REP01870

• Permit No: C1981010
• IBM Index Class Name: Report
• Doc Date: 10/6/1988
• Doc Name: TRAPPER MINE PN C-81-010 1987 AHR
• From: MLRD
• To: GREG SQUIRE
• Permit Index Doc Type: HYDROLOGY REPORT
• Media Type: D
• Archive: No

• • III IIIIIIIIIIIIIIII
STATE OF COLG~v ~~

Roy Romer, Govei
DEPARTMENT OFNATURALRESOURCES
MINED LAND RECLAMATION DIVISION
FRED R. BANTA, Director
DATE: October 6, 1988
T0: Greg Squire
FROM: Jim Stevens ~~9
RE: Trapper Mine (Permit C-81-010) 1987 AHR
I have reviewed the ground water portion of the above referenced report and
have the following comments.
1) Table 4.8-13, p. 4-243 of the permit application should be revised to
include the GP, CD-4, and Lux wells. Data for there wells is included in
the report, but the wells apparently are not listed in the monitoring
schedule.
2) Some quarterly water level and/or quality data are missing for wells
GC-2, GC-3, GF-1, and GP-3. Some acceptable reason should be provided
for this.
3) Some better or more understandable discussion of the behavior of
water levels in wells GD-2, p. 2-5 and GF-6, p. 2-6 should be provided.
Trapper's consultant says recent declines in water level in these wells
are thought to be due to returns to pre-mining levels after up gradient
mining caused water levels to rise. Other discussions in the AHR,
however, eg. wells GB-5 and Map 2-1 state that up gradient mining causes
water level declines not rises. Another statement in the discussion of
well GF-6 that the rise of down gradient water levels is thought to be
caused by ground water flowing faster down gradient due to increased
petmeabilities from mining is unclear. Is the increased permeability and
faster flow due to the open cut or post-mining fill? If fill is meant,
then water levels down gradient of fill areas, eg. GF-6, should rise
instead of decline as is observed. Is the scenario more that wells down
gradient of the mining cut initially suffer water level declines then
experience water level rises when the cut is replaced by up gradient
high-permeability fill and finally undergo declines toward pre-mining
water levels as the fill area compacts, loses permeability, and more
resembles undisturbed material? If something of this sort is believed to
be the case, it should be more clearly stated, and the various
discussions should be more consistent.
JS/ljt
0684E
215 Centennial Building, 1313 Sherman Street Denver, Colorado 80203.2273 Tel. [phone]
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