https://sswm.info/factsheet/arborloo
To decommission a pit, it can simply be filled with soil and covered. Although there is no received benefit, the full pit poses no immediate health risk and the contents will degrade naturally over time. Alternatively, the Arborloo is a shallow pit that is filled with excreta and soil/ash and then covered with soil; a tree planted on top of the nutrient-rich pit will vigorously grow. The pit (approximately 1.0 to 1.5 m deep) and the toilet superstructure (consisting of a ring beam, slab and structure) are both temporary and move from one site to the next at 6 to 12 month intervals while old pits are covered and the trees are growing.