Spoil management and revegetation success on waste rock dumps at a southern interior B.C. copper mine

• Main Author: Gizikoff, Katherine Gould
• Language: English
• Published: University of British Columbia 2010
• Subjects: Mine soils > British Columbia
• Online Access: http://hdl.handle.net/2429/29031

The primary aim of this study was to investigate vegetation production and soil management factors influencing forage establishment on the waste rock dumps at a Southern Interior B.C. copper mine. Total plant cover on the waste rock dumps ranged from less than 5 to greater than 80 percent. Vegetation and spoil from the major reclaimed sites were analyzed to determine possible causes for the differences in plant cover. Test case areas, which varied in production, topography, and treatment, were then selected for an investigation into the relationships between spoil and vegetation variables. Waste rock and overburden glacial till materials were generally low in N, P, and Mg. Spoil N and K levels varied throughout each reclaimed site, likely as a result of fertilizer placement. Significant positive relationships were found between spoil N and grass cover and spoil K and both grass and legume cover. P levels in legumes from most fertilized sites were still in a deficiency range. A negative relationship between coarse fragment content and legume cover was observed. High coarse fragment content, accompanied with low water holding capacity and dry climatic conditions, suggests that moisture deficiencies are likely a critical problem for revegetation success, particularly on the lower portions of the slope faces. High bulk density values on the flat terraces indicated that compaction could be impeding root growth. Multivariate cluster analysis, based on total percent plant cover and percent composition legumes, was used to categorize all study sites into four vegetation production groups: low cover, grass cover, mixed grass and legume cover, and high production legume dominated cover. Spoil characteristics that differentiated between groups were: N, P, K, Mg, pH, coarse fragment content, and bulk density. This classification system will assist in identifying the management requirements of each vegetation type, such as: level and type of fertilization, overburden capping to reduce coarse fragment content, and scarification. Multiple regression analysis was used to generate equations for predicting biomass production from spoil N, P, K, Mg, pH, and coarse fragment content. Reclamation costs were estimated and it was demonstrated that grass cover and mixed grass and legume cover types were the most desirable. Although costs per hectare were lowest for the low cover type, efficiency of reclamation dollars (dollars invested per tonne forage produced) was also lowest for this type. Establishment of a legume dominated cover type may not be desirable due to forage quality considerations: Cu:Mo ratios in legume foliage averaged less than the recommended 2:1 for cattle grazing. === Science, Faculty of === Resources, Environment and Sustainability (IRES), Institute for === Graduate