Concrete Transit Authority
Noremac Group helps multi-phase light rail project take shape in Edmonton.
Light rail transit (LRT) is hardly a new concept to residents of Edmonton, Alberta. In operation since 1978, LRT service in the province’s capital city has proven popular, regularly landing it in top ten lists for ridership in North America. That acceptance prompted the city to embark on a massive expansion of the service from a single central line to other parts of the metropolitan area. With four additional lines either already in progress or in the final design stage, Edmonton LRT is solidly poised to meet the city’s population growth, an upward trend that is outpacing both provincial and national rates. Heading the concrete pumping effort on one of those line expansions, the Valley Line Southeast (Phase One) — often with as many as eight pumps working at a time — Edmonton-based Noremac Group, is answering a call that few in the region could.
The Right Choice
With a fleet that is 31 pumps strong and runs the gamut from trailer pumps to a trio of S 61 SX units, the Noremac Group (Noremac, incidentally, is a reverse spelling of founder Cameron Currah’s first name) is concrete pumping epitomized. Founded in 1984, the company operates offices in Alberta, Saskatchewan and British Columbia, and completes projects from Ontario to B.C. Providing strengths in everything from residential work to heavy industrial/civil projects, they were an ideal fit for a lengthy, massive project like this facet of the Edmonton LRT expansion, according to Connor Currah, company vice president.
“For such a challenging, high-profile project, we bring a lot to the table in terms of fleet size, onsite dependability, safety record, and so on,” he said. “This is the first of two phases and it has been broken down into three individual scopes or segments: elevated guideways — all the above grade work; tunnel work; and track slab. We had the opportunity during the bid process, to bid on any of the individual scopes of the $1.8B (CAD) total project cost, or all three. We provided pricing for all three and were awarded the concrete pumping for Phase 1.”
To get a true feel for the size of the Valley Line Southeast , consider that the project is being delivered using the P3 model (public private partnership) and the general contracting duties, followed by a 30-year operating period, are being assumed by a consortium of four major global firms working under the umbrella, “TransEd Partners.” Each member of the consortium brings with it a particular specialty: EllisDon, construction; Bechtel, engineering; Bombardier, transportation; and Fengate Capital Management, finance. Noremac was awarded the concrete portion of the project in 2016 with work commencing in spring of the following year.
A Case for Smaller
At 13.1 km, the Valley Line Southeast project is one of the longest lines on the evolving Edmonton LRT network. And, unlike the traditional jobsite in which the work is fairly concentrated, here, individual projects — tunnel work, track slab, elevated stations, etc. — can all be taking place at the same time, making pump selection and availability key.
“We are using everything from our line pump to one or more of the 61-meter units — each pump has a place in the operation,” said Currah. “Because so many of the pours are trending smaller, so too is the reliance upon smaller pumps. Much of the track slab, for example, does not require a lot of reach so we are able to handle it with pumps offering less than 36-meters of reach. The length of the average dual track pour is 40m of -.52m thick slab.”
Smaller pumps are also proving popular with TransEd for their inherently smaller footprint. With the exception of the tunnel and guideways, the line extension itself, runs parallel — and, in some areas, close to — the city’s existing road system.
“In order to pour some of that track slab, the width of outrigger spread became more of a priority than what we are used to on other jobs,” said Currah. “In many cases, we can send a 40-meter pump to do a job in which a customer requested a 28-meter. But on this project the setups were so tight in spots that, if we were to send a bigger truck, we would have to either short-rig or request a costly lane closure and we generally try to avoid both. So smaller pump availability pays dividends.”
One of the more interesting components of the Valley Line Southeast project is a 400m long pair of 6m diam. tunnels that start beneath downtown and exit near the North Saskatchewan River where the line will connect with the newly constructed, 260m, cable-stayed Tawatinâ bridge and continue southward. No small feat of engineering, nearly 76,000 m3 of material was removed in the initial tunnel sequential excavation method (SEM) process, during which the newly excavated tunnel segments were immediately stabilized using a 300mm layer of shotcrete. With shotcrete in place, each tunnel was lined with a fully welded PVC waterproofing membrane, designed to ensure the structure remains impervious to the elements, before moving on to the creation of the tunnel walls.
