TunnelTalk Special Edition: Canada Focus and Case Studies

Direct by Design

SPECIAL EDITION FOCUS: CANADA CASE STUDIES

HERRENKNECHT IN CANADA

CONNECTING INNER CITIES With 5 EPB Shields, Herrenknecht supports the extension of the Canadian metro systems by more than 25 km. The subway lines in the Greater Toronto Area will be expanded by over 20 km. In Vancouver 7 km of additional tunnels will lead to 6 new subway stops. Herrenknecht guarantees the local support with their offices in Sumner, WA and Toronto, ON. herrenknecht.com

SCARBOROUGH SUBWAY EXTENSION, TORONTO Machine type: EPB Shield, S-1279 Diameter: 11,870 mm Contractor: Strabag Inc. EGLINTON CROSSTOWN WEST EXTENSION, TORONTO Machine type: 2 x EPB Shield, S-1302, S-1303 Diameter: 6,550 mm Contractor: WestEnd Connectors (Aecon / Dragados / Ghella GP) BROADWAY SUBWAY PROJECT, VANCOUVER Machine type: 2 x EPB Shield, S-1304, S-1305 Diameter: 5,980 mm Contractor: Broadway Subway Project Corporation (Acciona / Ghella GP)

TUNNELTALK SPECIAL EDITION CANADA FOCUS AND CASE STUDIES FROM THE EDITOR’S DESK

Canada hot house of experiment and ambition

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rom the beginning of its nation building, underground infrastructure has been a mainstay in Canada, not only for developing its vast mining wealth but also in creating the fabric of its urban societies, ensuring connectivity, resilience, protection against the elements and durable, low-maintenance road, rail, water supply, wastewater management and energy production facilities. It has done this through the efforts of its own immigrant nationals and increasingly by welcoming international teams. Today, the tunnelling and underground space development industry in Canada is busier than ever and with an astonishing workload in the pipeline.

The Tunnelling Association of Canada (TAC) reports an identified 50 tunnelling projects at the planning and start of construction phase during the coming 10 years, valued at a combined total of more than Can$50 billion. A majority, some 39, are for the utility sectors, with a smaller number for metro and highway projects accounting for most of the capital investment at about $39 billion. Many of the planned tunnels, 20, are based on TBM excavation with mined and trenchless methods accounting for nearly all the rest, in preference to more invasive cut-and-cover or immersed tube methods.

Bored tunnels, it is reported, represent more than $35 billion of the projected capital investment.

At all stages of development, Canada’s clients and design engineers have adopted an open mind to all aspects of an infrastructure project, from planning, funding and design to construction means and methods, and operation. In this regard Canada leads the way in trying new ideas, applying new thinking, and adopting advanced technologies.

In this Special Edition Focus, there are case study articles that illustrate the point. On Cape Breton in Nova Scotia, there is the development of a hard rock shielded machine for one of the earliest applications of a TBM in the coal mining industry; at St Clair there is early introduction of procurement by the client of the large diameter TBM and the segmental lining to get a jump start on construction; and at Niagara there is application of still the largest ever hard rock TBM at 14.14m diameter.

With these early projects pushing industry boundaries, Canada also has a case book of judicial precedent, first with cause of disputes, differences, and even contract terminations, and then through court trials, appeals, and on to Supreme Court rulings. In all cases, and no matter the cause of tension, all projects have been completed and invariably have been in service long before the outcome of the judicial process.

This has also led Canada to experiment with new contractual practices and methods for bypassing costly and lengthy litigation. The case studies include examples of partnering; design-build; P3 public-private partnerships; design-buildbuild-finance-operate and maintain concessions; and today, progressive design-bid-build and progressive design-build contracts, and the advocating of greater use of DRBs, dispute resolution boards.

This wealth of experience is invested today in engineers with consultants, clients, contractors and machine and supply specialists, all well equipped to take forward the huge programme of infrastructure investment. Pioneering and fairness is something that is in the national psyche of Canadians, and they expect the same from internationals wanting to be part of the marketplace. With so much work to do this can only be good for Canada and its expanding future. n

Shani Wallis, Executive Editor Most of the references in this Special Edition hotlink to articles in the Archive of the TunnelTalk.com web magazine which currently shows a security warning as we undertake every effort to regain control of the magazine and restore it to serve the industry and the readers. Although the warning is there, it is the genuine TunnelTalk. com site, only now hosted on a server owned by a former TunnelTalk contractor, and we have no access. We hope to have the magazine returned to the TunnelTalk server, to apply the new SSL certificate and resume normal operations, just as soon as possible.

CONTENTS 5

TORONTO HIGHWAY UNDERPASS SUCCESS

31 CAREER RECOGNITION FOR RICHARD LOVAT

10 MASS TRANSIT SYSTEMS UPDATES

32 TAC CANADIAN ACHIEVEMENT AWARDS SINCE 2013

15 CASE STUDY: EDMONTON LRT LABORATORY

34 LOVAT: HISTORY OF A GLOBAL CANADIAN BRAND

20 VANCOUVER LRT BROADWAY SUBWAY STARTS

35 CASE STUDY: NIAGARA HYDRO DIVERSION PROJECT

21 CASE STUDY: VANCOUVER LRT CANADA LINE

44 CASE STUDY: ST CLAIR UNDER-RIVER RAIL CONNECTION

27 CASE STUDY: TORONTO SHEPPARD SUBWAY BEGINNINGS

49 CASE STUDY: VANCOUVER SEYMOUR-CAPILANO TBM DRIVES

30 A LOOK BACK AT WTC 2010 VANCOUVER

60 CASE STUDY: TBM TREATMENT FOR CANADIAN COAL

Direct by Design

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Work On Progress.

Rethinking construction.

STRABAG Inc., the Canadian subsidiary of the STRABAG SE Group, has been successfully operating in the North American market mainly in infrastructure and tunnelling projects from 2005, specifically in Canada. STRABAG Inc. has executed/is executing the projects as the Niagara tunnel, Highway 401 tunnel, Mid Halton Outfall tunnel or the current Scarborough subway extension near Toronto. Our highly experienced team is the strongest motor for building a better future. Through the hard work and dedication of our approximately 74,000 employees, we generate an annual output volume of around CAD 21.6 billion within the STRABAG Group. work-on-progress.strabag.com STRABAG Inc 6790 Century Avenue, Suite 401 Mississauga, ON L5N 2V8, Canada Tel. +1 416 848 6353, www.strabag.com

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TUNNEL DESIGN | GEOTECHNICAL ENGINEERING | CONSTRUCTION MANAGEMENT INSTRUMENTATION & MONITORING | WATERPROOFING & WATER CONTROL TUNNEL REHABILITATION | MINING SUPPORT SERVICES

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Toronto highway underpass

concentrates SEM techniques TunnelTalk reporting

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October 2022

ow to take new twin rail tracks under the widest and one of busiest highways in North America - that was the challenge facing Metrolinx and Infrastructure Ontario when planning new rail services in the Toronto region. The new rails had to pass under the 21 lanes of highways and alongside the existing rail underpass to increase passenger rail capacity and carry double-stacked freight trains.

The project was originally envisioned as a single doubletrack tunnel through the highway embankment using a series of micro tunnels around the profile with heavy internal support frames to maintain operation of the adjacent tracks and avoid lane closures of the 21 lanes of highways and ramps above. During contract procurement, alternative concepts were considered, and a change was adopted when the contract was awarded as a designbuild-finance contract by Metrolinx to the TTP Toronto Transit Partners joint venture of Strabag as leader, and EllisDon of Canada, with WSP, Jensen Hughes and Dr G Sauer & Partners as the engineering team.

With its combined construction experience, the TTP team quickly determined that two individual SEM sequential

Underpassing the highway while keeping all in flow

excavation method tunnels, with bespoke excavation sequences and pre-support measures, would best manage advance under the multi-lane highway at shallow depths of 2.8m minimum and 4.7m maximum. SEM excavation would be less invasive, faster to excavate, and more economical to build, to complete the optimal scheme of twin 180m long x 10.6m high x 8.9m wide x 80m2 theoretical excavation profile (9.4m x 7.7m wide final lining inner dimensions) beneath the highway and adjacent to the operating double-track underpass.

The ground through which the tunnels pass is comprised mostly of backfill, loose sand and gravel and other debris from highway construction stages gone by with competent till in the lower part of the profile. The ground is complicated further by abandoned concrete structures such as old wingwalls, retaining walls and deep foundations to be encountered and removed throughout.

Fig 1. Longitudinal section and plan of the rail pass under the 21-lane highway with less than 3m cover between the two

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Figs 2 and 3. Design of the twin rail underpasses of the highway above

3D finite element study of the complex combination of the two new tunnels, under the highway and alongside the existing double track underpass

Mining through these almost cohesionless materials and negotiating the obstructions required effective presupport, tight excavation sequencing, skilled operators, flexible use of SEM toolbox methods and diligent management of stakeholders.

TTP and its design team landed on a pre-support system that comprised a 800mm steel pipe umbrella hugging both tunnel crowns (Fig 2). The 800mm diameter allowed operatives to enter the pipes and remove some of the obstructions for the auger and jacking installation of the pipes to progress. While not all obstructions could be removed or avoided, leaving some areas of pre-support out of the SEM toolbox, the approach provided valuable information about the location and composition of the obstructions ahead of main tunnel excavations.

Maintaining 21 lanes of live traffic at all times required extremely strict settlement criteria. This resulted in installation of one of the most complex and technically advanced tunnel monitoring systems in Canada to date.

Design also required development of a fire life safety concept that eliminated the need for jet fans inside the 180m long passages and avoided the need for larger cross-sections, opting instead for two short cross passages between the twin tunnels. During procurement, TTP also introduced an intermediate shaft located in the median of the highway to provide additional construction access.

