Thursday, February 5, 2015

New Project to Address Mine Water Quality at Tar Creek

Mayer Ranch Passive Treatment System 2013

CEES professors Robert W. Nairn and Robert C. Knox along with OU biology professor William J. Matthews were recently awarded a $1.6M grant from the Oklahoma Department of Environmental Quality for design, construction and initial evaluation of a full-scale passive treatment system to address mine drainage contamination in Ottawa County, Oklahoma.  This project is an outgrowth of the success of the first and only full-scale passive treatment system implemented in the Tri-State Lead-Zinc Mining District and Tar Creek Superfund Site, completed in 2008 by the OU Center for Restoration of Ecosystems and Watersheds.  The Mayer Ranch passive treatment system has successfully addressed metal-contaminated flows of abandoned mine waters for nearly six years.  Elevated iron, zinc, lead, cadmium and arsenic concentrations are decreased in a specifically-designed series of ponds, wetlands, and bioreactors. 

Collecting data at the MRPTS
The overall goal of the new project is to continue to "unlock the black box" of passive treatment by understanding and exploiting specific biogeochemical processes.  The objectives are to demonstrate improvement in mine drainage water quality prior to discharge to the receiving waters, evaluate ecosystem development in the system itself, and document biogeochemical and ecological changes in the receiving waters.  The system will address a major source of mine water discharging to a small first-order tributary to Tar Creek in Commerce, Oklahoma.  Since implementation of the first system, limited stream water quality improvement and ecological recovery (e.g., fish community development) have been documented.  The new system will be designed to i) effectively remove iron via aerobic processes, concurrently removing some trace metals via sorption or co-precipitation and degassing carbon dioxide, ii) sequester zinc, lead and cadmium via reductive mechanisms in vertical flow bioreactor substrates, iii) re-aerate the water to strip hydrogen sulfide and add oxygen and iv) polish the waters (removal of remaining dissolved and suspended solids) before final discharge.  Off-the-grid aeration devices for initial oxidation process units, as well as for the re-aeration process unit, are proposed.  Given the proximity of the proposed treatment system to schools, residential areas and commercial districts, the system will be designed not only as a functioning ecologically engineered treatment system, but as an aesthetically pleasing addition to the local landscape.