Purpose: Reliability centered maintenance (RCM) is a process used to determine activities to be taken to ensure an asset continues to perform asset's function in asset's present operating context by identifying asset's function, failure modes that could preclude performing asset's intended function, prioritizing failure modes and determining effective preventative maintenance tasks that can be cost effectively and efficiently implemented to reduce the likelihood of a failure.Design/methodology/approach: A comprehensive survey of literature was undertaken to examine the current industry state of practice. Various industries were examined to better understand applications of RCM within the various industry sectors and determine those industries that RCM has not historically been readily adopted. A case study example of RCM applied to radial gates for water control in open channel canals for water conveyance is presented to demonstrate a civil infrastructure application.Findings: The results found that RCM has been used since RCM's inception in the airline industry during the 1960s to reduce the cost of maintaining aircrafts. Over the past 40 years, an assortment of industries has begun implementing cost effective preventative maintenance tasks identified during RCM analysis. However, there is a noticeable lack of civil assets being analyzed by RCM, such as water conveyance systems and other civil infrastructure systems vital to the health and well-being of today's societies.Originality/value: The comprehensive literature review of the current state of practice will provide a better understanding of the various applications of RCM to facilitate RCM's application to other industries, thereby reducing failure due to early identification of maintenance tasks. An example RCM demonstrates the application to a radial gate, used in water conveyance for the drinking water and irrigation sectors, which have not historically used RCM for developing maintenance strategies.

The consequences of failures from large-diameter water pipelines can be severe. Results can include significant property damage, adjacent damage to infrastructure such as roads and bridges resulting in transportation delays or shutdowns, adjacent structural damage to buildings resulting in loss of business, service disruption to a significant number of customers, loss of water, costly emergency repairs, and even loss of life. The Washington Suburban Sanitary Commission (WSSC) in the United States found that flooding was the greatest concern due to its potential duration, the potential for broad geographic impact, and its role in crater creation. Public safety, property damage, social and economic consequences, and loss of water service and for how long is also of paramount concern. The American Water Works Association’s (AWWA) 2020 “State of the Water Industry” report states that the top issue facing the water industry since 2016 is aging infrastructure, with the second being financing for improvements. The industry needs to find novel ways of extending asset life and reducing maintenance expenditures. While there are many different assets that comprise the water/wastewater industry, pipelines are a major component and are often neglected because they are typically buried. Reliability-Centered Maintenance (RCM) is a process used to determine the most effective maintenance strategy for an asset, with the ultimate goal being to establish the required function of the asset considering the required reliability and availability at the lowest cost. The RCM philosophy considers Preventive Maintenance, Predictive Maintenance, Condition Based Monitoring, Reactive Maintenance, and Proactive Maintenance techniques in an integrated manner to increase the probability an asset will perform its designed function throughout its design life with minimal maintenance. RCM requires maintenance decisions be based on maintenance requirements supported by sound technical and economic justification. However, one industry where principles of RCM are in its infancy is the water/wastewater industry. This paper provides a case example and numeric modeling for use in RCM analyses for developing maintenance strategies for large-diameter water pipelines, particularly prestressed concrete pipelines, and proposes an approach for determining the most effective and efficient maintenance activities for large-diameter prestressed concrete water pipelines. The case study discussed in this paper analyzed wire breaks over time to predict when certain thresholds would be reached. The intent of this study is to predict when a specified threshold will be reached. From the RCM, a threshold was set to begin planning, budgeting, and scheduling maintenance activities when 55% of the wires in a frame or two adjoining frames are distressed or when 65% of the wires in non-adjacent frames are distressed. The results from the numeric model predict the 55% threshold may be reached in August 2025 for the most distressed pipe segment.