The low overburden, tight settlement criteria, a set of known and potential unknown obstructions along the tunnels and the mixed face conditions provided a real challenge for the excavation and support concept. Dr G Sauer & Partners (DSP) together with the technical office of Strabag, Zentrale Technik, studied multiple 6

options for presupport ranging from rebar spiling to small 140mm diameter pipe roof umbrella to the large pipes for the umbrella. The larger 800mm pipes were chosen following a risk assessment process to allow for man entry to deal with the known and unknown obstructions and provide added stiffness in the presupport. The pipes were installed using auger boring and a jacking frame to jack the pipes hydraulically into the ground from the west and east portals as well as from the intermediate shaft.

The four different pipe jacking locations were necessary to facilitate the curved alignment of the tunnels. A crew member was frequently skidded into a pipe to remove obstructions of wood or steel with a hand saw - no torching was permitted inside the confined environment.

The SEM design divided the profile into a topheading, bench and invert for excavation by a Liebherr 924 excavator and a full-face excavation option using a CAT tunnel excavator. The tunnel geometries and face stability sequences were confirmed by 3D finite element using multipurpose software Abaqus. DSP provided final design details for excavation and support, as well as for a membrane waterproofing system and the final cast-inplace concrete lining.

After installation of the 800mm diameter pipe arches over the two tunnels and grouting certain areas from within these pipes, excavation of the first tunnel started through a shotcrete and soil nail portal wall I October 2019 following the top heading and combined bench-invert sequence.

A daily review process was established for members of the construction team, monitoring team, the DSP SEM design representative and geotech engineer on site.

Construction activities were discussed and planned daily, based on a review of the monitoring data, ground conditions, probe drill logs and face maps. The next 24 hours of activities were defined in detail, documented and communicated to the operatives via the record of excavation and support RES sheets.

Once excavation of Tunnel 1 had advanced by 58.5m, excavation of Tunnel 02 started. In Tunnel 02 the excavation sequence was eventually changed to full face excavation as experience had shown that settlements were within the acceptable range and negligible when compared to the deformation encountered when installing the large presupport pipes.

Multiple known and unknown obstructions were encountered with the wing walls installed during construction of the adjacent rail tunnel creating one of the biggest challenges. In their shadow the large presupport

Complex mixed ground conditions with known and unknown obstacles and obstructions were expected and encountered during excavation, placing an emphasis on face mapping by the on-site geotech engineer and instrumentation monitoring and interpretation as part of the RES process and to ensure continuous availability of the highway above and the operating rail tracks alongside

pipes could not be installed which was a particular concern in an area of cohesionless ground and ill-compacted sand of the former construction backfill. Various SEM techniques were employed to deal with these conditions, including pocket excavation, split advances, reduced advance lengths, use of rebar spiles, face bolts, face wedge, use of wire mesh to stabilise the wet shotcrete on sandy surfaces, grouting the face, and the skills of the nozzlemen to use low impact, low pressure shotcreting techniques, to name a few. All helped overcome difficult encounters.

Following the fire-life-safety design two cross passages were identified. The use of those Cross Passages avoided the need for Jet Fans mounted in the ceiling. This would have required the individual SEM tunnels to be even higher than already required by the double stack freight container envelope requested by Metrolinx. Since the two SEM running tunnels were very close to each other at spring line, the length of the Cross Passages, measured at spring line, were less than 1m, which the team believed is a record for the shortest Cross Passages. Cross Passage 2 was broken through beginning of January 2021.

To minimize overall construction time, excavation progressed also from the west portals starting with a careful sequence. The skew between the highway embankment and the tunnel alignment meant that the

first five advances would not result in full ring closure.

The end of the 800mm pipe-roof pipes needed to be supported prior to starting excavation underneath. The design prescribed a steel portal beam wrapping around the tunnel opening following the 3-dimensional shape resulting of an ovoid tunnel section being intersected by the inclined and skewed plane of the portal wall. After the pipe ends were secured by welding them to the portal beam, SEM excavation was able to get underway.

Junction of the east and west headings for Tunnel 1 was achieved on in July 2020 with junction of the Tunnel 2 topheading achieved in November 2020. With excavation still underway for Tunnel 2, Tunnel 1 was cleaned out and the surface in the invert was prepped for start of the waterproofing system installation and final lining invert concrete pours. TTP developed an innovative sequence in which a 10m invert section was poured one day, the steel 7

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Excavation in progress from the east and west portals as well as from the intermediate shaft had excavation completed within 15 months

Installation of the waterproofing membrane ahead of casting the steel-fibre reinforced in-situ concrete lining with rebar reinforcement at the portals and location of the two cross passages

formwork providing the radial sheer connection key to the future tunnel arch was moved 10m ahead and on the third day the next mass concrete invert pour was placed.

Steel fibre reinforcement, rather than rebar, and adding accelerator to the CIP concrete mix, allowed for this fast invert construction. While the invert pours advanced, the arch waterproofing crew followed with a steel formwork gantry behind casting each 10m long arch section. Rebar reinforcement was only used for the lining at the portals and at the locations of the two cross passages. SEM excavation was finalised in Tunnel 2 by end of January 2021.

consider and ultimately implement innovative solutions.

It exemplifies the use of innovative solutions to tackle problems where traditional methods such as box jacking, sturdy bracing frames, or cut-and-cover options fall short.

With the arch pours completed in Tunnel 2, work on the permanent portal walls started and after finishing the rebar placement and complex shaped concrete pours, substantial completion of the project was achieved on 21 July 2021.

Closing out of this signature project, without any alarm of urgent concern or need for emergency response is to the success and satisfaction of all associated parties and the individuals involved. The project demonstrated commitment to teamwork and collaboration within the proponent team and owner, combined with the owner’s willingness to

TunnelTalk references

In recognition of the achievement and the success, the project was selected by the Tunnelling Association of Canada as winner of the 2022 TAC Project of the Year Award of more than Can$100 million. This follows the TAC Award for Strabag in the same category for the Niagara water diversion tunnel in 2013. n

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Video: TAC 2022 Canadian Project of the Year Award of +$100 million

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TAC salutes Canadian achievements - November 2013

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Exploring critical elements for NATM success - June 1995

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Variations on the NATM theme in Bonn - October 1990

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Celebrating 30 years of efficient design in USA - June 2017

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Constant face surveillance - November 2009

Canada’s largest effluent outfall complete

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n March 2022, an 8m diameter Robbins single shield TBM completed a record-setting run below Lake Ontario. The machine, for the Southland/Astaldi JV, bored the 7m i.d. x 3.5km tunnel through sedimentary rock from a 85m deep x 14m diameter TBM launch and working shaft at the Ashbridges Bay Treatment Plant.

The machine launched in March 2021 and began its bore in predominantly shale, with limestone, siltstone and sandstone. It recorded a best day of 30 rings or about 47m of advance. “This is a wonderful type of geology for our machines,” said Alfredo Garrido of Robbins Field Service. “During the entire excavation, a total of seven cutters were changed. The wear behaviour is incredible and everyone is amazed by the cutter performance.”

The crew operated the machine in two shifts of 12 hours from Monday to Friday. A Robbins continuous conveyor system, including a vertical conveyor, transported muck from behind the

Crews celebrate end of the segmentally lined rock TBM drive machine to the surface. After every 25 machine cycles, excavation stopped to drill a probe hole to assess possible water ingress.

The completed outfall will connect to 50 in-lake risers to enable efficient dispersion of treated effluent. The project for the City of Toronto will improve the city’s shoreline and Lake Ontario’s water quality by replacing a 70-year-old existing outfall. n

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he Quebec Provincial Government announced in May 2021 its intention to build a roadway tunnel to link Quebec City centre with its southern suburb of Levis.

The tunnel beneath the Saint Lawrence River will connect to Highway 20 on the Levis side and to Highway 440 on the Quebec side rerouting traffic around rather than through the city of Quebec (Fig 1).

An initial proposal was for a large 19.4m o.d. double-deck single-bore rock tunnel with three lanes on each deck, one of them dedicated to public transportation with two bus stations in the tunnel and additional bus stations at the tunnel

Fig 1. Proposed Quebec Levis roadway under the Saint Lawrence River portals. This proposal has since been overtaken by selection of a twin tunnel configuration with two lanes in each direction. The Government is undertaking a comprehensive geotechnical investigation

and it is tendering for the environmental studies and the preliminary design.

Construction is expected to start in 2025.

Construction cost has been estimated at between Can$6-7 billion. n

Credit: Quebec Ministry of Transportation

Quebec-Levis highway link

Canada mass transit systems updates

Seven cities of Canada — Toronto, Vancouver, Edmonton, Calgary, Montreal, Ottawa and Quebec City — operate transit rail systems, all with lengths of underground alignment. In each city the design, construction and procurement methods of previous underground projects provide the experiences and insights for success of the new works.

Calgary CTrain, Alberta

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Fig 1 (below). An underground section beneath the city centre is part of the new Green Line of the Calgary LRT (Fig 2 right)

algary in Alberta is the most recent city in Canada to add an underground section to its LRT CTrain network in the centre of the city for the new 46km Green Line. Phase 1 construction of the new Line, comprising the central 13 stations and 18km of LRT trackway from Shepard to Eau Claire Stations, will include the central 3km underground section and four underground stations (Fig 1). The other stations are at-grade or elevated with bridges taking the alignment over the Elbow and Bow Rivers and the Deerfoot and Blackfoot Trails. Planned future phases will extend the central core both north and south (Fig 2).

Construction of Phase 1 began officially in April 2022 when PCL Construction of Alberta was appointed by the Calgary City Council to provide construction management services for a design-build-finance (DBF) procurement model with a development phase. On 26 September 2022 a request for DBF proposals was released to two short-listed teams: • Bow Transit Connectors of Barnard Constructors; Flatiron Constructors and consulting engineer WSP and • City Link Partners of Aecon Infrastructure Management, Dragados Canada, Acciona Infrastructure Canada, with consultants Parsons and Aecom Within the two competing DBF teams, Flatiron and Dragados are majority owned by the ACS Group of Spain.

