Ways to Reduce Risk

The criticality of any given asset will change over time but there are also ways to reduce risk and thus change the criticality of an asset. Adding redundancy, monitoring, providing routine and preventive maintenance, developing a spare parts inventory, replacing an asset early and requiring specialized training are all ways overall risk can be reduced. Some of these approaches reduce the likelihood of failure of a given asset and some of these approaches reduce the consequence of failure of a given asset. Reducing either of these components ultimately reduces the criticality of the asset. A water, wastewater or stormwater system may not be able to adopt all of these risk mitigation strategies. The feasibility of implementing any of these approaches depends on several factors, such as budget or available personnel, but systems should consider these and any other ways to reduce risk for their assets.

Redundancy

Risk can be reduced by having redundant assets. Redundancy involves the use of duplicate assets in critical areas in order to provide a backup in the event of failure, as well as to allow for operational flexibility during day-to-day operations. If an asset fails, there is another asset that can operate in its place without causing downtime. For example, perhaps there are three pumps available but only two are needed to meet the demand. If one pump fails, the standby pump can take over so the demand will still be met. If there is total redundancy, then the consequence of the initial asset failing is greatly reduced. The probability of failure is not affected because the asset still has the same likelihood of failure, but its consequence is much less. The consequence does not fall to zero, however, because the asset would still need to be repaired; the redundant asset must be able to perform; and when the redundant asset is put into service, there is no redundancy until the failed asset is returned to service or replaced. Furthermore, there is always the potential that all of the assets will fail in the same manner, removing all redundancy. In general, the more redundancy, the lower the consequence of failure because redundant assets support uninterrupted service as well as minimize the financial and regulatory impacts caused by an asset failure.

Redundancy can be inherently part of green infrastructure. There are often several smaller green assets that are all providing the same service. When many of the same green assets are installed near each other, their consequences of failure rating may be lower because of the redundancy present. For example, in cities, rain gardens are often placed near each other to reduce stormwater flow and filter stormwater. If one of those rain gardens were to fail, the other rain gardens would likely be able to handle the additional stormwater flow. However, if several rain gardens fail then it is unlikely the remaining rain gardens will be able to handle the excess stormwater and could even fail because of that excess. This possibility needs to be considered when deciding how much to reduce the consequence of failure based on redundancy.

Routine & Preventive Maintenance

Proper, proactive maintenance will reduce the likelihood of failure of assets. Routine maintenance is regularly scheduled maintenance, completed on a calendar or use base schedule (e.g., every month or every 1000 hours of run time). This kind of maintenance would include lubricating a pump once per year or operating a valve every year. Preventive maintenance is more complicated. It is conducted to maintain operating condition, slow deterioration and prevent unexpected failure. It requires monitoring and an understanding of an asset’s condition. Systems should try to perform routine maintenance on all assets and preventive maintenance on the moderate to high-risk assets. Reviewing an asset’s likelihood of failure and consequence of failure can help determine which type of maintenance to provide. Proactive maintenance (both routine and preventive), practiced regularly and appropriately, not only reduces risk, but saves money. Reactive maintenance (i.e., after a problem occurs) is almost always more expensive than proactive maintenance. It is inefficient, unplanned, often complex, may require overtime, and may involve parts that are not available within the system’s spare parts inventory. To learn more about the maintenance types click here.

Spare Parts

System availability and system efficiency depend, among other things, on the availability of spare parts. The unavailability of the right parts may have serious, negative impacts on equipment availability, due to increased downtime, as well as on resource efficiency, due to schedule interruptions. The lack of parts may also impact water quality, cause environmental hazards or create hazards for staff. Having spare parts on hand greatly reduces downtime and eliminates the delay when parts are not locally and readily available. This situation is particularly acute in remote, rural areas, or on islands where delivery times can be quite long. Obtaining the appropriate spare parts can be expensive, but costs can be minimized by stocking only as many spare parts as are actually necessary for the number of failures anticipated over a specific time period (e.g., the number of parts needed per month if the part can be ordered quickly or per year if delivery takes longer.) Also, these parts should be stored properly to prevent premature failure or damage to the spare part. It is a good idea for systems to link their spare parts inventory to their electronic work order system, so it is easy to tell when assets are used. In this manner, parts can be restocked before the number on hand drops too low. At a minimum, it is necessary to have spare parts for high-risk assets that can be repaired and for assets that are intended to be run to failure.

Specialized Training

Specialized training may be needed to operate, repair, or maintain important assets. If an untrained employee undertakes a task using the wrong materials or techniques, it is possible that the asset can be damaged and fail due to the error. Additionally, specialized training may be required to ensure that a repair technique is done properly to prolong the life of the asset or maintain the warranty. As an example, lubrication can be done incorrectly if the employee does not know how much to use, what lubricant to use, and how to tell when it is needed. Education and training are especially important for operation and maintenance of green infrastructure because the field is still relatively new and there has been less time for institutional knowledge to accumulate. Green infrastructure projects are often implemented by local governments and nonprofit organizations who may rely on private residents or volunteers to conduct maintenance. In these cases, many of the participants do not have experience performing the maintenance activities required for the asset to function optimally. Many systems are working with outside partners to set up trainings programs to engage the community and ensure these assets receive the proper maintenance.

Replace Asset Early

Assets will decay over time, and, at some point, each asset will no longer meet the desired level of service. Knowing when an asset will no longer provide the minimum level of service is a best guess. Ideally, system staff want to replace, repair or rehabilitate an asset right before it stops meeting the acceptable level of service. However, it is nearly impossible to estimate correctly when this point is for every asset in the system. Part of the problem is that not all assets perform the same, and some assets have such long lives that it is not possible to watch them in operation through many years of service. The factors that help determine the optimal replacement are discussed in Remaining Useful Life.

Because this optimal replacement time frame cannot be determined easily, the next best approach is to choose to replace some assets early to prevent severe consequences from occurring. In this case, the tradeoff is to give up some of the asset’s life (lose asset value) in order to prevent a bad outcome. The asset replacement will hopefully save money in the long run because of avoided costs (e.g., legal expenses, environmental contamination, etc.) that could result from a failure.

Monitoring

Regular monitoring, such as visual inspections of facilities or equipment measurements (meter readings, water levels in wells etc.) ensure that assets in a system are operating properly and help staff identify problems, such as potential failures, early so they can act quickly and efficiently. Monitoring can be a simple, low-cost option or it can be an expensive, time-consuming activity. This type of monitoring is also called predictive maintenance and it uses technology to determine when an asset is likely to fail or to identify small problems before they become bigger problems. Predictive monitoring can involve processes, such as vibration analysis, precision alignment checks, lubrication analysis, pipe inspection, or many other procedures. How much monitoring should be done depends on the cost and personnel time involved as well as the benefit of the information. The benefit of the information is higher when the risk is higher and when there are actions that can be taken to intervene in the asset’s life and prevent failure.

Monitoring is also an effective technique for green assets. For example, condition monitoring can identify clogging levels of permeable pavement so that it can be cleaned before the levels are too high. This is important because clogging damages the asset and prevents it from providing an acceptable level of service and can be an indication of an erosion problem which can lead to more significant failures. Monitoring is also a critical component when investigating green assets during pilot project initiatives. Monitoring the pilot project’s performance allows decision makers to make informed decisions about how to adapt the design, operation, and/or maintenance of future projects. The lessons learned could decrease the risk associated with the next similar installation.

Redundancy for critical assets – Ted Riehle, Chief Operator, Old Forge Wastewater Treatment Plant, Old Forge, NY