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It is anticipated that mining will begin in September 1998 and be completed i 2005. The <br /> reclamation plan for the site will include open lakes, agricultural pasture land, d residential <br /> acreage. <br /> PROJECTED CONSUMPTIVE USE <br /> Water use at the site will include evaporation from the dewatering trenches,co ection basin, <br /> settling ponds, and existing pit which has been allowed to fill, dust control of ul roads and <br /> stockpiles, and water retained in material removed from the site. <br /> Evaporative Losses <br /> The NOAA Technical Report NWS 33, EvgMration Atlas for the Contiguous 4 United States <br /> (U.S. Department of Commerce)was used to determine gross evaporation. For ' location,the <br /> annual evaporation is 41.0 inches. Monthly evaporation percentages as suggest by the Office <br /> of the State Engineer were used to calculate monthly evaporation. <br /> Precipitation and temperature data was obtained from the Colorado Climate Ce er. The <br /> Windsor weather station was determined to be the closest weather station to the ite. Average <br /> values for the period 1941-1990 for the Windsor station were used for calculati <br /> Groundwater will be exposed in the dewatering trenches,collection basin, sett!' g ponds,and the <br /> existing pit during mining. There will be approximately 2500-3000 linear feet o dewatering <br /> trenches. The width of the dewatering trenches will average 10 feet. A consery 've total of 1 <br /> acre of exposed surface area was included for the dewatering trenches and collec 'on basin. <br /> Water in the dewatering trenches will gravity flow into the collection basin wh it will be <br /> pumped into the existing ponds located on the south end of the site and allowed seep out of the <br /> ponds and back to the river. The exposed water surface in the dewatering trench,collection <br /> basin,and existing settling ponds will be approximately 8.0 acres. Figure I displ ys the location <br /> of the dewatering trenches,collection basin,existing settling ponds and the previ usly mined pit, <br /> which has been allowed to fill. The existing pit was constructed after December 0, 1980 and <br /> therefore requires that replacements be made for evaporative losses. The existin pit,located in <br /> the southeast comer of the site,has approximately 5 acres of exposed surface and is in the <br /> process of being reclaimed. <br /> In summary, Water will be pumped from the existing settling ponds for the was ' g of sand and <br /> gravel. The total exposed water surface area for the mining site will be 13 acres. is will <br /> include 7 acres of settling ponds, I acre of dewatering trenches and collection basin, and a 5 acre <br /> existing pit that has been allowed to fill. The total evaporative consumptive use for the site was <br /> calculated as the product of net evaporation(2.69 ft)and exposed water surface(13 acres) <br /> resulting in 34.9 acre-feet for the year(Table No. 1). <br /> 3 <br />