REP15015

• Permit No: C1981044
• IBM Index Class Name: Report
• Doc Date: 6/3/2005
• Doc Name: 2004 AHR Response Part 2
• Annual Report Year: 2004
• Permit Index Doc Type: Hydrology Report
• Media Type: D
• Archive: No

RAG Empire Corporation, Eagle Mine Water Quality Assessment CO-0034142
Table A-5
Ambient Water Quality for the Williams Fork River Site WF-1
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H su 230 7.6 8.0 8.4 8.0 . 6.5-9 1
As, Trec u 12 0.11 0.4 1.4 0.83 Np _ 1
Fe, Dis (u S 351 624 1]09 728 r 300 1
Fe, Trec (u 55 188 705 2651 1595 . 1000 1'.
Mn, Dis u 9 7.3 13 23 15 ' S0 1
H ,Tot (u S 0 0 0 0 NA 1
A ,Dis (u 1 0 0 _ 0 0 'l.3 2,
Zn, Dis (u • 1 25 25 _
25 25' . 210 2 .
Zn, Trec (u 5 4.9 12 31 78 . NA 1
B, Trec (m 12 0.073 0.13 0.23 0.15 . NA 1
Chloride (m 13 2.2 4.1 7.4 4.8 250 1.
Sulfafe (m ] 3 40 67 ' +-113 76 , 250 1-
(Note 1:~'R~e 15th SQth, and 85th 9ercrntile.conceniratiotu are estimated assutmna a normal distrShution. _ ~. ~ ~ 1
III. -Water Quantity
~ The Colorado Regulations specify the use of low flow conditions when establishing water quality
based effluent limitations, specifically the acute and chronic low flows. The acute low flow,.referred
to as I E3, represents the one-day ]ow flow recumng in a three-yeaz interval. The chronic low flow,
.. , .30E3, represents the 30-day average ]ow flo~/,recurring.in ~ three-year interval. - .... ... .
Low Flow Analysis:
To determine the ]ow flows available to the Eagle Mine dischazges, a flow gage measurement
immediately upstream of tht; facility should be used. Because there were no:USGS flow gages
immediately upstream of the Eagle Mine, a downstream gage station was used. -
Daily flows from the USGS Gage Station 09249750 in the Williams Fork River approximately 1-2
miles downstream of the Eagle Mine discharges were obtained and the arulual lE3 and 30E3 ]ow
flows were calculated using U.S. Environmental Protection Agency (EPA) DFLOW software.
Because this gage station already includes the dischazge contributions from the Eagle Mine, the flow
contributions •from Outfalls 003, 022, 023, and 024 were detemrined and deducted to derive an
upstream slow. Specifically, average effluent flow data for these outfalls based on a period of record
of September 1995 through June 200I were obtained from PCS. Because the flow data are reported
quarterly, the average quarterly data were assumed to be representative for each of the months in the
respective quarter. These average flows were then deducted. ,
Appendix A Page 7 of 13
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