It’s unclear when the City of Tempe last inspected the 50-year-old water line that burst and has shut down a section of a major East Valley freeway for days. The 24-inch water line, which was supposed to last for another 25 years, broke Saturday, flooding a portion of the US 60 with 8 million gallons of water.
Over the past eight years, Tempe proactively replaced nearly 40 miles of concrete water lines, according to a statement from the city. The city added that steel lines, like the one that gave way, “have historically not been part of the same proactive inspection and replacement program that other pipe materials undergo.”
Tempe prioritizes its inspections and replacement based on the likelihood of failure. But after the pipe failure, the city says they will re-examine that strategy and has already started talking about the need to assess the risks. It’s still unclear when the freeway will be even close to reopening. The Arizona Department of Transporation sent the following statement:
Tempe’s contractors, with support from ADOT staff, are assessing conditions now that the city was able to stop the flow of water coming into the area (beneath the freeway). That was a necessary step in the process. The assessments will continue tomorrow as Tempe and ADOT work together on plans for repairing damage. The US 60 closures need to remain in place until repairs can be made and the freeway is deemed safe.
The City of Tempe sent the following statement about its inspections:
An abundance of infrastructure is under the ground throughout the city. In the case of water lines, among the types are concrete or steel or a combination. We prioritize our inspections and replacement program based on the likelihood of failure. In the last eight years, we have proactively replaced 38 miles of concrete water lines. That program has reduced the number of breaks throughout Tempe, saving money and disruption to residents and businesses.
Until early Saturday morning, a steel cylinder transmission line (a commonly used pipe) had never failed in the City of Tempe unless it was damaged by an external force, such as the work of a contractor. Historically in Tempe, steel lines have not failed because of things like corrosion or other ‘natural’ reasons. Their lifespans are typically 75 years and this pipe under the US 60 is 50 years old. Tempe will fully evaluate the cause of the failure in this instance but the city will offer no speculation or premature conclusions about cause.
Steel lines have performed according to specifications and have historically not been part of the same proactive inspection and replacement program that other pipe materials undergo. City staff have been planning for a new assessment program for steel transmission lines. Field work for the program should begin in the next several months. Given the current event, staff will re-examine that plan before launching it.
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