7.9. For disposal facilities for waste from mining and mineral processing, surveillance should start in the pre-operational period and should finish either at the end of the period of active institutional control or at closure of the facility, depending on the nature of the disposal system, for example, if access to the engineered barriers is no longer possible. The assumptions regarding the duration of institutional stability and continuity of knowledge are usually a major factor in defining the duration of surveillance after closure. An example of a long term surveillance plan (for the period after closure) for a uranium mill tailings site is provided in annex I of Ref. [8].