REP50441

• Permit No: C1980001
• IBM Index Class Name: Report
• Doc Date: 5/8/1997
• From: DMG
• To: PITTSBURGH & MIDWAY COAL CO
• Permit Index Doc Type: HYDROLOGY REPORT
• Media Type: D
• Archive: No

Y ~~. III IIIIII IIIIIII III
STATE OF COLORADO
DIVISION OF MINERALS AND GEOLOGY
Deparimenl of Natural Resources
1313 Sherman 51., Room ?15
Denver, Colorado 8020]
Phone: [phone]
FAX [phone]
Mr Brian Gontarek
Pittsburg & Midway Coal Mining Co.
P.O. Box 6518
Englewood CO 80155-6518
8 May 1997
Dear Mr Gontarek:
~I~~~
DEPARTMENT OF
NATURAL
RESOURCES
Roy Romer
Governor
James S Lochhead
Executive Director
Michael B. LOng
D~v~s~on Director
The Division of Minerals and Geology personnel have reviewed the
submitted Annual Hydrology Report for 1996 for the Edna Mine. The
following are observations and comments concerning this report.
Surface Water: Over the last several years, the difference in TDS and
in individual dissolved components between waters from sampling sites C
and D on Trout Creek has almost vanished. This may coincide with switch
in sampling points from old site D in section 19, upstream more than a
mile to new site C in sec. 26. It would be a good idea to keep this in
mind and consider what may be causing those changes.
The following comments address observations of hydrochemical
characteristics from recent sampling. These are compared to the
narrative of Probable Hydrologic Consequences from the permit and should
be included in revision of that section of the permit application
document itself:
* Predicted groundwater TDS to rise to 3000 mg/1 (p. 2.5-96J•
This change is happening, but the higher concentrations are found at
TR-1.5 (supposed to be upgradient station ... upstream of mining
activity). AHR attributes that to old underground mine upstream.
The situation that results from this is that water w/ similar dissolved
solids contents from spoils (represented by WR-1 well) is being added to
this high-TDS groundwater found at TR-1.5. Ignoring details of mixing,
this will probably produce higher TDS contents as waters mix. This high
TDS water will probably migrate down to downstream stations TR-3 and 4
in next several years. Because of this influx of high TDS water from
upstream, predictions for groundwater TDS content will probably be
exceeded in the future.
* predicted post-mining groundwater TDS of 2828 at West Ridge (p. 2.5-
101)
This concentration is exceeded as demonstrated by water from well WR-1;
last four years WR-1 water has ranged from 3000 to >4000 mg/1 TDS.
Another important issue is the validity of the data, particularly the