Wall pours were completed using an SP 4800 line pump feeding a pair of 6m DEMA Infrastructural Tunnel Formwork systems. According to Dallas Lindskoog, TransEd representative, both tunnel pours (northbound and southbound) started with a single forming system at each tunnel entrance.
“These areas feature a much tighter radius than anywhere else in the tunnel, so we went with a shorter length, single form,” he said. “With those areas completed, we bolted two formwork traveler frames together and began advancing at longer 12m intervals for the balance of the tunnel straight sections. The concrete, a 5,000 psi, steel-fibre reinforced mix, is pumped into the travelling forms in multiple lifts, also 300mm thick, to keep the form balanced and aligned. It takes approximately six hours for each section to be pumped. Ports and windows at various levels allow us to ensure that the concrete is consolidating properly. Despite the stiffness of the mix and more than 90 m of hose, the line pump handled it nicely.”
Although the SP 4800 pumped most of the more than 10,000 m3 of concrete on the tunnel interior, access challenges at the structure’s entrance and exit demanded a much different approach. “We used some of our bigger units in those areas,” said Currah. “Because of the lack of good access in those areas — the riverbank in particular — we had some interesting pour setups with our 61- 55- and 47-meter pumps. But I believe it’s that ability to meet any need that made us a valued part of the team out here.”
OMG in the OMF
Nowhere was the value of pump availability more evident than in the slab pour for a structure called the Operations and Maintenance Facility. The OMF as it is known, is used to store and maintain rail vehicles that are part of the Valley Line LRT system. The structure, despite being warehouse-scale huge, offered limited overhead space, according to Currah.
“The 250 mm thick slab was roughly 13,700 m2 in size, so this was a fairly sizeable pour,” he said. “The conventional way to tackle it would be to set the pump up outside the building and run line into the structure. Instead, by choosing the S 31 XT, our operator, Justin Loimand, was able to drive the pump directly into the building and unfold in there, despite the low roof clearance.”
The 31-meter pump to which Currah refers, features a five-section extendable boom that requires only 18’- 8” of unfolding clearance, which played well into work at the OMF. It also afforded Noremac 15’-3” of smooth telescopic action, which allowed their operator to accurately position the boom where needed and reach 87-feet horizontally without exceeding the unfolding height, yet still pour back to the front bumper.
“Having those capabilities made things much easier, both for us and for the placing crews,” said Currah. “Any time you can pump right off the boom and avoid the back-breaking work of dragging line around, it’s better for everyone and keeps production levels up.”
One additional benefit of the 31-meter pump they drew upon is how efficient it is in set up and tear down times. “We’ve found that to be great on track slab pours,” he said. “When we get to a point where we max out the reach on a pour, it is quick and easy to tear down and reset further down the line. That minimizes any risk of having the concrete time-out because of a move.”
Given that the LRT expansion is one of the largest and highest-profile infrastructure projects currently taking place in Alberta, the pressure has been great for Noremac to consistently meet TransEd’s needs. That can include anything from ensuring minimum pump requirements (five at all times) to guaranteeing specific pump availability.
“During some particularly busy periods, for example, TransEd wanted us to make certain that the 31-meter pump was available for several months at a time,” said Currah. “That took some doing; we had to convince the manager in our Saskatchewan branch to let us borrow theirs for a couple summers. At the same time, we had to make certain we still provided great service to our other customers. But this was a rare opportunity to secure a four-year project and we certainly didn’t want to jeopardize it. Cameron, our owner, has always had the philosophy that if you buy the highest-quality equipment and put together the best team, success will follow. It’s served us well for 37 years now and is proving itself every day on the LRT project.”
The Valley Line Southeast is scheduled to open to passengers in 2021.
Owners: City of Edmonton.
P3 General Contractor: TransEd Partners (EllisDon Construction Co., Bechtel Canada Corp.; Bombardier, Inc..; Fengate Capital Management, Ltd.)
Pumping Contractor: The Noremac Group, Edmonton, Ab.
Concrete Supplier: Rolling Mix, Calgary, Ab.
Equipment: Schwing SP 4800 line pump, S 31 XT, S 32 X, S 36 X, S 38 SX, S 40 SX, S 42 SX, S 47 SX, S 55 SX, and S 61 SX truck-mounted concrete pumps with placing boom.