The large-strain consolidation behavior of a uranium tailings storage facility was investigated by analyzing survey data (bathymetric and topographic) from 1996 to 2008, laboratory testing of the mill tailings using a consolidation test system, and history matching of the deposited tailings using numerical modeling. The average cumulative consolidated height in the Deilmann Tailings Management Facility (DTMF) can be divided into four distinct stages: (1) rapid increase of 13 m/year from 1996 to 1999, (2) steady height increase of 2.5 m/year over the next 3 years, (3) relatively large height increase of approximately 7 m/year from 2002 to 2005, and (4) a steady height increase of 3 m/year over the next 3 years. During the large-strain consolidation test of the investigated mill tailings (σ′ of 0.3–8 kPa), the void ratio decreased from 5.8 to 3.3 and the solids content increased from 32 to 46%. The vertical hydraulic conductivity was found to range from 6×10−7 to 1×10−7 m/s. The numerical modeling results closely approximated the consolidated tailings elevations and effective stress profiles in the DTMF over the period of 1996 to 2008. The field effective stress values correlated quite well with the modeling results, thereby validating the predictions. Overall, the results indicate that the effective stress increased from 0 kPa at the surface to the following values at the DTMF bottom: 200 kPa in 1999, 530 kPa in 2005, and 680 kPa in 2008.
The Key Lake Mine is located within the Athabasca Basin in northern Saskatchewan and has been active as a mining and/or milling operation since the early 1980s. The mine site will undergo significant reclamation activities over the next one to two decades. Surficial soil in the area is dominated by erodible, well-drained, outwash sand with low nutrient levels. The climate is cold and dry, meaning plants must be cold-hardy and drought-tolerant. Vegetation is also the primary means of erosion control. Re-establishing vegetation on reclaimed areas is challenging, but is also critical to the long term success of reclamation. Early efforts at revegetation focussed on replanting the climax vegetation (typically jack pine) directly to recreate the forest. The methodology evolved over time to combine seeding of grasses with tree planting; this was more successful, but was still not achieving the goal of regenerating the forest.
Observations of the initial stages of natural succession on waste rock piles have suggested that revegetation should begin with pioneer species such as mosses, lichens and shrubs. Creating suitable micro-topography for the introduction and establishment of key pioneer species, and taking advantage of available sources of nutrients and soil amendments can propel the revegetation process onto a trajectory of ecological succession and natural reforestation. Recently, Cameco has adopted a multi-disciplinary approach to revegetation efforts. This paper provides a brief description of our efforts to take advantage of the available resources (local plants, soil amendments) to facilitate the revegetation process.
'/%3e%3c/defs%3e%3cpath fill='%23012169' d='M0 0h10080v5040H0z'/%3e%3cpath stroke='%23fff' stroke-width='.6' d='m0 0 6 3m0-3L0 3' clip-path='url(%23b)' transform='scale(840)'/%3e%3cpath stroke='%23e4002b' stroke-width='.4' d='m0 0 6 3m0-3L0 3' clip-path='url(%23c)' transform='scale(840)'/%3e%3cpath stroke='%23fff' stroke-width='840' d='M2520 0v2520M0 1260h5040'/%3e%3cpath stroke='%23e4002b' stroke-width='504' d='M2520 0v2520M0 1260h5040'/%3e%3cg fill='%23fff'%3e%3cuse xlink:href='%23d' x='2520' y='3780'/%3e%3cuse xlink:href='%23a' x='7560' y='4200'/%3e%3cuse xlink:href='%23a' x='6300' y='2205'/%3e%3cuse xlink:href='%23a' x='7560' y='840'/%3e%3cuse xlink:href='%23a' x='8680' y='1869'/%3e%3cuse xlink:href='%23e' x='8064' y='2730'/%3e%3c/g%3e%3c/svg%3e)