Water Resources Professional Project Reports

Document Type

Report

Publication Date

Spring 2019

Abstract

It is imperative to properly and proactively maintain a distribution pipe system. The benefits to optimizing a pipe distribution system include ensuring a safe water quality, reducing water loss from leaks and line breaks, minimizing revenue losses and providing a reliable service. There are also economic concerns as pipe replacement is extremely expensive; in the state of New Mexico, an estimated $1.16 billion in drinking water infrastructure is needed over the next 20 years. (USEPA 2013). Because distribution pipe is so costly to replace, an approach that only looks at age or type or non-system specific data may overestimate the quantity of pipe that needs to be replaced in order to receive the benefits of reduced pipe breaks and less water loss. An approach that incorporates system specific factors allows a utility to make better decisions regarding pipeline management that will achieve more benefits at a lower cost. This paper presents one method of using site specific data, specifically for the Albuquerque Bernalillo County Water Utility Authority (Water Authority) that serves the greater Albuquerque area, to drive infrastructure decisions. The risk model created incorporates a variety of site-specific inputs that can affect the probability of failure (turbulence, head loss, pipes installed from 1950-1960, metalloid pipes) and that affect the consequence of failure. (historical failures, failure frequency, water quality, point sources, public facilities and infrastructure) The inputs can then be entered into the model and used to predict which pipes are likely to leak. The information from the model can be used to direct a proactive leak detection program that seeks to find leaks while they are still hidden to the utility. This approach helps a utility repair pipes while leaks are still relatively small and reduces the overall water loss rate. In addition, the model can inform which pipes should be proactively replaced. The model does this by combining factors that predict a higher potential or probability of failure with those that predict higher consequences of failure. Those pipes that are highly likely to fail and will cause significant consequences if they do, are ones that should be prioritized for proactive leak detection or pipe replacement. While this work was done specifically for Albuquerque, NM, an approach such as this one can be used by water managers anywhere. The specific inputs to a similar pipe risk model might vary, a similar analysis can be done in other distribution systems to assess risk and further direct leak detection efforts. Completing this type of planning has the potential to have the triple bottom line benefits of financial (reduced number of breaks, less pipe needing to be replaced), environmental (reduced water loss), and social (more proactive, less reactive pipe replacement that is less disruptive to customers.) This pipe risk model was used to focus leak detection efforts for Albuquerque, NM in 2016-2017. The focus was identifying an approach to target the high risk metal pipes in the distribution network, which account for approximately 40% of the pipes. The resulting list of high risk pipe generated from this model prioritized leak detection surveys for 31 miles of metal pipe, or about 10% of the total 3,300 miles of distribution pipe. Also, the acoustic leak loggers were relocated to an area that had a higher concentration of high risk pipe. These two efforts resulted in locating 58% more main-line leaks proactively from FY 2015 (July 2015-June2016) to FY 2016 (July 2016-June 2017) and saved an estimated 19% more water annually.

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