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<br />disturbance and on the intensity and duration of storm events that occur prior to implementation <br />of permanent BMPs. <br />The primary differences between temporary and permanent BMPs are the design life and the <br />materials used. Permanent designs and materials will normally be used preferentially over <br />temporary ones. Under most circumstances, the project component life or the magnitude of <br />component disturbance associated with the Yankee Gulch Project components would warrant <br />the use of permanent options. Permanent BMPs may function as temporary BMPs, but the <br />reverse is usually not true. The applicability of BMPs is indicated on Table I. <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 />serve to prevent or minimize impacts to receiving water, and support and enhance the long-term <br />stability of reclaimed areas. There are a variety BMPs that may be employed to accomplish <br />these goals during development, operation and reclamation of project components. BMPs may <br />be used individually or in combination to accomplish erosion and sediment control objectives. <br />While serving a common purpose, there are distinct applications to which BMPs are best <br />suited. Erosion and sediment control requires the use of specitic BMPs that address different <br />physical conditions than those associated with channel reconstruction. Generally, surface sheet <br />tlow control practices vary physically from those used to control concentrated surface tlows <br />because of the differences in environmental conditions and requirements. Selecting an <br />individual BMP or a combination of BMPs for use on a site must take into consideration the <br />variety of flow conditions that may occur there. Often there is not a correct solution, but rather <br />a variety of combinations that may accomplish erosion and sediment control objectives for a <br />given location. Typically, complex flows require more sophisticated structures and practices <br />than less complex tlows. In the following two subsections, installation considerations and <br />construction specifications are presented for BMP structures and practices <br />3.3.1 BMP Installation <br />Control of erosion and prevention of sedimentation are important within and adjacent to the <br />disturbed area. Diversion of undisturbed mnoff around or passing it safely through the <br />disturbed area serves to facilitate operations and avoid unnecessary sedimentation. Among the <br />most important features For maintaining stability of the postmining landscape are reconstructed <br />drainages. Reclaimed slope characteristics also play a critical role in erosion and sediment <br />control. <br />Since erosion and sediment control structures and practices play such an important role in land <br />form stability and surface productivity, utmost care will be taken to ensure that structures are <br />properly installed. When constructing or implementing erosion convol and sedimentation <br />structures, methods or practices, American Soda will accomplish the following: <br />• Care will be taken to ensure that structures are properly installed. This is critical to the <br />effective use of a structure. The most common cause of structure failure is improper <br />installation. <br />• Time will be taken [o evaluate the problem using reliable, experienced information sources <br />whenever possible. The more complicated the problem becomes, the more time it usually <br />requires to develop proper effective control solutions. <br />American Suda. L.L.P. 3-.5 <br />Suil Comcrvanon. &osion and Scduncnl <br />Cunltol. Rcclamuian, and Revegelanon Plan <br />Ocrobcr 2tl, IY98 <br />Rcviud Apnl Y. IH99 <br />