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The permit area is not prone to flooding from adjoining properties. The predominate drainage course found in the <br />vicinity of the site is the Colorado River approximately 1000 feet south of the site. A review of the Flood Rate <br />Insurance Map indicates that part of the site is prone to flooding by the Colorado River during a 100 year flood <br />event. Other than the establishment of the Constructed Wetland Mitigation Bank, no other activities will occur <br />within the identified flood plain. <br />Mining is conducted in a manner that will not increase the amount of surface storm water runoff above historic <br />flows. Any storm water runoff entering the site will be captured within the pit area and allowed to evaporate or <br />percolate into the ground. In order to maintain the quality of any surface storm water that crosses any exposed <br />ground areas, a Storm Water Management Plan (SWMP) has been prepared. A key element of the plan calls for <br />grading the area in a manner that will not allow the discharge of any silt laden storm water from the property in the <br />event of a storm. <br />Test borings on the property have revealed that the seasonal high ground water table is at an average elevation <br />4588 feet above sea level. Therefore, de-watering will be required as part of the mining efforts. Water will be <br />pumped at various locations within the separate mining areas to existing drainage ditches adjoining the permit <br />boundary. These ditches will transport the water to the Colorado River. De-watering associated with the gravel <br />mining will be monitored to insure water discharged will not have adverse impacts. <br />Mining and processing requires the consumption of water. Since the mine will encounter water in the mining <br />operation below 10 feet of excavation, and permanent lakes will be left as part of the reclamation plan, it is <br />demonstrated in this section there is sufficient water available for this operation and the reclaimed lake once the <br />mining is complete. A well permit is being applied for with the Division of Water Resources. The well permit will <br />cover pit pumping as well as all consumptive uses for the operation. During the mining stage of the project, <br />consumptive uses will be limited to evaporation of exposed ground water, road watering, plant water sprays, and <br />gravel retention. After mining, the consumptive use will be lake evaporation. Since this mining operation is <br />phased to include active mining operations along with reclaimed mined areas, the chart presented below provides <br />water usage estimates of both mining and post mining uses. Other than moisture in the sand and gravel <br />products removed from the site, no water will be hauled away from the property. <br />Water used by the operations described above will be augmented by the Colorado River, which lies about 1000 <br />feet south of the mined area. The operators of the D Road Gravel Pit currently posses water rights from the <br />Colorado River, Case # 93CW186 in the Absolute amount of 2.033 cfs. This amount translates into <br />approximately 1,472 acre feet per year. This amount is well in excess of the estimated annual consumptive use <br />of 276.40 acre feet per year shown in the chart below. <br /> <br />• <br />USE • <br />GAL./DAY <br />AC. FT./YR. <br />57 Acre Lake Eva oration Varies 261.00 <br />Dust Control 4,200 1.15 <br />Process 25,000 6.90 <br />A re ate Moisture N.A. 7.35 <br />Total Annual Maximum Usa e 276.40 <br />Revised October, 2002 <br />