In the 1990s, microtunneling was in its infancy in Canada and the projects had mixed results, leading owners and engineers to shy away from the technology in favor of traditional tunneling or other trenchless methods. Then, in 2011, Ward & Burke Construction Ltd., re-introduced the method to the country, and the rest, as they say is history.
Ward and Burke Construction Ltd., based in Ireland, brought the updated microtunneling technology – already a mainstay in Europe – to Canada to complete the Gore Road project – a new 1,200-mm ID sanitary sewer pipe running directly under an existing 1,800-mm concrete pressure pipe water transmission line and an existing creek at Gore Road, in Brampton, Ontario. Based on the success of that project, owners and engineers took note, and the door began to open for additional projects in Ontario.
That marked a trend of increased innovation in the microtunneling market in Canada and across North America. The first curved drive in Canada took place in 2013. Longer drive lengths, compound curves, and now tighter radii and larger diameters increase the range of what can be accomplished with microtunneling techniques.
“The market is emerging and varies greatly [by province],” says Craig Vandaelle, general manager, tunneling Michels Corp. “Ontario seems to be more progressive and definitely the most active and strongest market for microtunneling.”
In the United States, microtunneling was introduced in the 1980s and remained a fixture in the utility construction market. However, growth was limited and owners and engineers were reluctant to specify technologies like curved microtunneling that were prevalent in other parts of the world.
That began to change around 2010 when the first curved drive was completed by Northeast Remsco in Hartford, Connecticut, that resulted from a value engineering proposal. In 2012, Frank Coluccio Construction Co. completed the first compound curve in the United States – an S-curve in Honolulu, Hawaii – which also happened to be the first curved microtunnel drive specified in the design documents in the United States.
The trend is here to stay as curved drives are becoming more and more common across the United States. In combination with longer drive lengths, curved drives can lead to the elimination of intermediate shafts that can lower the cost of construction and reduce disruption on the surface.
Microtunneling in Canada
Let’s take a look briefly at what changed from the 1990s to 2011, and 2011 to today.
The mixed results in the 1990s were due to machines not being robust enough to handle the glacial till ground conditions across the county. According to John Grennan, P.Eng., director of Ward & Burke Construction in Canada and the United States, the ground conditions contain granite cobbles and boulders and, in most locations, are unavoidable.
“The tunnel boring equipment must be able to break them down and ingest them to advance forward,” Grennan says. “The older microtunnel boring machines (MTBMs) manufactured in the 1980s and 1990s did not have the torque and the cutting head technology to deal with these cobbles and boulders.”
The end result when the machines met these earthen adversaries – was the construction of rescue pits to remove the obstructions and with that, came increased project costs. The methodology fell by the wayside until the Gore Road project.
“Owners and engineers quickly realized that the microtunnel equipment could now deal with these glacial till ground conditions and also provide many advantages over traditional open-face tunneling systems,” Grennan says. “Groundwater and cohesionless ground conditions had plagued many tunnel projects with open-face tunnel equipment. Massive dewatering and ground improvement attempts had failed on many occasions due to varying and varied ground conditions, resulting in tunnel delays and cost overruns.”
In these conditions, microtunneling did not need dewatering or ground improvement and after years of owner and engineer frustration when it came to dealing with these conditions, microtunneling has grown especially in Ontario.
“It has grown from non-existent to a significant market in the last five years. It’s expanding with greater expertise by consultants, contractors and suppliers,” says David Archer, P.Eng., engineering and business development, DECAST.
DECAST, based in Utopia, Ontario, manufactures reinforced concrete microtunneling pipe. In 2016, it expanded its facility to 475,500 sq ft, to meet the increasing demand for the pipe across Canada.
According to DECAST, in addition to the improved technologies, the resurgence is due to the fact that projects to install underground conduits – water main, sewers and others – are now tunneled or partially tunneled and microtunneling offers less disruption while construction is performed. The company adds that microtunneling involves no underground labor.
“Tunnels have to be deeper to clear the web of utilities less than 10 m in depth. Open-cut methods are not so easy when the risk of cutting a T1 line for a building or housing development is considered,” says Tom Fuerst, utility tunneling manager, The Robbins Co. “Microtunneling puts the pipe below this web of utilities in shafts that are not so expensive – even though the entry and exit shafts could be the most expensive components of the project cost.”
According to Fuerst’s estimate, 10 years ago, there were 10 or fewer microtunneling systems in Canada. Today, that number is about 40 or more, he says.