After evaluation the successful proponent will work with the owner’s team through a period of about 12 months to advance civil and M&E design, including selection of underground station and tunnel construction methods, and to determine risk allocation, price and project schedule. Following the development phase,

160 Ave N 144 Ave N North Pointe 96 Ave N

Tuscany Crowfoot Dalhousie Brentwood

Martindale

SAIT/ACAD/Jubilee

2 Ave SW

Sunnyside 45 St Westbrook

7 St

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Bridgeland/ Memorial Zoo

City Hall

7 Ave SW

Shaganappi 8 St 6 St 3 St Point Sunalta Centre St S Downtown Erlton/ West/Kerby Stampede

Red Line Blue Line Green Line Downtown Free Fare Zone

Whitehorn

28 Ave N

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Calgary CTrain

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Franklin Centre St Victoria Park/Stampede Inglewood/Ramsay 4 St SE

26 Ave SE Highfield

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Lynnwood/Millican Ogden South Hill Quarry Park Douglas Glen Shepard

Canyon Meadows Fish Creek - Lacombe Shawnessy Somerset - Bridlewood

Prestwick McKenzie Towne Auburn Bay/Mahogany Hospital Seton

a project agreement will be signed, and the construction phase will begin.

Selection of the successful Phase I proponent is expected by early next year (2023) for a construction agreement to be signed and work to begin in about mid-2024. Early works began in 2017 with utility relocations and environmental projects along the alignment and in November 2021, Construcciones y Auxiliar de Ferrocarriles (CAF) of Spain was awarded the contract to supply the Green Line’s new fleet of low floor trains. Phase I of the new Line is due to be completed in 2027. n

Edmonton LRT, Alberta

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rom opening the first underground section in 1978, in an ongoing programme of expansion, the City of Edmonton has a long-range programme to add significantly to the city’s existing metro network. While several lengths of new service are currently in construction for phased opening to 2027, the only new extension with underground works is on the 13km Valley Line southeast section from downtown to Mill Woods (Fig 1). The line includes a short twin tube tunnel of about 400m long from the north face of the River Valley and beneath the Quarters redevelopment area.

Construction activities on the Can$1.8 billion capital investment started in Spring 2016 as a P3 public-private partnership by the TransEd LRT, a Bechtel-EllisDon Construction joint venture.

BeMo Tunnelling of Austria is consultant for the SEM/NATM excavation of the tunnel section. The work included application of spile umbrella pre-support, a shallow 3.5m underpass of the Jasper Ave intersection and operating under extreme weather conditions of -30°C winter temperatures.

Tunnel construction ended in 2018 and opening of the full line was due by end of 2020. However the Covid pandemic

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Fig 1. Buildout plans for the Edmonton LRT and technical issues with concrete piles on the elevated sections have delayed the opening to a date that is yet to be confirmed.

The Mayor of Edmonton is also on record as being critical of the P3 procurement model saying that the City, as the project’s ultimate owner, has less control and oversight over P3 projects and that the processes lack transparency and accountability, which are essential he said when public money is being invested on public SEM/NATM excavation of the twin tunnels under the Quarters area of infrastructure.

the Valley Line Southeast

SEM/NATM excavation through the glacial till, which is partly permeated with water-bearing sand Hydroshield slurry TBM excavation, on lenses of up to 1.5m thick, follows the introduction earlier sections of the Edmonton LRT of the method to North America, together with network (see case study p15). n

Toronto Metro, Ontario

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etro extensions in the greater Toronto area have kept local and international contractors busy and are still doing so today. After opening the first section of the Yonge Subway as Canada’s first subway line in 1954, the Toronto system has expanded gradually over the decades to a system that now spans some 77km of trackway and 75 stations with more currently in construction and planned, to add new extensive lengths of underground alignment.

proposals for advance contracts for the design, finance and construction of the running tunnels for the Scarborough and Eglinton Crosstown West extensions in August 2020.

Scarborough Subway extension

In May 2021, a Can$757.1 million fixedpriced 3P public-private partnership

Following the underground Sheppard Subway line in the mid-1990s (see case study p27), work progressed on the the 8.6km underground Spadina Line extension that opened in December 2017.

There followed the first phase of the Eglington Crosstown line, which is currently nearing completion, to current planning and construction of four new projects - the Eglington Crosstown West extension, the Scarborough Subway, and the Ontario Line and Yonge Subway extensions, adding significantly to the network (Table 1 and Fig 1). The Finch West LRT and the Sheppard East LRT projects are aligned on the surface with a short length of subsurface work on the Sheppard East project to link with the existing Sheppard Subway underground station at Don Mills.

contract was signed with Strabag and its design team of Arup Canada and Brian Isherwood & Associates for construction of the Scarborough Subway project.

The contract covers procurement of the 11.9m diameter Herrenknecht EPB TBM for excavation of the 7.8km single-tube, double-track segmentally-lined running tunnel plus design and construction of

Table 1. Details of the four metro line priorities in Toronto Line Cost (Can$) Length and completion date Ontario Line $10.9 billion 16km, 9km underground TBC Yonge Subway extension $5.6 billion 7.4km, most underground TBC Scarborough Subway extension $5.5 billion 7.8km, all underground 2030 Eglinton West extension $4.7 billion 9.2km, 6km underground 2031

To get work on the four Can$16 billion program priority projects underway, Infrastructure Ontario as owner and Metrolinx as the service operator called

Fig 1. Existing lines of the Toronto Metro and alignment of the new extensions

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the launch and reception shafts and fabrication of the precast concrete segments.

Construction of the stations, plus installation of the rail and M&E and systems fitout is to be let under a separate contract. In February 2022, three shortlisted teams were invited to present proposals for the progressive design-build delivery contract: • Dragados Canada with design engineer Aecom • KSX Integrated Design-Builders led by Peter Kiewit Sons, SNC-Lavalin Constructors (Pacific) • Scarborough Transit Connect led by Aecon and FCC with designer Mott MacDonald After evaluating proposals, Infrastructure Ontario and Metrolinx will select a partner to work through a development phase towards awarding the design-build contract.

Eglinton Crosstown West extension

An advanced contract was awarded also in May 2021 for excavation of the 6km twin running tunnels for the 9.2km Eglinton Crosstown West extension from Renforth in the west to Mount Dennis Station in the east. The Can$729.2 million fixed price design-build and finance contract under a 3P publicprivate partnership delivery model was awarded to the West End Contractors of Aecon, Dragados and Ghella, with design engineers TYPSA and EXP Services. Two Herrenknecht TBMs started excavation of the twin drives from the Renforth portal structure in April 2022. A request for qualifications for the separate design-build contract for construction of the stations with five of the seven aligned underground, plus elevated trackway and fitout of the systems is to be launched in late 2023.

With construction of the Eglinton Crosstown West extension underway, Ontario Infrastructure and Metrolinx remain committed to building the 5km link from Renforth Drive to Pearson International Airport (Fig 1). The link is designed conceptually as an elevated guideway over Highway 401 to an at grade alignment to the airport terminal station.

Also in early 2021, three groups were shortlisted for the design-buildfinance-operate and maintain contract for the Ontario Line rolling stock, systems, operations and maintenance package. Of these Connect 6ix is the selected preferred team that includes Hitachi Rail, Webuild, Transdev, IBI Group, NGE Contracting and financiers National Bank Financial and Sumitomo Mitsui Banking Corporation.

Metrolinx and Infrastructure Ontario expect to award the contracts in 2022.

The northern section civil works comprise 10km of underground and elevated trackway with a bridge over the Don River and eight stations, one of two underground stations connecting underground at Pape Station to Line 2, and six elevated and at grade stations.

A request for qualifications for the design-build-finance contract is expected before end of 2022.

Yonge Subway extension

The fourth of the four current priority projects is the 8km extension Yonge Subway Extension from Finch Station to the Richmond Hill/Langstaff Station at Highway 7. Current plans are for about 5km of single-tube, double-track running tunnel with a 831m long triple-track underground train storage facility at the north end. A request for qualification for the proposed design-build-financemaintain type contract was issued in April 2022 towards having the extension in operation in the early 2030s.

Eglinton Crosstown Line Phase 1

Work on the current Eglington-Crosstown Phase 1 began in 2012 with award of the first of two tunnelling contracts to the ObayashiKenny-Kenaidan-Technicore JV. Under a bid of Can$320 million the contract comprised 6.25km of 5.75m i.d. twin-tube running tunnels between the Black Creek launch site near Eglinton West Station and from there to Eglinton Station, just west of Yonge Street (Fig 3).

The second contract for design-bid-build construction of the remaining 3.25km running tunnels from the eastern most point near Laird Station westwards towards Eglinton Station at Yonge Street was awarded for Can$177 million to the 50/50 JV of ASC Dragados and Aecon in November 2013.

Fig 3. Underground and at-grade alignment of the Eglinton-Crosstown Subway project

Fig 2. Ontario Line calls for extensive underground works

Ontario Line

Procurement is also underway for two contracts for the new Ontario Line. The Can$10.9 billion project is the largest transit project in Canada and will include 15.6km of subway line and 15 stations from Exhibition Place in the southwest, through the heart of downtown, and north to the Ontario Science Centre interchange station on the Eglinton Crosstown line in the northeast (Fig 2). The line is to be procured as three large contracts, one each for the south and northern sections of running track and stations civil works, and a third for the supply of rolling stock, track and M&E installations, and line operations and maintenance.

In early 2021, three design-build-finance teams qualified to submit proposals for the southern section civil works from Exhibition Station to the Don Yard portal, comprising 6km of tunnel and six underground stations. Of these three, Ontario Transit Group (OTG) Ferrovial Vinci with consultants Aecom, Cowi, GHD and Sener, and financier HSBC has been selected as the preferred team. The competitors were Aeocn-Dragados-Strabag with Hatch-Arup, and Webuild-Astaldi with IBI-Arcadis.

