Across the world, many utilities are facing challenges of aging infrastructure in their drinking water distribution systems. To be able to continue to serve their communities and customers, utilities have been putting an increasing emphasis on effective asset management planning for sustainable asset management. To build an asset management plan that allocates spending efficiently to areas that need it and defers for areas that do not, an understanding of current asset condition is necessary.
That is where condition assessment comes in, particularly when it comes to distribution networks where the assets are buried, and visual or operational assessments are not possible. Condition assessment is critical to ensuring that utilities are not replacing pipe that has many years left in service while other pipes are left in the ground that need replacement. Time and time again, the efficiency of replacement programs has seen an improvement by capitalizing on condition assessment tools, technologies, and services whether it is quantified by dollars not spent replacing good pipes or by reduced replacement expenditure or other social, economic, and environmental benefits.
The term condition assessment has been used in the water distribution industry to refer to anything from a desktop analysis to destructive testing. There is a time and a place in any asset management or condition assessment program for each of these approaches but knowing when and how to best leverage these tools is imperative to optimizing condition assessment and asset management. This article highlights some key considerations and best practices utilities should consider when building a condition assessment or asset management plan.
Setting objectives to determine a budget
To effectively build a condition assessment plan hinges on the knowledge and understanding of the key objectives and budget. These two criteria are both critical in managing expectations of the condition assessment plan and in narrowing down the possible technologies or solutions to fit your needs. While many utilities may not have any immediate control over the budget allocated for condition assessment, defining objectives and program success criteria can be a great place to get a condition assessment program started. Often, building a plan within this framework for condition assessment as part of an asset management program can serve to identify where a budget is needed or can be better allocated.
It is recommended that utilities look to answer the following questions to help ensure that the key objectives and program success criteria are well-defined and understood:
- What problem are you trying to solve (i.e., aging infrastructure, system maintenance, water loss)?
- What are the targets to come out of the condition assessment to address the problems (i.e., is there a target break rate to achieve, is there a reduction in network risk target, is there a target to reduce replacement of good pipe, is there a target to reduce replacement budgets)?
- What is the plan of action for the data obtained from the condition assessment (i.e., build long-term asset management plans, plan short-term condition assessment, identify repair or replacement needs)?
Establishing these criteria early in the planning process can help to manage expectations and provide support and justification for the selection of the appropriate strategy or technology to obtain the data. However, it is important that a utility is comfortable iterating on these criteria to ensure that objectives continue to align with the budget as a utility moves into approach and technology selection.
Determining what condition assessment tools to use
Once the key objectives and success criteria are understood and with a budget in mind, a utility can then start to look at identifying the right type of condition assessment to meet its needs. Most asset management plans use some version of the inverse triangle with desktop analysis at the top and material testing at the bottom. The structure of the inverse triangle is such that the technologies at the top typically cover more area at a higher level and have lower time and money investment requirements per unit and the bottom of the triangle.
At the top of the inverse triangle (see Figure 1) is the desktop analysis/risk model, which can provide a strong overview of risk across the entire distribution network. Effective models can provide valuable information to support data-backed long term asset planning. These models are extremely valuable in targeting asset management resources (repair, replacement, or condition assessment) to areas that have a higher risk, likelihood of failure or consequence of failure, and ultimately enabling budgets to go to the regions that need it the most. There is a wide range of options available for technologies that fall into the category of desktop models, from age-based asset tracking to AI risk models that factor in multiple contributing factors to pipe failure. The latter has been proven to more effectively predict where the risk truly exists in a utility network and many have built-in planning functions to help utilities plan next steps such as condition assessment, repair or replacement. If a utility lacks funding, doesn’t know where to start, or needs data to justify a budgetary request, a desktop model is a great place to start.
Down the triangle is survey-level condition assessment, which can be done separately from or after desktop modeling. This level of assessment typically requires a higher per-unit investment of time and money than desktop modelling and therefore is often carried out on a smaller portion of the network to confirm the current actual condition of specific assets. It is recommended that utilities deploy survey-level condition assessment on pipes that have been identified for assessment or replacement by desktop models to validate the need for replacement of those specific assets. Using desktop models, even as simple as an age-based asset model if needed, can enable utilities to effectively target this level of condition assessment. There are several technologies that fall into this category of condition assessment, with a key emphasis on a look at the overall structural integrity of the pipe as opposed to localized defects. At this level of detail, utilities can make informed decisions about replacement plans to target replacements where needed. Due to the granularity of the data and the intended network coverage at this level of condition assessment, technologies offered in this band tend to strive to minimize impact on network operation during the survey assessment.
