Gilmore Place Phase I & II

Vancouver, BC

OVERVIEW3

Gilmore Place is a master-planned community that will transform Burnaby’s western gateway into an incredible urban hub for residents and visitors alike. Featuring one of Canada’s tallest residential towers, the seamlessly­ integrated Gilmore SkyTrain Station, world-class shopping and entertainment, convenient office space and luxurious residential towers, Gilmore Place will redefine metropolitan living in one of Burnaby’s most up-and-coming neighborhoods,  Brentwood.

Phase I and II of Gilmore Place  is  a  mixed -use transit-oriented development in  Burnaby,  BC  consisting  of six combined office and residential towers. This development replaced the underutilized space surrounding the existing SkyTrain  Station. GFL Infrastructure Group Inc. (GFL) was contracted by ONNI Contracting to install 1,229 secant piles and 2,689 strand anchors to support the excavation for Phase I and II of Gilmore Place.

GFL mobilized four large BG rotary drill rigs (two BG 39s, BG30 and BG33) for vertical drilling operations. These rigs were utilized to drill and install temporary-cased secant piles at depths up to 37.om around the perimeter of the site as well as immediately adjacent to Gilmore SkyTrain Station and the SkyTrain Guideway Supporting Caissons. Gilmore is the deepest secant pile wall constructed in Metro Vancouver under stringent QC requirements.

GFL had mobilized two KLEMM 807-7G drill rigs to drill and install strand anchors to advance the  excavation .  These anchors were redesigned to take advantage of our ability to install high  capacity  anchors.

Ground conditions in this area are comprised of medium to fine grained sandstone overlaid by alternating layers of till- like soils and sandy/silty gravel. Porewater pressures were found to be high due to the surrounding developments as well as the historic Still Creek  that had previously occupied the area. Artesian conditions were present in the bedrock..

VALUE  ENGINEERING

In the early stages, GFL re-designed the shoring based on proven anchor capabilities. GFL engaged value engineering services with GeoPacific Consultants Ltd. to eliminate 387 anchors and reduce total drilling length by 7,000 metres. This had resulted in significant savings in cost and schedule.

To increase  efficiency when installing anchors, GFL utilized an automated grout plant located at street level. This allowed large quantities of cement to be easily delivered to site while allowing the operator   to   quickly   supply   grout   to   any   location   on   site.

CHALLENGES

The eastern side of the site had presented the most difficulty when installing secant piles due to the interaction between drilling and a gravel layer above bedrock. To overcome these challenging drilling conditions, GFL used a  range of tools and techniques such as oscillators  and drilling  fluids.

INNOVATION

To meet the logistically challenging conditions of working underneath the active SkyTrain running through the site, GFL used a newly developed ultra-low headroom configuration of a BG39 drill rig. This unique drill rig installed secant piles in a circular configuration within 2 feet of the guideway columns which supported  the  SkyTrain.

Finch West LRT

Toronto, ON

The Finch West LRT (Light Rail Transit) project will bring 11km of modern, reliable rapid transit to northwest Toronto. It will have 18 stops including 16 surface stops, plus an underground interchange station at Finch West (connecting to the new Toronto-York-Spadina Subway Extension), and one below-grade terminal stop at Humber College, connecting to other local transit services like GO, Miway, Viva, and Züm. It will provide rapid transit for the Jamestown, Rexdale and Black Creek neighbourhoods, providing vital connections between communities and supporting growth in northwest Toronto. In May 2018, Mosaic Transit Group was awarded a contract by Infrastructure Ontario (IO) and Metrolinx to design, build, finance and maintain the new Finch West LRT line. (Infrastructure Ontario Project Backgrounder, dated May 2018).

The GFL team has been awarded multiple scopes and stages on the project thus far including: wet utilities, excavation, shoring and soil remediation. All work on site is being completed by our Civil, Shoring and Soil Remediation teams and the project is proceeding as planned.

The site requires the drilling of 330 permanent soldier pile holes ranging from 610mm to 1000mm in diameter that are located at the West Portal, U-Section, Sump Pit and the two Access Ramps of Finch West LRT Project. The site also requires the drilling of about 400 permanent interlocking secant wall holes with that to form a continuous caisson wall around the perimeter of the excavation with a 100 year service life. The secant wall holes are 1300 mm in diameter and are to act as a permanent secant water cut-off wall. The soldier piles extend 20ft to 50ft below existing grade elevations. The secant wall shoring system at the Main Entrance, Main Station and Pedestrian Tunnel ranges from 80ft to 110ft in depth and also acts as a “cut-off wall” around the site to keep water from seeping into the excavation due to presence of high water table.

