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Sedgwick County Road and Bridge Gravel Pit Page 2 <br /> 112(c) Operation Reclamation Permit February 25, 2024 <br /> 4.0 EXHIBIT D -Mining Plan <br /> 4.1 Process Description <br /> Mining shall be done in three, approximately 7 year-long phases, over 20 years. Each phase of <br /> mining will be accomplished by first removing 6-12 inches of topsoil over time that will be <br /> stockpiled for reclamation use after excavation has been completed. Gravel will then be removed <br /> with the use of a front-end loader. The expected amount of material to be mined is 5,000 tons per <br /> year for 20 years. Mining will generally start at the West end of the affected area and progress <br /> eastward.As shown in Figure 5, mining will start on the tops of three dunes in the affected area <br /> and progress downward and outward. Mining shall be done such that there are no slopes greater <br /> than a 3:1 gradient in the mining area. Gravel will be removed to the contours shown in Figure 5. <br /> Extracted gravel will not be processed on site. Material that is removed but contains insufficient <br /> gravel for use (overburden) will be stockpiled to be used as backfill after mining activities have <br /> ceased.Any additional mining after the first 20 years will be carried out in the similar manner as <br /> described in this mining plan. <br /> After extraction,any backfilling and final grading will be done to control erosion from stormwater <br /> runoff and ensure that there are no slopes greater than 3:1 in the mined area. Backfill will be <br /> compacted so that the ground remains stable. <br /> After any backfilling and grading a 6-12 inch thick topsoil cover will be placed and seeded in <br /> accordance with the reclamation plan. <br /> 4.2 Water Diversions and Impoundments <br /> Three siltation ponds will be built prior to any mining activities. They will be located downslope <br /> of the mined area in existing depressions in the ground. Their proposed locations are shown in <br /> Figure 6. The ground will be excavated to the approximate boundaries shown such that there is 3 <br /> feet of depth from the outlet of the ponds. Each pond is more than 9,500 square feet in area. The <br /> expected rainfall from a 25-year 24 hour storm is 3.76 inches, see Appendix H for supporting <br /> documentation for this claim.The largest mining phase is about 88,000 square feet. If all the runoff <br /> from a 25 year 24 hour storm from a mining area collected in a single basin it would total 1,021 <br /> Z:IP%lectslSedgweck County12023 Gravel Pet PermtttmglPerm:t AEC <br />