4.5. The monitoring programme should be designed using an optimization process in which the costs and benefits of monitoring are taken into consideration. The extent and duration of monitoring all contribute to the cost, both directly (costs for monitoring equipment and monitoring activity and for mitigating any ensuing risks to workers) and indirectly (costs relating to maintaining and operating the facility in a manner that allows such activity). In determining the costs of monitoring, an assessment should be carried out of the financial risks associated with missing important information that could lead to performance failure or failure to be able to retrieve waste. The benefits of monitoring also have to be considered against any detriment that might result from monitoring.