Due to the presence of complex soil strata, high water table and proximity to the existing Finch West Station GFL Infrastructure Group Inc. has developed special in-house proprietary drilling procedures using BAUER (BG40 & BG55) machinery to deal with the challenging ground conditions at hand. The BAUER machines use an integral auger and liner system to install sectional casing without the need of a vibratory hammer. The casing is advanced prior to drilling to ensure that the ground loss does not occur, especially because the soil strata in this area ranged from silty clays and clayey silt tills to a wet sandy silt and sand layer above the glacial till.

At the Main Entrance, Main Station, North Pedestrian Tunnel and the partial U-Section of the FWLRT Project, the interlocking secant pile holes were braced by 4 levels of regroutable tiebacks averaging up to 60ft in depth. There was a total of 230 regroutable tiebacks out of which 70 tiebacks were located at the low-overhead clearance conditions which requires special low-headroom tiebacks drilling machinery that GFL Infrastructure Group Inc. owns. At the Pedestrian Tunnel, West Portal, Sump Pit, 2 additional access ramps and partial U-Section of FWLRT Project interlocking secant piles and soldier piles were braced by up to 4 levels of steel struts (150 in total) varying up to 90ft in length. The piles in the Main Entrance are also reinforced with 4 levels of regroutable soil anchors including a complex truss system with internal bracing system.

The project also requires structural brackets that tie into the permanent structural slabs and are used for permanent uplift at the main station design. There are 4 traffic decks located at various locations of FWLRT Project. The traffic decks are designed for complex construction staging of the project that would allow the flow of both the vehicles and pedestrians to continue whilst the excavation & forming is progressing without interruption. Furthermore, due to multiple underground utility interferences between live services and interlocking secant pile walls we were required to install a total of 8 micropile walls at multiple project locations in order to maintain the “cut off wall” requirements on the FWLRT project. The micropile walls are up to 22m in depth and range from 8 to 12 micropiles at each location.

The Civil team performed the installation of large diameter storm sewers between Romfield Lane and Tangiers Rd, crossing the intersection of Finch and Keele. The challenges included working alongside existing critical wet and dry utilities such as 400mm water-main and 750mm gas main, working at depths of 5-7m, crossing of the busy Keele/Finch intersection, and overall space/schedule constraints. With advanced investigative work, planning, and re-design proposals, the work was executed accurately and efficiently. A combination of open-cut and cap/lag tunneling methods were used to minimize the risk of working alongside the existing 750mm gas main.

Proposed re-alignment of the storm sewer crossing the intersection permitted the work to be completed under a continuous 36 hour operation. Additionally, GFL has been contracted to perform the realignment of the existing City of Toronto large diameter transmission water-mains at various locations along the Finch LRT corridor. These involve installation of new 1500mm diameter steel transmission mains, multiple chambers, difficult commissioning plans, and intricate final connections. The Covid-19 pandemic also introduced new challenges on the steel pipe fabrication timelines and delivery schedule coordination, and so a combination of traditional and sophisticated installation methodologies must be applied to ensure maximum precision during the installations.

Stouffville RER – Grade Separation

Scarborough, ON

Steeles Grade Separation

GFL was contracted by EllisDon to supply and install structural retaining wall caissons that comprised of 354 king piles/caissons and 347 fillers that stretched across a total of 389.424 linear meters along steeles avenue east, Scarborough, ON. Scope of work comprised also of supplying and installation of pier caissons and temporary shoring to facilitate the construction of the new bridge deck. GFL was responsible to supply and install circular secant wall to be utilized as a pumping station connecting the newly construction retention storage tank to the proposed structures nearby.

Agincourt GO Station

GFL contract involved supply and installation of the temporary shoring for all 4 newly constructed Agincourt GO station platforms, which included 2,069m² of shored area to facilitate build back and erection of proposed structures. Scope of work also comprised of supplying and installation of 154 canopy caissons connecting all platforms. GFL also assisted in the vertical drilling of noise wall posts to mitigate noise/vibration to the neighboring structures. Site utilized multiple methods to stage around up to three tracks at each location including track removals in major closures, track diversions and night work for crews when required.

Milliken GO Station

GFL contract involved supply and installation of the temporary shoring for all 4 newly constructed Agincourt GO station platforms, which included 2,453m² of shored area to facilitate build back and erection of proposed structures. Scope of work also comprised of supplying and installation of 102 canopy caissons connecting all platforms. Site utilized multiple methods to stage around up to three tracks at each location including track removals in major/minor track closures, track diversions and night work for crews when required.

Unionville GO Station

GFL contract involved supply and installation of the temporary shoring for all 4 newly constructed Agincourt GO station platforms, which included 403m² of shored area to facilitate build back and erection of proposed structures. Scope of work also comprised of supplying and installation of 101 canopy caissons connecting all platforms. Site utilized multiple methods to stage around up to three tracks at each location including track removals in minor track closures, and track diversions.

