2012-01-09_HYDROLOGY - M1977300 (2)

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DIVISION OF RECLAMATION, MINING AND SAFETY Department of Natural Resources 1313 Sherman St., Room 215 Denver, Colorado 80203 Phone: (303) 866 -3567 FAX: (303) 832 -8106 'January 9, 2012 Mr. Randy Whicker "Cotter Corporation P O Box 1720 Canon City, CO 81215 RE: Cotter Corporation, Schwartzwalder Mine, Permit No. M- 1977 -300 ✓Addit s nal Bedrock Groundwater Monitoring Wells Required Dear Mr. Whicker: Well Location Mined Land Reclamation 1 Schwarz Trend – Shallow (same location proposed in AM -02) 2 Schwarz Trend – Deep (same location proposed in AM -02) 3 Between Schwarz Trend wells and Illinois Fault - Shallow 4 Between Schwarz Trend wells and Illinois Fault - Deep 5 Near alluvial monitoring well MW3A at a location likely to allow completion in the Illinois fault zone - Shallow STATE OF COLORADO Hard Rock Mining Rule 3.1.7(7)(a) requires a groundwater monitoring program "on a case -by -case basis where an adverse impact on groundwater quality may reasonably be expected." In the case of the Schwartzwalder Mine, it is reasonable to expect that the mine pool will adversely impact surrounding groundwater quality based on (a) the complexity and extent of the flooded mine workings, (b) dramatically elevated concentrations of uranium, radium, sulfates and other pollutants in the mine pool, and (c) the presence of multiple fractures and faults that intercept the mine pool and create potential hydrologic conduits. Cotter's current groundwater monitoring activities' are insufficient to address reasonably expected adverse impacts from the mine pool. Accordingly, the Division directs Cotter to submit a Technical Revision (TR) by February 12, 2012 that describes a bedrock ground water monitoring program comprised of a minimum of the following seven wells: Total minimum depth, feet below ground surface Purpose COLORADO D I V I S I O N O F RECLAMATION MINING — &— SAFETY John W Hickenlooper Governor Mike King Executive Director Loretta E Pineda Director 300 Shallow bedrock ground water point of compliance (POC) 800 Deep bedrock POC 300 Early- warning monitoring for POC 1,000 Early- warning monitoring for POC 100 Detect mine pool flow to Ralston Creek and alluvium /bedrock head differences 1 Cotter's shallow alluvial groundwater monitoring wells and upgradient bedrock groundwater monitoring wells are insufficient to effectively monitor adverse groundwater impacts resulting from the migration of mine pool water. 2 Cotter has previously proposed two bedrock ground water monitoring wells in the Schwartz Trend (pages 15 and 16 of Amendment application AM -02). These wells are included in the list of required monitoring locations along with additional wells required as set forth in this letter. OK /I/ Office of Office of Denver • Grand Junction • Durango Active and Inactive Mines