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The two JVs used four new EPBMs, procured for the project by Metrolinx from Toronto-based Caterpillar Tunneling Division, and by then sold to Liaoning Censcience Industry of China (see p34).

Construction of the stations on the line, 12 of them underground, and the M&E installations and rolling stock procurement is being completed under a separate 30-year Can$9.1 billion design-buildfinance-maintain contract awarded in June 2015 to Crosslinx Transit Solutions (CTS), a consortium of SNC-Lavalin, EllisDon, Aecon, and ACS Infrastructure Canada. Opening of the new line has been delayed and is further delayed from its Fall 2022 date to a date yet to be confirmed. n

TunnelTalk references •

Toronto Metro gears up for Spadina Line tender - September 2009

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Launching for final leg of Spadina drive - September 2013

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Spadina Line tunnel segments go high tech - October 2011

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Final TBM breakthrough for Eglinton Crosstown LRT – August 2016

•

Scarborough and Eglinton Crosstown West shortlists - August 2020

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Shortlists for two Ontario Line metro contracts – January 2021

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Preferred route for Toronto Metro Yonge extension - April 2021

Quebec City Tramway, Quebec

T

he City of Quebec has approved construction of a Can$3.3 billion, 19.3km tramway system with a 2.1km underground section and two underground stations near the city’s Parliament Building. The original intention of the City was to have one design-build-finance-maintain and operate contract that included procurement of rolling stock and three teams prequalified in August 2020. A request for proposals was to be issued in April 2021 but

this was halted in January 2021 when Alstom acquired Bombardier Transportation and two of the pre-qualified teams withdrew.

In June 2021 the City announced that it would revise its tendering process to allow a more competitive bidding process of two contracts for the rolling stock and the civil infrastructure separately. Each package has received two proponent teams and bids are due in Fall 2022 for the rolling stock and in Spring 2023 for the infrastructure package. n

Fig 1. Route of the proposed tramway line for Quebec City

Design of the underground tramway stations in the city centre

Montreal REM and Metro, Quebec

I

n Montreal, work has progressed on the initial section of the REM Reseau Express Metropolitain automated LRT project which adds 67km of service and 26 stations to the current 71km long Metro network. REM includes two sections of underground work, at the airport and under the city centre. At the airport a Robbins EPB TBM completed its 3km long single-track tunnel under a runway and taxiway to connect services to the underground airport station. After starting in Fall 2020, ground freezing from the surface was required to assist maintenance and cutter changes on the 7.4m diameter TBM through complex mixed ground conditions. The TBM completed the drive in July 2022 maintaining settlement to practically zero.

In the center of the city, the existing 100-year-old 5km long Mont Royal Tunnel is being converted from commuter rail to REM light rail operation with two new underground stations being added to the line. The 70m deep EdouardMontpetit Station is in the heart of the University of Montreal Campus and a shallower station is being built near McGill University Campus to connect to the existing Green Line. Services on this first section of the REM are expected to start in 2022 from the South Shore to Bonaventure-Central Station. Other

branches of the network will come into service in 2023-2024. Upgrade of the Mont Royal tunnel to modern LRT service for the REM project was selected as the winner of the TAC 2022 Canadian Project of the Year up to $100 million.

In November 2021, CDPQInfra, the Infrastructure arm of the Quebec public pension fund and the private partner of the P3 REM project, announced further extension of its current LRT network to the east and northeast of the city (Fig 2). The extension will add 32km and 23 stations and connect to the existing Montreal Metro network at several locations. Tendering for construction of the Can$10 billion investment is underway and consists of four major packages with two including underground works. Lot 3 consists of an

8km long underground alignment with seven underground stations, two of which will be transfer stations with the existing Metro. Lot 4 has an underground portion that is currently under evaluation with the local community keen to extend the length of a proposed short 500m underground section to 3km. Proposals are expected to be called for Lot 3 in Fall 2022 and Lot 4 in Summer 2023.

Funding for the projects is provided by CDPQInfra and Federal and Provincial Governments, as well as investment from HydroQuebec as part of the larger electrification of the public transportation system. There is also a collection from property tax revenes as the project is expected to increase property values within the vicinity of its stations.

Left: The 70m deep Edouard-Montpetit station; Right with video link: TAC 2022 Award for reconstruction of the southern portion of the Mont Royal Tunnel

Fig 1. REM network and existing Montreal Metro and its proposed Blue Line extension; Fig 2. Planned REM de l’Est extension

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Also in Montréal, the Société de transport de Montréal (STM) as operator of the existing Metro system, opened its new Garage Cote Vertu in June 2022 and is finalising design of its Can$2.6 billion Blue Line Extension.

The three parallel tunnels of the Garage Cote Vertu provide a total 2.5km of underground train storage and maintenance workshops. The location of the facility is selected to support

future northern extension of the Metro Orange Line. Excavation of the tunnels and underground facilities was by roadheaders with drill+blast for open cut excavations. Excavation crossed known fault zones and under an existing rail junction tunnel with caverns as wide as 19m span and a rock cover as low as 3.4m.

The 6km long Blue Line extension will add five new underground stations to the north-east of the current network (Fig

1). A single-tube, double-track alignment is expected to be excavated using a 9m diameter TBM to match the existing Metro configuration. This will be the first use of TBM excavation for STM with most of the previous Metro tunnelling work completed by drill+blast and roadheaders.

With Provincial and City funding secured for the Blue Line extension project, construction is scheduled to start in 2023 towards opening the extension in 2029. n

Ottawa LRT, Quebec

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or the capital city of Canada, modern mass transit rail services began in September 2019 with opening of the Confederation Line, now named the O-Train Line 1. A 2.5km section of the line aligned underground with three underground stations beneath the city center is the cornerstone of future O-Train expansion plans.

The first line of the system was built under a 30-year designbuild-finance-maintain contract awarded in 2012 to the Rideau Transit Group (RTG), a team led by ACS Infrastructure of Spain with its construction company Dragados and team partner SNCLavalin of Canada managing the construction phase with team engineers Hatch Mott MacDonald, Dr Sauer & Partners, and Veolia Transportation. OC Transpo, the city’s public transportation agency and its employees, operates the system.

RTG agreed to deliver the 12.5km long LRT Line 1 with its 13 stations for a fixed-price delivery contract of Can$1.2 billion and bear responsibility for all cost overruns and penalty clauses in the event of late delivery. Excavation of the single-tube double-track running tunnel and the three mined underground stations was

by NATM or SEM to avoid disruptive open cut works. Powerful roadheaders excavated the mainly competent limestone to NATM/SEM designs by Dr Sauer & Partners.

Excavation began in late 2013 and was completed in early 2017. The scope of the project and an innovative design and application of permanent tensioned tie rods across the span of the large underground mined stations earned for those involved the Tunnelling Association of Canada TAC Award for Project of the Year in 2017 and the TAC Innovation Initiative Award of 2019 respectively. The tie rods maintain the integrity of the caverns under shallow cover below the city streets, and between the basements of buildings either side.

Current extension works are extending the first line east, west and south. The 12km extension east with five

14

Fig 1. Underground section of the initial Ottawa LRT route new stations is all on the surface, the south extension includes a 4km link to the airport and is all on the surface, and the 15km west extension with 11 new stations includes two underground lengths of cut-and-cover work, 270m under Connaught Avenue and 3km with two cut-and-cover stations at Orchard and Cleary running under the Sir John A Macdonald highway and Byron Linear Park (Fig 2 inset). The extensions are set to open south in Spring 2023, east in 2024 and west in 2025. n

Fig 2. Extensions of the initial Confederation Line with cut-and-cover work included on the west extension (inset) Below: SEM station cavern excavation (left) and singletube double-track running tunnel excavation on Line 1

Completed Hydroshield tunnel with precast segmental liner

Edmonton light rail transit,

a tunnelling laboratory for North America CASE STUDY: Construction of Edmonton’s light rail transit system saw the first application of NATM in soft ground and the first use of bentonite slurry TBM excavation in North America. The organisation and management of the project, as well as the contractual arrangements for the execution of TBM and SEM observational excavation methods, marked the Edmonton experience as a test case from which other urban metro authorities learned a great deal.

SITE VISIT REPORT: MARCH 1992

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dmonton, the capital of Canada’s oil-rich province of Alberta, is to open a new section of its light rail system in late August 1992. Inauguration of the new 2.4km section will extend the existing 10.3km line and will provide a vital bridge connection over the North Saskatchewan River to link the city’s commercial centre with the University of Alberta campus. Of this length, 7.7km is on the surface and 3.4km is in twin-tube tunnel with five stations on the surface and seven underground (Fig 1).

Construction of the system started in 1975, with the first 7.2km length from Central Station to Belvedere opened in 1978. The 2.2km surface extension from Belevedere to Clareview Station opened in 1981. The third phase, a 900m underground extension, included two underground stations, opened in 1983. The next phase, the 900m underground section between Corona and Grandin (Government Centre) Stations started in September 1986 and opened in September 1989. Work on the last leg, from Grandin across the river to University Station, began in late 1988 and will open at the end of August 1992.

the good-quality till, a favourable medium for costeffective tunnelling.

2. Experience gained by the city’s Water and Sanitation Department during excavation of deep-level sewer tunnels using full face TBMs inspired confidence • Owner: City of Edmonton, Transportation Department • Project administrators: City of Edmonton, Public Works Department • Managing consultant: Stanley Associates Engineering Ltd • Geotechnical adviser: Professor Dan Z Eisenstein, University of Alberta, Edmonton • Contractors: Several on different contract packages

From here, the masterplan is to extend this one line further south past Crawford Centre to Southgate Mall with a branch going ultimately to the famous West Edmonton Mall (Fig 1). Another line is proposed to serve the Northgate area. Design of the next phase, the 2.5km section from University Station to Crawford Centre Station with an additional station at the Health Sciences, is in the preliminary phase and is scheduled to be constructed by the year 2000. About 1km of this 2.5km length will be underground, with the Crawford Centre Station being located on the surface. A debate continues as to whether the proposed Health Sciences Station will be underground or on the surface.

