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Pronounced temperature changes a culprit in winter water system outages

Low snow cover, an aging system, incorrect pipe installation, improper materials surrounding the pipes and corrosive soil also contributing factors

This winter, the Eagle River Water & Sanitation District Field Operations team made several repairs to water main breaks throughout the system within a period of six weeks in January and early February. The cluster of breaks is attributed to dramatic changes in temperature, among other factors.
Eagle River Water & Sanitation District/Courtesy photo

Since the start of the 2023-2024 winter season in November, there have been 14 water main breaks within the Eagle River Water & Sanitation District coverage area. Most of these unplanned water outages took place during a six-week period from January to early February.

“When we look at the averages over several years, that’s not necessarily an abnormal number of breaks,” said Brad Zachman, director of operations for the Eagle River Water & Sanitation District. There have been 10 breaks so far in 2024, and there were 12 in 2023, and 8 in 2022.

“I don’t think it’s uncommon to see a cluster of main breaks like this, particularly during the early and late winter, when temperature is starting to fluctuate above and below the freezing point,” Zachman said.



Eagle River Water & Sanitation District staff have conducted extensive research into the cause of the breaks, and found no change in system operations, and no abnormal pressure issues inside the system. As a result, Zachman said, “We attribute these breaks to environmental conditions.”

Causes of leaks

A water main break can be caused by “dozens of factors,” Zachman said, making it difficult to determine the exact cause of a break. In the Eagle River Water & Sanitation District system, there are four main factors that typically cause breaks. 

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First, the age of the pipe 鈥 older pipes are more susceptible to failures, and there are water mains in the system that were installed beginning in the 1960s.

Clean vertical breaks across the water pipe, called “circumferential breaks,” are evidence of the effect of a freeze-thaw cycle.
Eagle River Water & Sanitation District/Courtesy photo

Second, improper installation. “If a pipe is not properly set into a fitting 鈥 it might be offset a little bit, or not quite set all the way in 鈥 then over time, that improper installation can weaken the pipe and result in a failure years down the line,” Zachman said.

Third, the use of improper bedding or backfill material, which is the rock and scree that goes into the hole around the pipe to support and protect it. This is “probably the most common reason that we’re seeing failures right now,” Zachman said.

“Pipe, when it’s installed now in the current district specifications, has very specific bedding (and backfill) material requirements of how you fill in the trench and where the pipe is installed,” Zachman said.

In the 1960s through 1980s, bedding material was not installed, and backfill was made up of the same native material excavated from the hole. “In many cases, it’s rocks and boulders that are pulled out when they were doing the excavation, and if care wasn’t taken to pull those out before backfilling the pipe, then often we will see large rocks and boulders that are sitting on top of the pipe and creating these stresses and point loads on the pipe,” Zachman said.

Correct bedding material can also drain water away from the pipe and flex with the freeze-thaw cycle, removing some of the stress from hitting the pipe itself. All but one of the breaks this year did not have proper bedding installed, Zachman said.

The fourth main reason for pipe failures is corrosive soil. While current specifications require wrapping the metal pipe in a coated polyethylene wrap, which slows the corrosion on the pipe, original installations do not have the wrap, and can be weakened by the soil.

These four reasons are likely the underlying cause of the cluster of breaks this season. The ultimate cause, however, is the aggressive freeze-thaw cycle caused by dramatic changes in temperature.

This winter’s snow telemetry graph shows that snow levels were below average until mid-January. A lower snow total means a smaller snow blanket, which would otherwise insulate underground pipes from the effects of temperature swings.
Eagle River Water & Sanitation District/Courtesy photo

As air temperature begins to cool in the fall and early winter, moisture in the soil freezes. As it freezes, it expands, creating a downward force. While water pipes are buried several feet below the line at which the groundwater stops freezing, or the frost depth, the stress from the expansion creates an additional load. During a freeze-thaw cycle of rapid temperature fluctuations, the moisture in the soil will expand and contract, which can cause a pipe to break.

An extended cold snap, like in January, can trigger the same effect as a freeze-thaw cycle by forcing the frost depth deeper, increasing stress on the pipes.

A pipe can physically break in a number of ways, and when it breaks due to fluctuations in temperature, it displays what is called a circumferential break, which looks like “a clean vertical break across the pipe that looks almost like it was cut with a saw,” Zachman said.

“Most, but not all, of the breaks that we observed this season had this characteristic, in this cluster of events,” Zachman said.

Pipes can be protected from freeze-thaw cycles by the presence of a deep snow blanket, which prevents the frost layer from diving as deeply into the ground. Data from the U.S. Department of Agriculture’s Snotel site on Vail Mountain shows that this winter, snow cover was below average until mid-January, meaning there was less of a snow blanket to protect the pipes.

Fixing leaks

The amount of time it takes to fix a main break varies based on how difficult it is to access the pipe. “It usually takes from start to finish two to three days to make a repair, sometimes up to a couple of weeks, if it’s very complicated,” Zachman said.

To make repairs on an underground pipe, Eagle River Water & Sanitation District staff have to contact all other utilities to see if digging or taking other steps, such as removing trees, to make the repair might impact another utility’s operation, such as a power line.
Eagle River Water & Sanitation District/Courtesy photo

Removing trees, fences, and concrete, as well as deeper pipes, traffic, and use of the area, “complicates and extends the repairs,” Zachman said.

The operations team usually has all the parts they need on hand to get through “most major emergencies that we have,” Zachman said. This year, with the clustered outages, they had to make regular weekly trips to suppliers.

Before making any repair, Eagle River Water & Sanitation District staff must call all the other utilities to ask if they might encounter buried utility lines, sewer lines, gas lines, and more.

When it’s a planned repair, they can make the calls in advance. In an emergency, they must wait for responses to the calls, even if the water is completely shut off.

If other utilities are found in the area, the repair can take a lot longer because operations staff must hand dig around the lines.

Leak monitoring and detection

Throughout the year, the operations team does as much preventative maintenance as possible. Routine leak detection testing is conducted twice a year using a non-invasive acoustic to locate possible leaks, as well as constant pressure and water tank monitoring, to actively observe the behavior of a leak before it surfaces.

Detecting a leak in a pipe can be done through acoustic sounding, which involves attaching an acoustic system on opposite sides of the suspected leak and listening for signs of a break to find, or correlate, the leak location.
Eagle River Water & Sanitation District/Courtesy photo

If a leak is suspected, the field team will conduct a correlation analysis with acoustic equipment, which allows them to narrow in on where the leak likely occurred and excavate there to make the repair.

Zachman said his team is developing a strategy to replace the pipes in certain areas of Vail that experienced more breaks recently, although the majority of this winter’s breaks were spread throughout the system.

Heading into spring, the late winter freeze-thaw cycle is already occurring, which may lead to more water main breaks.

“If you see water running and you think that it’s a break, call us,” said Diane Johnson, communications and public affairs manager for the Eagle River Water & Sanitation District.

Often, visible running water in the spring is actually snowmelt, but it is better to have it examined just in case, Johnson said. Eagle River Water & Sanitation District staff can be reached 24/7 by calling the Vail Public Safety Communications Center non-emergency line at 970-479-2201.


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