2006-06-13_REVISION - M2004009 - Laserfiche WebLink

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Page 4 • The offset shown on the map for the distance of the hydraulic barrier trench is shown correctly. An agreement with the ditch company has no[ been reached at this time. They aze agreeable to the concept and the basic design, but an agreement has not been formalized at this time. We expect the agreement to be Formalized in the next several months. In lieu of an agreement, ASCI commits to NOT mining on the entire west side of Boulder Creek until either an agreement is signed between the ditch company and ASCI, or a geotechnical study is submitted showing that our design can hydraulically isolate the irrigation ditch from the effects of dry mining. • The high-pressure gas line will not be affected by the dry mining. The in-place and undisturbed overburden supporting the pipeline will not be affected by the dry mining in the water table below the depth of the pipeline. The mining ends -30 ft. "inside" of the extent of the hydraulic barrier. The map has been revised to show a "wingwall" of barrier a certain distance to the west and east of the ditch to preclude any residual effects of the dry mining at both the upstream (south) and downstream (north) ends of the ditch. • Design information for the hydraulic barrier is included in the revised Exhibit E, Attachment E-1, and Exhibit F, Sheet 4, all of which aze enclosed with this letter. • Exhibit L has been updated [o include bonding costs for [he hydraulic barrier and is enclosed 14. All dewatering trenches will be located within the mining cells, at the toes of the pit slopes, as currently being done in the original permit area. As described in Response 7, the sumps aze just slightly wider and deeper dewatering trench excavations at the ends of these trenches to encourage settling prior to dischazge to the creek or recharge trench. Locations of the dewatering trenches aze shown in drawings that were copied from the SWSP and are included in the enclosed revised Exhibit G. 15. The maps and tables have been corrected to be consistent. 6.4.5 EXHIBIT E -Reclamation Plan 16. As noted in Exhibit E (enclosed), overburden (and with the little topsoil onsite mixed-in with overburden) will be placed at a minimum depth of 0.5 ft over 100 acres, will not be compacted and will be prepazed for seeding. 17. The enclosed, revised Exhibit E reflects that Cell 6 will be backfilled to approximate historic grade using material from the Borrow Cell, instead of being left as a depression. Exhibits E and F have been updated to include this change. It should be noted that in the previous application, the Borrow Cell was not included in the earthwork volume calculations and therefore it was thought that there was not enough volume onsite to backfill Cell 6. Cell 4 will be a clay-lined depression and is not expected to accumulate significant amounts of stormwater. Exhibit L has been updated to include the cost of lining Ce114 and is enclosed. 18. The corrugated metal pipe routing the seep through the Cell 6 will be installed below grade during reclamation of Cell 6. Detailed design calculations and specifications have been included in the revised Exhibit E (Attachment E-1) and on Exhibit F, Sheet 4, all of which are enclosed. 19. The compacted clay liner compaction specification has been revised in Exhibit E to be up to 2% or greater than the optimum moisture content. 20. The enclosed Exhibit F has been revised to show the clay liner keyed in to the bedrock.