PERMFILE117745

• Permit No: C1982055
• IBM Index Class Name: Permit File
• Doc Date: 12/11/2001
• Section_Exhibit Name: ADDENDUM A SUITABILITY EVALAUATION OF THE RATON CREEK MINE REFUSE COVER MATERIALS
• Media Type: D
• Archive: No

• associated with regrading is considered, thus no problems appear to be
associated with the quality of these materials with respect to their EC
values.
Saturation Percentage (SP). The Wyoming Guidelines rate topsoil substitute
materials as being of "suitable" quality when the SP value ranges between
25 and 80 percent. The SP values for the Raton Creek Mine overburden and
bench materials range between 28 and 68 with a weighted mean value of 45.9
percent, suggesting that all of these materials have a "suitable" ranking
with respect to overburden quality. Therefore, it appears that there are no
limitations associated with the quality of these materials with respect to
their SP values.
Texture. The Wyoming Guidelines rate topsoil substitute materials as being
of "suitable" quality when the texture is composed on texture classes other
than those associated with clays, silty clays and sands. Two colluvial
samples were found to be clay textured materials. On a volumetric basis
these clayey materials amount to 19.95 percent of the overburden materials
sampled. Given the volume of materials associated with this clayey zone it
is doubtful the inimical zone would be eliminated via mixing.
Another aspect to be considered with respect to soil texture deals with
documented changes that are associated with the mixing of soils sampled in
the undisturbed state and soil materials that have been mixed via the removal
and reapplication process. Abundant documentation is available demonstrating
that clay content significantly increases during the mixing processes. In
North Dakota, Wali and Pemble (1982) reported that clay content in mined
areas normally is increased from 23.8 to 28.8 percent or by 21.0 percent,
while Gee and Bauer (1976) reported that the clay content of stockpiled
topsoils was increased an average of 49.6 percent, from a premining clay
content of 19.57 percent to a stockpiled clay content of 29.29 percent.
Working on a large surface mine in Wyoming, Toy and Shay (1987) reported that
the clay content of undisturbed areas averaged 13.11 percent while the
average clay content of respread topsoil was 20.19 percent, which amounted
to an increase in clay content of 54.0 percent. Numerous other examples
could be cited to demonstrate that the clay content of mine soil material as
determined by sampling prior to disturbance consistently underestimates the
clay content associated with the reclaimed soil. The reason for this
increase in clay content results from the mixing of horizons during the soil
handling processes. Given the consistent occurrence of this phenomenon, the
likelihood of increases in clay content should be considered in the 'N
formulation of a sound reclamation plan. Using the most conservative of ~
these three studies cited above, it is reasonable to assume that the clay t~'''•I.
content of these potential cover soil materials will increase by at leas b~~ o
percent. Six of the remaining 22 overburden samples collected were found to y
have clay loam textures. These six samples comprise 31.17 percent of the
potential overburden materials found on this site. Thus, if the clay content
of these six samples were to increase by 21 percent they would all become
clay textured materials and would be classified as being of "marginal"
suitability as topsoil substitute materials using the Wyoming DEQ criteria.
Examination of the existing permit soils section reveals that 27 soils
. pits were dug in the immediate vicinity of the potential borrow area. Most
of these pits have notations on soil texture. These data found on pages 180
to 187, 195, and 206 to 207 of the existing Raton Creek Mine Permit document
that the clay content of these soils is quite high. Six of the 21 holes
correlate to the immediate area sampled in this evaluation. Soil Test Area