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Eagle River Water and Sanitation District to investigate sewer line after discovering invading tree roots

No immediate impacts to service are expected

The Eagle River Water & Sanitation staff are launching an investigation into the interceptor sewer that runs from West Vail to Avon after discovering that large tree roots have infiltrated the pipe.
Eagle River Water & Sanitation District/Courtesy photo

The Eagle River Water and Sanitation District has begun an investigation into overactive tree roots that have breached the large-diameter sewer main, or interceptor, that conveys large volumes of flow from West Vail to Avon.

The roots have thus far been uncovered in a section of pipe in EagleVail that was experiencing surcharging (slow draining due to flow issues), and the rest of the pipe is under investigation. Despite the presence of roots, water district staff does not expect any immediate impact on service.

“This is not an emergency situation for us,” said Brad Zachman, district director of operations. “It’s concerning, and we’re working to characterize it, and we’ll work to do the rehabilitation that we need to do. But it’s not something that is of imminent emergency situation for the interceptor line.”



The interceptor is essential to the movement of wastewater between the Vail Wastewater Treatment Facility to the Avon Wastewater Treatment Facility. The interceptor has numerous service connections that feed into the pipe, including in Cascade, West Vail, Minturn and EagleVail, and the amount of flow in the pipe increases as it travels down the valley.

Vitrified clay pipe prone to root infiltration

While the exact age of the pipe is unknown, district staff estimate that it was installed in the 1960s or 1970s. The section of pipe that has been inspected and identified to have root infiltration issues is a vitrified clay pipe.

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Vitrified clay pipe is “actually a really excellent material, because it’s got great chemical resistance properties and can be very watertight,” Zachman said.

Years ago, vitrified clay pipe was the material of choice. However, most pipes installed today are made of plastic.

Captured on camera, tree roots have infiltrated deep into some sections of the interceptor, made of vitrified clay pipe.
Eagle River Water & Sanitation District/Courtesy photo

One of the identified problems with the vitrified clay pipe is that, with slight shifting of the pipe over time, small voids can form in the connections between pipe segments, Zachman said. Plant roots will then often try to access the water inside the sewer pipe.

“That one little pathway, even if it’s microscopic, can lead to more and more roots finding that same pathway and can actually create pressure and crack the pipe, which we think is what’s happening right now,” Zachman said. “So it’s largely attributed to age of the pipe and in many cases, large trees or other wooded material that have been planted above the sewer line that’s allowing these roots to dive deep and get into the sewer main.”

Though there is an easement over the interceptor, over the years, many trees have been planted on or near the pipe, causing concerns for district staff.

Large, essential pipe requires in-depth investigation, repair

When district staff first began to investigate the surcharging, or slow draining in the sewer system, they were not sure what was causing the problem.

Due to the pipe’s larger diameter and service to much of the upper valley community, it flows all day, every day. Investigating a section of pipe requires drying the pipe and putting cameras inside. 

The only way to stop the flow of the pipe in a particular area is to create a physical diversion. To conduct the initial inspection, district staff employed a special contractor to run two piping bypasses around the initial areas of investigation. The bypasses were each roughly a few hundred feet in length, dictated by the distance between manholes.

A lot of planning goes into implementing the bypasses, which are taking on the responsibility for the sewage flow usually handled by the interceptor, and overflow is not an option.

“It’s a very complicated planning process because you cannot take any chances with that equipment failing,” Zachman said.

For the initial investigation in EagleVail, planning for the two bypasses included multiple days of talking with stakeholders and customers in the area to pick a time to run the bypass to minimize the risk of overflow.

An investigation is ongoing to determine how much of the interceptor, which runs from West Vail to Avon, might be experiencing infiltration by tree roots.
Eagle River Water & Sanitation District/Courtesy photo

The actual bypassing work took about four to six hours. Staff dried out the pipe, cleaned the pipe with specialized equipment, and then used cameras to inspect the pipe. This was the first time district staff were able to identify the roots as the cause of the problem.

Before returning flow to the pipe, the investigated areas were cleared of roots and the pipe was reinforced with a cured-in-place pipe, a resin-soaked liner that hardens in place to reinforce the pipe, sealing off one of the areas where roots were entering the pipe.

During the bypasses, only the sole customer located within the bypass range was asked to limit their use of water. All other customers did not experience impacts to service due to the bypass, Zachman said, and this is the standard practice for all work on the pipe going forward.

The presence of roots in the interceptor in EagleVail alerted district staff to the possibility of similar issues in other stretches of the same pipe in other locations. An investigation will be taking place into the extent of the root infiltration.

Zachman said impacts on the community will be minimal throughout the investigation, with little to no impact on service for customers.

Water district’s three-pronged approach to repairs

It is difficult to know exactly how much of the interceptor might be experiencing impacts from tree roots, but some assessment can be done by looking at where trees have grown on top of the pipe easement. The situation is complicated by the size and essential nature of the pipe.

Much of the investigative and repair work will need to be done with the assistance of an outside contractor. While water district staff are familiar with handling root infiltration in sewer pipes, and employ preventative maintenance programs in other areas of the system that use vitrified clay pipe, the interceptor is too big for water district staff to use their regular tools to cut the roots out.

A section of the interceptor that has been cleared of tree roots and fitted with the cured-in-place pipe to protect against further infiltration.
Eagle River Water & Sanitation District/Courtesy photo

The water district is taking a three-pronged approach to fixing the problem. First, it is working to systematically characterize the extent of the issue. The problem may be isolated to a small section, or small segments, of pipe, something that will be ascertained in the initial assessment.

To determine the highest priority sections of pipe to analyze, district staff are first looking aboveground at areas with large trees that are likely to have long roots. The project will then proceed to manhole-to-manhole inspections of each segment of the pipe that may have root infiltration, involving bypassing, cleaning and videoing each section.

Next, district staff will do rehabilitation work on the sections of pipe found to need it. That includes using a contractor to cut out the tree roots and either completely replace the pipe or line it with a cured-in-place pipe, the resin-soaked liner that hardens in place and can reinforce the pipe.


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“Once it’s cured, then that liner is very hard. It’s seamless, meaning there’s no joints along the entire segment of pipe from manhole to manhole and does an excellent job of rehabilitating an existing pipe that might have cracks in it or joints that are getting roots infiltrating in,” Zachman said.

The cured-in-place pipe liner is a less expensive option than a full replacement, and “can last decades. It’s very much like a plastic PVC pipe, so it would have a similar lifespan to a brand-new pipe going in the ground, which is why it makes it such an attractive technology for this sort of application,” Zachman said.

The third step involves building money into the 2025 water budget to finance the repairs.

Work may begin as soon as late summer or fall, but the exact timeline has yet to be determined.


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