For more critical pipes, larger transmission mains, pipes, or pipe types where localized defects have caused significant issues over time or pipes where replacement is more difficult, there is often value in moving to the next stage of the triangle: detailed condition assessment. In some instances, utilities have used desktop models or survey-level condition assessment to identify specific pipes or areas of pipes where further, a more detailed inspection is required. Once again, this level of the inverse triangle involves a higher per-unit investment of time and money than the previous level. These technologies and tools provide more discrete information about assets and are likely to be deployed to a subset of the network where the cost of replacement, consequence of failure or other utility-specific criteria are high.
Finally, on a very select portion of the network, utilities will look to do materials destructive testing to understand the actual condition of small sections of pipe that have been removed. Due to the requirement to physically remove a section of the pipe to facilitate this type of testing, it is not recommended to use this as a primary strategy for condition assessment. This type of testing can, however, be effectively used to validate condition assessment or desktop analysis results, or to calibrate maintenance programs, where necessary.
The selection of the correct technology involves an understanding of both levels of the triangle and the available technology that fits within a utility’s budget and objectives. In many cases, the available budget allocated for condition assessment can drive a utility into one of the approach levels and/or a technology.
Condition assessment considerations for smaller budgets
For utilities that are just starting out with a condition assessment approach, budgets allocated for this service are often lower and data on the network can be limited, making it hard to set objectives or make informed decisions about selection. It is typically recommended that utilities that fall into this category look to start with desktop models and/or survey level assessment. As these have lower cost-to-coverage ratios, a utility can typically get a better picture of more of its network sooner. These categories may be driven by budget alone or primarily by objectives as there is significant variance within each category on price points and output data.
Alternatively, if a utility has more immediate needs or risks to address through condition assessment, there may be value in circumventing the first two categories and focusing on detailed inspection. Utilities in these circumstances may not have a regular condition assessment plan, as it often involves a small area or set of pipes that a utility knows is a problem and wants to understand the problem more completely before making repair or replacement decisions.
Here are some approaches to manage competing interests for utilities that are striving for effective condition assessment but lack the budget to deploy:
- Restructure condition assessment plans to a phased approach. Spreading out condition assessment into phases across budget years can enable utilities to meet their objectives within severe budget constraints. Further, it enables the utility to better map out planned expenditure on condition assessment to identify and remedy potential future budget gaps.
- Reduce scope to maintain objectives. As an alternative to phasing, utilities could explore reducing scope by means of reducing additional features or add-ons of a service or narrowing the physical scope of pipes in the network that a condition assessment project will cover for that year. Though this would require lower network coverage, it could strike a fine balance between budget and objectives, depending on priorities.
- Proceed with a pilot project on targeted high-risk pipes or areas. This enables utilities to explore condition assessment solutions with a lower investment in a manner that, upon the success of the pilot, can provide strong justification to increase budgetary allotments for condition assessment in subsequent years. Many utilities also use this approach to validate technologies prior to making a larger investment when significant budget constraints are of concern.
- Reallocation of budget from capital replacement plans. Leverage condition assessment to instead prioritize replacement where it is needed most. As noted above, conducting condition assessment can have financial benefits to the capital replacement expenditure.
At each level of the inverse triangle, there are multiple technology options for a utility to choose from, each with its own advantages and disadvantages. Selection of the right technology for a given utility requires the utility to circle back to the established objectives and success criteria.
In conclusion
In an ideal world, every utility’s asset management plan would include condition assessment that is addressed in stages through the inverse triangle and hitting every step along the way. The reality, however, is that often the value of leveraging a staged condition assessment approach is not reflected in allocated budgets, and utilities are forced to be more selective about which levels of condition assessment to hit. The best way to manage the limitation on resources to deliver the best results for the utility is to circle back to the initial questions and leverage objectives and success criteria to select condition assessment approach and technology that will truly address specific utility needs.
As a best practice approach, it also is important for utilities to evaluate the success of their asset management and condition assessment programs at regular intervals to ensure that time and money expended on these plans continue to align with utility objectives. More specific steps and information on best practices of condition assessment can be explored in AWWA Manual M77. This manual is dedicated to condition assessment best practices and provides more detailed information on acceptable approaches and specifications for different types of condition assessments and pipe materials.
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