Four major factors influenced the decision to take the LRT services underground in the downtown area of Edmonton: 1. Tunnelling costs would be relatively inexpensive in

Fig 1. Existing and planned routes of the LRT network 15

among the planners of the LRT as to Edmonton’s tunnelling capability.

3. There is little surface street capacity for exclusive transit use.

4. It offered easier interconnection with Edmonton’s developing underground walkway systems.

In 1984, following an international selection process, Stanley Associates of Edmonton was retained to provide project management services. Stanley is also responsible for three design packages: for track and signalling; line communications; and commissioning of the completed project prior to official opening

Distinctive system

Changes to the Provincial funding po­licy included a share from the City Government. For the new 2.4km extension from Corona Station to University Station, which involves 31 engineering design packages, 61 construction contracts and a cost of Can$150 million, 75% was funded by the Province of Alberta through its Urban Transportation Fund, with 25% contributed by the City of Edmonton.

There are several points about the Edmonton LRT system which differentiate it from others in existence: • With a city population of about 605,500 (in 1991) and a metropolitan regional population of 800,500, Edmonton was the first city in North America with less than one million population to build a light rail transit system. The first section was built and opened in time for Edmonton’s hosting of the Commonwealth Games in 1978.

• The electrical LRT system is powered from an overhead catenary. An innovative direct rail fixing system keeps the rail low in the tunnel invert, thus minimising the excavated space required.

• The design of all underground stations on the Edmonton LRT must comply with the Alberta building code of practice in respect to access, emergency escape and a fully reversible ventilation system.

In addition, all stations must be accessible by all, including those in wheel chairs. The LRT underground stations in the downtown area are quite shallow, at about 15m deep on average, and are built by cut-andcover between tangent piled walls. A mined solution was considered for the 23m-deep University Station but this proved uneconomical.

Ridership on Edmonton’s LRT to date is small, averaging about 24,000 rides/week/day. Its full capacity is about 11,600/hr in both directions in the peak hours. Ticket prices are reasonable at Can$1.50 to ride the full length of the system in peak hours and rides on the section from Churchill to Grandin Stations in the downtown area are free between 9am and 3pm on weekdays and extended until 6pm on Saturdays.

Extension of the system from Corona to Grandin Station did not increase rider­ship significantly. Opening of the current extension across the river to the University of Alberta, one of the largest in Canada, is expected to increase ridership from 24,000/day to 32,000/day.

Operating three-car trains on a five minute headway, the extension will provide 5,800 riders/hr/direction additional capacity in cross river traffic.

Management evolution

In the early stages, all design and construction of the LRT was managed publicly by the City Government with almost the full 100% funding provided by the Provincial Government. Most of the construction work was carried out by the City’s own construction departments.

In the mid-1980s there was a call from the private sector for a greater involvement in the design and construction of public works facilities. Also, the dramatic drop in oil prices at that time led to financial constraints by the Provincial Government. Cuts in public spending suspended any further work on the LRT beyond completion of Corona Station, which opened in 1983.

Engineering of the extension to the University started again in 1984, but under different management and funding arrangements.

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“As project manager, one of our most important duties is the role of conceptual estimating group and cash flow watchdog”, said Don Hickey, Director of Stanley’s LRT Project Management team, who took up his post in mid-1990. “In what I believe is an unusual practice, we monitor expenditure against commitment instead of cost. This keeps the project’s progress always in sight of the budget and guards more effectively against budget overruns. One of the greatest difficulties is setting aside sufficient sums to meet possible contingencies such as design changes, market forces and contingencies arising during construction.”

Once the conceptual design and budget was approved, Stanley and the City together selected a consultant for the engineering and design contract from a group of three or four designers who have prequalified for each contract. The final scope of the contract and the fee is then settled. “This is the Qualification Based Selection System of awarding design contracts”, said Bob Kavanagh, Stanley’s project adviser. “It is a system that is gaining recognition in Canada and FIDIC is examining the advantages of the practice.”

The chosen design firm produces a preliminary engineering report using the concept design and budget. In the interest of time and scope of detail design responsibility, options are studied and eliminated in the Stanley concept planning stage. This report includes an estimate to within +/-10% of the lowest likely construction bid. Once accepted, contract documents are prepared and fixed price tenders are invited. The contract is publicly tendered but, as each contract package is quite small, this generally excludes international competition.

The form of contract used in Edmonton is a version of the Canadian Construction Association’s Standard Stipulated Sum Form. “Tenders for the construction of this last section have come in between -8% and +5% on the Engineer’s estimate”, said Kavanagh. “Some packages have been up to 25% below estimate.”

Wherever possible, construction risks are left with the contractors and risks related to unforeseeable situations are with the project, according to Kavanagh. Each construction contract allows for notification of a possible change of contract conditions and for reconciliation by negotiation. If this fails, there is provision for voluntary, not compulsory, arbitration, with litigation offered as a last recourse.

The site investigations and geotechnical reports for the last construction phase were completed under two separate consultancy packages. The site report, including the engineering properties of each soil type, is incorporated as part of the contract document. It is

from these data that acceptable settlement and ground movement tolerances are calculated.

Each design firm appoints its own site resident engineer who, in conjunction with Jon Masters, the construction coordinator for Stanley, is responsible for overall site supervision and for keeping construction work on schedule.

Through all the changes over the years. one post has remained constant and that is the role of the special advisor for tunnelling and geotechnical engineering.

This post has been filled since 1976 by Professor Z (Dan) Eisenstein. As Professor of Civil Engineering at the University of Alberta, Eisenstein has overseen the introduction and successful application of several tunnelling and ground engineering techniques that had never been used before in North America.

In his role as special tunnelling and geotechnical consultant, Eisenstein is involved in the decision making process at all levels. In addition to fulfilling his advisory role, he has monitored and documented each stage of the underground excavation works and records are freely available through publication of papers in the international technical press and in the proceedings of international conferences. The greatest opportunity to study the work at Edmonton occurred on this last construction phase where three very different tunnelling methods were applied.

Geological profile

Under the central area of Edmonton, the geology is homogeneous, comprising relatively young, overconsolidated glacial till deposits. Most of the initial LRT tunnelling was completed in this type of ground using a Canadian Lovat TBM. The fully mechanised TBM worked well in the dry silty clay with steel ribs and wood lagging erected as primary lining. No special ground treatment was required, although buildings under passed by the tunnels were underpinned and building foundations were extended to below tunnel level. “In this till, settlement was typically about 10mm,” said Eisenstein.

Geological conditions for the section from Corona Station to University are more complex. As the alignment ap­ proaches the deep river valley, it passes through complex statigraphy on both sides (Fig 3). The recent geological deposits have, over the years, caused slope stability problems in the river valley and dormant slides are a known risk.

“In such conditions, settlement control is the greatest concern”, said Eisenstein. “The choice is either to use conventional methods and necessary ground treatments to prevent settlement or to apply modern tunnelling technologies which provide sufficient ground control as an integral part of the system. As it happens, we used three different tunnelling techniques on this section - a Lovat TBM with ribs and lagging, the sequential excavation method (SEM), and the bentonite slurry Hydroshield TBM system (Fig 2). In all cases, the contractor was responsible for limiting movements to within the specified tolerances.

“To assist the contractor, we, as technical advisers to the project, established computer-controlled ground instrumentation monitoring stations just before recognised critical zones. These warned of any likely problems and allowed the contractor to assure us that his chosen excavation method could meet the movement tolerances or to modify his procedure to better guarantee adequate ground control before reaching the critical zone.”

All instrumentation was installed and continuously monitored by an independent consultant. All data were made available immediately to all parties - the owner, managing consultant, designers, special advisers and the contractors. For the data to be useful, all parties had to agree on their interpretation, which was the direct responsibility of Eisenstein as the special tunnelling and geotechnical adviser.

“The warning benefit of this observational tunnelling method was extremely effective and its assistance in the successful completion of the work from both a technical and contractual point of view is invaluable,” said Eisenstein. “In just one example of its effectiveness, the monitoring programme identified failure of the rubber tail seal on the Hydroshield before the contractor was aware of it. The information allowed replacement of the seal with a wire brush type before any serious settlement damage occurred.”

Sequential method

Immediately south of the existing Corona Station, the two short 120m curved tunnels to the crossover chamber, Figs 2 and 3. Plan and profile of the current 7.7km extension of which 3.4km is in twin-tube tunnel and includes a bridge crossing of the deep river valley

On the north bank, a large sheet of till overlain by lacustrine deposits is resting on preglacial Saskatchewan Sands and Gravels. There are frequent waterbearing sand lenses in the stiff silty clay and the preglacial sands are dry and of uniform grain size gradation. The north wall of the river valley is formed by postglacial out wash sediments, underlain by Cretaceous bedrock consisting mainly of shales. The sediments are mainly uncemented sands of variable gradation with uneven standup time and with boulders of up to 250mm at the base.

The geology of the south side of the valley comprises mainly lacustrine clays overlying an extensive body of glacial sand, below which are discontinuous sheets of till. The glacial sands are of variable grain sizes with course sand and gravel at the lower levels and uniform fine sands near the top.

17

Fig 4 (left). Typical sequential excavation and initial support of the SEM headings; Right: Advancing an SEM tunnel face

plus the chamber itself and the 356m of the east running tunnel from the crossover chamber to Grandin Station was completed by WA Stephenson Construction (Western) of Calgary using SEM. SEM is the title used for NATM in Canada. The title NATM is not generally used because many engineers argue that there is nothing particularly new nor Austrian about the technique. It was said also that the term NATM implies that experienced foreign engineers must be engaged to design the schemes, to apply the technique and to· supervise the construction.

