Prioritizing Your Aging Water Infrastructure Needs through a Systematic, Comprehensive Approach
By Ahmad Habibian
The deteriorating state of the nation’s water infrastructure has resulted in premature failures, costly emergency repairs and negative publicity. Given the limited availability of resources, utilities are looking for cost-effective condition assessment technologies that allow them to prioritize their assets in need of rehabilitation.
In order to receive the full benefit of condition assessment, utilities must adopt a systematic and comprehensive approach that establishes a framework for prioritization of assets for inspection, establishes protocols for inspection and develops analysis tools for interpreting the inspection data. This approach culminates in the development of a condition assessment program, which is an integral part of an asset management program.
Once a utility establishes a condition assessment program, it can easily integrate the program within an asset management program in the future. It should be noted that while many water utilities in the United States have aspirations to establish an asset management program, they are facing budget constraints, which hinder them from achieving this goal. Establishing a condition assessment program will allow such utilities to take a step toward this goal with much less financial impact. As the condition assessment program matures, it can gradually be expanded to realize the benefits of a full asset management program.
Transmission vs. Distribution Mains
For a typical water utility, a large percentage of its system falls in the small diameter or distribution category and a smaller portion falls in the large diameter or transmission category. The issue is whether to treat these two categories the same when it comes to condition assessment. The answer to this question lies in what the consequence of failure is for each category.
For small water mains, consequences of failure are typically not significant. Of course, there may be situations where a small main break may have significant consequences, but most such failures do not have significant consequences. Thus, the focus for small diameter mains should be on failure management. When failure occurs, the utility should be prepared to quickly move in and fix the break.
Figure 1: Small Diameter Mains Constitute a Major Portion of a Water System.
On the other hand, the consequence of failure is typically significant for large water mains. When a large main fails, many customers can be affected. Fire protection over a wide area can be compromised and damage to the environment can be substantial. It can cause major traffic problems, it is typically more expensive to fix the break and a lot of water will be lost from the mains before the line can be shut down for repair. As such, the goal should be to prevent such failures to the extent possible.
Figure 2: Risk Matrix for Asset Prioritization.
Prioritization of Assets for Inspection
A risk-based approach to asset prioritization for inspection has gained popularity in recent years. The risk-based approach identifies high risk assets which are targeted for inspection. The first step in performing the risk analysis is the development of an inventory of the water mains and bundling them in meaningful groups, based on factors such as size, age, material and geographic location. It is recognized that risk is a function of likelihood of failure and consequence of failure. When likelihood or consequence increases, risk increases. In order to quantify the risk, a system should be developed to quantify the two components comprising the risk – the likelihood of failure and the consequence of failure.
To quantify the likelihood of failure, three broad categories of parameters may be used. These are:
- Physical parameters such as pipe age, size, and material,
- Condition parameters such as pipe condition, soil type, groundwater regime, and
- Performance parameters, such as break and leak history, and maintenance data.
A scoring and weighting system should be developed for these parameters to be able to assign a likelihood score to each pipe in the system.
Similarly, the consequence of failure can be quantified by utilizing parameters such as the number of customers affected, type of customers (critical, large, commercial, industrial, residential), environmental impact and adverse publicity.
Once the likelihood of failure and consequence of failure are quantified, a risk matrix is developed, which becomes the primary tool for prioritization. The risk matrix identifies several zones ranging from high risk to low risk. The assets that fall in the high-risk zone are given high priority for inspections.
Condition Assessment Technologies
Once a prioritized list of water mains to be inspected is developed, the utility should decide what technologies are available and applicable for inspection. Figure 3 provides an overview of various inspection technologies available in the marketplace.
Figure 3: Condition Assessment Technologies.
Long-Term Rehab & Replacement Budgeting Needs
Another element of a condition assessment program is the development of long-term budgeting needs for replacement and/or rehabilitation. To achieve this objective, survival curves must be developed for various pipe classes, and used in conjunction with tools such as the Water Research Foundation KANEW Model or the AWWA Buried No Longer Pipe Replacement Modeling Tool to develop budget needs projections. In these types of analyses, the utilities often are encountered with a situation where significant catch-up spending is required initially to compensate for the lack of replacement or rehabilitation in the past. To be able to absorb this significant upfront need, it is customary to distribute the initial budgetary need over a period of time. By extending the catch-up period, the utility can match its budgetary needs with available funds.
Moving Towards A Condition Assessment Program
The first step in developing a Condition Assessment Program is the establishment of an organizational unit within the utility with the mission of developing, implementing and monitoring the program. Management support systems such as Geographic Information Systems (GIS) and Computerized Maintenance Management Systems (CMMS), as well as resources such as leak detection crews and equipment, protocols or standard operating procedures, and a road map or action plan on how to implement the program are other elements of a Condition Assessment Program.
The organizational unit size and composition can be elaborate, basic or bare bone. No matter what organization is chosen, there is a need for a champion who can also serve as the Program Manager. This person can be supported by engineering, administrative, GIS and field staff, or can assume some of these responsibilities himself/herself. Often times, it helps to establish a steering committee with representatives from planning, engineering, operation and maintenance staff. This steering committee will be a place to nurture an atmosphere of team work. It also helps with the buy-in of the program across the organization.
The Action Plan or Road Map will identify the prioritized assets for inspection and will identify what elements of work can be done with in-house resources and what elements needs to be outsourced.
While a proactive condition assessment program is very effective in minimizing the number of failures, unexpected failures can still happen. It is therefore critical that the utility has an effective Emergency Action Plan (EAP) in place for cases when a main break occurs. The EAP will establish procedures for responding to water main breaks. It may include having one or more on-call contractors in-place, having an adequate supply of parts for repair, and identifying which valves need to be closed to isolate an area where a main break has occurred.
Concluding Remarks
Starting a condition assessment program is a necessity for water utilities facing an aging infrastructure. Such a program will not only allow the utility to identify and prioritize its water mains in need of rehabilitation, but it will also serve as a cornerstone of an asset management program. To jumpstart such a program, the utility must identify a dynamic program champion to establish and lead the program in collaboration with a steering committee of representatives from planning, engineering, operation and maintenance staff. Other elements of the program include development of an inventory, performing risk analysis to establish priorities, developing an action plan, and implementing the plan. While such programs can be fully staffed by in-house resources, it is often more practical and cost-effective to utilize a combination of in-house and outsourced staff to establish and implement such programs.
Ahmad Habibian, Ph.D., P.E.
Technical Strategy Leader for Conveyance | CDM SmithDr. Ahmad Habibian has more than 30 years of infrastructure management, pipeline assessment and rehabilitation and trenchless technology experience. He has served in several leadership positions with ASCE and AWWA and has been recognized for his services through the 2015 AWWA DPOD Peak Performance Award and the 2008 ASCE Pipeline Division Award of Excellence.
