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Minor Revision No. 239 Page 2 <br />February /6, 1998 <br />The french drains will be constructed above and below the interception trench and <br />will collect groundwater at the head of the slide and in the slope above MB-1 and <br />FW-1. The interception trench and the french drains will not be connected. The <br />water will be routed to stone columns, which were previously constructed or to <br />existing surface drainage structures. The french drains will also be constructed in <br />phases. At this point, MCC has planned to construct a total of 17 french drains. Six <br />of the french drains, three on the east side and three on the west side, are located in <br />areas that have not been previously disturbed. Portions of seven of the drains are <br />located in areas that have not been previously disturbed. The remaining drains will <br />be constructed in areas that have been disturbed. The vegetation in the undisturbed <br />areas is oakbrush, which will be brush crushed. Topsoil will then be stripped and <br />stockpiled in either the Water Tank topsoil pile (if constructed in time for this <br />project) or in the Material Storage Bench topsoil stockpile. It is difficult to <br />accurately determine the amount of topsoil that will be stripped, as the width of the <br />french drains will vary due to the angle of the side slopes in the trench. It is possible; <br />depending on field conditions that the locations of the drains may vary slightly or the <br />number of drains installed may decrease or increase. <br />The depth of the french drains may also vary, but will be approximately 30-feet <br />deep. They will be backfilled with granular fill. Geotextile fabric will be placed <br />over the granular fill and then the trench will be backfilled to the surface with <br />common backfill. The french drains will drain either into existing surface drainage <br />structures or into stone columns. It is also difficult to estimate the amount of subsoil <br />that will be hauled to the Live Subsoil Pile in Sylvester Gulch, as the width and <br />depth of the french drains will vary as they are constructed in the field. The french <br />drains are also intended to be long-term; to remain after final reclamation. <br />As the interception trench and the french drains will remain upon final reclamation, <br />the only reclamation that will be necessary, is the retopsoiling of the areas stripped <br />for the french drains and seeding. Reclamation of the main mine haul/access road is <br />already included in the reclamation cost estimate. The Live Subsoil Pi]e in Sylvester <br />Gulch is intended to be a soil stockpile that can be used for construction projects and <br />not intended for reclamation. <br />MCC will plan to update the Division as construction of the interception trench and <br />french drains progress. In addition, MCC will submit as-bunts, including volumes of <br />soil moved and stockpiled, upon completion of the project. <br />It is urgent that MCC begin this project immediately, therefore, MCC would <br />appreciate the Division's immediate review. Please call or fax any questions that <br />you may have regarding this revision application. <br />