PHOENIX, AZ, Apr. 7, 2009 -- Silver Bell Mining will pay $170,000 in civil penalties for releasing 340,000 gallons of wastewater containing sulfuric acid and heavy metals into dry washes during three separate incidents at its open pit copper mine near Marana in Pima County, ADEQ Acting Director Patrick J. Cunningham announced today.
The pollutants seeped into the soil, which endangered the groundwater in the aquifer below the mine and exceeded Arizona surface water quality standards.
On Oct. 19, 2006, a pipeline break discharged 90,000 gallons of sulfuric acid to the roadside downstream from the pipeline. Between Nov. 6 and Dec. 11, 150,000 gallons of leach solution containing sulfuric acid and heavy metals escaped from a leaking impoundment. And between Nov. 11 and Dec. 13, another 100,000 gallons of stormwater containing sulfuric acid and heavy metals escaped from a storage pit.
The company's Aquifer Protection Permit did not authorize the release of these substances into the environment.
In response to the release from the leaking impoundment, the company installed a second liner with a leak detection sump between the two liners and has begun monitoring weekly for the presence and amount of solution detected from between the two liners.
Under terms of the settlement, the company has agreed to increase the frequency of its inspections to monitor for leaks from its dams, ponds and impoundments above what is required in its Aquifer Protection Permit.
"The leaks from the impoundment and the pit could have been minimized had they been immediately discovered. The company endangered the health and safety of the public and put Arizona's natural resources at risk," Cunningham said, "and the penalty reflects the seriousness of the violations. That said, we are pleased Silver Bell and its parent company ASARCO have begun more frequent monitoring to prevent this from happening again."
"I appreciate ASARCO's commitment to remedy this contamination. I hope this case sends a message that we all must be good stewards of our natural resources," Arizona Attorney General Terry Goddard said.
Sulfuric acid is a known carcinogen. Some of the heavy metals in the wastewater include cadmium, a known carcinogen, and nickel, a suspected carcinogen that can cause stomach and kidney problems when consumed.