6.70. In many cases involving large volumes of waste containing radionuclides of natural origin, at least given current technical and economical possibilities, all existing alternatives for disposal necessitate at least some level of ongoing institutional control. The required function of institutional controls in such cases may range from preventing human intrusion, to ensuring through surveillance and maintenance programmes that the barriers (e.g. covers) remain intact, to addressing detrimental impacts on the integrity of barriers. Such impacts may have occurred, for example, through natural processes such as erosion or degradation of covers by roots or burrowing animals.