HYDRO30269

• Permit No: C1981010
• IBM Index Class Name: Hydrology
• Doc Date: 2/18/1986
• Doc Name: GBB GROUNDWATER MONITORING WELLS TRAPPER MINING FN C-81-010
• From: MLRD
• To: TRAPPER MINING INC
• Permit Index Doc Type: OTHER GROUND WATER
• Media Type: D
• Archive: No

gichard D. Lamm
Governor
•
DEPARTMENT OF NATURAL RESOURCES
David H. Getches, Executive Director
MINED LAND RECLAMATION DI\
DAVID C. SHELTO N, Director
February 18, 1986
Mr. Bruce Humphries
Trapper Mining Inc.
P.O. Box 187
Craig, Colorado 81626
.. JL
• III III IIIIIIIIII III
RE: GBB Groundwater Monitoring Wells - Trapper Mining - File No. C-81-010
Dear Mr. Humphries:
After review of the reports you submitted by Bookcliffs Laboratory and
Hydro -Engineering and after communication with Mr. Bill Harding of Trapper,
the following are the Division's conclusions:
1) For unknown reasons, the cement used for completion of Wells GBB-1
and 2 did not properly set and invaded the casing and perforated
zones. The Division's sampling of August, 1985 showed that the wells
both had extremely low recovery leading to the assumption that
communication with the bedrock system had been lost. When first
completed the wells were flowing.
2) The chemistry of the water in the wells is governed by cement
contamination. Specifically, the high levels of conductivity (10,000
MmhOs and above), calcium and potassium and pH values of greater than
12 appear to be due to cement contamination and subsequent stagnancy of
the well bore water.
3) From water chemistry data collected in Well GBB-1, the September 1984
attempt to cleanse the well seemed successful. The water chemistry is
now in the range expected for the aquifer.
4) The GBB-2 sample collected September 19, 1985 may be representative of
the bedrock zone, however, since that time the chemistry of sampled
water has returned to high conductivity and pH levels that are
indicative of cement contamination.
5) Well GBB-3 completed in the alluvium does not appear to be
significantly affected by cement contamination.
In summary, as stated by George Hoffinen in the Hydro-Engineering Report of
January, 1985, the Division agrees with his conclusion that the aberrant
chemistry of Wells GBB-1 and 2 as detailed above is a result of improper
completion of these wells.
423 Centennial Building, 1313 Sherman Street Denver, Colorado 80203 Tel. [phone]