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• • RECLAMATION PLAN <br />The second advantage of using this process is to increase the lag time for return of <br />groundwater to the river. This will help reduce the amount of water that must be dedicated to the <br />augmentation plan and helps control lake level fluctuations to a more gentle form. Slow rises and <br />falls in the lake level are advantageous to the development of wetland vegetation, whereas rapid <br />rises and falls tend to make it more difficult for the vegetation to adjust to the varying habitat <br />characteristics. <br />Final grading of the lake slopes need not be done until the end of the mining process. <br />However, if desired and a large enough area is available, final grading of portions of the lake slope <br />can be done in phases similar to the backfilling process. The advantages of waiting until the end of <br />the backfilling process are, 1) the ability to make any final adjustments before the lake is allowed to <br />fill with water and, 2) the avoidance of needing to regrade previously graded slopes that were <br />subsequently damaged by erosion due to runoff before the basin was allowed to fill with water. <br />Topsoil placement is discussed in a later section of this exhibit. <br />Water Resources <br />The water utilized in the operation will be obtained through the Substitute Water Supply <br />Plan required by the Colorado Division of Water Resources. Water obtained for the operation will <br />come from the groundwater sources exposed in the mining. The details of the water amounts and <br />sources will be provided in the Substitute Water Supply Plan, a copy of which will be provided the <br />Division when it is approved. <br />In the reclamation process, as briefly described previously, an aquifer recharge system will <br />be established similar that in operation at the Great Blue Heron Pit. This system utilizes primarily a <br />lake that acts as a storage basin during the summer. Water from the Lester Attebury Ditch will be <br />input to the lake to maintain a high level in the summer. This level and the amount of water input <br />is closely monitored so the amount of water input into the system is known. <br />During the winter months, the input of water is stopped. The stored water then returns to <br />the aquifer and ultimately back to the river through the alluvium. This helps to maintain a steady <br />water table throughout the year and reduces the need for augmentation water to account for <br />evaporative losses. <br />A key element in the effectiveness of this system is to have the lakes located as far from the <br />river as possible. This increases the lag time which is the amount of time it takes the water to return <br />to the river. The greater this lag time, the greater the effectiveness of the system and the more stable <br />the water table down gradient from the recharge lake. <br />At the Great Blue Heron Pit the recharge system is designed around a double lake pattern. <br />In this operation (Grisenti) only a single lake in each phase is used. Thus the replacement water is <br />Grisenti Farms Gravel Pit Original Application Exhibit E Page E-3 <br />