Bermingham takes on a dynamic project to show what they can do
One of Canada’s oldest foundation specialists is helping Parks Canada turn the page on troubles with its historic Trent Severn Waterway.
When the Canadian federal government needed to repair Dam #37 at Bolsover near Lake Simcoe, they turned to Bermingham Foundation Solutions for the initial stages that would allow for the demolition of the dam and reconstruction. Working with general contractor Metric Contracting, shoring designer Isherwood Geostructural Engineers, contract administrator EXP and Public Works Canada, Bermingham crews would have to dewater the area immediately adjacent to the existing lock and dam and pro- vide a temporary diversion. This is all in a day’s work for a company that has been putting Canada on solid ground since 1897.
The Trent Severn Waterway is a hard-won piece of Canadian history with politicians and business interests fighting it out section by section. Joining Lake Huron with Lake Ontario, the 386-kilometre canal system was started in the early part of the 19th century and slowly completed over 100 years, at which time it was quickly made redundant by the completion of the larger Welland Canal. Today, the system is operated by Parks Canada as a tourist destination that brings boat traffic to cottage country through the locks between May and October. Last year, there was close to 100,000 lock operations.
With this traffic comes responsibility for upkeep and repair. The Bolsover lock #37 and dam at kilometre 284.9 was built in 1903 and had been showing considerable signs of its age. In 2013, the federal government announced a total expenditure of more than $24 million for the full replacement project at Bolsover, Ont.
According to Brian Abele, senior project manager at Bermingham Foundation Solutions, on-site construction of the Bolsover Dam, including the installation and removal of a water diversion and cofferdam system, began in the winter of 2013 and will last for approximately two years, over which time the lock facility will continue to remain operational.
“The project objective for Bermingham was to install a combi-wall/secant wall with various steel sheet pile walls to provide a temporary shoring system to dewater the area around the existing dam,” he said, reporting further that the shoring system was installed to allow Metric Contracting the ability to proceed with the main part of the project: the dam removal and replacement. To get this done, Bermingham constructed a double wall steel sheet pile diversion channel of 500 feet with an adjustable inlet structure and two drop structures to dissipate energy and reduce flow velocity.
“This allows for base flow and storm surge during the period the existing dam was being demolished and reconstructed,” said Abele, adding that stop logs were also used in the inlet structure to allow for volumetric control of bypass channel. Overall, Bermingham drove over 1,100 steel sheet piles for a total length of over 23,000 meters.
“The logistics of the site is such that it is very confining with limited access. This meant shoring designed by Isherwood was very complex and demanded precision,” said Abele. For example, Bermingham crews built a cellular bin wall system with combi-wall and sheet steel pile wall to separate the existing dam from the upstream reach. Each of these completed cells then provided an independent platform on which the Manitowoc 14000 crane base could operate. As each cell was completed, the new platform allowed a small area for crews and equipment to work in a process that was like a game of leapfrog.
According to Abele, precision driving was required for the combi-wall interlocks between 13-ton pipes and AZ 13 section specific sheets. Bermingham also used caisson wall and steel sheet piling on three sides of the dam to allow for excavation to bedrock. More, tiebacks and toe pins were used for anchoring the shoring system to the dewatering area. In fact, the project saw three levels of tiebacks that were staged with the demolition. Here, Bermingham crews used a Hütte HBR 605 hydraulic drill rig to get the job done with soil and rock anchors.
“We had to build out with a bin wall system combi-wall on one side, with straight sheet piling with rock anchors on the other. The entire platform had to be wide enough for both men and our Manitowoc 14000 crane,” he said, adding that this particular job used almost every type of shoring imaginable. “The on-site coordination was a constant challenge and we had to ensure that the lock kept operating.”
Abele reports that the project utilized a variable flow inlet to allow some semblance of normalcy while the project was underway. However, the fact that the work was taking place during winter months meant things were often far from normal. For exam-ple, crews had to break ice every day. Another factor in the difficulty of the undertaking was the need to drive piles into hard rock. To achieve the desired effect, piling had welded sleeves where toe pins were attached.
“The key thing is that this is an old structure. This meant a lot of monitoring, and we had limitations in the amount of vibration we could generate,” said Abele. The original drawings showed the structure was built using non-reinforced concrete with old timber piles. As such, it was extremely difficult to fully know the integrity of the lock and dam. “So, we had to be very, very careful at all times and used equipment such as an inclinometer on lock and roadway to tell us how things like the shoring system was behaving. Overall, this was a very dynamic project and we really took it on as a challenge.”
Challenges are something that Bermingham has become well known for over its long history. According to the senior project manager, they have been fortunate to have a strong skill set within the organization. For instance, operations manager Karl Christensen brought some 45 years of construction experience to the table while company CEO Patrick Bermingham offered regular input that sought to push the envelope and move teams to find interesting solutions to problems.
“When you have been around as long as this company, you have a far amount of experience on which to draw,” said Abele. “Without question, we turned to this experience on this job, which had lots of unique aspects and gave us an opportunity to show what we can do.” 