Maintenance Types

Maintenance involves activities that help keep the assets in good working order, so it will operate as intended. Maintenance falls into the broad categories described here. Examples of the different types of maintenance are provided below.

Proactive maintenance activities are those that are carried out in a planned fashion. Reactive maintenance activities are those that are completed after the asset fails to meet the desired level of service or fails to function at all. Different types of assets need different ratios of proactive and reactive maintenance. For gray assets, there is enough historical information to establish a best management practice of 80 percent planned maintenance (including the categories of planned, preventive, and warranty-related) and 20 percent reactionary (corrective) maintenance. For green infrastructure, data is still needed to define best management practices. However, for both green and gray assets, the type of asset, its risk level, and its replacement cost must be considered when optimizing maintenance funds.

For low-risk assets, the most economical option might be to allow the asset to fail. This allows the full life span of the asset to be achieved. This management strategy is called “run to failure,” or managed failure. In this case, the operations staff are choosing to let the asset run until it fails, at which time it is repaired, rehabilitated, or replaced.

Green assets can become more self-sustaining over time, so staff might be able to reduce the frequency of planned maintenance. Gray assets typically need higher levels of planned maintenance over time. When considering full life-cycle costs, consider these differences in planned maintenance costs, as it might impact the comparison of a green asset to a gray asset intended to perform the same function.

Risk should be a factor in determining how much to invest in maintenance for each asset. The maintenance needs for green assets are often highly dependent on the specific location, rather than the asset type. Therefore, risk might need to consider asset location, not just asset type, for green infrastructure.

A companion activity to maintenance is monitoring, which includes inspection. Monitoring can help determine when maintenance should be performed. Monitoring can be ongoing and permanent using continuous read equipment, or it can be intermittent. Monitoring might also allow the asset’s operation and maintenance to be adjusted and improved over time. Permanent monitoring might also be called predictive maintenance, which is conducted to monitor specific condition attributes used to predict when asset failure might occur. Asset temperature, vibration, and oil quality are some attributes that can be permanently monitored. Intermittent monitoring might also be called inspection. During the inspection of an asset, staff might check specific attributes, such as oil levels, or review the overall condition of the asset. Green assets likely require more frequent inspection in early stages of the asset’s life, while a gray asset might require more frequent inspection at the later stages of the asset’s life. Monitoring might allow an asset to be adjusted and improved over time.

To know the best way to maintain the asset, it is important to collect maintenance data. This data should include the costs for any maintenance activities conducted. Maintenance data can aid informed decision-making. Data can also be used to improve decision-making after failures. WRFThe Water Research Foundation’s Asset Management Framework for Forested and Natural Assets provides example of maintenance activities required for natural assets as shown below.

WRFThe Water Research Foundation‘s Asset Management Framework for Forested and Natural Assets: Table 9-3. Examples of Specific Maintenance Activities for Different Natural Assets.

The importance of maintenance – David Montgomery, SCADA Manager, Albuquerque Bernalillo County Water Utility Authority, Albuquerque, NM