This is viewed with wariness and opposition by both engineers and contractors in North America.

All SEM work on the project was designed without any foreign expertise. However, Canadian engineers have toured Europe under the guidance of Professor Eisenstein to investigate the application of the technique.

Study of the tunnelling principles has been added to the university’s civil engineering curriculum to provide training in the technique for Alberta’s engineers. This is claimed as the first use of the technique in soft ground in North America.

As SEM work progressed, the Public Works Department of Edmonton launched the Lovat TBM from the north portal to complete the first 789m-long north running tunnel to the crossover chamber. Ribs and lagging on 1.5m centres with 100mm timbers formed the initial support behind a 300mm in-situ concrete final lining. “Here in the river valley, we were no longer in the hospitable clay till, but rather in the fine glacial sands of the river valley”, said Eisenstein. “For successful application of the Lovat TBM, we knew that the sands would require ground treatment.”

Due to the grain size and nature of the sand, chemical grouting could not be expected to be sufficiently effective.

Vertical jet piling from the surface using a water/cement/ bentonite mix was therefore chosen (Fig 5). Based on a 1m spaced pattern, each jet pile was designed to intersect.

However, intersection of the piles was not as effective as anticipated. As the TBM cut into a window in the jet piling, sand was lost.

Jet piling was undertaken over the 100m of the alignment under a street and adjacent to highrise buildings. For the 30m at the start of the drive under the publicly owned river valley parkland, jet piling was not considered necessary.

As a result, just 80m into the drive and under 12m cover in what is now considered an old river bed terrace, overexcavation of the dry running sand caused a collapse. A surface depression of 3m2 x 4m deep resulted. This was excavated and used as a temporary shaft during the drive.

When working in the good-quality, dry, substan­tially selfsupporting till, the 6.3m diameter running tunnels were excavated on a top heading and bench/invert sequence with the top heading about 3m or 4m ahead of the bench (Fig 4). Immediate support comprised steel I-beams on 600cm to 1.2m centres and a minimum 150mm of shotcrete. In an unusual application, Fig 5. Jet pile ground support the circular steel ribs generally used for the ribs and lagging behind the Lovat TBM are used also on the SEM headings. The full profile of the SEM tunnel is therefore perfectly circular, with the bench and invert excavated at the same time and supported with the full half section of the steel rib.

“The steel ribs carried about 10% of the ground load in the good-quality materials”, said Masters. “In these cases we could have used shotcrete without the steel beams but no one had ever used SEM in soft ground in North America before and we erred on the side of caution.” In poorer ground, extensive spiling had to be applied to control un­ stable sands ahead of the face. All the SEM work was finished with a 300mm thick nominally reinforced in-situ concrete lining.

18

The Lovat machine carried on and completed the 789m of the west running tunnel to the crossover chamber. However, the slow progress of the jet piling and the difficulty to control loss of sand between the piles was of considerable concern for the east running tunnel that would be driven only 2.5m from expensive highrise apartment blocks on the street opposite the city’s government centre.

Bentonite support

A search for a suitable method for the 320m west running tunnel from the north portal to Grandin Station ended in acceptance of a JV proposal from PCL Construction and the German tunnelling contractor Hochtief that proposed completing the tunnel using a bentonite slurry Hydroshield.

The pressurised bentonite support of the tunnel face would over­come the ground loss problems encountered on the parallel Lovat TBM drive and without the need for costly, slow and unpredictable pre-consolidation of the ground. Underpinning alone can cost up to Can$3 million/building.

Hochtief shipped the Hydroshield from Germany in July 1989 and launched it at the north portal in September 1989 to complete the tunnel on a design/build basis. As it progressed, a 350mm-thick precast bolted concrete segmental lining with a water sealing gasket was erected and the annulus back grouted as the ring left the tail skin. Bentonite pressures averaged about 1.2 bar during the drive and on several occasions, man-entry into the excavation chamber was required to remove cobbles, since this particular Lovat EPBM completed two 6% downhill drives in 2004 Hydroshield had no integral stone crusher.

TBM is most economical in glacial till, becoming more On the south side of the LRT bridge, the two short 6.5m expensive in bedrock and very expensive in nondiameter x 318m tunnels to University Station and a 40m cohesive or unstable material when necessary ground stub tunnel was completed by Stuart Olson Construction treatment must also be applied. using the SEM method in the good quality Cretaceous bedrock of the south bank of the river valley. Designed Completion of this phase of the Edmonton LRT has by local consultant EBA Engineering, SEM was chosen advanced the study and the modern tunnelling for this section as the length was too short for costtechniques will be appreciated as a tunnelling laboratory effective application of a TBM. A TBM would also be for modern times. difficult to retrieve with the station box located in the heart of the university.

Follow on works In the course of completing this length, the tunnels had to pass just 1m beneath the deepest of the foundation piles of the Hub Mall, a 20-year-old building belonging to the University. Differential settlement at floor level was limited to 5mm but settlement of 20mm was recorded at the surface without causing visual stress to the building.

Cost comparisons

Application of the three distinct tunnelling methods on the project presented the rare opportunity to compare the direct costs of applying each technique. The different methods are applied in the same geology, within the same relative time, and under similar contracting terms and conditions. To undertake such a study, all the cost data of the construction contracts completed in the period from 1984 to 1990 have been put into a common data base and compared to determine under what conditions the cost of construction favours one tunnelling method over another under otherwise equal conditions.

In a nutshell, the data show that: • SEM, with the lowest initial cost, is very economic in consistent material and for short tunnels but that when spiling is required for ground control, the cost curve alters dramatically. They also indicate that about 500m is the breakpoint at which it is more economical to develop a niche or side adit to store the excavating equipment rather than take it out of the tunnel during muck removal; • the running cost of the Hydroshield, following the high one-time set-up cost, is dependent on the advance rate, which is dependent in turn on the geology encountered. The cost is lowest in sand and increases as the material becomes stiffer; • the conventional open faced, non-pressurised Lovat

In 2004, the McNally/Kiewit JV completed two 6.3m o.d.

(5.8m i.d.) x 280m long tunnels on a 6% down gradient to provide the transition to the surface from the existing University of Alberta station for a southward extension of the LRT on the surface.

As well as driving through sand above the water table, and glacial till and a soft rock below the water table, the 6.3m Lovat EPBM had to negotiate tight 250m radius curves and pass beneath structures sensitive to surface settlement. Special safety measures were also needed to control operation of service trains on the 6% gradient, using three locos linked together to pull fully loaded 170 tonne muck trains up the slope.

The Lovat EPBM had worked previously in Singapore and launched after assembly in Edmonton in early August 2003 to complete the first drive in early November 2003. It was relaunched in January 2004 to complete the second drive in early March. Excavation advanced at up to 40 x 1.2m wide rings of precast segmental lining/ week, peaking at 11 rings/shift, working one 9hr shift/day, 5 days/week. “We worked only one shift/day to ensure availability of adequate supervision at all times. On this job alignment and settlement control were the key priorities,” said Steve Skelhorn of McNally and Project Manager for the JV. To continue through winter, a 5 million BTU heater was installed and tied into the tunnel ventilation to maintain a good working environment despite -30˚C Alberta winter temperatures. As well as controlling settlement to an overall average of 5mm and a maximum of 12mm under a parking garage footings, alignment was controlled to within 25mm of design for the majority of the drives. A good deal of the project success is a result of “preplanning and constant on-the-job vigilance,” said Skelhorn. n 19

Vancouver SkyTrain, British Columbia

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n Vancouver, underground is the alignment of the next extension of the city’s SkyTrain network. Twin running tunnels for the new 5.7km long Broadway Subway extension of the Millenium Line will link six new underground stations with an interchange to the Canada Line at the underground Broadway-City Hall Station (Fig 1).

In July 2020 the Government of British Columbia selected the proposal of the 60-40% Acciona-Ghella JV from two shortlisted proponents for award of the design, build and partial-fund contract to construct the new westward extension.

Designers with the JV are IBI Group of Canada; Dialog BC Architecture Engineering Interior Design Planning; Mott MacDonald; and Acciona Ingenieria Especializada Obra Civil e Industrial with systems integration contractor Parsons.

Since contract award, excavation of the cover-and-cut underground stations is well underway and two new EPBMs supplied by Herrenknecht are excavating the 15m to 18m deep x 6m o.d. (5.2m i.d.) segmentally lined tunnels through weak sandstone of less than 30MPa and zones of glacial till. The TBMs will advance below the water table from the Great Northern Way-Emily Carr Station box which is also start of the 700m transition from the underground alignment to the existing elevated Millennium Line. The top-down station excavations beneath the Broadway Corridor are decked over to reinstate traffic and allow excavation to continue to base level with the interior construction then progressing from the bottom up.

Fig 1. Broadway Subway extension of elevated Millennium Line and planned underground extension to the University of British Columbia; Fig 2 (right).

Vancouver SkyTrain network The TBMs are expected to take about a year to excavate each 5km running tunnel. Segments for the drives are being manufactured by the JV in nearby Nanaimo and muck will be hauled by a continuous conveyor system. Once excavation is complete the JV will install all the M&E support systems and take the new line through testing and commissioning.

In addition to partial funding by the JV, construction of the project is funded Can$1.82 billion from the Provincial Government of British Columbia; $888.4 million from the Federal Government; and $99.8 million in-kind contribution from the City of Vancouver. An additional $17 million went towards the full project cost under phase one of the city’s 10-year

Underground connection with the Canada Line at the Broadway-City Hall Station

vision plan for extending the mass transit network. The 10-year vision also includes a follow on extension, underground, of the Millennium Line from Arbutus to the University of British Columbia (Fig 1). The new Broadway Millennium Line extension is programmed to open in 2025.

