2008-09-17_REVISION - M1980244 ‎(28)‎

• Permit No: M1980244
• IBM Index Class Name: REVISION
• Doc Date: 9/17/2008
• Doc Name: Response to Adequacy Review
• From: CC&V
• To: DRMS
• Type & Sequence: AM9
• Media Type: D
• Archive: No

•
8000-8500 3441 6.1 209 692
7500-8000 3074 5.1 156 848
7000-7500 2730 5.6 152 1000
6500-7000 2427 7.8 189 1188
6000-6500 2142 8.0 172 1360
5500-6000 1986 8.7 173 1533
This conservative assumption reduces the available calcium carbonate to 1188 million tons,
compared with 1883 million tons including the high carbonate materials.
Using this value, 0.32% of the total inventory TlYould be consumed in neutralizing the potential
acid produced by complete oxidation of available sulfides in the overburden produced by the
end of the Cresson Project. The prior value was 0.20%.
Accordingly, ignoring the results from the high carbonate borehole still results in a very small
percentage of the available carbonate being used to neutralize all potential acid products that
may result from mining at the Cresson Project. Making this conservative assumption does
not change the conclusion that "No deleterious change in the average regional groundwater
quality will occur due to the proposed future MLE (2006-2016)" (MLE Project Application,
Appendix 1, p.19).
P. The DRMS is concerned that the three deep drill holes do not provide adequate spatial
sampling representation. Please provide a map showing the locations of the three deep drill
• holes used for carbonate characterization.
Response:
The three deep holes are located on Figure 10 included as Attachment 9.
Q. Lacking the quantity of data for deep lithology, it would be prudent to continue to update
and calibrate the environmental model with ABA analyses of blast hole or mine face sample
as mining progresses.
Response:
CC&V does not concur in this observation. The deepest elevation to which mining is
scheduled to occur as proposed within the MLE Project Application is 8,990 ft. At this depth
and above, there is a large quantity of data available for evaluation of carbonate. ABA
analyses of blast hole or mine face samples will not significantly improve the database of
carbonate information for neutralization analysis.
R. Applicant states that dissolution of carbonate minerals creating enlarged preferential
pathways is not a concern because the carbonate would give way to gypsum and maintain
the integrity of the pathway. This may be correct from a physical hydrologic standpoint,
but this scenario would result in a progressive depletion of carbonate in favor of the non-
neutralizing minerals gypsum or anhydrite. Thus, infiltration through those pathways
might eventually encounter progressively less carbonate as time goes. One mitigating
circumstance surrounding this concern is the fact that the Carlton Tunnel discharge
alkalinity has been increasing again of late.
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