REV104535

• Permit No: C1981010
• IBM Index Class Name: Revision
• Doc Date: 8/29/2002
• Doc Name: Adequacy letter
• From: DMG
• To: Trapper Mining Inc
• Type & Sequence: RN4
• Media Type: D
• Archive: No

Soils
38. TMI submitted Table 4.9-3 showing proposed Topsoil salvage and replacement acreage and
volumes. Table 4.9-3 indicates the TMI project a deficit of 361,000 bulk cubic yards of topsoil
in the 2003-2007 permit term. Table 4.9-4 projects an excess of 134,000 bulk cubic yards of
topsoil inventory during the 2003-2007 permit term. Please provide an explanation of these
seemingly conflicting projections. Please assure that topsoil replacement predictions do not
result in a deficit for the proposed 2003-2007 mine plan.
Backfilling and Grading; Rule 2.05.4(2)(c)
39. TMI provide map M12, sheets 1, 2, and 3, proposing postmining topography for the 2003-2007
mine plan. The Division finds that the proposed post-Honing contours do not meet the terms of
Rule 4.14.2(1). Rule 4.14.2(1) requires that the post-mining topography approximate the general
nature of the pre-mining topography. Rule 1.04(13) provides a definition of "approximate
original contour". The deviation from approximate original contour is most pronounced on M12
sheet 2 of 3 and sheet 3 of 3, from Easting 1440000 to Easting 1429000, and Northing 407500 to
Northing 402000.
a) Please revise the post-mining topography maps, M12 sheets 1, 2 and 3, to bring the
proposed final contours into compliance with Rule 4.14.2.
b) The proposed West Flume drainage truncates the approved Oak drainage. The sediment
ponds were designed based on a model using watershed areas illustrated on Map 51.
Routing the West Flume drainage as presented on M12 sheet 2 would require remodeling of
the West Flume pond and deviates significantly from the pre-mining drainage basin
configuration. Please revise the West Flume drainage to keep with previously agreed upon
drainage basin azeas and to comply with Rule 4.14.2(1).
c) The orientation of the proposed Ease Pyeatt No. 3 drainage deviates significantly from the
orientation of the pre-mining drainages. Please bring this drainage configuration into
agreement with approximate original contour or provide and explanation to the Division of
the necessity for this significant change.
d) Proposed drainage cross-sections shown on Map M14 show some reaches with greater than
20% slopes. Please provide additional information to demonstrate that these steep reaches
will not be prone to excessive erosion.
e) Please provide cross-sections of TMI's proposed post-mining contours. Cross-sections
should extend from undisturbed topography on the South end, cleazly show the proposed
regraded topography, and extend into undisturbed topography on the North. (Rule
2.05.4(2)(c))
f) Please assure that proposed post-mining topography maps have been certified and signed in
accordance with Rule 2.10.
g) Proposed M12 sheet 1 shows proposed post-mining contours in the D pit area. These
proposed contours differ from previously approved contours in this area. The proposed
contours should blend more smoothly with the surrounding topography.
C-1981-010 RN04/PROS 10 08/29/02