REV92482

• Permit No: C1981026
• IBM Index Class Name: Revision
• Doc Date: 9/7/1995
• Doc Name: INTRODUCTION
• Type & Sequence: SL2
• Media Type: D
• Archive: No

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The results of the 1995 survey indicate a
permanent and relatively diverse vegetative
cover has become established at the
Canadian Strip Mine. Because this cover is
established on the reclaimed area, Slurco
believes the reclaimed area meets the
requirements for Phase II bond release.
SOIL EROSION CONTROL
Soil erosion for pre-mining and post-mining
conditions was estimated using the Universal
Soil Loss Equation. The analyses accounted
for soil types, slopes, soil erodibiliry, and
cover and management. The results are
summarized below.
Results indicate the revegetated mine site is
experiencing less soil loss than it did prior
to mining. Calculated pre-mining soil loss
is 0.88 tons/acre/year. Calculated post-
mining loss is 0.39 tons/acre/year.
Consequently, the site is not contributing
suspended solids to streamtlow or runoff
outside the permit area in excess of pre-
mising levels.
Comparison of pre- and post-mining erosion
rates with soil-loss tolerance factors
calculated by the Coil Conservation Service
(SCS) indicates soil erosion at the mine site
was and is within tolerance limits. For soils
found on the mine site, soil-loss tolerances
range from 2 to 5 tons/acre/year.
Consequently, soil losses of 0.39 and 0.88
tons/acre/year would not be considered
excessive by SCS standards. Because the
present annual soil loss is less than pre-
mising conditions and is well within soil-
loss tolerance capacity, Slurco believes soil
erosion from the reclaimed mine site has
been controlled.
The DMG approved the sediment anal sis
(Grey_stone~990), in the previous partial
Phase II release application in 1991 (DMG
199~DIGIG indicated, "In summary,
modeling shows that post-mining sediment
generation is less than in the pre-mining
situation throughout the site. Untreated
drainage from the disturbed area ceases to
contribute additional suspended solids above
natural conditions, per Rule 4.05.2(2).
Field observations document that current
erosion at the site would not be disruptive to
the post-mining land use."
Slurco believes that the analysis conducted
in 1991 is valid for this release application
due to consistent vegetative cover on the site
and due to the fact that the ponds have not
been cleaned or that there has not been
significant rill or gully repair. Rill and
Gully reports which document repair
activities are provided in Appendix B.
' 92-01\Bond\09/07/95 7