This is the fifth extension of the Vancouver Metro system since the first element of the elevated Millennium Line was inaugurated in 1986. It was followed by the elevated Expo Line; the Canada Line from the international airport with half of the line underground in cut-and-cover and bored tunnels under the city streets (see case study p21); and the underground section of the Evergreen Line extension northeast of the Millennium Line.

In January 2013, EGRT Construction, a consortium led by SNC-Lavalin with Seli as its tunnelling partner, won the Can$889 million construction contract for the 11km Evergreen Line project with seven stations and a 2km section of single-bore, double-track tunnel excavated by a 9.84m diameter mixed face EPBM supplied by Caterpillar which had bought Lovat (see p34). The Evergreen extension opened in December 2016. n

Launch of the two TBMs at the transition ramp to the elevated line ready to excavate the Broadway Subway running tunnels

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Vancouver LRT: Canada Line on track to meet Olympic deadline CASE STUDY: Construction of the rapid transit Canada Line between downtown and the international airport was a flagship project for hosting the Vancouver 2010 Winter Olympic Games. Critical to meeting the commitment was the 2.45km of twin TBM tunnels and underground stations in the heart of the city. While the works did meet the deadline, the project is an example of how tunnelling could have been continued to avoid a long and disruptive section of open cut work that ended in a court case finding for the plaintiffs against the city planners.

SITE VISIT REPORT: MARCH 2007

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he critical path on the 19km long Canada Line rapid transit construction program is excavation of the 2.45km twin bored TBM tunnels through the downtown area of Vancouver. Not only are geological conditions complex, the logistics are daunting. The TBM is required to work though abrasive sandstone and boulder infested glacial and interglacial till, on steep gradients of up to 5.5%, through tight radius curves of 200m radius, and within meters of existing underground infrastructure and private property lines.

To manage the challenge, the tunnel contract was awarded as a design-build undertaking to a joint venture of SNCLavalin Constructors Pacific of Canada and tunnelling specialist SELI of Italy. Tunnel boring started in June 2006 and broke through into the Vancouver City Center station box on March 1, 2007, just days adrift of the late-February milestone. “With the remaining 500m of this first drive expected to finish by mid-April, we are on schedule and on program, which is a fortunate position after a slow start and tough progress through a stretch of wet interglacial material at the end of last year,” said Brendan Henry, Chief Engineer of SNC-Lavalin/SELI JV.

• Client: A 35 year PPP concession by InTransitBC majority owned by SNC-Lavalin Inc • Contractor: An EPC contract with SNC-Lavalin in JV with Seli of Italy for the TBM underground section the same time, the JV contracted with Lovat of Toronto to supply a 6m diameter EPB TBM. Ahead of its arrival, excavation of the Yaletown and Vancouver City Center station boxes also started to facilitate progress of the TBM drives ahead of architectural and M&E fit-out of the three stations under separate contract.

In the restricted city location, the two mid-city stations presented particular challenges. The 20m wide excavations stretch to within 600mm of high-rise towers Fig 1. Canada Line alignment built within a dense downtown urban setting (inset)

Together with the city center bored tunnels, the Line and its total 16 stations comprises a 7km length of cut-and-cover connecting sections of elevated and at grade guideway taking the route south over new transit bridges across the Middle and North Arms of the Frazer River to the airport and beyond to Richmond (Fig 1). Civil work on all elements began in late 2005 with the commitment to have the line operating in time for the city’s hosting of the 2010 Winter Olympic Games. Since then the race has been on to have construction completed and the line opened in early November 2009 ahead of the Opening Ceremony in February 2010.

By mid-February 2007, at 20 months into the 4 1/2 year procurement, Roger Woodhead, Technical Director for the Line’s Engineering, Procurement and Construction Project Office confirmed that work was about 36% complete, adding that “overall construction is on program and things are looking good”.

TBM point of attack

Work by the SNC-Lavalin/SELI JV (SSJV) started in November 2005 with excavation of the Olympic Village station box to provide access for the TBM drives. At 21

Olympic Village station box provides access for the segmentally lined TBM running tunnel drives (right)

and their foundations either side of the streets. In some cases, the walls of underground parking garages were only narrowly set back from or actually border the property lines. To provide a stiff support of the 20m deep excavations the JV elected to install walls of slim micro- and mini-drilled piling within a minimum 600mm clearance of the property lines. In these excavations the JV installed two upper levels of internal bracing and tie back anchors below the basement and foundation structures. The urban setting further complicated station excavation by requiring extensive utility diversions, complex traffic and pedestrian detours and decking, and heavy truck transportation of materials and muck haulage through congested city streets.

Permeability in the strata is low at about 10-7 in the sandstone/siltstones and 10-8 in the dense glacial tills but the potential of meeting interglacial deposits of saturated sand and silts has required the dual mode rock/ mixed face EPB TBM to operate for the most part in the closed pressure balancing mode, using extensive soil conditioning to lower abrasivity, extract more competent material through the screw conveyor and lower full plenum cutterhead torque. Groundwater levels vary along the alignment from 3m to some 25m above the tunnel invert. Under False Creek, which is a tidal basin, the groundwater table is subject to daily tidal fluctuations of up to 3m.

The cutterhead is a mixed face design incorporating 17in twin tip disc cutters that are interchangeable with Lovat High-spec TBM ripper type teeth. The head can be configured with either To match the tunnel excavation challenges, the JV has a full face of disc cutters for reaches in rock, or a full face of procured from Lovat one of the most advanced TBM ripper teeth for the soft ground sections. The cutterhead is systems used in Canada to date, incorporating features an eight-spoke design with Lovat scraper collecting tools, used on TBMs for the first time in Canada and designed seven independent ground conditioning injection ports specifically to ensure absolute minimum on the face, and chromium carbide plate ground settlement through highly Table 1. Machine dimensions for abrasion protection. The main drive Shield diameter 6.026m variable geology. consists of a variable frequency electric drive (VFD) incorporating a high capacity Cut diameter 6.064m triple roller bearing, gear reducers, Geological conditions range from weak, Overcut diameter 6.089m integral pinions, water cooled electric generally massive (low RQD) sandstone Shield length 9.0m motors and VFD units controlling electric and siltstones of 5 to 10MPa UCS, to Overall length 81m frequency and voltage to the system. dense glacial till of a clay-silt-sand 650t matrix interspersed with granite and Overall weight granodiorite boulders of up to 2-3m The TBM screw conveyor enters the across and more than 250MPa in UCS. Table 2. Drive specifications cutterhead chamber at the invert and has 1,200kW The till contains interglacial waterbearing Installed power a peripheral drive that allows material to layers of sand and gravel and pockets of 1,104 kW available at cuttinghead flow through the drive and out the back coarse saturated running sand while the 6,180 kNm torque at O to 1.7rpm (Fig x). This provides for more controlled abrasive sandstone includes cemented Maximum speed discharge and helps in aligning the 3.2rpm sandstone floaters of up to 50MPa UCS location of the trailing belt conveyor Peak starting torque 7,750 kNm and occasional harder volcanic dykes. to accept the material from the screw Mixed face cutterhead dressed for rock conditions; Peripheral drive screw conveyor; Vacuum segment erector

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conveyor. The trailing belt conveyor discharges onto a moving shuttle conveyor that loads the muck train. The shuttle conveyor eliminates the need for the muck train to move during the loading operation.

The machine is fitted with first use of a vacuum segment erector on a TBM project in Canada. This requires segments manufactured to a much higher quality than usual to maintain the vacuum during lifting. The segments must also be kept cleaner during handling as debris will clog the vacuum system and require increased maintenance. The benefits of the vacuum erector are realized in the structural design of the segments. Over a certain size, the use of the more typical mechanical ball-and-cup mechanism is not possible due to the high amount of reinforcement required in the pick-up point.

The vacuum system distributes the pick-up loads more evenly and allows for a reduction in reinforcement and the use also of steel fiber segment reinforcement as an alternative to rebar cages.

Further weapons in the arsenal to minimize settlement include the first use in Canada of a through-the-tailskin annular grouting system and a two-component grout.

The system, supplied by Team Mixing Technologies of Canada, comprises a batch plant on the surface and separate Part A and Part B injection pumps on the TBM backup. Both the Part A cement, flyash and bentonite mortar and the Part B accelerator is mixed and pumped from the surface to holding tanks on the TBM backup.

From there the components are conveyed via six Part A and six Part B peristaltic pumps to six independent tailskin injection lines and ports. Usually only the upper four of these ports are used. The benefits of the Japanese developed two-component system are quick setting times, providing immediate support to the lining as it moves out of the TBM tailshield; inert grout that does not set up in the lines during stops; and fine control of grouting volumes and pressures.

To further combat settlement, annular grouting is linked via plc to the excavation cycle to prevent advance until the grouting system is on-line and ready to fill immediately the void created as the machine moves forward. At shut down for the next ring build, the Part A pumps continue for an extra 30 seconds to prevent clogging of the injection ports. Other TBM design features include predictive software for guidance control, articulation for a minimum 150m radius curve and a conveyor belt weighing and volume scanner.

In full EPB mode, the machine is designed to operate at up to 4 bar pressure. The Foamex TR soil conditioning system provided by Lamberti generates and injects foam to the plenum via seven independent injection ports.

Eight pressure sensors in the system - two in the screw conveyor and six in the plenum - monitor operating pressures and provide real time data to the operating screens in the operator’s cabin. There is also a bentonite replacement system to provide fine control of EPB pressure in the plenum and guard against rapid ground loss settlement.

As the TBM advances, the tunnels are lined with rings of rebar reinforced precast concrete segments. Each 250mm thick x 1.4m wide bolted and gasketed ring comprising five segments and a key. The segments are produced at a casting yard in Nanaimo on Vancouver Island where the JV supplied three sets of segment moulds from S.A.M.E.

