A review of dry cover placement on extremely weak, compressible tailings

CIM Bulletin, Vol. 93, No. 1043, 2000

C. Wels, A. MacG. Robertson, Robertson GeoConsultants Inc., Vancouver, British Columbia, and A.T. Jakubick, WISMUT GmbH, Chemnitz, Germany

This paper reviews key issues related to the placement of dry (soil) covers on extremely weak, compressible fine tailings. The design and construction of soil covers on such tailings often presents a formidable challenge to the geotechnical as well as the environmental engineer due to the low shear strength, poor trafficability, and high settlement of underconsolidated tailings at the time of reclamation. The geotechnical issues to be considered include: (1) consolidation of near-surface tailings to achieve strength gains, improve trafficability, and allow safe placement of initial cover layer; (2) stability of tailings slopes during dewatering of tailings ponds and/or cover placement; and (3) long-term settlement of tailings and its impact on cover integrity and final surface shaping. The environmental issues to be considered include: (1) management of contaminated (free) pond water; (2) management of contaminated pore water expelled during tailings consolidation; and (3) management of (uncontaminated) surface water on top of the cover. This paper summarizes recent experiences gained in a large
Keywords: Tailings reclamation, Soft tailings, Consolidation, Dry cover placement