PERMFILE55696

• Permit No: C1981014
• IBM Index Class Name: Permit File
• Doc Date: 12/11/2001
• Section_Exhibit Name: EXHIBIT 09 COMPARISON OF REFUSE AND SOIL SUITABILITIES
• Media Type: D
• Archive: No

• biased in regards to the potential °reduced" properties of these materials,
rather than their "weathered" characteristics. Recognizing that the refuse
materials sampled spanned a broad range in ages, the various refuse
samples were subjected to a regression analysis to determine which
parameters are signficantly effected by weathering or sample age, the results
of which are presented in Table 11.
Examination of these data suggests that the properties of the refuse
materials are spatially dynamic. In every instance where chemical changes
over time are statistically signficant, the changes are in the direction of
improvement in overall quality with increased age or weathering. Positive
improvements in quality with respect to pH, EC, SAR, Na, Zn and Mg are
evident from these data The improvement in nutrient properties involving Zn
are evident from these data. The decline in percent siR suggests that these
materials are actively weathering over time. A strict interpretation of these
data suggests that all of the parameters of potential concern in the refuse
materials are decreasing in concentrations and improving in overall quality
with time. This Vend is entirely consistent with the normal processes of soil
genesis.
Since the oldest refuse samples represent materials generated by
technologically less efficient methods of mining and processing and much
harsher conditions than are associated with the newer more efficient coal
recovery techniques, the very old samples represent poorer quality refuse
• materials, such as higher coal content, coarser fragments, etc., than the
newer samples.
In order to quantify the overall suitability of the refuse materials with other
potential cover materials that are required by regulation to be placed on the
refuse pile to a depth of four feet, the suitability criteria in the NMMMD and
WDEQ guidelines for topsoil substitute materials were applied to all of the soil
and refuse data available from the Southfield Mine. In order to present a
"worst case' comparison the properties of the soil materials were initially
compared with the refuse materials. Since R is known that the overall quality
of cover soil materials decreases with depth, this comparison grossly over
emphasizes potential quality of the cover soil materials. Each parameter was
individually evaluated using the methodology outlined in Table 12.
This suitability comparison indicates that the overall suitability of the refuse
material from the Southfield Mine is superior to that of the soil materials. The
refuse materials are statistically superior with respect to rock fragments less
than three inches in size, acid-base potential, N03-N and Fe. The soil is
statistically superior with respect to pH and SAR. The mean suitability values
for the other parameters were not statistically different. This comparison is
considered to be a "worst case' comparison since it is biased by the addition
of several very old and very new refuse samples. Sampling of the very old
refuse piles was restricted to areas having the very highest coal content and
the least amount of vegetation. Given this deliberate sampling bias, it is
surprising that the refuse materials have a suitability ranking as high as they
,, do. Inclusion of the very new refuse samples biases these samples because
it assumes that samples taken from a reduced environment will possess
identical characteristics in an aerobic environment. Such a set of
assumptions are chemically impossible to achieve due to the inability to
obtain suitable chemical equilibriums under such conditions.
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