The major components of the water supply system are monitored by a SCADA telemetry system and many routine functions controlled by automatic PLC (programme logic control) computers. The telemetry data is returned to the engineering officers who have direct access to the information and can monitor real time data and trending of the parameters. A 24/7 standby roster is maintained to monitor the system and an automated tiered alerting system is employed to ensure system alarms are responded to. Maintenance Information – In December 2014 a new asset management information system was implemented to replace the Hansen system that had been used for around 15 years. The new system provides greater analytical and reporting tools. The maintenance history has been migrated to the new system. All maintenance activity will be recorded through work orders. The AMIS is intrinsically linked to the purchasing and financial software and the costs of maintenance will be recorded as well as the nature of the repair and details of the performance and condition of the asset. 4.3.3 O & M Decision Making The maintenance decision making process seeks to resolve conflicting issues. Levels of service versus risk and costs - A guaranteed uninterrupted 24/7 water supply can be delivered to the Marlborough customers. However the cost of engineering and maintaining such a service has to be balanced against the willingness and ability of the community to pay for it and managing the risks and consequences of a lower level of service. The costs of providing improved service levels can increase disproportionately to the marginal benefit. For example improving the target for restoring a water supply interruption from, say, 10 hours to 8 hours has a relatively small marginal cost. However to further improve the response time to, say, four hours or less would have significant additional cost in terms of man-power and disruption to scheduled work programme. The current levels of service have been developed to provide risk based prioritisation and a balance of cost and customer expectation. Asset maintenance versus renewal - The A & S Department seeks the optimum balance between replacing an asset that is reaching the end of its useful life and the costs of repairing it. Currently this is achieved by the judgement of the operational engineers. One of the priority aims of the upgraded asset management information system is to provide good data on maintenance costs and frequency to support the engineers’ decisions. Planned versus unplanned maintenance - A well planned preventative maintenance schedule may reduce disruption to service, reduce whole life costs, schedule work to be undertaken in cost effective and organised manner and reduce the risks associated with failure. However there are considerable costs associated with investigating and implementing the correct intervention interval. In cases where the risks of failure are low it can be cost effective to allow the asset fail and respond to the breakdown. Planned maintenance schedules have evolved for the critical components of the water supply infrastructure. More formal documentation and evaluation of the current process is required as there is a reliance on the experience of individual staff that may not be sustainable. Efficient asset utilisation versus providing redundant capacity - There is a strong efficiency motive to correctly optimise the use of assets. However there can be serious consequences to the failure of some critical assets and a level of redundancy or contingency options can be a valued attribute. Blenheim and Picton have two independent sources of supply. Distribution pumps are duplicated and have duty/standby capacity. Storage reservoirs are designed to provide a continued supply in the event of power failure. Wherever possible water distribution pipelines are configured into inter-linked networks that can provide alternative supply routes in the event of a pipe failure. Resolving these conflicting issues exists within the context of risk. The function of each of the components of the infrastructure is assessed for its critical contribution to achieving the desired Page 65