Soil capping and vegetation trials on waste rock at Cameco Key Lake uranium mine

Abstract

Reclamation and revegetation of the Deilmann North Waste Rock Pile (DNWRP) is needed to create a sustainable landscape with stable slopes and a forest cover with diversity that resembles the natural uplands in the area. In addition to providing a suitable landscape, the cover needs to minimise deep percolation of precipitation and the resulting seepage from the underlying waste rock. A research site was established on a waste rock pile at Cameco’s Key Lake Mine in Northern Saskatchewan. Test plots to evaluate the efficacy of eight soil amendments to store water and support eight types of boreal forest plants were located within a trial soil cover constructed of locally available sandy glacial till. Two methods of transplanting native moss species were also evaluated. The soil amendments included commercial peat, lake sediments, underlying straw/hay, mulch + forest floor (LFH) layer, inorganic fertiliser, organic pellets and control plots. The surface soil of each plot was sampled for baseline characterisation of soil salinity, pH, soluble ions, available nutrients, total carbon and nitrogen, metals regulated by the Canadian Council of Ministers of the Environment (CCME), cation exchange capacity (CEC) and texture in fall of 2010. Vegetation was planted in September of 2010 and will be monitored for growth characteristics. Preliminary findings include the following: (a) the cover soils have very low nutrient contents and moisture holding capacities; (b) the lake sediment has high total and available nutrients and water holding capacity, but elevated arsenic (As) and nickel (Ni) concentrations; (c) the use of specialised amendments such as straw, lake sediments and peat moss showed a potential to improve water storage within the sandy cover material.