PERMFILE116859

• Permit No: C1980006
• IBM Index Class Name: Permit File
• Doc Date: 12/11/2001
• Section_Exhibit Name: PART 779 Environmental Resources
• Media Type: D
• Archive: No

Section 779.14(a) Continued.
Rule 2.04.6
surface water samples evaluated, none has contained a concentration of
molybdenum above the detectable limit of 0.01 mg/1. Water quality
sampling and analysis are discussed in detail in Section 2.04.7, Hydrology
Description.
Selenium (Se). A total of 54 Kerr overburden samples were analyzed with
respect to selenium. Values for selenium ranged from 0.00 to 0.24 ppm
with a mean value of 0.057 ppm. Twelve samples exceed the suspect level
of 0.10 ppm contained in the Wyoming guidelines. It can be documented
that ten (10) of these samples are from holes drilled with mud and hence
may be biased due to contamination. Excluding the selenium values from
holes drilled with mud, the average selenium value is 0.04 ppm. On a
volumetric basis the two (2) remaining elevated selenium values amount Lo
12.76 percent of the overburden holes drilled without mud. The two (2)
• elevated selenium values correspond to Hole 28-19-61 at the 15 to 75 foot
interval and Hole 28-80-29C at the 100 to 200 foot interval. Since 83
percent of the high selenium values can be identified as being
contaminated by drill mud it is highly possible that these holes are
likewise contaminated. Given the ample amount of potentially clean
chemical material present in the overburden, mixing will almost certainly
eliminate this problem.
In a recent review of reclamation issues for western surface coal
operations (U.S. Congress, Office of Technology Assessment, 1986), it was
reported that a volumetric limit of 15 percent had been set as the limit
for mixing of unsuitable materials in dragline operations. A similar
volumetric limit of 20 percent was set for mixing of unsuitable materials
in truck/shovel operations. Given that the remaining suspect values
constitute only 12.76 percent of the total overburden volume, the mixing
inherent in normal mining operations should effectively dilute any
potentially unsuitable materials. Consequently, no problems are
. anticipated with toxicity or groundwater quality with respect to selenium
r n (As). A total of 54 Kerr overburden samples were analyzed with
respect to arsenic. Arsenic values in the samples were very low, ranging
from 0.00 to 0.81 ppm with a mean value of 0.15 ppm. No limitations are
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