GENERAL50306

• Permit No: C1981010
• IBM Index Class Name: General Documents
• Doc Date: 7/5/1996
• Doc Name: HISTORICAL TOPSOIL DEPTH INFORMATION
• From: TRAPPER MINING INC
• To: DMG
• Permit Index Doc Type: SOILS
• Media Type: D
• Archive: No

TRAPPER ~ININC INC.
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Mr. Joseph J. Dudash
Environmental Protection Specialist
Colorado Division of Minerals & Geology
1313 Sherman Street, Room 215
Denver. CO 80203
Dear ]oe:
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July 2, 1996 rFIVED
4C
JUL ~ 5 f996
Division of Minerals & Geology
Re: Trapper Mining Inc., Permit No. C-81-010
Phases I & II Bond Release; Historical Topsoil Depth Information
Please consider this letter and the enclosed information as our response to DMG's request to
provide available data and information regarding Trapper Mine historical topsoil replacement
depths on reclaimed lands. As you will recall, we discussed this issue at our March 25, 1996
meeting concerning a Phase I ~Yc ll bond release submittal. Enclosed Table 1 provides a summary
of topsoil depth replacement on all reclaimed land parcels for the life of Trapper Mine. Table 2
gives backup information for those reclaimed parcels where mean topsoil replacement depths were
estimated using scraper load count information. Figure 1 outlines Trapper Mine reclaimed land
parcels through 1995. Finally, backup information on DMG historical topsoil depth field sampling
is enclosed.
As we suspected, backup data for topsoil replacement depths during some years aze not available.
However, Trapper's topsoil replacement monitoring practices have been very uniform throughout
the life of mine and have been conducted in such a way as to ensure adequate topsoil replacement
depths. Trapper has always closely monitored topsoil replacement depths by means of concurrent,
systematic field depth sampling by trained individuals. This field monitoring has always occurred
within one to several days of topsoil replacement by scraper crews and was conducted before the
crews left the area. In azeas where topsoil was found to be replaced at less than the approved
depth, scrapers were sent back into the area to lay down at least the required topsoil depth. In
many cases, topsoil replacement depth data were not formally kept because it was not known until
recently that this data would be necessary for Phase I[ bond release.
Table 1 summarizes available topsoil depth data and provides information on data origin. Results
of topsoil depth sampling during the early years of reclamation at Trapper Mine, through about
1984, were summarized on reclamation working maps. Reclaimed parcels for which this type of
data are available aze labeled as "field sampling" under Methods of Measurement in Table 1.
Mean topsoil replacement depths during the more recent years of mine reclamation, during 1985
and from 1989 through 1995, were determined by scraper load counts and are so designated in
Table 1. (Table 2 provides a backup summary of load count information J In addition, as
indicated in Table 1, a very limited amourrt of replacement depth data are available from DMG
field inspections. Formal topsoil replacement depth data for 1986 through 1988, except for the
limited DMG data, could not be located.
P.O. Box 187 Craig, Colorado 81626 [phone]