| Summary: | Mount Polley Mining Corporation, operated by Imperial Metals Ltd, is located in the Fraser Plateau physiographic region in central British Columbia, approximately 56 km northeast of Williams Lake and 8 km southwest of Likely. The mining method employed is open-pit mining of a gold/copper porphyry deposit. Reclamation research has been conducted since 1998 to develop innovative techniques for restoring sustainable forest ecosystems and critical wildlife habitat. In 1998 and 1999, a total of 12 treatments in triplicate were established on top of the 1,170 m dump. In 2000, an additional 12 treatments were established on the side slope of this dump. The treatments were established to evaluate the following variables, parameters and components: depth of topsoil required to meet reclamation objectives; suitability of tailings and biosolids as a growth medium; selection of tree species for reclamation objectives; interaction of vegetation competition with tree survival and growth; extent of metal uptake by vegetation; and vegetation relationships to various soil amendments. The trials were measured in 2006, and detailed statistics were generated. The analysis indicates the following: a minimum of 15 cm of soil is required to established trees; there is a significant positive response to tree growth to a soil depth of 40 cm, and thereafter no significance in growth is seen with increasing soil depth; 40 cm of soil amendments is currently meeting tree growth objectives; there is a positive response in tree and vegetation growth to biosolids amendments on the 1998 and 1999 trial, but no response in seen on the 2000 trial; tree mortality is significantly higher (α=0.05) with biosolids amendments for all trials (ammonia toxicity to the young seedlings is suspected); vegetation competition is also a significant negative factor in seedling survival and growth (vegetation growth is directly related to available soil nutrient supply); and vegetation cover and diversity increased with increase in soil amendment depth or addition of biosolids. This paper presents the 8-to-9-year results of vegetative growth of this trial, examines the effects of combinations of variables and proposes further investigation to more specifically describe the causes of the results observed.
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