Many underground infrastructure capital enchancment tasks are driven by capability points.
The South Surrey Interceptor undertaking is not any totally different. Work is wrapping up on Part 2 of the Johnston Street Section of the undertaking and — what many consider to be — the most important diameter microtunnelling undertaking in North America.
The venture owner, the Metro Vancouver Regional District (Metro Vancouver), manages roughly 530 km of trunk sewers for the 23 communities and serves roughly 2.5 million individuals within the Decrease Mainland. When complete, the South Surrey Interceptor will gather sewage from South Surrey, White Rock and Langley and convey it to the Annacis Island Wastewater Remedy Plant.
The undertaking is a twinning and is needed to reinforce capacity and improve environmental protection in the area. When the undertaking is complete in 2022, Metro Vancouver can use both pipes to convey sewage, regulate flows as needed and even use one of the strains to hold sewage earlier than delivering it to the remedy plant.
Johnston Street Section Part 1, an open-cut section, was completed in December 2018. Part 2 of the part began in June 2018 and consists of roughly 800 m of 3,050-mm ID (3,600-mm OD) strengthened concrete gravity sewer in Surrey, British Columbia. Key undertaking challenges embrace tunnelling beneath enterprise parks and metropolis streets, bouldery ground and tunnelling near several utilities.
“The prevailing South Surrey Interceptor is a concrete box sewer that was constructed within the 1970s,” says Mike Jokic, senior venture engineer for Metro Vancouver. “The twinning of the 10.5-km interceptor began in 1999 and these phases are the final of the undertaking.”
The Johnston Street Part Part 2 venture was designed by Stantec Consulting Ltd. (Stantec) with Part 2 microtunnelling handled by Ward & Burke Microtunneling Ltd. Stantec was additionally concerned in previous open reduce sections.
Stantec’s unique plans for Part 2 referred to as for 2 brief tunnel sections totalling roughly 400 m and two open-cut sections. The originally designed open-cut sections have been adjoining to buildings — approximately 10 m away — and throughout 152nd Road, a busy North-South route that intersects with British Columbia Highway 10.
In accordance with Anil Dean, P.Eng., Stantec’s international apply leader for its water tunneling and trenchless apply, there were initial considerations about settlement and low cover — less than 2 m — that resulted in the two open-cut phase designs. Nevertheless, a value-added proposal in the Ward & Burke bid submission eliminated these segments in favour of microtunnelling the entire stretch.
“We allowed a number of totally different development strategies to maximise contractor flexibility. We favored microtunnelling because of the bottom and groundwater pressures by way of the glacial sort supplies, a few of which have been granular. Additionally, the water desk might have been within the tunnel heading, so ideally, we needed the contractor to make use of a know-how that would handle the water bearing soil,” Dean says. “We had one curved alignment within the unique design and Ward & Burke added a second curved alignment to Drive four.”
Ward & Burke proposed the change in plans because it might make the challenge inexpensive per metre, enhance logistics and mobilization, stay within Metro Vancouver’s accepted proper of approach and would solely add one caisson shaft to the challenge.
“There have been a number of benefits to Ward and Burke’s proposal. The primary one was that it eradicated the open-cut part by way of the Benchmark Business Centre and across 152nd Road,” Dean says. “As you possibly can imagine, open slicing with a 3,600-mm OD pipe, there’s a whole lot of impression. With it being tunnelled, the one impression is thru the 4 shafts.”
Jokic adds, “The primary challenge with crossing 152nd Road is that it’s about 450 m away from the intersection with Highway 10. We might have had to utterly shut the street to get it achieved by way of open reduce. We have been additionally involved concerning the 10 providers within the street together with a metropolis sanitary sewer and an intermediate strain fuel line.”
As a result of this challenge marks Ward & Burke’s first in British Columbia, Metro Vancouver accomplished its due diligence before agreeing to go ahead with the adjusted plan. Jokic notes that comparable Ward & Burke tasks in Ontario and the USA gave Metro Vancouver the arrogance that this was the correct determination. He adds that even if the prices have been equal, the decreased disruption of microtunnelling made this the best way to go.
