干旱区生态环境知识资源中心

Much like many of the cities in the Western United States, specifically Arizona; the majority of Tucson's water pipelines average 30 years old. Contrast that with large municipalities east of the Mississippi that have average pipes in their system that are still performing quite well at over 100 years old, and many might question why a City like Tucson would invest in an assessment program specifically for their asbestos cement pipe (ACP). Tucson Water provides water for more than 730,000 customers and growing. Tucson, Arizona is located in the Sonoran Desert about 100 miles south of the capital city of Phoenix, and about 60 miles north of the Mexico border. The City officially dates back to 1775. Due to a large military base, mining, and the University of Arizona (U of A, founded 1885), the City has been growing for quite some time, but the retirement population starting in the 1970's has resulted in significant growth over the last 40 years. While Tucson Water has ACP dating back to the 1930s in their system, the majority of their 2,200 miles of ACP was installed during the past 50 years. To address this enormous, aging inventory of ACP in their system, Tucson Water has developed a collaborative public, private, and academia program team designed to manage, track and study every ACP failure that occurs in its system. Initiated in 2014, Tucson Water hired a local corrosion company to assist with the corrosion testing of its ACP, and most recently included to its team experts from the U of A construction materials lab. The nuts and bolts of the program is that when an ACP failure occurs, Tucson Water staff enters the failure event and type into Tucson Water's online Pipeline Risk Management (PRMS) database developed specifically for Condition Assessment, that initiates a process flow system for pipe, soil, and water samples to be collected from the location of the event. Each of the samples is tested; pipe by U of A, soil by the local corrosion company, and water sample by Tucson Water staff. As the testing is completed, the data is entered into predetermined fields in a database that can be tracked and queried by Tucson Water staff. Those queries can then be used to search for failure trends in a GIS/geospatial map, including failure types that can ultimately lead to identifying the root causes of failure. Examples of root causes of pipe failure could include acidic soils, aggressive waters, differential settling, poor construction, and operational concerns. Ultimately capital planning decision for repair, rehabilitation, and replacement can be made.