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PHYTOSTABILIZATION OF COPPER SMELTER TAILINGS NEAR ANACONDA, MONTANA

Laboratory tests to assess ameliorative effects of several chemical and biological amendments and greenhouse trials to select tolerant plant species were conducted prior to construction of field demonstration plots at five different areas impacted by the smelting processes.

Two of these experimental plots were located on the acid producing, low pH smelter tailings known as the Opportunity Ponds and the Anaconda Ponds. Combinations of lime products (CaCO3 and Ca(OH)2), composted organic matter, and smelter slag were incorporated into the tailings to a depth of approximately 20 inches (50 cm) using specialized equipment.

Selected grasses and legumes were seeded in the spring of 1995. In addition, shrub and tree seedlings were planted. Monitoring consisted of measurements of root zone hydrology, amended tailings chemical environment, erosion, and vegetation response. Measurements of vegetation cover as well as shrub and tree mortality were recorded.

Measurements of tailings acidity and water soluble metal and arsenic levels both on and off the experimental plots have been determined. Instruments to measure water content and movement within the root zone were installed. Simulated rainfall/runoff tests defined the quality and quantity of surface waters affected by the phytostabilization of these tailings.

Key words: reclamation, tailings, metals, Superfund