REP32429

• Permit No: C1981044
• IBM Index Class Name: Report
• Doc Date: 2/3/1989
• Doc Name: 1987 AHR Review Comments
• From: MLRD
• To: GREG SQUIRE
• Permit Index Doc Type: Hydrology Report 1987
• Media Type: D
• Archive: No

iii iiiiiiiiniii iii
STATE OF COLORr~.J9
Roy Romer, Governor
S Q
DEPARTMENT OF NATURAL RESOURCES
MINED LAND RECLAMATION DIVISION
FRED R. BANTA, Dlreetor
DATE: February 3, 1989
T0: Greg Squire
FROM: Bill Crick ~~'
RE: 1987 ANNUAL HYDROLOGIC REPORT, EAGLE N0. 5 AND 9 MINES
(PERMIT C-81-0440
The Eagle Mines monitoring program and the above-mentioned report are
well-organized. Considering the potential impact of the mining operation on
the adjacent alluvial valleys, any problems being caused are relatively minor.
There are several required data items which are missing from the report.
These include the annual water quality parameter measurements for the
No. 5 Mine Well (which monitors the Trout Creek Sandstone) and the No. 9 Mine
Well (Twentymile Sandstone). Although the mines are not expected to impact
these aquifers due to their stratigraphic distances from the coal seams, and
each has at least one other monitoring point, we should ask the operator why
these data are missing. In addition, six monthly discharge readings were
missed at station WF-1 (Williams Fork River, upstream).
Water levels in the Middle Sandstone are steady in walls TR-7A, 81-01, and
81-03, but dropped almost 40 feet between September and the end of 1987 in
well 83-02 (near the east edge of the permit area). An unexpected drop in
water level in Middle Sandstone monitoring wells TR-7A and 81-01 was discussed
in the Findings document dated April 24, 1987, but recovery of water levels
was underway at that time. The Probable Hydrologic Consequences portion of
the document predicted future subsidence-related dewatering of the Middle
Sandstone over a large area, but stated that this is acceptable given that its
water has not been put to beneficial use in the area.
The only possible water quality concern I have is an increase in TDS (mainly
Sodium, Calcium, and Sulfate) in Williams Fork alluvial wells AVF-3 and AVF-6
(1449 and 1608 mg/1, respectively). These 1987 readings were 25 to 40 per
cent higher than those of previous years. Well AVF-5, located about 1200 feet
downstream from ACF-6, actually experienced a 14 per cent decrease in TDS. I
agree with the report that the increase is not caused by discharges of mine
water, but it may be related to activity around the #5 portals and/or leaching
in the coal pad area. There is also a correlation with lower average Williams
Fork surface flows in 1986 and 1987. If this is to be more than a local
process, the effects should be seen in well AVF-5 within a year or two.
cc: Jim Stevens
3132E/scg
215 Centennial Building, 1313 Sherman Street Denver, Colorado 80203-2273 Tel. [phone]