Abstract: The mining industry has made tremendous strides in the last 20 years in the prevention and control of acid mine drainage. However, there remain a number of circumstances where the long-term operation, care and maintenance of tailings management facilities will be required. The application of progressive environmental technologies and management systems is key to cost control and environmental liability management at these sites. Mine Waste Management Inc. currently operates Rio Algom Limited's five effluent treatment plants and seven waste management areas in the Elliot Lake, Ontario region using a Remote Plant Monitoring and Control Network (RPMCN). This system, based on Intellutions's “Fix 32” technology, enables the monitoring and control of these plants from a centralized location thus reducing labour costs while providing 24-hour surveillance. Scheduling, auditing and reporting of plant operating and environmental monitoring programs are integrated and controlled using the Envista (super TM) environmental information management system. Proper application of these technologies and management systems facilitates delivery of cost-effective environmental monitoring, and care and maintenance programs at these sites and provides tools to demonstrate compliance with all environmental performance criteria.

Abstract: The Leadville Mine Drainage Tunnel (LMDT) is a 3.3 kilometer structure that was constructed in the complicated geology of the Leadville mine district in the 1940's. Discharge from the LMDT is impacted by heavy metals and is treated at a plant built in 1992 operated by the United States Bureau of Reclamation. On the surface waste rock and other remnants of the mining operations litter the landscape and this material is exposed to precipitation. As a result of contact with this material, surface water often has pH of less than 3 and its containment and disposal is necessary before it impacts surface drainage and the nearby Arkansas River. Using a borehole drilled into the mine workings the U.S. EPA has devised a plan in which the impacted water is contained on the surface which then can be discharged into the mine workings to discharge from the LMDT and be treated. The percentage of water discharging from the mining district along the drainage tunnel is unknown, and since there is no access, information about the condition of the tunnel with regards to blockages is also relatively obscure. Application of quantitative water tracing using fluorescent dyes was used to model the flow parameters at the scale of hours in the tunnel and evaluate the likelihood of blockages. Because the tunnel has intersected several lithologies and faults, other locations such as discharging shafts, adits and surface streams that could be hydraulically connected to the LMDT were also monitored. An initial tracer experiment was done using an instantaneous injection, which was followed by additional injections of water. Another tracer injection was done when there was a continuous flow of impacted water into the workings. Analysis of the tracer concentration responses at water-filled shafts and at the portal were used to model the flow along the tunnel and estimate several hydraulic parameters. Waters in these settings are mixtures of components with different residence times, so, qualitative tritium data were used to evaluate residence times of decades. The combined injected tracer and tritium data as well as other geochemical data were used to infer the nature of flow and recharge into the tunnel.

Abstract: The Kidd Creek Cu-Zn sulphide mine is located near Timmins, Ontario. Mill tailings are thickened and deposited as a thickened slurry in a circular, conical-shaped pile with an area of approximately 1200 ha. Deposition of tailings as a thickened slurry results in a relatively uniform grain-size distribution and hydraulic conductivity, and a thick tension-saturated zone above the water table. The tailings are drained by numerous small, ephemeral stream channels, which have developed in a radial pattern. During storms, water from these streams collects in catchment ponds where it is held before treatment. The contribution of tailings pore water to the run off is of interest because of the potential for discharge of pore water containing high concentrations of Fe(II)-acidity, metals and SO4 to the stream. Hydraulic head measurements, measurements of water-table elevation and groundwater how modelling were conducted to determine the mechanisms responsible for tailings pore water entering the surface streams. Chemical hydrograph separation of storm run off in one of these streams, during three rainfall events, using Na and Cl as conservative tracers, indicates that the integrated tailings pore water fraction makes up between less than 1% and 20% of the total hydrograph. This range is less than the maximum fraction of tailings pore water of 22-65% reported for run off from a conventional tailings deposit. At this site, preferential flow through permeable fractures may be the dominant mechanism causing discharge of tailings pore water to storm run off. Estimates of the mass of Fe(II) that discharges to the surface run off from the pore water range up to 2800 mg s(-1) during a moderate intensity, long duration rainfall event. The greatest potential for discharge of significant masses of solutes derived from the pore water exists during long duration rainfall events, when the water table rises to the surface over large areas of the tailings impoundment.