A ferrochrome smelter in South Africa is in the process of upgrading its waste management facilities to comply with the requirements of local legislation. As part of this process, a previously decommissioned hazardous waste facility required an upgraded capping design. The facility was originally decommissioned and capped in 1999, with a geomembrane covered by a protective layer of slag fines on the top surface, while the steep outer slopes were capped with concrete filled geocells. Due to settlement of the waste body, the existing concrete cap on the side slopes has cracked, while some areas have been subject to mechanical damage. This paper presents the engineering solution applied to effectively upgrade the cap with particular focus on the steep (1V:1.5H) side slopes and the use of geosynthetics to overcome the associated stability challenges. Given the space constraints at the site, the side slopes had to be capped without significant modification to their shape. This, coupled with the requirement for a geomembrane with appropriate protective cover on the slopes, presented challenging design criteria. The design includes a protection geotextile placed over the existing concrete surface on the side slopes, which is covered by the HDPE geomembrane. A specialised geogrid was included to carry the load of the cover soil over the geomembrane. The geogrid is bonded to a textured geomat which provides adequate friction forces to hold the cover soil in place. The design represents a feasible and effective geosynthetic solution
Menu