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Memo to Grua Crosby 3 Junc 1, 2(Nl6 <br />Gcotechnical .Ad~guacv Review Permit No M- I't8?-OZR <br />dumping into areas that were supporting the growth of shrubs and trees. 'rhe pending permit <br />conversion CN-f!1 application proposes more extensive waste rock disposal than was <br />previously approved in the current section l 10 limited impact pcmtit. The waste ruck dump <br />reclamation plan states that all dumps will be graded to no steeper than 3H: I V, which is <br />inherently stable and is acceptable to the DMG. However, no plan for reclamation grading of <br />waste rock concurrent with yuarty operations is provided. Absent such a plan, DMG must <br />assume. Ibr the purpose of reclamation cost estimating, that all dump grading will occur at the <br />conclusion of the operation. 7hc Uperator is encouraged w provide a plan ti,r concurrent dump <br />grading, and whether such a plan is provided or not, the (lperutor must provide dimensions ti,r <br />the waste dumps, in ternts ofout-slope length, height, and repose angle that will no[ he <br />exceeded during the life of the quarry. These dimensions will be used by DMG to estimate a <br />cost to g'ade the dumps to 311:1 V and these costs mill be included in the amount of the <br />reclantalion bond to be required, and DMG would consider exceeding of the specified <br />maximum dump dimension to be a violation of the pcmtit. The following issues relating to the <br />dumps must also be addressed. <br />a. 'the Operator must provide a plan for waste dump fi~undation preparation. 'ihc plan <br />must describe clcanng and grubbing, topsoil preservation, and the disposition of <br />rerttuved woody vegetation. 'this plan must descnbe the extent to +ahich areas beYOnd <br />the toe of the dumps will be cleared and grubbed; if this area is nut prepared to ultimate <br />extent of the reclaimed 3H:1 V Jumps, then the DMG will estimate a rnst for any <br />needed dump foundation preparation at the time of reclamation fur inclusion into the <br />amount ol'reyuired bond. <br />h. The Operator must thoroughly describe drainage considerations relating to the disposal <br />ol'wastc rock, including the following. <br />i) "Ilte DMG's April 25, 2(106 adequacy letter inquires about final reclaimed <br />drainage patterns. In conjunction with responses to those inquiries, the <br />Uperttor must describe the relationship of the graded and reclaimed dumps <br />with flows around and through dump locations shat would result for the <br />QO-year'24-hour storm event. [fit is determined that high velocity flows <br />resulting from the design storm would cause erosion of the reclaimed <br />dumps, the Operator must provide a drainage plan, which may include <br />amtoring of areas susceptible to erosion, to assure that the reclaimed <br />dumps will remain stable ti~llowing large storm events. <br />iil It was observed during DMG's May 26, 2006 inspection of the yuam~ that <br />the ultimate waste dump would bury some small tributaries to Taylor <br />Gulch. Prior to dumping run of quarry waste ruck, these tributaries must <br />he tilled with hard, durable, non-slaking coarse grained waste rock to <br />provide under drainage. <br />