Commenting open: August 24, 2026 09:54AM MT - September 28, 2026 05:00PM MT.
DP-459: Randy B. Ellison, General Manager, Freeport-McMoRan Chino Mines Company, proposes to modify the existing Discharge Permit which allows for up to 7,128,000 gallons per day of acidic leachate solution (raffinate) applied for leaching copper from one stockpile. The modification of this permit consists of increasing the capacity of Reservoir 9 within the Open Pit Surface Drainage Area, located in Section 3, Township 18 South, Range 12 West, from 15 million gallons up to 720 million gallons and authorizing the discharge/transfer of process water from the Santa Rita Open Pit to Reservoir 9. Potential contaminants from this type of discharge include total dissolved solids, sulfate, and metals. The facility is located 3 miles northeast of Bayard, in Sections 23, 26-28, 33-35, Township 17 South, Range 12 West, and Sections 2, 3 and 10, Township 18 South, Range 12 West, Grant County. Groundwater most likely to be affected ranges in depth from approximately 22 to 276 feet and had a pre-discharge TDS concentration of approximately 220 milligrams per liter.
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