2011-05-03_REVISION - M1981185

• Permit No: M1981185
• IBM Index Class Name: REVISION
• Doc Date: 5/3/2011
• Doc Name: Third adequacy letter for amendment to CN-01
• From: DRMS
• To: R Squared Incorporated
• Type & Sequence: CN1
• Email Name: WHE
• Media Type: D
• Archive: No

STATE OF COLORADO
DIVISION OF RECLAMATION, MINING AND SAFETY
Department of Natural Resources
1313 Sherman St., Room 215 COL O RA DO
Denver, Colorado 80203 DIVISION OF
Phone: [phone] RECLAMATION
FAX: [phone] TECHNICAL MEMORANDUM MINING
SAF ETY
John W. Hickenlooper
DATE: 3 May 2011 Governor
Mike King
TO: Wallace Erickson Executive Director
Loretta E. Pineda
FROM: David Bird Director
SUBJECT: Geochemistry and Water Quality Review of Adequacy Responses;
Wildcat Mayday; DRMS File No. M-1981-185; Conversion. Application CN-1
The following comments are provided in response to the Conversion Application CN-1
"Response to Geochemistry and Water Quality Review" from the Applicant dated April 19,
2011:
1) Adequate.
2) Adequate.
3) Geochemical testing quarterly or every 5,000 tons, whichever occurs first, is adequate_for
routine characterization. However, occurrences of rock with elevated acid-generating
characteristics or metals content may warrant more frequent testing.
4) Adequate.
5) A. The use of a ground water quality point of compliance (POC) is acceptable as a
proposed location for the characterization of ambient ground water quality. However, the
proposal to use the ground water production well located on the May Day No. 1 bench as
a POC may not be acceptable. Under Hard Rock Rule 3.1.7(6)(a), the Division has the
authority to require more than one POC. For this site, I recommend at least two POCs,
one of which should be directly down-gradient of the tailings deposition location. In
addition, under Hard Rock Rule 3.1.7(6)(b), the Division may require a POC at the
hydrologically down-gradient limit of the area in which contamination has been
identified, or at the facility permit boundary. However, at this time insufficient
hydrologic data exist to accurately determine the hydrologically down-gradient limit,. so
the optimal location for POCs based upon the hydrologic gradient remains unknown.
The determination of the remaining POC(s) will depend on data gathered during the
baseline hydrologic characterization which is yet to be conducted. The Division cannot
sign off on a POC location without appropriate data such as depths to ground water,
directions of ground water flow, hydraulic gradient, and other aquifer parameters as
deemed necessary, such as hydraulic conductivity.
Office of Office of
Mined Land Reclamation Denver • Grand Junction • Durango Active and Inactive Mines