Going with the Flow: Kingston Replaced Major Corridor’s Watermain Without Stopping Traffic
Princess Street in Kingston, Ontario, has been one its busiest streets for over 200 years. It was part of the original 1817 Kingston Road from Toronto. It was called Store Street at that time due to a large government store at the lower end nearer the shore of Lake Ontario. It was given its current name in 1840 to honor the birth of Queen Victoria’s oldest daughter.
Over its long life, it’s taken part in a number of regional firsts. It was one of the first roads ever to be surfaced with macadam, and later, with concrete. It had been part of the first toll road between Toronto and Montreal. It was host to horse-drawn streetcars, until those were replaced by an electric street car system, which gave way to city bus routes. It’s still the most direct route for motorists coming in from the outlying neighbourhood of Western Heights and, further west, the community of Odessa to get to downtown Kingston and to waterfront attractions on the shores of Lake Ontario.
Now it’s among the first in the region to benefit from a trenchless technique known as the pipe bursting method.
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At only 2.4 m wide, the machine pit allows work to be done from a single lane with ample room for the operator, his assistant and the HammerHead HB125 pulling machine.
Open-cut construction anywhere along Princess Street poses a significant traffic problem. That’s a primary reason, said Matt Glass, engineering technologist for Utilities Kingston, that the City specified the pipe bursting method when it needed to replace a 820-m run of 200 mm and 250 mm (8 in. and 10 in.) cast-iron water main.
The section of pipe that lay between Princess Street’s intersections with Sir John A. MacDonald Boulevard and Concession Street had a history of leakage. It was under a traffic lane passing alongside commercial and institutional complexes with a strip mall on one side and the Kingston Centre shopping mall on the other, a Canadian Tire store and the Ontario Government Building, among others.
Specifying Pipe Bursting
Kingston is the only municipality in southeast Ontario to approve of and specify the pipe bursting method in its tendered projects. Glass said the trenchless method is one more “tool in its toolbox” to keep up with scheduled watermain replacement. All of Utilities Kingston’s pipe bursting project planning is done in-house to established criteria for determining when it is the most viable option. These factors include the depth of the watermain, the type and proximity of other infrastructure in the area, whether the existing pipe needs to be upsized, and traffic conditions. A high-traffic area like Princess Street, where watermain improvement is the sole purpose of the construction activity, certainly qualifies as a candidate for the method.
The work was performed by Gordon Barr Ltd. Founded in 1959 by Gordon and Ethel Barr, the company has been under management of their three sons, Bert, Brian and Brent, since 1979. Its experienced and knowledgeable field supervisory staff and highly skilled equipment operators and laborers are supported by the most extensive fleet of construction equipment and machinery in southeast Ontario. The company’s services include water, sewer, force-main and yard piping installation; tank and reservoir installation for fire protection, potable water and storm water detention systems; mass excavation and grading services; road and parking lot construction; landscaping; and heavy equipment rental. It’s a full-service company, covering everything from all required site remediation, clearing or grubbing at the outset of a project to the concrete flatwork, asphalt paving and landscaping for completion or restoration at the end of a project.
Mark Kent is estimator and project manager for Gordon Barr. He said although Gordon Barr primarily uses conventional, open-cut methods for pipe installation and replacement, it’s also the region’s premier pipe bursting contractor and the only contractor to offer pipe bursting as an in-house specialty. As such, Gordon Barr was first in the region to conduct a pipe bursting replacement project for a municipality and has now performed the two longest large-diameter watermain runs in its 100-km wide service area.
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For project consultation and pipe bursting equipment, it calls upon Andy Braithwaite, of HammerHead Trenchless based in Ennismore, Ontario, located about 100 miles northwest of Toronto. Braithwaite said most cities in other areas of Ontario have approved of the pipe bursting method. Just a few years ago, he might only see two to three pipe bursting jobs a year. Now his customers are doing two to three a month. In southeast Ontario, that’s Gordon Barr.
Commercial and institutional sections of the run require excavation, bursting and restoration to be done during nighttime hours. The narrow entry pit for this section of replacement PVC pipe permits traffic to continue unimpeded in the adjacent lane.
Project Requirements
Of the 820-m job, the pipe bursting method was specified for 675 m in a one- and two-step upsize of the existing cast-iron main with 300 mm, DR11 Fusible Brute PVC pipe. Work windows varied along the route. In business areas where traffic was highest during the day, all excavating, bursting, installation of valves and backfill and restoration took place in multiple shifts limited to nighttime hours. In residential areas, however, all work was restricted to daytime hours.