Population growth drives the construction market and Canada, in most provinces, is a growing country. According to Statistics Canada, the population of Canada grew to 35,151,728 (a 5 percent increase) from 2011 to the 2016 Census. Most microtunnel projects are driven by a need for increased capacity for water and wastewater systems.
Microtunneling in the United States
While microtunneling in Canada has gone from “0 to 60” in the last few years, the market has been steadier in the United States, despite the apprehension of taking on curved drives.
“The market in the United States has been pretty steady,” said Rob Dill, associate vice president with Aecom. “We are now seeing a steady diet of microtunnels in places like Cleveland, as well as other locations. There is also a pent-up demand for tunnels. There was a lot of talk about infrastructure spending in the 2016 U.S. elections and I think a lot of owners are taking a wait-and-see approach to see what develops in that regard. Additional funding would lead to an uptick in microtunneling.”
The work in Cleveland is a result of a consent decree to update water and sewer infrastructure. Even cities and agencies that are not under consent decrees face challenges related to updating aging infrastructure.
“The U.S. microtunneling market is growing for many reasons,” said Lester Bradshaw, president of Bradshaw Construction Corp. and interim chair of the North American Microtunneling Association (NAMA). “First, aging infrastructure replacement and/or expansion is an increasingly critical problem throughout the U.S. The recent severe recession exacerbated the problem by delaying much of the needed work, but it is now moving forward.
“Second, advances such as microtunneling in all types of rock and curved microtunneling have broadened demand and lowered both costs and the impact to the public.
“And third, NAMA helping to add the microtunneling specification standards to industry participants increases the understanding and use of microtunneling throughout the U.S.”
While the market is generally growing, the growth is sporadic. The work in the Midwest comes at a time when work on the West Coast seems to be slowing down.
Other trends include longer drives lengths. While the U.S.-record of 3,000 ft was set in 2008 by Kieiwit working on the East Side CSO project in Portland, Oregon, drives lengths exceeding 1,000 ft or 1,500 ft are becoming more routine.
Noteworthy recent projects include the Westerly Low Level Relief Sewer for NEORSD in Cleveland, completed by Ward and Burke. This included a 1,857-ft drive that marked the longest curved microtunnel distance record in the United States through a value engineered change proposal to the original scope.
Ward and Burke is currently working on the Kingsbury Run Culvert Repair, which will include a value engineered curved drive of over 2,400 ft with a horizontal radius of 1,000 ft, which would set a new mark for the longest curved drive completed in North America.
With the successful jobs completed for NEORSD by Ward and Burke and Super Excavators, which completed the first curved drive for the district and recently completed a 760-ft curved drive with a 5.5 percent slope, the district has developed a sense of comfort with curved drives. In fact, the district is including a curve in the designs for its upcoming Doan Valley project. Previously, the district had allowed curves as value engineering proposals.
The 2017 Trenchless Technology Project of the Year for New Installation is the Rebecca Trunk Wastewater Main for Halton region. The project involved more than 4 km of 1,200- and 1,350-mm microtunnels within Oakville, an urban and affluent town along the shore of Lake Ontario. The project included nine microtunneling drives (eight curved) ranging in length from 180 to 626 m), with seven of the drives completed in rock. Ward & Burke was the contractor on the project.
And the 2017 Trenchless Technology Project of the Year for New Installation Honorable Mention went to the Crabtree & Upper Pigeon House Sewer Tunnels Project for the City of Raleigh, North Carlonia was engineered by Hazen & Sawyer and completed by Bradshaw Construction Corp. The project involved 2,880 lf of 75.4-in. and 60-in. using microtunneling in 10 tunnels by both two-pass and one-pass pipejacking. Ground conditions were highly variable, ranging from very soft ground to rock of 25,000-plus psi UCS.
“This [success]has resulted in a great confidence in the area for microtunneling,” Grennan says. “Owners and engineers have become very comfortable with the installation method and want to use it as their No. 1 method due to the high success rate and low number of issues to date.”
What Lies Ahead?
“We still have a nervousness by owners and engineers to utilize the advantages of the equipment and technology available to them,” Grennan says. “It is very similar to the Toronto market six years ago. It will take a few successful projects to build confidence in the area.
“We still see a reluctance by some owners to let go of the old tunneling systems and embrace the technology available. We are also seeing a reluctance to utilize the full potential of the equipment in terms of the diameter of installation and length of installation.
“Numerous successful projects have been constructed to drive the industry further forward. We hope that these successful projects will help increase further acceptance of the method.”