6.52. Future human actions may disrupt a waste disposal system. Human action affecting the integrity of a disposal facility and potentially giving rise to radiological consequences is known as human intrusion. Human intrusion is particularly relevant for disposal facilities at or near the surface. Most human activities (e.g. construction operations, farming, etc.) that could lead to inadvertent human intrusion into a waste disposal facility take place at limited depths of tens of metres (typically down to 30 to 50 m below the surface). Over long time frames, human intrusion into such a facility may be quite likely. Human activities that reach depths greater than 30 m are much less likely, but include drilling (e.g. for water, oil or gas), exploration and mining activities, geothermal heat extraction or the storage of oil, gas or carbon dioxide. In this respect, the following guidance addresses mainly disposal facilities at or near the surface. A discussion of the relevance of human intrusion scenarios for deep geological disposal facilities is presented in para. 6.65.