The project plan initially called for five separate pulls ranging in length from 60 to 150 m. To maintain one of the pipe bursting methods primary benefits – keeping traffic moving – Gordon Barr and Utilities Kingston worked together to modify pit locations. While the pipe bursting operation itself could be confined to the curbside lane, the new product pipe on the surface could not be fused up to a length that required pulling pipe across an intersection, impeding cross-traffic. This meant changing the number and location of entry and exit pits. Kent said they were still able to minimize excavation by locating the pits over existing valves and services where they could.
Bursting was also limited by active parallel services running next to the pipe. One 50-m section of the 200 mm cast-iron main was excavated rather than burst due to the proximity of a sanitary sewer. Gordon Barr replaced that section of sanitary sewer and its service connections, as well.
Gordon Barr began by creating a temporary water supply on the surface to residences and commercial, industrial and institutional customers along the route. Its crews excavated and disconnected the existing services and valves in preparation for bursting.
Depth of the main varied from 1.5 to 2.4 m, much of it backfilled over rock. The crew used a hydraulic hoe-ram when it needed to deepen some of the machine pits to line up the pulling unit with the pipe.
The machine pit dimensions were approximately 6 by 2.4 m, ample room to accommodate the HammerHead HB125 bursting unit and its operator and helper inside the required trench box. Road plates were used where traffic flow needed to be restored between shifts. Entry pits were ranged from 9 to 15 m, varying with pipe depth, to accommodate the large bend radius of the stiff, thick-walled fusible PVC.
The HB125 is designed for use on pipe 152 to 508 mm in diameter. The machine uses heat-treated alloy pull rod with API-style joints. The rods will not buckle in long pay-outs through encrusted pipe or sweeping bends and can handle the machine’s 113-tonne pulling force capability during the simultaneous pipe bursting and product pullback operation.
Once pull rod had been paid out from the HB125 in the machine pit to the entry pit, the crew attached a pipe pilot, bursting head and 406 mm expander. Kent Westendorf, onsite HammerHead consultant during the project, said the 406 mm width was necessary to accommodate the true outside diameter of 12-inch PVC, which is closer to 360 mm.
Inside the expander, the fusible PVC was attached to a special pulling head. As the bursting head and expander moved through the pipe, fracturing the brittle cast-iron pipe and pressing its pieces into the sides of the enlarged bore path, the pulling head simultaneously drew the fused-up length of PVC into place behind it.
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Site Challenges
The job was so well planned that Gordon Barr encountered no significant problems during the project. However, Kent said, there are a couple of things they would have done differently. The most significant lesson they learned was to begin with a complete CCTV inspection of the entire project instead of section by section.
“Our initial decision was based on a previous project, where we held off starting until we could get the CCTV through excessively corroded pipe,” he said. “In hindsight, the section we sampled for this job before we started had not had that kind of corrosion. It wouldn’t have been an issue on this job. So, while we wanted to avoid delay in starting this project, it cost us time in the end.”
The first three pulls on this job had each been made in a single shift. On one pull, however, the crew ran into an obstacle they suspected was a recently replaced valve. They struggled to burst through it for a while before suspending operations to open the extra lane for the peak traffic hour. Whatever it was, the crew pulled through successfully the next shift. Excavation was not necessary.
However, when the crews discovered bends in the final runs of pipe that would not permit pipe bursting, they did have to break the run into two parts, digging over the bend to separate the runs.
Of 12 catch basins lying over the pipe path, 10 were damaged by the slight swelling of the ground. This had been expected due to their proximity with the water main. They were excavated and repaired. Restoration was completed as they progressed down the run. The pipe run was tested and returned to service in relatively short time for so large a project.
“Using the pipe bursting method,” Glass said, “Utilities Kingston was able to complete the project, from groundbreaking to completed restoration, in nine weeks. The short timeframe accommodated our high traffic volume.”
During that time, impact on local traffic and commerce was minimal, Kent said. “Our temporary water supply pipe was shallow-buried under the asphalt at entrances to businesses. Water interruptions were kept to just once at the beginning of the project while switching over to temporary supply and once again near the end of the project, switching back to the new main. All shutdowns were coordinated in advance with the businesses and some of the shutoffs were performed during nighttime hours with no impact on their operations.”
This was Gordon Barr’s first project using an HB125. They had used an HB100 on a previous municipal job. Kent said he has been pleased with HammerHead products and service. “The pipe bursting equipment supplied by Hammerhead worked flawlessly, and the on-site technical support they provided was second to none.” For instance, Kent said, when a 200 mm splitting head deformed after a tough pull, “Hammerhead was able to expedite a replacement for us on a rush schedule.”
While there are as yet no further projects scheduled for pipe bursting, the City of Kingston has again demonstrated its value as a viable alternative for replacing infrastructure, reducing restoration costs and the project’s impact on community activities. In this case, the method permitted Princess Street, it continues its two-century-old legacy as one of Kingston’s busiest streets without interruption.
