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<br />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 prevent or minimize impacts to receiving waters, and supports and enhances the long- <br />term stability of reclaimed areas. There are a variety BMPs that 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 sediment 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 reconswction. 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 correct 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 swctures 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 />minimize conswction and treatment costs, while striving to maximize the effectiveness of <br />BMPs. <br />CONCENTRA'T'ED FLOW STRUCTURES <br />Concentrated flow swctures are used to carry concentrated surface flows around, through or <br />from undisturi~ed, disturbed. and reclaimed areas and facilities. Berms (Figure B-1), <br />diversions (Figure B-2), and reconswcted channels (Figure B-3) are commonly used <br />concentrated Flow swctures. 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 />swctures within reclaimed areas. Diversions may also result in beneficial use of the diverted <br />Flow. Concentrated Flow swctures may be designed for temporary or permanent uses. Soils <br />data should be analyzed, particularly for erodiblity, when developing specifications for <br />concentrated flow swctures. Concenwted flow swctures should be designed by a qualified <br />professional. <br />Concentrated flow swctures may take a variety of forms ranging from swctures composed <br />entirely of fill materials to those which are completely incised into the ground, or some <br />combination thereof. Various channel configurations and lining materials may be used ro <br />provide stability for various Flow volumes and velocities. The shape of the channel used to <br />convey runoff may be triangular, parabolic or trapezoidal and will be specified to fit the <br />environmental conditions and Flow characteristics of the location in which they are used. <br />swctures will be sized and capable of passing the predicted Flows for the type and duration of <br />use. Permanent and critical swctures will be capable of passing larger volumes of runoff than <br />temporary ones. During conswction all trees, brush, stumps, obswctions and other <br />B-1 <br />