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• <br />u <br /> <br />III IIIIIIIIIIIIIIII <br />Doc Date:1y11 p2/ p~ <br />~~; 4.14 BACKFILLING AND GRADING <br />Rule 4-14 <br />According to the MLRD January 1987 Proposed Decision and Findings of Compliance, <br />problems identified during both the original permit application review and during the permit <br />revision review related to overburden handling procedures, swell factors, stability of the excess <br />spoil pile and configuration of the proposed reclaimed surface. All these concerns were <br />satisfactorily resolved. Technical Revisions 51 and 52 respectively addressed final reclamation <br />topography and drainage design for the reclaimed mine. These TRs, which are described in <br />Section 2.05.4(1), were approved by the MLRD in 1986. <br />Periodic monitoring of reclamation success since 1987 has confirmed that all backfilled and <br />graded areas have remained stable with the exception of a very small area located near the <br />former highwall at the sou[hern limit of the pit. Over the years, a slump feature developed <br />along a portion of the boundary between the backfilled spoil material and undisturbed stratum <br />immediately up-dip of the reclaimed area. Investigations indicated that the slump was <br />potentially being caused by water inflow into the spoil material from the up-dip strata. A <br />mitigation plan was developed and approved by DMG via MR-7 on September 27, 1994. <br />Mitigation involved installation of a french drain system along a trench pazallel to the former <br />highwall boundary to intercept groundwater and convey it away from the reclaimed area. In <br />July 1995, slump movement monuments were installed to facilitate stability evaluation of the <br />slump area and minor regrading was done along the drain channel backfill area to eliminate <br />surface inflow. In October 1995, all disturbed azeas associated with the french drain and surface <br />water diversions were broadcast seeded. <br />H: V ]]V+ERMrf VtULE41~.HC <br />11/39/95 9:10un mrsv~,.~~ 4.14-1 Revised - 11/28/95 <br />