2011-11-18_REPORT - C1981022

• Permit No: C1981022
• IBM Index Class Name: Report
• Doc Date: 11/18/2011
• Doc Name: 2010 Annual Hydrology Report - Preliminary Adequacy Review
• From: DRMS
• To: Oxbow Mining, LLC
• Email Name: BFB
• Email Name: SB1
• Media Type: D
• Archive: No

DIVISION OF RECLAMATION, MINING AND SAFETY
Department of Natural Resources
1313 Sherman St., Room 215
Denver, Colorado 80203
Phone: [phone]
FAX: [phone]
November 18, 2011
James A. Kiger
Oxbow Mining, LLC.
P.O. Box 535
3737 Highway 133
Somerset, CO 81434
RE: Elk Creek Mine (Permit No. C- 1981 -022)
2010 Annual Hydrology Report — Preliminary Adequacy Review
Dear Mr. Kiger:
STATE OF COLORADO
John W. Hickenlooper
Governor
Mike King
Executive Director
Loretta E. Pineda
Director
The Colorado Division of Reclamation, Mining and Safety (Division) has finished its preliminary
adequacy review of the 2010 Annual Hydrology Report. The Division is requesting in this letter that
Oxbow provide additional monitoring results, therefore no determination of the effects of mining on
the hydrologic regime is being made by the division at this time. The Division has the following
questions and comments:
1. White font is used for chart symbols; however, on white paper, this makes the legend difficult
to interpret when it is used for more than one symbol on a single chart. Please change the font
color of the symbols in the following charts: station H -1 — Mg and Ca, station E -1 — TSS and
TDS, station E -2 — TSS and TDS, station S -1 — Ca and Na, station NF -1 — TSS and Cl, station
NF -1 Se and Zn, station NF -3 — Zn and Hg, station HN -1 — TSS and Cl, station HN -1 Ca and
Na, station EC -14 — Na and SO4.
2. Station NF -1 and NF -3 are to be tested in August for additional parameters including chromium
III and IV. The data included in the 2010 AHR show results for chromium III and VI. Please
explain.
3. Stations NF -1 and NF -3 are scheduled to have lab analyses done in the 2 3 and 4 quarters
of each year. An analysis was done in the 2 quarter for NF -1 but not NF -3. Please explain.
4. In the water monitoring data, a trend was seen where many of the measured parameters were
significantly higher in 2010 than in previous years. This trend (abnormality) was not discussed
in the report but is seen in the surface water, ground water, up- gradient and down - gradient
water monitoring data. Seasonal variation was considered but ruled out when the 2010 data
was compared to the corresponding month in previous years. This is demonstrated in bullet `a'
Office of
Mined Land Reclamation
COLORADO
D I V I S I O N O F
RECLAMATION
MINING
- &-
SAFETY
Office of
Denver • Grand Junction • Durango Active and Inactive Mines