Revegetation of a Mine Tailings Impoundment Using Municipal Biosolids in a Semi-arid Environment

Five separate test sites were established in 1994 to evaluate the use of municipal sewage sludge as a soil amendment and conditioner (hereafter referred to as “biosolids”) on the Kennecott Utah Copper Corporation’s tailings impoundment near Magna, Utah. Each site was divided into 16 test plots to evaluate four replications of the four rates of biosolids addition and incorporation into the tailings. The sites were monitored for potential leaching of total heavy metals as required under 40 CFR 503, agronomic properties, total metals, extractable metals, plant tissue analysis for heavy metals, biomass production, percent cover and plant species diversity. This paper presents the results through the second year of the project to include a comparison of soils and vegetation properties versus changes in the properties after two growing seasons. All agronomic properties of the tailings showed continued improvement following the initial biosolids addition. Significant improvements were seen when comparing the control plots to all treated plots. A statistically significant continued improvement in biomass production and percent cover by plant species occurred for all biosolids application rates when compared to the control plots. These important long-term reclamation objectives are related to the increase in biodiversity as well as to the amount of dead vegetation (winter rye) left from the 1995 growing season.