Eglington Crosstown Subway Extension

Toronto, ON

Overview

The Eglinton Crosstown Subway extension in Toronto was the construction of a new subway line through an existing and well established part of the city. It provides for a new underground commuter service along one of the densest surface routes in Toronto. Eglinton Avenue is mostly 2 lanes of traffic in each direction with a small sidewalk on each side before existing storefronts and residential towers. The roadway corridor is also densely packed with underground utilities, including trunk sewers over 2m in diameter. There are 3 exisitng interchanges with existing subway lines, which the new line will pass underneath.

GFL performed the shoring, foundation and temporary roadway decking works for 8 of the underground stations. GFL worked with the successful consortium throughout the bid phase of the project to help refine designs, staging, schedule and the management of project risks.

Value Engineering

GFL utilized our unmatched fleet of hydraulic drills and experienced workforce to cater the right techniques for each project constraint. We worked with the consortium to outline project risks and constraints and actively participated in the management process and development of contingencies.

GFL then deployed an overall project specific team to tackle what would ordinarily have been 8 individual major urban infrastructure projects (1 at each station location). WE worked with the client to manage and co-ordinate the crews and staging to optimize not only the shoring installation but the overall project schedule and impacts to the existing roadways.

Challenges and Innovation

GFL executed the shoring and temporary decking for the 8 underground stations utilizing the largest hydraulic foundation drill rigs in Canada in a dense urban location. Some of the sites were only 20m x 20m in plan area and we were drilling in excess of 45m depth.
As a part of the project, GFL drilled caissons at 1.3m diameter over 54m in depth and drilled interlocking secant walls over 45m in depth. These required pushing our drill rigs past what was commonly understood as practical limits for these technologies in the local market. GFL was able to prove to the engineers the quality of installation and the commercial and schedule efficiencies to the client. WE have since built on these innovations and continued to push to greater depths in more and more challenging situations.

CIBC Square Phase 2

Toronto, ON

Overview

Situated between Yonge St and Bay St neighboring Union Station lies the CIBC Square II site. This mixed use tower reaching 48 stories and 238 m above street level offers a combination of office, public and retail space with up to 3 levels of underground parking extending to 17 m below grade.

GFL Infrastructure Group Inc. (GFL) was engaged by Ellis Don to provide a multi-divisional approach to the project which included contracting the demolition, shoring and excavation arms. The synergy between divisions would ensure that the aggressive schedule milestones were achieved on time and under budget. The shoring scope was extensive and included 603 secant pile shafts, 539 rock anchors, a series of structural caissons, micropiles, jet grouting, tie rods, partial top down construction and intricate bracing all being completed within stringent Metrolinx requirements. Up to four Bauer drill rigs and an extensive crew were utilized during vertical drilling including a specialized BG39 drill rig for working in a low headroom condition beneath the Union Station Overbuild structure above.

Utilizing GFL’s wealth of experience and multi-divisional approach, the project team were able to identify areas of efficiency in the construction staging and sequencing that would provide savings on both cost and schedule during execution of the work. This synergy resulted in benefits to Ellis Don and the demolition, shoring and excavation divisions of GFL who were able to collaborate on an ongoing basis and make adjustments to suit the fluidity of the job.

Value Engineering

Optimization of the vast amount of steel work and structural welding was achieved by working alongside the project consultants and drawing upon years of experience from the GFL welding and operations team. Additional savings were also recognized through the use of alternate shoring systems for sensitive areas adjacent to Union Station. By approaching the complexity of the job with a systemic and targeted approach, the team was able to identify these areas during the planning stage resulting in time and cost savings during construction.

Challenges & Innovation

A significant hurdle during construction was working around the existing THES vault and conduit which was to remain active and in place just below grade elevation throughout the entirety of the work. To achieve this, several techniques were implemented at various stages of the work to support and protect this sensitive service. A specially engineered drill platform/bridge was constructed during vertical drilling to distribute equipment loading, jet grouting columns were installed at entry and egress points of the conduit to close the shoring system while protecting the integrity of the vault and, horizontal steel bracing was erected beneath the vault so that it could be attached to the top down slab and hung approximately 10 m above the excavation. Once the vault was supported overhead, tiebacks and additional bracing were installed in the surrounding low headroom areas. Months of planning went into this specific challenge and the work continues successfully to date.

Port Lands Flood Protection (Phases 1 & 2)

Toronto, ON

Overview

The Don Mouth Naturalization and Portland Flood Protection (PLFP) project is a precedent-setting undertaking to revitalize the mouth of the Don River in Toronto. It transforms the existing mouth of the Don River, into a healthier, more naturalized river outlet, while simultaneously providing critical flood protection to 240 hectares of Toronto’s eastern waterfront.

