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• BEST MANAGEMENT PRACTICES OVERVIEW <br />Maintaining or establishing surface hydrologic stability is a critical component in the mining <br />and reclamation process. Adequately controlling erosion and minimizing sediment transport <br />serves to prevem or minimize impacts to receiving waters, and supports and enhances the long- <br />term stability of reclaimed areas. There are a variety BMPs thaz may be employed to <br />accomplish these goals during development, operation and reclamation of the project. BMPs <br />may be used independently or in combination to accomplish erosion and sedunent control <br />objectives. While serving a common purpose there are distinct applications to which BMPs are <br />best suited. <br />Erosion and sediment control requires the use of specific BMPs that address different physical <br />conditions than those associated with channel reconstruction. Generally, surface sheet flow <br />control practices vary physically from those used to control concentrated surface flows because <br />of the differences in environmental conditions and requirements. Selecting a single or <br />combination of BMPs for use on a site must take into consideration the variety of flow <br />conditions that may occur there. Often there isn't a connect solution, but rather a variety of <br />combinations that may accomplish erosion and sediment control objectives for a given location. <br />Typically, complex flows require more sophisticated structures and practices than less complex <br />flows. <br />BMPs have been grouped in these appendices based on their primary uses or applications. <br />While the use of some of them may be limited to the category in which they are placed, many <br />of them present useful applications in multiple categories. Typical installations for BMPs are <br />provided for clarity. The practice of routinely prescribing controls for erosion and <br />sedimentation problems will be avoided. Each drainage situation will be treated creatively to <br />• minimi~r construction and treatment costs, While Striving to maxim;~e the effectiveness of <br />BMPs. <br />CONCENTRATED FLOW STRUCTURES <br />Concentrated flow structures are used to carry concentrated surface flows azound, through or <br />from undisturbed, disturbed, and reclaimed areas and facilities. Berms (Figure B-1), <br />diversions (Figure B-2), and reconstructed channels (Figure B3) are commonly used <br />concentrated flow structures. Diversions may be placed to prevent the commingling of <br />undisturbed and disturbed runoff and to reduce treatment volumes. Also, undisturbed area <br />runoff may be diverted to reduce the volume that must be routed through concentrated flow <br />structures within reclaimed areas. Diversions may also result in beneficial use of the diverted <br />flow. Concentrated flow structures may be designed for temporary or permanent uses. Soils <br />data should be analyzed, particularly for erodibGty, when developing specifications for <br />concentrated flow structures. Concentrated flow structures should be designed by a qualified <br />professional. <br />Concentrated flow structures may take a variety of forms ranging from structures composed <br />entirely of fill materials to those which are completely incised rnto the ground, or some <br />combination thereof. Various channel configurations and lining materials may be used to <br />provide stability for various flow volumes and velocities. The shape of the channel used to <br />convey runoff may be triangulaz, parabolic or trapezoidal and will be specified to fit the <br />environmental conditions and flow characteristics of the logtion in which they are used. <br />Stnrctures will be sized and capable of passing the predicted flows for the type and duration of <br />use. Pemtanent and critical stnrctrrres will be capable of passing larger volumes of runoff than <br />. temporary ones. During construction all trees, brush, stumps, obstructions and other <br />B-1 <br />