Florence Copper Inc. received a draft permit for a 14-acre test site at where it plans to develop an in-situ copper mine. The permit was issued by the U.S. Environmental Protection Agency (EPA).
If the mine obtains the permit after the public comment period, and works out regulators' concerns to obtain a similar permit from state environmental regulators, it can begin producing copper cathodes from a test facility, AZCentral.com reported.
The EPA and the Arizona Department of Environmental Quality both have determined Florence Copper Inc. can safely inject a weak acid solution more than 122 m (400 ft) underground to separate copper from ore, then pump the fluid back to the surface to process the metal.
"EPA believes the activities allowed under the proposed draft permit are adequately protective of underground sources of drinking water as required by the Safe Drinking Water Act," the federal agency wrote in the draft permit.
The test-project permit allows the company to run a test facility for 14 months, followed by nine months of clean-up and remediation of the site, and five years of monitoring to ensure the site has been restored.
Florence Copper initially sought permits to operate on more than 200 acres of private and state land. It later submitted an application to inject acid at a smaller test facility first in hopes of proving the process is safe.
The mine's opponents say regardless of the EPA determination to issue a permit, they anticipate they can stop the mine.
ADEQ issued its permit for the test facility in 2013, but last month, the Arizona Water Quality Appeals Board sent the state permit back to ADEQ to address areas of concern.
The appeals board found shortcomings in the requirements to monitor and ensure the acid isn't flowing where it's not supposed to.