GFL Infrastructure Group Inc. (GFL) was contracted by EllisDon (ED) to supply and install 2/3rds of this multi-purpose cut-off wall. Work commenced in early April 2019 on Phase 1 and was substantially complete Phase 2 by December 2020.

The Phase 1 portion of the work consisted of installing nearly 1500 interlocking secant piles of either 1000mm or 1180mm diameters into the bedrock a minimum of 3m. The depth of each secant pile ranged substantially with the following averages: Eastern wall – 2om, Southern wall – 27m, Northern wall – 35m, Western wall – 45m. With the first phase well under way, GFL commenced Phase 2. This secant wall consisted of interlocking 1000-1180mm diameter piles at the North and South of the project which permitted a cantilevered excavation. Where the structural element of the wall was not required , cut-off was instead achieved with a cement-bentonite slurry.

Value Engineering

This work involved creating a new river channel, extending from the current mouth of the Don River (where it feeds into the Keating Channel) all the way to Polson Slip. The existing ground conditions primarily comprised of contaminated fill, due to land expansions done in the early 1900’s and again in the mid 1900’s. Attempting to excavate the river channel via open excavation would result in releasing contaminates into the ground water, and into Lake Ontario. Therefore a below grade wall would need to be constructed, that achieves the following goals: Retain earth to allow an excavated cut depth of upwards of 7m, via cantilever with no additional support. This is to allow open and unobstructed excavation. Cut off water ingress from coming through the wall, and up through the bedrock. This is to allow excavation and placement of clean material in a dry manner. Prevent contaminates from leaching through the wall. This is to keep the new river free of contamination from the surrounding fill.

Challenges

Tasked with a substantial volume of drilling, GFL was uniquely positioned in the Toronto market. At the height of Phase 1’s production, GFL had 6 drill rigs running 20 hours/day at 6 days per week. The operation was so substantial that a concrete batch plant was mobilized to site and dedicated solely to the project, in order to produce the 54,000 cu.m. of concrete required for this wall. This is enough concrete to fill up 1.5m of the Rogers Centre.

Innovation

In Phase 2, GFL engaged prime subcontractor Canada Geo-Solutions to support a mixed technology solution of secant pile and cement-bentonite slurry walls. Though not part of the original design, GFL proposed and installed a test panel of the cement-bentonite slurry to prove it would meet site requirements. Shortly thereafter mobile batch plant was installed to supply two long-reach trenching excavators with slurry along the East and West perimeters of the site. Simultaneous work headings of both secant and cement-bentonite walls allowed GFL to expedite installation substantially ahead of anticipated production.

PLFP Cherry & Commissioners Bridges

Toronto, ON

The Cherry Street Bridge is part of the larger Port Lands Flood Protection Project aimed at revitalizing the mouth of the Don River. The area currently consists of 290 hectares of highly industrialized waterscape that is subject to risk of flooding. When complete, the project will have provided the necessary flood protection to the last significant undeveloped space in downtown Toronto.

A total of 12 caissons (2.4m diameter) were installed for the bridge pier and abutment foundations. A 275T crane and APE Model 400 Vibratory Hammer or “King Kong” was used to install permanent steel casing to bedrock which was then drilled out using the BG40. The North Pier & Abutment were installed as planned to depths of 24m (79 ft).

Difficult ground conditions and depths of up to 51m (167 ft) prevented the Cherry Street Team from advancing the steel casing fully at the South Pier & Abutment. An alternative solution was found in the form of synthetic polymer slurry. The slurry system is composed of four main products that work in conjunction to provide excavation stability during drilling. The two main additives act to increase the viscosity of the system while forming a membrane on the sidewalls of the excavation in order to control fluid loss and provide stability. In difficult soil layers where fluid loss was a concern, another additive was used which acts as a plug in porous soils to prevent fluid from escaping and provides increased sidewall stability. The last additive acts as a flocculent within the system to drop suspended soils from the slurry, essentially cleaning the hole during the drilling process. Continuous testing of the slurry was performed throughout the operation to ensure the viscosity, density, sand content and pH were within the design requirements – Adjustments were made if needed to ensure the system was working as intended. The system is so effective that upon completion of drilling the column of slurry is completely clean, eliminating the need for air lifting while still passing the stringent testing requirements. The holes were left open for as much as 48 hours allowing the team to install full length rebar cages prior to tremie of 230m³ of concrete and the used slurry was pumped to storage tanks to be reused at the next caisson location.

While it was a steep learning curve on a difficult project, the Cherry Street Team deserves many thanks for overcoming numerous challenges. The success of the project would not have been possible without the coordinated effort of the entire team – A job well done. The team moves on to the next bridge on Commissioners St which has a total of 14 caissons (2.4m diameter) with depths of 21m (69 ft). Permanent casing will be seated to rock similar to the North Pier & Abutment however, the polymer slurry system will be used to help facilitate the cleanout process.