering trench and the collection area during the mining period. In order to facilitate dry mining at the site, Lafarge will excavate a dewatering trench around the perimeter of the mining cells. The total length of the dewatering trench around the mining cells in Phases IA, I B and IC is approximately 13,700 feet. Assuming a width of 5 feet, the trench will expose an area of approximately 1.6 acres. A collection area at the discharge points from the dewatering trench will expose approximately 0.8 acre of water. Total exposed surface area at the Parsons Mine during mining will be approximately 2.4 acres. The total evaporative consumptive use during mining is 7 acre-feet. This is the volume which will be augmented during Phases 1 A, 1 B and 1 C. The exposed surface area will vary slightly during each phase of the Parsons Mine, but all evaporative consumptive use will be augmented during mining. Operational Losses The moisture content of the material removed from the site is four percent by weight as required in the State Engineer's Office (SEO) Guidelines. The production rate for the mining site is 750,000 tons of aggregate material per year. This results in an annual consumptive use of 22.1 acre-feet for water retained in product. :Lafarge will apply water to haul roads and stockpiles for dust control. The estimated annual consumptive use for dust control is 2.0 acre-feet with a distribution throughout the year based on the same percentages as the production of the aggregate mined. The total annual operational consumptive use at the Parsons Mine is 24.1 acre-feet. Parsons Mine DRMS 112 Reclamation Permit Application Page G2 of G3