The Central Arizona Project (CAP) operates and maintains three (3) 21-foot diameter pre-stressed concrete non-cylinder pipes (PCP) as part of the aqueduct system that delivers almost 1,950 million gallons of Colorado River water per day, to Maricopa, Pinal, and Pima Counties in central and southern Arizona. The pipelines, installed in the late 1970’s, have experienced pre-stressing wire breaks and have been repaired several times since the early 1990’s. The wires have broken primarily due to defects in the wire. One of the pipes, the Centennial Wash Siphon, conveys water beneath Interstate-10 and the Centennial Wash, about 80 miles west of Phoenix, AZ. The siphon is upstream of CAP's first customer turnout, and as such is critical in the aqueduct's conveyance and delivery system. An internal electromagnetic inspection in January 2013 discovered several pieces of the pipe comprising the siphon had many broken prestressing wires, prompting a closer inspection and assessment of the siphon. The case study described herein examines inspections, assessment, monitoring, and subsequent repair using post-tension tendons of the Centennial Wash Siphon. This paper further discusses the ongoing efforts of monitoring, assessing, repairing, and maintenance practices for the largest prestressed concrete pipes in the world. A brief history of the siphons includes manufacturing of the 252-inch diameter prestressed concrete pipes, installation of the pipelines, and early investigations and repairs. The focus of this paper is on the assessment and monitoring since the last repairs in 2006, specifically newer technologies that have emerged to assist CAP in monitoring and making decisions in the repair methods and locations. Relevant points include a discussion on the excavation of the pipes requiring repair, the repair work (post-tension tendons), and maintenance practices. A brief discussion will follow on new technology recently installed in all three of CAP’s prestressed concrete siphons.

The Central Arizona Project (CAP) owns, operates, and maintains 73 acoustic, ultrasonic, transit-time flowmeters measuring flow through 103 pipes - either measuring flow from pumping plant discharges, measuring water delivered to customers, or measuring flow for groundwater recharge credits. Flowmeters are essential to CAP's operations, water accounting, and customer billing. The CAP performed an analysis of each of its acoustic transit-time flowmeters in an effort to: (1) identify existing or potential problems with the accuracy of the flowmeters and make recommendations for corrective action; (2) review and improve maintenance procedures; and (3)examine the long-term viability of the flowmeters. Justification for the study was derived from the following difficulties: ≤ Inconsistent losses reported in monthly water balance studies ≤ Occasional discrepancies between CAP flowmeters and some customer's own metering systems. The desired outcomes of the investigation are to: ≤ Improve the accuracy and reliability of CAP's flowmeters by developing guidelines that are consistently applied in the maintenance and operation of the flowmeters ≤ Identify which flowmeters have reached, or are nearing, the end of their useful life and develop a program to replace those identified flowmeters This paper reviews the replacement project that resulted from the initial investigation.

The Central Arizona Project (CAP) recently completed relining two 12-ft diameter steel pipes and associated manifold systems at the Mark Wilmer Pumping Plant on Lake Havasu in western Arizona, using the construction manager at risk (CMAR) project delivery method. The Mark Wilmer Pumping Plant withdraws about 1.6 million acre-feet (ac-ft) of water each year from the Colorado River and via six pumps lifts the water through two 12-ft diameter steel pipes about 850 ft to the Buckskin Mountain Tunnel. The pumps are arranged in two-sets of three units which allows isolation of three pumps, a single manifold, and a single discharge pipe for maintenance while still operating the other three units and associated valves and piping. The two 144-in diameter steel discharge pipes are each about 2,300 ft long with slopes that vary from about 9° to 45°. The discharge pipes and manifolds were installed with the construction of the pumping plant in the early 1980s, and the pipes and manifolds lined with a hot-applied-cold-tar-enamel (HACTE) in 1982. In 1986, the plant was commissioned and has been moving water for over 30 years. In 2016, the right pipe and manifold was relined, and in 2017 the left pipe and manifold was relined. As part of CAP’s ongoing asset management program, the manifolds and discharge pipes have been inspected multiple times, and while it was apparent the HACTE was failing, CAP performed spot repairs of the lining as outages and internal man-power allowed. In 2012, it became evident the lining had reached its end and more than just spot repairs would be required to protect the integrity of the steel pipe. A project was developed to remove the HACTE and replace it with a modern coating system. Due to the physical extremes of the work and short outage window, it was decided to use an outside contractor to perform the work, and rather than use the traditional design-bid-build delivery method, CAP decided to use the CMAR approach. This paper will examine the initial development of the project surrounding the decision to use CMAR, outline the contractor selection process and the pros/cons surrounding that process, discuss the role the selected contractor played in the design (pre-construction services) of the new coatings system, then look at the development (negotiations) of the guaranteed maximum price (GMP), and finally review the delivery of the project. A brief discussion of CMAR versus design-bid-build and how the CAP approaches each will also be included.