Water from precipitation and groundwater sources collected in the mine workings and periodically seeps into a small dry wash below the property. Several methods have been used to control the flow of water. However, a small flow of acidic water resumed and further actions to prevent seepage were necessary.

A remedial action plan was submitted and approved by the Arizona Department of Environmental Quality under the Voluntary Remediation Program.  The major elements of the plan include a temporary re-circulation system and a larger de-watering and treatment system. The goal is to eliminate the seepage and allow Phelps Dodge to evaluate the long-term solutions for the site.

ARCADIS has treated the contaminated mine water inside the mine using its patented bioremediation technology to reduce the risk of release of contaminants and to avoid having to operate a expensive membrane-based water treatment system every year. By treating the heavy metals in the mine, ARCADIS will show that there is a reservoir of clean water for eventual discharge, rather than the ongoing risk exposure to the mine from the potential release of untreated contaminants to streams or alluvial groundwater.