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Sedimentation Ponds <br />All runoff from the disturbed area will be routed through one sediment pond. <br />The sediment pond is designed to contain the runoff from a 10-year 24-hour <br />runoff event. The sediment pond (Pond A) is designed to contain one year of <br />accumulated sediment. The applicant has committed to semi-annual sediment <br />cleanout, therefore the design should be adequate. <br />Sediment Pond A is designed with an emergency spillway capable of passing the <br />peak flow from a 25-year 24-hour precipitation event. The sediment pond is <br />not equipped with a principal spillway. Instead, the applicant proposes to <br />install a pumping system to dewater the sediment pond and use the water in the <br />hydraulic mining system. The pumping system is capable of dewatering the pond <br />within 48 hours of the beginning of a 10-year 24-hour storm event. <br />VI. Water Rights and Replacement -Rules 2.04.7(3) and 4.05.15 <br />The Storm King Mine is proposed as a hydraulic mining operation. As such, the <br />operation requires large quantities of water for operations such as cutting of <br />the coal. The operation has facilities designed to process and recirculate <br />the majority of water required for the operation. The water circulation is <br />designed as aclosed-system with the major water loss occurring through <br />evaporation, adhesion to coal and refuse, and by seepage underground during <br />mining. The application projects that water loss through these processes will <br />require a make-up of approximately 600 acre-feet of water annually to the <br />system. <br />The Storm King Mine has acquired water rights more than sufficient to augment <br />their annual projected water consumption. The proposed operation is in <br />compliance with the requirements of this section. <br />VII. ~drologic Balance: Ground Water -Rules 2.04.5, 2.04.7 <br />7~7~ ..J A of <br />The descriptions of ground water within the permit application are located in <br />Sections 3.3.4, 5.1, and 5.2; appendices 3.3-3a, 3.3-4, 3.3-5, 3.3-7, 3.3-9, <br />and 3.3-10; and Figures 3.3-11, 3.3-12, 3.3-17, and 5.2-2. A detailed <br />description of the ground water in the permit and adjacent areas is contained <br />in the Description of the Environment section of this findings document. A <br />Description of the ground water in the general area is contained in the <br />Cumulative Hydrologic Impacts Study and Probable Hydrologic Consequences of <br />Mining section of this findings document. <br />The descriptions of mining impacts on ground water are located in sections <br />4.2.3.3, 4.2.3.4, 5.2.4.2.2, 4.2.4.2.4, 4.2.4.2.6, 4.5.3, and 5.2 of the <br />application. The discussions on ground water contained in the Cumulative <br />Hydrologic Impacts Study and Probable Hydrologic Consequences of Mining <br />section of this findings document present an analysis of these impacts. <br />