![[logo] US EPA](http://www.epa.gov/epafiles/images/logo_epaseal.gif){kind=logo}
Remediation of Underground Mine Discharge Using Source Control and Passive Technologies
Primary Issue Addressed: Source Control
Secondary Issues Addressed: Acid Drainage/Water Treatment and Trace Metal Removal
Project Site: Lee Mountain Mine, Rimini, Montana
Collaborating Entities: MSE, EPA Region 8, Montana Department of Environmental Quality, CDM (EPA Region 8’s Contractor), and the Rimini Citizens Group
Cost Share: In-kind services provided by EPA Region 8.
Project Description
At many of the abandoned mines in the United States, the water discharging from the mine adit is the main source of contamination at the site. If possible, the preferred method of eliminating the contamination (i.e., flow) is achieved by using a source control technology. Based on the results of a previous MWTP project, Underground Mine Source Control Demonstration Project, underground source control methods can successfully reduce the flow discharging from the mine, which results in reduced metal loading to receiving waters. However, the total influx of water into underground mine systems is usually not eliminated. In most instances, a residual flow continues to discharge from the mine portal. For this demonstration, a source control technology will be implemented to reduce the amount of water discharging from the selected mine. A passive treatment system will then be installed to treat any residual flow. Application of these two technologies will provide full treatment of the discharge from the mine.
This project has three phases:
– Phase I – Site Selection, Site Characterization, and Mine
Remediation Technology Selection;
– Phase II – Source Control Technology Emplacement; and
– Phase III – Passive Treatment Technology Emplacement.
Status
Phase I is nearing completion. The Lee Mountain Mine, which is part of the Ten Mile Creek National Priorities List site near Helena, Montana, has been selected as the demonstration site. Consent for site access and for implementation of the technologies at the site was prearranged by the site owners and the U.S. Environmental Protection Agency (EPA) Region 8. The U.S. Department of Energy and EPA have approved the National Environmental Policy Act of 1969 (NEPA)/Categorical Exclusion documentation. Site access and characterization work outside the mine has been completed; however, until the underground workings have been opened and are accessible, continuation and implementation of the scheduled work is inhibited. The work to reopen the underground workings is scheduled to occur during the summer of 2005. Site characterization of water exiting the adit has been collected over the last year. Typical data and appropriate discharge criteria are presented in Table 2 below.
During Phase II, the source control material will be selected and emplaced if the underground workings are amenable to grouting. Flows and water quality will be monitored, evaluated, and an interim report will be written discussing the results. The passive treatment system will be selected based on bench-scale testing performed during Phase II while the source control technology is being monitored.
During Phase III, the passive treatment technology will be installed at the mine site to treat any residual flow. After monitoring of the passive system has been completed, site closure and final reporting activities will be performed.
| Parameter | Discharge Criteria (?g/L), unless otherwise noted | Parameter Sample Results (?g/L), unless otherwise noted |
|---|---|---|
| PH (SU) | 6.5-8.5 | 2.8 |
| Dissolved Arsenic | 10 | 8270 |
| Dissolved Cadmium | 0.27 | 350 |
| Dissolved Copper | 9.3 | 350 |
| Dissolved Iron | 300 | 154,000 |
| Dissolved Lead | 3.2 | 560 |
| Dissolved Manganese | 50 | 21,100 |
| Dissolved Zinc | 120 | 56,700 |