HYDRO21937

• Permit No: C1981012
• IBM Index Class Name: Hydrology
• Doc Date: 3/30/1994
• Doc Name: REFUSE DISPOSAL AREA NEW ELK MINE PN C-81-012 BASIN RESOURCES INC
• From: DMG
• To: BASIN RESOURCES INC
• Permit Index Doc Type: CORRESPONDENCE
• Media Type: D
• Archive: No

III IIIIIIIIIIIII III
STATE OF COLORADO
DIVISION OF MINERALS AND GEOLOGY
Depanmenl o! Natural Resources
1313 Sherman Si., Room 215
Denver, Colorado 80203
Phone: [phone]
FA%:13071 872-8106
March 30, 1994
Mr. Ralph Lopez
Environmental Engineer
Basin Resources, Inc.
14300 Highway 12
Weston, CO 81091
Re: Refuse Disposal Area, New Elk Mine, Permit No. C-81-012
Basin Resources,lnc.
Dear Mr. Lopez:
~~~
DEPARTMENT OF
NATURAL
RESOURCES
Roy Romer
Go~e~nor
Ken Salaaar
E.ecwive Dirermr
Michael B. long
Division Director
In reviewing the 1991 and 1993 geotechnical analyses conducted by CTL/Thompson, Inc., on
the New Elk refuse disposal area, the Division has a concern with the moisture content of the
refuse. In the April 29, 1991 report by CTL/Thompson, "Density and Stability Study, Refuse
Disposal Area, New Elk Coal Mine," the consultants', on page 10, conclusions numbers 2 and 3,
expressed a concern about a wet zone within the refuse pile. CTLlThompson stated that
measures should be taken to reduce the moisture content of the refuse at the time of place-
ment. On page 9 of this same report, it is stated that if drier refuse is placed on the pile in the
future, then the computed safety factor would be 1.6. A factor of safety of .8 was computed
for the condition of continued placement of wet refuse without other precautions being taken.
In the May 3, 1993 letter from CTLlThompson to Basin Resources, it was stated that the
consultants believed that the moisture content had been reduced from 25 to 30 percent down
to 15 to 18 percent, and that this reduction in moisture occurred before disposal. Further, the
consultants recommended that the refuse coming off of the refuse belt be sampled for material
properties because, at that time, no refuse was coming off of the belt for them to sample.
In the May 20, 1993 report from CTL/Thompson, it was stated that Basin Resources had
implemented the actions as outlined in the May 3, 1993 letter, to lower the moisture content of
the refuse.
In a letter to the Division dated March 17, 1994 and received at the Division on March 21 ,
1994, Basin Resources stated that the moisture content of the refuse coming off of the belt
was 25 to 30 percent. The Division has a concern with this, in that the wet material is being
allowed to stand at the temporary stockpile and at temporary windrow sites until the refuse is
workable for grading and compaction. This excess moisture may be draining downward into the
refuse pile, potentially decreasing the factor of safety for the refuse pile as a whole or for
portions of the refuse pile, such as the temporary stockpile area and the windrow area. As
CTLlfhompson stated in the May 20, 1993 letter, on page 3, the stability of the refuse pile is
relatively insensitive to compaction. Therefore, the Proctor test results that have been obtained
to date cannot be used alone to assure slope stability.