Post-Event Influences

Post-event influences fall into two categories:

• Those which the organization can influence.
• Those which are beyond the control of the organization.

The first can be largely overcome by development of failure management plans that will enable the organization to respond quickly to the failure and therefore reduce the consequences of failure.

Some effects that are beyond the control of the organization are:

• Whether or not the asset had redundancy/backup facilities available
• Whether or not the asset was at peak utilization or was currently operating at below peak capacity
• What are the weather conditions at the time of failure and will they have an impact on the post-event activities, for example: heavy rain hindering the repair crew?
• When did the failure occur — at night or during the day?
• What are the availability of spares and contractors available?
• Is the asset located below high groundwater levels and therefore more difficult to repair or replace?

Post-event influences will have an effect on the consequences of failure, and need to be considered in Failure Management Plans. Staff also need to be aware that these issues may influence their post failure activities.

Examples of reducing the impact of asset failure

Asset failures will occur through normal use and as the asset ages.

For service authorities, the performance of the service will be judged by the frequency with which the service fails to meet its standard level. If this measure is to be used effectively, it must be based on the number of interrupted customers and the time that they are interrupted, e.g.: equivalent customer hour interruptions.

Asset managers need to consider the way in which they can reduce the impact or severity of service failures. This can be done in two ways, by reducing the:

• Number of customers affected
• Impact on major customers.

It is important that managers have a feel for the number of equivalent consumers affected. Consumption or usage data need to be interpreted to derive "equivalent customers" for those services that are not average residential dwellings. Each consumer area can then be compared in terms of significance or impact on the service authority.

Example 1

The number of people affected can be reduced by the insertion of greater number of isolation valves. This will enable repair crews to reduce the impact of the failure by reducing the area affected by re-routing supply through adjacent services.

It could be argued that when assets are new, isolation valves or switching systems are not required to the same degree as for aged assets. The isolation valves themselves may fail before the parent asset has reached a period where failure is likely.

Installing new isolation valves in water reticulation mains when the first failures occur is a cost effective way of reducing the impact of main failure without incurring the gross cost of renewal or replacement.

When water mains reach the point where replacement is economically justified, isolation valves can be moved to other aging areas of reticulation, provided the valves themselves are still in good condition.

Example 2

An interim service can meet most customer demands.

Trailer or truck mounted water tanks with pressurizing units can be connected to the house connections of major water users. Units of different sizes could be carried by repair crews such that even single tapping problems could be given a temporary service.

In a sewer failure, plugging manholes and using tankers to educt the sewage from the surcharged upstream manholes will reduce the environmental overflows as well as providing a service for as many customers as possible during the interruption.

There are many other ways in which good asset managers can reduce the impact of asset failure. Good information systems will help them judge and economically justify the investments required to adopt specialist activities and equipment to overcome the effect of failures.

Risk Analysis Approach

Advanced Management Implementation, Quickwin Activity – Risk Assessment