Arizona mine runoff draws federal concern

December 30, 2014

Abandoned mining operations regularly present environmental concerns. Because most were active before industry regulations were enforced and later abandoned with little regard for future impact, today these sites create expensive and involved remediation challenges.

For example, the Lead Queen and Trench mines outside of Tucson, Arizona, have recently taken the media spotlight for leaking a bright orange runoff into local streams and tributaries. The Lead Queen Mine has been closed since the 1940s, though areas resumed operation under the supervision of mining giant Asarco from 1939 to 1957, according to The Arizona Daily Star's analysis of data from the Arizona Geological Survey.

According to Floyd Gray of the United States Geological Survey (USGS), contamination in this mine compounded for years in the internal tunnel systems. Monsoon storms in the area outside Tucson this September flushed out iron and other minerals and heavy metals, creating orange slush that is now escaping into nearby waterways. 

"This happens every year but not the way it happened in September," Gray explained to the source. "We've got a dynamic problem, in that these things are engineered up to a point, but these rains have exceeded that capacity."

The situation caused the Arizona Department of Environmental Quality to issue a violation notice to a private environmental trust that currently owns the Trench Mine. Listed violations included the unauthorized discharges of the reddish-brown liquids, failure to document conditions at the site and violating state water quality standards, according to state documents. 

The trust is now working to develop a strategy to stabilize the mine to avoid another flushing-out of the metals and minerals inside into local waterways. Short-term solutions include putting bales of straw into nearby creeks to filter out some of the heavier metals and creating a "choke point" to reduce contamination downstream. 

While the mine will continue to pose risks, environmental consultants can help develop strategies to keep dangerous contaminants contained.