To dig or not to dig? Trenchless technologies like ultraviolet (UV) curing point to a future for rehabilitating underground pipes without digging.
Communities of all sizes now have an additional tool to rehabilitate water and sewer pipes without digging them up. It’s ultra violet (UV) cured-in-place piping (CIPP), and some industry experts see it as the future of trenchless technology. One community in the Twin Cities metropolitan used the new technique to rehabilitate utilities with minimal disruption to property owners. This first UV curing application in Minnesota was completed at Medicine Lake in Plymouth on sewage piping.
Why did Medicine Lake choose to use UV curing?
The City’s sewer main had reached its life expectancy and needed rehabilitation. The community is located on a narrow 210-acre peninsula on a lake, so a less invasive approach seemed attractive. Traditional curing, which uses steam and hot water, comes with disadvantes such as requiring an extensive footprint, a long time to perform and heavy equipment. When the City turned to UV curing, they were able to avoid digging up residents’ pristine shorelines and dramatically reduced the impact that heavy equipment would have made.
Explore the top ten reasons why UV curing may be the appropriate solution for your next pipe rehabilitation.
Top 10 reasons to use UV curing CIPP
1. Infiltration installation
A sock liner is installed inside of the existing pipe and inflated with compressed air. Using robotics, UV light is then applied to cure and harden the sock liner, thus creating a new pipe. Without the need to pre-line or apply grout to stop infiltration, infiltration installation requires fewer steps in the rehabilitation process.
2. Small construction footprint
Lightweight and portable equipment used during UV curing makes it easy to get to difficult-to-reach areas. This is a key advantage for working in constrained and sensitive quarters, such as near lakes and in residential backyards.
3. Environmentally friendly and safe
The UV curing process doesn’t use water, so there's no need for heavy water equipment, which reduces the footprint and impact on residential properties. Traditional steam and water methods also create gas, causing a need to protect both workers and residents.
4. Faster cure times
You can service approximately 5 ft. of piping per minute, although time varies based on liner thickness. UV curing dramatically shortens the time required to rehab piping, which means less downtime local utility services for residents.
5. Completely trenchless
With UV curing, robots access the piping through manholes. No digging is required, and this is a benefit because digging can be an expensive and destructive process.
6. Easy inspection
Closed-circuit TV is used to inspect the liner for wrinkles or folds prior to curing. Traditional lining with steam or hot water does not enable liner inspection until the pipe is cured out and hardened.
7. No damage to current pipes
There’s no concern about damaging PVC pipe with excess heat, which is a possibility with other trenchless methods.
8. Minimal impact to sewer capacity
The stronger yet thinner material minimizes impact to the existing sewer capacity. The high-strength fiberglass lining results in thinner wall design, maximim hydraulic capacity and reduced resin exposure.
9. Health concerns minimized
Any odors and effects of styrene resin, which is used to cake pipes, is minimized as UV-cured CIPP fully encapsulates old pipes, sealing them and limiting potential harm.
10. No "cooking"
UV curing is an environmentallyl friendly process that involves no cooking of the existing pipes, therefore restricting the amount of stryene released.
It’s cool! UV technology and tools naturally harden when exposed to the sun's UV rays. For this reason, the uses of UV curing continue to expand. UV curing works on pipes of every shape and size. Some agencies and municipalities use UV curing to repair highway culverts and water mains and to rehabilitate the piping systems used for process wastewater.
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Top 10 Reasons to Use Ultra Violet Cure
Bringing it together
UV curing is the future of trenchless technology due to its efficiency and environmentally friendly techniques and applications. Towns and cities of any size could benefit from UV curing -- especially if the project area is adjacent to water or is in a confined area.
About the Experts
Dave Hutton, PE, is a senior project manager who helps cities, utilities, agencies and private industry improve their infrastructure, with a focus on applying trenchless technologies to aging pipe networks. Contact Dave