HYDRO25590

• Permit No: C1980006
• IBM Index Class Name: Hydrology
• Doc Date: 6/13/2007
• Doc Name: Ground Water Points of Compliance Determination Memo
• From: Tom Kaldenbach
• To: File
• Permit Index Doc Type: Other Ground Water
• Media Type: D
• Archive: No

:,
STATE OF COLORADO
DIVISION OF RECLAMATION, MINING AND SAFETY
Department of Natural Resources
1373 Sherman St., Room 215
Denver
Colorado 80203 C O L O R A D O
, DIVISION o e
Phone: [phone] RECLAMATION
FAX: [phone] M I N I M Ci
- St-
SAFETY
MEMO
Bill Ritter, Jr.
Date: June 13, 207 Governor
Harris D. Sherman
Executive Director
From: Tom Kaldenbach
Ronald W. Cattany
Division Director
TO• Fde Natural Resource Trustee
Marr Mine (Permit C-80-006)
Hydrology
Re: Ground Water Points of Compliance Determination
I have reviewed the need for establishing ground water points of compliance at the Marr
Mine. I reviewed the mine's past annual hydrology reports, hydrogeologic maps in the
permit application, and ground water well data from the Division of Water Resources.
Rule 4.05.13 requires establishment of ground water points of compliance if the mine has
the potential to negatively impact ground water for which quality standards have been
established by the Water Quality Control Commission. I have concluded that ground
water points of compliance are unwarranted at the Marr Mine, as explained below.
Alluvial Ground Water - Alluvium within the azea of influence of the mine (the
specified area) is too laterally discontinuous and is too limited in azeal extent (less than
300 acres in aggregate) to be used as a water resource; therefore, ground water in these
units may be considered to be "limited use and quality". No quality standazds apply to
the limited use and quality classification; therefore, a ground water point of compliance is
unwarranted for alluvium.
Bedrock Cround Water in Mine Area - The mine does not have the potential to
negatively impact bedrock ground water in the mine area because spoil leachate lacks
significant potential for migrating from the backfilled pit into stratigraphic units exposed
in the walls of the pit. Excavations of the mine pits on the west flank of the Johnny
Moore Syncline would have promoted eastward ground water migration across the
synclinal axis into the east side of permit area from the undisturbed east flank of the
syncline. (Map 15a in the permit application shows the geologic structure and premining
potentimetric surface.) This migration would have prevented leachate from migrating
away From the pits. Historical water levels in the mine's spoil monitoring well and
surrounding pit perimeter monitoring wells indicate the water level in the backfilled pit
has remained more than 100 feet below the sunrounding ground water table and
potentiometric surface.
Office of Office of
Mined Land Reclamation Denver Grand Junction Durango Active and Inactive Mines