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“The most important cause we proposed microtunnelling the entire challenge was due to value. For us to mobilize, from Alberta, for 2 brief tunnel drives, it makes it far costlier per metre, whereas we do the entire venture (800 m) it was inexpensive per metre for Metro Vancouver.” Cillian Cotter, most important website engineer for Ward & Burke. “We have been in a position so as to add a second curve to stay within Metro Vancouver’s proper of means with the addition of an extra shaft.”
The undertaking is divided into 4 drives with approximate lengths as follows — drive one is 370 m, drive two is 110 m, drive three is 40 m and drive 4 is 285 m — and the curved sections have been in drives one and four.
Acquainted Gear, New Pipe
Ward & Burke is utilizing a Herrenknecht AVN2500D, which that they had up-skinned in Germany to a three.6 m OD, two centrifuges for slurry dealing with and separation and a VMT steerage system for steering. Cotter notes that Ward & Burke has used this similar machine on 2 m and a couple of.7 m tasks in Alberta and Manitoba. Cotter notes that it is the success of those other tasks — and the experience of its TBM operator — that they have been confident within the success of this venture.
Up to now, Ward and Burke has relied on Decast to provide its jacking pipe for Canadian tasks, for logistical and prices causes, the strengthened concrete pipe for this challenge is sourced regionally.
“The large consideration, particularly with a challenge going via the winter, is transporting the pipe via the Rocky Mountains,” Cotter says. “For us, that may be a high danger in case you have a nasty winter, your pipe provide might be severely interrupted and could have a big influence on the venture.”
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Ward and Burke worked with Langley Concrete Group in Chilliwack, British Columbia, about an hour away from the challenge on the jacking pipe manufacturing. This is the primary jacking pipe Langley has produced and Ward and Burke offered the pipe specs and the mould, as well as help from the mould producer.
“They grasped the production of the microtunnelling pipe shortly and have made top quality pipes for this undertaking,” Cotter says. “The most important consideration with this pipe is the logistics of creating the pipe and transporting it to the job. Langley made the pipe for the open reduce part, so that was not a priority.”
As with all giant capital enchancment undertaking, challenges all the time come up. The only issues with the development process happened during drive one beneath a less populated space and an arterial street.
“On this drive, we had clay over sand and we had some inadvertent returns while Ward & Burke was understanding its grout and slurry pressures. As soon as they acquired the grout and slurry pressures adjusted, Ward & Burke, at occasions have been going 12 to 15 m a day, which was good. They’ve used principally one shift except in areas the place the jacking pressures received too excessive, the place they worked 24 hours.” Jokic says. “The inadvertent returns are much less regarding than settlement, which was an enormous concern due to the low cowl and we have been tunnelling within 10 m of buildings.”
To deal with settlement considerations, the venture referred to as for a radical settlement and vibration monitoring format, which has yielded useful knowledge about this machine’s vibration and noise levels that Ward & Burke will use on future tasks, in addition to priceless settlement knowledge. At the extra important sections, Ward & Burke put in a hydroshield to help mitigate settlement and improve the tunnels stability.
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One other problem that cropped up publish bid acceptance, however before the work commenced, was the Province’s Ministry of Setting decreased the edge for allowable iron in soil; this meant that Metro Vancouver and Ward & Burke had to find a facility that not only might settle for its wet spoils, but in addition one which was allowed to handle the iron laden soil. Though this was a headache, Jokic notes that had the venture remained a mixture of open-cut and microtunnel, the soil displaced would have been higher.
Despite these venture challenges, Jokic says that putting in the line by way of microtunnelling proved to be the best various. He doesn’t have to look any additional than the assembly he attended with Metro Vancouver’s public info officer for the venture. Jokic recollects that the owner of the business park — originally slated for open-cut — was not completely satisfied, however once they sat down to debate the microtunnel strategy they virtually jumped for joy.
“Yes, it’s disruptive, however we’ve got managed to maintain the location as tight as attainable. They could have misplaced some parking areas, however there wasn’t an enormous trench dividing their enterprise park in half,” Jokic says.
Microtunnelling is on monitor for completion in Might, and Jokic says that Metro Vancouver is happy with the challenge staff and the progress made.
Mike Kezdi is managing editor of Trenchless Know-how Canada.