May 1, 2010
FEATURE | Water, Wastewater, Sewer & Watermain
Alberta town uses trenchless system for manhole rehabilitation
When it came time to rehabilitate a number of aging manholes in a small community north of Edmonton, the town decided to use a trenchless system that saved both time, money and the aggravation of torn up streets.
The Town of Morinville recently contracted Edmonton-based Ivis Inc. to rehabilitate 12 manholes at a cost of $150,000.
Morinville’s director of public works Claude Valcourt said that this is the second year of a multi-year rehabilitation project and that 10 manholes were rehabilitated in 2009.
The new trenchless process involved installing a cured-in-place manhole (CIPM) liner consisting of multiple layers of load bearing laminates over the existing hole structure.
The public works director said the process took about two days per manhole, compared to five to seven days using conventional methods.
“Cost wise, it’s a little more up front, but if you figure out the road repair, the equipment and labour to do it the old way – it’s pretty close,” Valcourt said, noting that when the time savings, lack of traffic disruption and the product’s 20-year guarantee were factored in, the CIPM system was the way to go.
It is an opinion shared by Roger Ficko, an engineer and operations manager with Ivis Inc., who said trenchless technology and cured-in-place systems are growing exponentially each year.
“Anything that’s underground that needs to be replaced can be, in many cases, relined for a fraction of the cost,” he said, noting that cured-in-place technology is now also being used in pressure pipe and potable water applications.
Ficko explained that the Poly-Triplex CIPM liner that his company uses is made up of four materials: an epoxy resin, multiple layers of fibreglass, an impermeable layer to hold out moisture from the surrounding ground and a disposable bladder used in the installation process.
“The liner is designed to be a jacket, but it fits on the inside instead of on the outside,” Ficko said.
He noted that the liner has the flexibility to handle more than one million PSI.
“It’s multiple times stronger than PVC in bending strength.”
As each liner jacket is a custom fit, Ficko said detailed measurements must be made before the liner is ordered from its Florida manufacturer. Turnaround is about three weeks from order to installation.
Although the liner can be installed in hole structures that are only marginally clean, Ficko said preparation work is often necessary before the installation can go ahead.
Once the liner is ready to be installed, the epoxy resin is soaked into the liner material above ground, usually at the company’s shop.
Performing the process, which involves literally mopping the resin onto the liner, is done indoors to prevent any elements getting at the liner, which could compromise the epoxy’s adhesion integrity.
With the epoxy applied, the liner is transported to the jobsite by trailer, hoisted into the air and lowered into the manhole attached to an installation canister, which expands the liner into place with air pressure.
Ficko said that once the air pressure has stretched the liner out to its form-fitting dimensions, steam is applied to cure the liner in place.
“The steam is just shot down into the inside of the bladder-slash-liner, and after about 45 minutes, the epoxy then cures and you’ve got yourself a very stiff rigid liner.”
The Ivis engineer said the liner is so rigid that as the concrete or brick behind it deteriorates over time, the liner is designed to withstand the forces that are in place inside the manhole.
The products longevity was one of the motivating factors behind the Town of Morinville using CIPM technology for their rehabilitation project, a situation that has prompted neighbouring municipalities, including Spruce Grove, St. Albert and Sturgeon County to look into the system.
But bigger centres are also beginning to consider the benefits of CIPM liners.
Ficko said Ivis has already installed a 65-foot manhole liner in Edmonton and that the city is currently looking at having a 100-foot-plus manhole liner designed.
Ficko said the increase in popularity of CIPM liners has already led to a decrease in price, with liners costing half what they did just five years ago.
“There’s going to be more and more installed because it’s only slightly higher than some of the other options that are out there that are trenchless,” Ficko said.
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