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than approximately 15 feet. Mining is proposed to stay at least two feet above groundwater. <br /> Because ofthis,dewatering is not proposed.The CDPHE permit will be a`stormwater only'permit. <br /> Alluvium materials similar to the material being mined are located beneath the material to be mined. <br /> The water table is greater than 2 feet below the level to which Weld County will mine. To prevent <br /> the exposure of ground water, Weld County will not mine the alluvium materials located beneath <br /> the material to be mined.Additionally,the deepest excavation will be slightly higher than the bench <br /> terrace located directly east of and adjacent to the site. This will assist in avoiding exposure of <br /> groundwater and facilitation of surface water drainage out of the pit. According to information <br /> obtained from the State Engineer's Office, the Koskie site is not located within a designated <br /> groundwater basin. <br /> There is one well that is used for stock watering within 200 feet of the mine permit area. Water <br /> needs for gravel mining and processing operations are expected to minimal; water for dust control <br /> can be obtained and hauled from existing County-owned wells that have been decreed for the <br /> appropriate uses. Water from the nearby well will not be used for any County operations. Water <br /> used in mining and crushing operations and for dust control is estimated to not exceed <br /> approximately 4,000 gallons per month during those operations. <br /> d) Size of areas to be worked:The enclosed mine plan map(Exhibit C3)shows the proposed locations <br /> for the haul road, gravel processing(crusher location), soil and gravel product stockpile areas.The <br /> application proposes a mining area of 122.9 acres. Of this mining area, about 77.75 acres will be <br /> mined. The remaining acreage may be used for topsoil stockpiling or will be left unmined. All <br /> topsoil in the amended mining area will be stripped, stockpiled, and stabilized at one time. Once <br /> mining begins, approximately 20-25 acres will be exposed at any one time. <br /> e) It is anticipated that sand and gravel excavation, processing (rock crushing and screening), and <br /> stockpiling at the Koskie site will commence upon receipt of approval from the Colorado Division <br /> of Reclamation, Mining and Safety (DBMS) and receipt of other necessary permits. Gravel <br /> excavation and processing will be seasonal with stockpiling of gravel for later County uses <br /> depending upon the local road repair and construction needs. While gravel excavation and <br /> processing are expected to be seasonal, it is anticipated that the material stockpiles will be hauled <br /> out of the site year-round. The Koskie site should not be considered an intermittent operation. <br /> i. The mining operation in the amendment area is not proposed to be phased. The Koskie <br /> amendment area likely has only 10 years or less of gravel and sand reserves. <br /> ii. Approximately 123 acres will be disturbed during the amended mining operation. <br /> Approximately 20-25 acres will be exposed at any one time. <br /> iii. The mining operation in the amendment area is not proposed to be phased. <br /> f) Please see exhibit C3. <br /> i. The estimated thickness of gravel-bearing zones varies from between 0 and 15 feet thick <br /> at the Koskie site. <br /> ii. The gravel deposits proposed to be mined are stream channel deposits associated with Lone <br /> Tree Creek, an ephemeral stream that is located approximately '/2 mile to the east of the <br /> Koskie site. Therefore,the thickness of overburden to be removed during gravel extraction <br /> is expected to be minimal. Minimal stockpiling of overburden is anticipated. Mined soils <br /> MAMining\Koskie\DRMS\DRMS Application\Amendment to Expand Acreage\Adequacy Review Response 08-18-20.docx <br /> Page 4 of 5 <br />