Condition Assessment To Extend Life Of Critical Assets Risk
The most pressing issue surrounding water and wastewater assets is with aging pipelines. While there are many of miles of pipes beneath the ground, the most critical are large-diameter water and wastewater mains, which are often the most valuable asset a municipality owns. These pipelines provide critical services for communities and are beginning to leak and rupture more frequently; not only does this disrupt these vital services but also costs municipalities billions of dollars annually.
While the cost of replacement is high, it is less expensive than allowing these assets to operate until failure. However, for many utilities, it doesn’t need to be all or nothing – the majority of water and wastewater systems can be safely and efficiently managed using a risk-based condition assessment approach.
The primary misconception that many operators have is that the majority of aging pipelines need replacement. This thought process often comes after a critical large-diameter failure, which can cause a negative public perception that the majority of pipe in a system is in near-failing or poor condition. Replacing large sections of pipe is not only extremely expensive – the average cost to replace one mile of pipe is US$1.8 million – but is also extremely difficult logistically, especially as urbanization continues.
Fortunately for utilities, the vast majority of pipelines can remain operational well beyond their intended design life, provided they are managed properly.
Pipe distress is a localized problem, meaning that one pipe section that is badly deteriorated or has failed could be neighbored by pipes that have virtually no damage at all. This is because local factors – such as load, soil conditions, operating conditions and installation – affect how quickly a pipe deteriorates. Through more than 8,000 miles of pressure pipe assessment, Pure Technologies has found that only 4 percent of pipe has some level of distress while less than 1 percent requires immediate renewal.
By managing assets, operators can combine the best of each approach – renewing large-diameter pipe with isolated damage and replacing lower cost assets – to achieve the highest return on investment. Proactive utilities have realized that when implementing condition assessment for a system of pipelines, a risk-based approach is an effective way to ensure resources are invested in an intelligent, defensible and repeatable manner that maximizes the benefit of a program.
To determine risk, operators must measure the probability and consequence of uncertain future events – in this case, pipe failure. This can be determined by multiplying two factors, consequence and likelihood of failure. Consequence of Failure (COF) refers to the damage a failure would cause based on factors such as its location, the amount of users it supplies and its size and operating pressure. Likelihood of Failure (LOF) refers to the probability of a failure occurring based on factors such as age, pipe material, soil conditions, operating pressure, failure history, among others.
Generally, the Consequence of Failure is well-defined by the potential damage a pipeline failure would impose on the surrounding environment and is generally fairly static, or, once defined it is unlikely going to change rapidly. With this in mind the key to managing risk – or the uncertainty that a pipeline could fail – is in understanding the likelihood of failure. This can be achieved by quantifying the physical condition of the pipeline and understanding and quantifying the factors that affect the potential for deterioration of the assets.
To determine the physical condition of an asset, there are a number of technologies that can identify both the presence and level of distress. When determining which to use for each asset, risk is the most important factor. For high-risk assets, a detailed assessment is needed, while lower risk assets may warrant a lower-resolution screening or no assessment at all, as the cost of assessment would outweigh the benefit of replacing the asset entirely.
Naturally, as the resolution increases on an inspection technology, so does the certainty it provides to the operator, as well as the cost of the project. However, when deciding how to best assess critical pipeline assets, a simple comparison to how people should handle a significant health concern draws an important parallel for operators of large-diameter pipelines.
For example, if a person gets chest pain when they exercise – a serious problem – there are different levels of medical certainty they can attain. Going online to search medical journals or websites and completing a self-diagnosis is a free option, but it provides little certainty of long term health. A second option is visiting a general practitioner. He will be able to decide whether or not something is wrong, but won’t be able to diagnose it specifically and will recommend further investigation. To be confident in the results, the person would need to visit a heart specialist and complete specific tests.
While each of these options gets more detailed and expensive, the risk of leaving a heart problem untreated outweighs the cost of a detailed evaluation from a specialist. Utility managers should treat their critical large-diameter pipeline assets the same way a significant health problem, as the risk of uncertainty far outweighs the cost of being sure.
As municipal operators continue to grapple with aging water and wastewater infrastructure, identifying and managing risk should be an important consideration in the development of pipeline management, renewal and replacement programs.
We provide water and wastewater organizations a comprehensive suite of technologies that provide actionable pipeline information to better understand the condition of their pipe.
Pure Technologies is helping utilities manage their buried infrastructure through its Assess & Address which can often be implemented for only a fraction of the capital replacement cost.