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REV88868
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REV88868
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Last modified
8/25/2016 3:10:55 AM
Creation date
11/21/2007 10:46:06 PM
Metadata
Fields
Template:
DRMS Permit Index
Permit No
M1993059
IBM Index Class Name
Revision
Doc Date
10/22/1998
Doc Name
PRELIMINARY ADEQUACY REVIEW FN M-93-059
From
DMG
To
GREG LEWISK AND ASSOCIATES
Type & Sequence
AM1
Media Type
D
Archive
No
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<br />concept is then for the dredge to mine in a large circular fashion, backfilling and reclaiming behind i[ as it <br />moves away from the initial cut and overburden stockpile, and eventually ending up back next to the <br />overburden pile. Since approximately 25% of the mined material is removed and sold as product, <br />whenever a phase is completed, a void is left which will become a permanent lake. [n this mining plan <br />this void will be divided into two separate lakes. When [Ite dredge reaches its farthest point away from <br />the initial overburden pile, a lake will be left at that point, and when the initial overburden pile is <br />backfilled into the final cut, a lake will be left at that location. In order to maintain a reasonable financial <br />warranty, the backfilled area immediately behind the dredge is regraded, topsoiled and revegetated as soon <br />as possible so that it is not counted as disturbed area. <br />In general, the Division has no problem with this mining concept, however, there are a couple of concerns <br />that were raised after the pre-operational inspection was conducted. Using the active phase as an example, <br />the general direction of mining is in acounter-clockwise fashion moving from east to west, [hen south, <br />then back east and eventually north again to end up next to the overburden stockpile. However, for some <br />reason the dredge was moved diagonally from the western edge of phase I to the southeast eventually <br />ending up almost directly south of the overburden stockpile. As a result of this "shortcut", the screening <br />deck was also moved and now sits right in the middle of the backfilled and regraded area just west of the <br />overburden stockpile, along with the slurry line from the dredge to the screening deck, the slurry line <br />return line into the lake, and the conveyor over to the prep plant area. This is a fairly sizeable area that has <br />been backfilled, regraded and in some cases topsoiled. What the activites that have occurred in Phase l <br />serve to illustrate is that some mining related activities are going to be conducted on the regraded area and <br />topsoil should not be replaced until this activity is completed, and if topsoil has been replaced and the area <br />is once again needed for mining related activities, the topsoil must be re-stripped and stockpiled. <br />In observing what has occurred in Phase 1, it seems that even though areas that have been mined and <br />backfilled can then be re-graded, it may not be possible to topsoil and seed these areas until almost all <br />mining in a phase is completed. This is due to the fact that as mining progresses, the suction dredge <br />support equipment (slurry lines, screening deck, conveyors, etc.) are moved around on the backfilled and <br />regraded areas as the dredge moves, and until the dredge and lake aze almost back to the beginning point, <br />all areas that have been backfilled could be used in support of the active mining process. What this <br />ultimately means is that some areas may not be topsoiled and seeded as soon as backfilling is completed. <br />As a result, topsoil handling procedures may need to be reviewed since some of the proposed live-handled <br />topsoil may now have to be stockpiled until more of the mining phase is completed. In addition, the total <br />maximum disturbed area will probably need to be enlarged to account for the delay in final reclamation <br />that will occur on certain backfilled and regraded areas until mining has progressed to the point that these <br />area will definitely not be re-affected. <br />Also, in reviewing the proposed plan it seems that once Phase 1 is completed, it may be possible to <br />transition into Phase 2 by just continuing to operate out of the "Final Lake" that will remain in Phase 1. <br />This would eliminate the need to construct another overburden sand pile which would also greatly reduce <br />the reclamation and financial liability of the mining plan since reducing the initial overburden sand pile by <br />putting it back in to the dredge lake is the single largest cost associated with the reclamation plan. If this <br />pile could be permanently eliminated, the overall reclamation bond would basically be reduced by half on <br />the remaining mining phases. All of this is dependent on whether or not the remaining lake is large <br />enough to continue operating the dredge after backfilling of the initial overburden stockpile is completed. <br />This is something that will have to be evaluated as Phase I nears completion. However, it may be <br />something [hat you want to include as a possibility with [his amendment so that if [his becomes possible in <br />
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