REP11387

• Permit No: C1980001
• IBM Index Class Name: Report
• Doc Date: 7/26/2000
• Doc Name: INTEROFFICE MEMO EDNA MINE PN C-001-80 1999 ANNUAL HYDROLOGY REPORT REVIEW
• From: DMG
• To: SANDRA BROWN
• Permit Index Doc Type: HYDROLOGY REPORT
• Media Type: D
• Archive: No

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DIVISION OF MINERALS AND GEOLOGY
Department o(Natural Resources
1313 Sherman St., Room 215
Denver, Colorado 80203
Phone: [phone]
FAX: [phone]
STATE OF COLORADO
INTEROFFICE MEMORANDUM
TO: Sandra Brown
FROM: Mike Boulay M
DATE: July 26, 2000
SUBJECT: Edna Mine -Permit No. C-001-80, 1999 Annual Hydrology Report Review
DIVISION OF
MINERALS
GEOLOGY
RECLAMATION
MIN ING•SAFETY
Bill Owen.
Governor
GreRE Walchei
Eiecalrve Director
Michael B. Long
Drv~sion Dneclor
I have reviewed Western Water Consultant's 1999 Annual Hydrology Report for the Edna Mine.
As noted in your memorandum to me dated April 25, 2000, the frequency of data collection is in
compliance with the approved monitoring plan contained in the permit document. The Division
has the following comments concerning the 1999 AHR.
The Division notes that the CDPS sulfate limitation was exceeded for discharges to Truut
Creek on four occasions during 1999. These exceedances occurred in July, August, and
December at DMP 004 and in December at DMP 007.
Based on review of data from surface water monitoring sites TR-A, TR-B, TR-C, and TR-D,
the numeric standard for sulfate for the mainstem of Trout Creek (Segment 13c of the Yampa
River Sub-basin) was not exceeded on any occasion during 1999. Therefore, there are no
specific material damage issues to be addressed by the Division at this time as a result of the
CDPS sulfate criteria exceedances.
There is a significant increase in sulfate concentration from the upstream monitoring location on
Trout Creek (TR-A) to the downstream monitoring point (TR-D). The highest concentration
reported for TR-D in 1999 is 660 mg/1 which is within the PHC prediction. The PHC prediction
contained in the PAP states [hat sulfate concentrations in Trout Creek may be expected to reach
an upper limit of approximately 842 mgll at some time during the mining and post-mining era at
the EDNA Mine.
Please note that DMP 007 is not shown on the Water Monitoring Location Map (Exhibit 4.6-26).
2. On page 9 of the 1999 AHR, P&M states that "although elevated TDS concentrations
have moved downstream in conjunction with mining and reclamation activities, all values for
TDS are consistent with the probable hydrologic consequences projections". It is evident that