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It is extremely unlikely that any toxic or acid-producing materials will be encountered during the <br />mining operation since the total depth of excavation (21~ is shallow and tests down to this depth <br />show that the material is alluvial in nature. However, in the event that such materials are encoun- <br />tered, they will be covered with topsoil from the stockpiles to the same depths outlined in the recla- <br />mation plan and no more mining will occur in this area. <br />The operator commits to clearly marking the permit boundary at all corners. <br />2. Water Information, Bights and Augmentation <br />Since the mine will encounter water in the mining operation below 5-10 feet of excavation, and a <br />permanent lake will be left as part of the reclamation plan, it is demonstrated in this section that <br />there are sufficient water rights/augmentation for this operation. A well permit has been applied for <br />with the Division of Water Resources. The Colorado River has unused water in this area and an <br />augmentation plan is not needed. The well permit will wver pit pumping as well as all consumptive <br />uses for the operation. All consumptive uses are shown below: <br />1) The permanent lake will be approximately 7.5 acres in size, which may fluctuate between 7.2 <br />acres and 7.6 acres, depending upon the river level. Since the lake bottom and sides are always satu- <br />rated due to the level of alluvial water, no losses will occur due to infiltration. Losses will occur due <br />to evaporation at the water surface. Based upon evaporation data for this location from the State <br />Engineers office and precipitation data for this area, this pond will evaporate 55 inches per year or <br />4.58 acre-feet of water per acre of water surface. This results in a consumptive use of 34.8 acre-feet <br />annually using a maximum area of 7.6 acres. <br />2) Additional consumptive use will occur as a result of mining the gravel in a wet condition and <br />accounting for retention. It is estimated that the gravel will contain 20% moisture when it is exca- <br />vated below water level but 16% moisture will seep back into the ground at the location, leaving 4% <br />of [he aggregate weight mined to exit the property with the end product as a consumptive use.The <br />volume of use will be based on the higher annual tonnage for Phase 2 (140,000 tons per year). <br />Therefore, this consumptive use will be 4800 tons of water pet year or 3.08 acre-feet for the highest <br />19 Road Pit 10!02 12 <br />