Importance of topography and topsoil selection and storage in successfully rehabilitating post-closure sand mines featuring pit lakes.
Faculty of Computing, Health and Science
School of Natural Sciences / Centre for Ecosystem Management
Rehabilitation at a silica sand mine on the Swan Coastal Plain of Western Australia, where the post-mine landscape consists of small pit lakes (dredge ponds) with surrounding battered slopes, and where a range of ecological restoration techniques have been applied, was monitored for several years to gauge success or otherwise of these techniques. Results clearly showed the benefits of using fresh topsoil for restoration over topsoil that has been stockpiled for several years. Most topsoil used in restoration was from seasonal wetlands and consequently restoration was most successful in the riparian zone from the edge of pit lakes to ∼2 m vertically above the water table. Rehabilitated areas above this level remained poor in plant species and cover with remedial actions largely unsuccessful. We believe that matching topsoil to site and development of topographic profiles similar to natural wetlands of the region are the keys to optimising rehabilitation success around pit lakes formed by sand mining in areas with shallow groundwater.