Commuters and residents on Alma Street undoubtedly noticed City Utilities trucks and crews surrounding a large hole in the recently repaved road on Friday May 17.
What's going on? Thurday, May 16,a crack occurred on a coupling (joint) of a water main pipeline on Alma Street north of El Carmelo, resulting in a major water spill. Utilities crews had to dig into the street to access the broken pipeline and worked through the night to replace the coupling and repair the pipeline. (Details here.)
The coupling break occured on an older concrete pipeline that leads up to the primary main on Alma. It was the primary main, and not this older pipe that was involved in the recent water main replacement project on Alma. This replacement project was completed earlier this year by the Utilities Department, after which the Public Works Department repaved the street with high-quality rubberized asphalt.
Was there a way to avoid digging into the new road? Unfortuantely, no. Portions of the pipeline lay directly beneath Alma and there was no way to access them to make the repairs without excavating all around the pipeline.
What happens next? Now that the pipeline is repaired and water service restored, the City Utilities crew restored the lane on Alma Street by Monday May 20th. Utilities and Public Works will coordinate for a long-term street repair solution.
Why not just replace the entire pipeline that broke? The simple answer is that the process is complicated! Here is some background:
The water distribution system resembles a map of an underground subway. There are primary "main lines" and then secondary "main lines" that branch off and then further smaller pipelines that branch off and lead up to the meters on every property. These various pipelines have been installed at different times and with different materials over the years. (The Water Utility was established in 1896!)
The recent main replacement project on Alma involved installing a brand new primary main to replace the aging pipeline that had been there before. But older pipelines still connect to the new main. We have an aggressive program to replace all the water mains in the City, but we are talking about 214 miles of pipeline and there is neither time nor resources to replace it all at once!
We prioritize replacing aging mains that we estimate are more likely reaching the end of their useful life, but this is not an exact science. Factors ranging from ground movement and weather/temperature to parts failing sooner than expected (e.g. a part with a 75 year “expected life” might go after “60 years” unexpectedly) all contribute to why a pipeline may fail in a certain spot. When there is a break, depending on what the ultimate cause is determined to be, it certainly raises the priority of replacing a given line.
In the case of the pipeline that just cracked, there were no signs of cracks or any other defects causing the break other than the failure right at the coupling. This pipeline is not on the current 5-year capital improvement project list. (See map link below.)
Once a pipeline is identified as needing replacement, that’s still not something City crews can just rush out and do. A major main replacement requires engineering plans to be developed, money put in the budget and approved by Council, a contract put out to bid for the actual work etc.
To view a map showing scheduled water main replacement projects through 2015, click here.
For general information on water main replacement and other Utilities projects, visit here.