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Permanent design issues relate to measures which will be expected <br />to remain in place and perform as designed as "permanent" <br />components of the landscape, after the pile is reclaimed and bond <br />is released. In some cases, it may not be feasible to install <br />permanent design features until refuse pile final design elevation <br />is attained. In many instances, however, it is both feasible and <br />desirable to implement permanent stabilization measures such as <br />riprap installation or vegetation establishment in grass lined <br />channels early in the construction phase, before the channels <br />experience significant flow events. <br />Based on our review and field observations, additional design <br />detail will need to be incorporated into the operation/reclamation <br />plan, and a timeline for installation of interim and permanent <br />stabilization measures will need to be established. In general, it <br />is recommended that the installation of erosion control measures be <br />initiated at the upper end of the watershed or drainage of concern, <br />and proceed down-drainage, and this consideration should be kept in <br />mind with regard to the installation timeline. Regular monitoring <br />and maintenance of both interim and permanent stabilization <br />measures is critical, and will need to be specifically addressed in <br />the revision. For any situations where permanent sediment/drainage <br />control design features will not be installed at the time of <br />initial site deve:Lopment, explanation should be provided in the <br />application, along with a discussion of interim measures which will <br />be employed until the permanent feature is installed. <br />Please contact me if you have any questions. <br />Sincer y`r_ <br />~a <br />Dan T. Mathews <br />Environmental Protection Specialist <br />enclosure <br />cc: Larry Routten, DMG <br />Susan Burgmaier, DMG <br />des\tr39rev.ltr <br />2 <br />