6.55. In some geological disposal programmes, it is envisaged that the facility could remain open for some considerable time after waste emplacement has ceased. This would extend the operating period even further, thus providing increasing amounts of monitoring data relevant to the performance of the facility after closure (e.g. corrosion of waste packages, wetting of backfill materials, changes in hydrological conditions). Procedures should be developed for the evaluation of monitoring data with respect to the impact of the extended operating period on the post-closure safety of the facility (e.g. re-evaluation of safety on the basis of the monitoring data). Documentation of the monitoring data, of any relevant changes from baseline conditions and, as necessary, of the impact of the extended operating period on post-closure safety should be clear and thorough.