The Ranger Uranium Mine is surrounded by Kakadu National Park in the Northern Territory, Australia. Mining commenced in 1980 and the mine area is due for the release back into Kakadu National Park in 2026 once restoration of the mine is completed.
As part of the restoration program a Trial Landform was constructed in 2009. The primary purpose of the Trial Landform was to assess rates of erosion and the likelihood of successful revegetation rates. As part of the assessment, the Trial Landform is monitored with its own rainfall gauge and collection points which record surface runoff volumes and sediment load. On average, for the period 2009-2018, surface runoff is 20% of rainfall.
In order to better understand water infiltration into the Trial Landform and provide a baseline for future investigations direct infiltration measurements, using a disc permeameter, were undertaken. This information can be used to better understand how infiltration rates vary across the Trial Landform and hence provide a further input to inform understanding of plant water availability on the final landform. This data could also be used to help refine recharge estimates for the groundwater model.
The results from these trials indicated that infiltration rates range between 9 and 99mm/hr indicating highly variable infiltration rates which are likely to be replicated on the final landform and so inform planning to achieve the best environmental outcomes.