A Sound Approach to Evaluating NRW Loss and Aging Pipelines

As water distribution infrastructure ages, the potential for leaks grows and the need for condition-driven asset management increases proportionally. As with so many other aspects of water operations, planning ahead is key. Good system diagnosis using noninvasive procedures provides an accurate and cost-effective assessment of distribution system integrity, just as noninvasive monitoring of heartbeat, pulse, and blood pressure plays an important role in human health.

Start With A Sound Strategic Approach

Unlike plumbing problems that can be solved with a couple of wrenches and some fittings, identifying, calculating, and addressing problems of non-revenue water (NRW) losses due to leak require higher-level strategic approaches. That starts with big-picture perspective on utility goals and system conditions.

The better the data a utility has regarding its infrastructure, the better positioned it will be to adopt condition-driven asset management (CDAM).

Employing a CDAM strategy helps utilities make the right decisions on prioritizing and resolving the most pressing issues without overspending. It includes:

• Baseline understanding of water main condition.

   Replacement and rehabilitation planning.

   Strategic deployment of nonintrusive condition assessment technologies.

   Reduction in the number water main breaks experienced.

   Rate-case justification.

The Checkpoints of a Good Assessment

The first step is a good condition assessment of the existing infrastructure. If some form of asset management plan is already in place, review any historical data on the age of pipes and the history of breaks, sector by sector. Validate that historical data with acoustic assessment, in case it has been skewed by other anomalies in the system — soil, bedding, or corrosive influences. Acoustic assessment — whether done with a permanent leak detection system or other technology — will help pinpoint the location of the biggest issues.

Because of cost, most utilities don’t install a total leak detection system right away. Most try to project potential return on investment (ROI) by testing critical areas in their systems. An initial leak detection trial can identify the most pressing problems before they cause more damage than necessary and indicate how to allocate resources across the system. Doing this acoustically, as opposed to visually, is important, because leaks follow the path of least resistance and might never show themselves above ground. Leaks that go unidentified too long can lead to costly catastrophic breaks or to customer service issues that require a complete shutoff of service. There are current cases where leaks caused environmental issues that compounded the costs of NRW losses — including instances with heavy fines for environmental pollution.

The Changing Awareness and Implementation of Leak Detection Technology

Utility managers are raising awareness about the capabilities and opportunities of leak detection technology. In some cases, this is due to mandatory measures for coping with water scarcity issues (e.g., California SB 555). In other cases, it is where source water is relatively plentiful, but aging infrastructure is driving the need for better understanding of leak detection technology.

Regardless of the drivers behind leak detection interest, implementation typically starts out with smaller proof-of-concept pilot projects to document success with the technology, based on the ROI. This can mean as few as 50 to 100 leak detection units to start proving the technology without a large capital commitment (Figure 2).

Before laying out a pilot program, it is important for the vendor and customer to agree upon the concept being tested, the capital costs, the relative cost of services, and the criteria on which the performance is going to be evaluated. Evaluation criteria can range from the simplicity of system installation to supporting-software features and the ease of user operation.

As pilot projects prove the savings to be gained from the detection and repair of leaks, utilities typically expand use of the technology based on this proven ROI. Even in areas that choose large-scale deployment of leak detection, the technology is often phased in — 1,000 or 2,000 units at a time.

Being Realistic about Identifying and Repairing Leaks

Implementation of leak detection systems evolves over multiple steps — planning, design, construction, training utility personnel, commissioning the system, turning it over to the utility, or running the system as a service for a utility short on the manpower resources to manage it itself.

A good leak detection system can help quantify and prioritize leaks on the basis of severity, letting utilities know which leak repairs will save the most in the shortest amount of time. If one of the leaks gets progressively worse, repair priorities can be adjusted based on the upgraded status. Ideally, the same system should take into account key details such as the age of the pipe, type of material, diameter, and so on. It should also be able to change priorities based on the critical need of the service area (e.g., hospital, school) or on complexity of repair (e.g., under a major highway or in a congested area).

Leak data collection should start with pulling in geographic information system (GIS) data automatically (ideally without a lot of manual intervention), mapping out the utility infrastructure, and establishing a baseline for every leak. Once baselines are established, a systematic approach to leak management involves adding newly identified leaks, continuously monitoring the progression of all leaks beyond baseline levels, and then reprioritizing repairs according to changes in leak severity over time.

Acoustic Technology, Sound Approach

Leak detection technology can be built into a hydrant cap, with signals being transmitted via cellular data to the cloud. A robust user interface web portal can provide access from anywhere with internet or cellular data access.

A turnkey system supplier will install, fine-tune, and commission a new leak detection system before turning it over to the water distribution utility. This gives the utility a ready-to-use solution without requiring a large commitment of labor beyond initial operator training.

While it is important to spot leaks as early as practical, not every noise in a line actually indicates a leak. A system that monitors points of interest, day by day, can fine-tune its readings and scoring criteria to have a higher likelihood of identifying an actual leak. This saves the cost of dispatching repair crews based on “false-negative” readings. 

The most advanced systems can pinpoint leaks within a 6’ radius based on readings taken from as far as 600 to 1,000’ away from each node, depending on pipeline configuration and ground conditions.

Planning Ahead To Attack Infrastructure Challenges By Priority

The lead time for a large-scale leak detection solution can involve a relatively long cycle from initial inquiry to completed installation — including the time and steps required to deliver in-depth cost and performance analysis. By contrast, the actual time to install a small leak detection pilot project can be a matter of just days or weeks, typically followed by a 90-day test period that provides time for some blind testing and intentional leak creation. The end result is a proven ROI to help provide data for further expansion of leak detection monitoring. Either approach, however, should start with a similar review of pain points, key drivers, and planned evaluation criteria.

Once a sound assessment establishes the baseline for current system infrastructure, resulting data can be used to quantify the four factors required to reduce real losses:

• Pressure Management

• Active Leakage Control

• Speed and Quality of Repairs

• Asset Renewal and Replacement

Once the utility understands where and why it is experiencing NRW loss, it can take the appropriate steps to reduce water loss.