Two part annular grout is pumped from the surface and injected through the tailskin via a touch screen control system

of Italy. To match the planned TBM production schedule, segments for nine complete rings must be cast/day.

Steam curing helps achieve the minimum 15MPa strength for the five-hour strike needed to achieve the necessary three casts/mould/24hr. Segments are stored in the yard until they reach the 40MPa design strength and are transported via truck on ferry to the Olympic Village access site.

The machine’s tacs acs guidance system forecasts the correct build of the tapered ring and provides accurate steering through the numerous horizontal and vertical curves of the alignment. The bored tunnel construction program is based on completing an excavation cycle in 40 minutes and a ring build in 20 minutes. The TBM is serviced by trains of four muck cars, two segment cars, a flat car and a man carrier pulled by a 35 ton Schöma loco. Traction power is shared between the loco and two muck cars to assist full train haulage up the maximum 5.5% gradients.

Long-term disposal of natural non-contaminated muck is barged to sea for controlled ocean disposal.

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and near the foundations of two 35 storey high towers. In addition, the schedule was nearing the Christmas holiday shut down. Given the circumstances, it was decided to halt the machine for the holiday break before going under the buildings. Polyurethane grout into the shield annulus was attempted to allow access to the cutting head for tool changes before entering the footprint of the buildings, but without success.

Breakthrough into the partially excavated station box

The TBM supplied by Lovat for the project has an installed torque capacity some 18% higher than recent machines of similar diameter and of 100% higher than similar diameter machines built only eight years ago. “Meeting the demands of this project has pushed EPB system specifications to a higher level than anything used previously in Canada,” said Henry for the JV.

TBM delivery and performance

The TBM arrived on site in May 2006 and was assembled in time to start boring by the end of June. “Since then, progress has gone through a roller coaster,” said Henry.

After launching on a down slope of 2% the alignment dived quickly to 5.5% to clear the foundations of a high rise building and pass immediately into a downward left hand curve under False Creek. “Fortunately we started in good quality sandstone and while the TBM performed well, its delivery was delayed by influences beyond Lovat’s control, and the backup system caused us delay through the learning curve, which altogether set us about six weeks behind schedule.” On the far side of the Creek, the TBM passed through an interface into the till without any problems but a high concentration of boulders damaged the grizzle-bars across the cutterhead openings and caused some blockages of the 10m long screw conveyor that extends into the invert of the plenum.

In the dense till, repair of the grizzle bars could be carried out in free air but the work did cost time.

The machine then entered another reach of good dense till in which the best advance rates to date were achieved at 19 rings or 27m in a production day with penetration rates of up to 100mm/min. This however came to an abrupt slow down when the heading entered a zone of saturated sand that lasted about 350m.

The saturated sand was not a surprise to the team according to Henry, but its persistent length and permeability was. “Pockets of saturated sand in the glacial till of Vancouver are known to exist but we are excavating at a deeper level than anything completed in the city to date and this was not a pocket. It was a long length in which EPB pressures were up to 2.2 bar.” In these conditions volumes of water were flowing into the plenum and along the annulus of the shield as well as causing an out rush of water through the screw at start of every stroke.

At the time the TBM was heading toward the tight 200m curve from Davie Street into Granville Street and under 24

Following the holiday break the TBM inched through the curve and back into sandstone for the first opportunity after more than 450m to carry out a man entry inspection in free air. All the 17in twin disc cutters and most of the ripper tools were thoroughly worn down and all needed replacing. Abrasivity of the material, particularly of the sandstone, was said to be proving higher than expected with samples testing to some 50% quartz content against the 27-30% anticipated. After driving through the earlier Yaletown station box, breakthrough into the Vancouver City Centre station box provided the first opportunity to inspect the body of the shield and the chromium carbide plate applied to protect the cutterhead face against abrasive wear. First impressions of the cutterhead, prior to cleaning, were that it looked good, according to Henry.

Following the extended maintenance and tool change programme, progress picked up again to steady rates of 18 rings a day through the sandstone. By mid-February, after completing some 2km of the first 2.45km drive, work was almost back on schedule. At the beginning of the drive crews worked two 10hr shift/day with a 4hr maintenance program 5 days/week but quickly changed to three 8hr shifts, 6 days/week to catch up the schedule with maintenance on Sundays.

For the most part the TBM has operated in the closed EPB mode under pressures ranging from 0.6 to 2.6 bar at the center of the plenum and settlement readings along the route have been negligible - mostly less than 4mm and a maximum of less than 7mm. According to Henry the ground conditioning and two-part grouting systems have performed quite well. “We do get some clogs of accelerated grout at the ports but replacement of an injection pipe is a quick 20-30 minute job. We are also suspecting some clumping of the grout rather than a uniform annular fill. We have worked with different mix designs and will introduce some refinements for the systems before starting the second drive.”

Advance program

Breakthrough into the partially excavated Vancouver City Center station box exposed the top of the TBM from about spring line up. As the machine advances it will excavate the remaining bench and will build full rings of lining behind. Building only invert segments was considered but this presented issues of preventing buckling of the invert segments against the forward thrust, as well as requiring some kind of upper thrust ring system and raising concerns for staying on line and level. Building full rings of segments grouted in the invert with the quick setting two-part grout will allow the TBM to maintain normal production through the partially excavated box and eliminate the potential for any time loss through the station.

After programmed inspection and maintenance of the machine in the station box, the remaining 500m of the first drive to the TBM reception shaft is expected to hole through by mid April. Once transported back to the

Cut-and-cover work along Cambie Street with the top deck and side walls cast as one to create the interior finish

Olympic Village site, the second drive is expected to start within 2.5 months and take ten months to complete. The TBM will be pushed through fully excavated station boxes at Yaletown and Vancouver City Center and is scheduled to reach the reception shaft by about March 2008. The Line’s end station at Waterfront Center is being completed under a separate contract that includes a 400m link of cut-and-cover to the TBM reception shaft. With the first drive behind them, the SSJV team has good knowledge of what awaits them on the second.

Cut-and-cover on a roll

In the meantime, cut-and-cover construction of the 7km section south along Cambie Street is progressing from five rolling-program fronts between four open cut stations.

For the most part, the cut-and-cover alignment is a sideby-side configuration of 10m wide and between 8-10m deep, with a section of 5m wide x 14m deep double deck configuration between the 23rd and 15th Street junctions.

Traffic management around the vital four-lane carriageway must maintain at least one operating lane in each direction and with decking to maintain access across intersections at all times.

Excavation is mostly by excavator and hydraulic breakers with a section of drill+blast needed through a zone of volcanic rock for a distance of less than 1km from 29th to 35th Streets. Support of the trench consists of shotcrete and wire mesh and rockbolts in the rock section. Behind the invert base slab, the reinforced walls, center divide and top deck of the box structure are cast as one composite pour using 20m long forms supplied by Peri.

Each 20m long casting of the 450mm walls and 500mm thick deck consumes some 173m3 of concrete with up to 48 turn-buckles supporting the Peri forms. Cut-and-cover is programmed on one 20m long casting every three days for a total of 40m finished each week.

The cut-and-cover contract started in early 2006 but fell behind schedule when a month of heavy rainfall slowed progress. To improve the situation the original 14m long Peri forms were extended to 20m, an extra front of rolling program was introduced and the work week was increased from five to six days to complete two concrete pours/week.

“Progress through the second half of 2006 was very positive”, said Woodhead who added that by mid-February 2007 the cut-and-cover section was set to finish six to eight months ahead of schedule.

This flexibility of program was said to be one of the principle reasons for proposing a combination of cutand-cover as well as bored tunnel excavation. “The procurement contract baseline design suggested more bored tunnelling excavated with up to three TBMs to meet program”, explained Woodhead. “In our winning alternative, we increased the cut-and-cover work to advance as many points of attack as possible to add greater predictability and flexibility, provide for shallower, less expensive, more user-friendly stations and reduce significantly the risk to completing the project within the tight construction period. The TBM tunnel operation also has the possibility of increasing to a 24hr/day, 7 days/week but with no major delays or downtimes it is doing well and we are very pleased with overall progress including on the elevated, at grade and bridge sections.”

Project realization of the Line is a 35-year PPP (publicprivate partnership) concession awarded to InTransitBC, a limited partnership owned by Canada’s construction/ engineering consortium SNC-Lavalin Inc and two pension fund financial investors. Of the Can$2 billion cost, private equity is contributing $750 million with the public funds from the Federal and Provincial Governments and the Airport Authority, with the Cities of Vancouver and Richmond meeting the remainder. To manage construction, InTransitBC awarded an Engineering, Procurement, Construction (EPC) contract to SNC-Lavalin Inc which in turn has awarded various subcontracts to complete the civil, M&E and equipment supply requirements.

Costly consequences of open cut work

In 2018, local traders and residents secured a significant win against the disruption and loss of business caused by the open cut section of the Canada Line project. A large portion of the 19km LRT route, advanced between 2005 and 2008 to provide a public transit link to Vancouver Airport in time for the Vancouver Winter Olympics of 2010, was aligned underground in TBM running tunnels and open cut underground stations in the heart of the city with a 7km long section under Cambie Street, converted from the original bored tunnel plan to the less expensive 25

In September 2018 a ruling by the court, after hearing the first three claims presented by the owners of a local theatre, a village restaurant and a general store, were awarded damages of Can$128,000, $44,560 and $7,600 respectively. In his ruling Justice Christopher Grauer wrote: “What made the construction intolerable... was the extended time over which access was restricted.” TransLink has been ordered to pay the damages and the ruling is seen as an important precedent for selecting bored tunnel construction over open cut works and for resolving the more than 100 remaining claims from Cambie Village business owners.

The last meter of ground falls away to finish 2.4 kilometer of running tunnels under Vancouver, British Columbia. The 19km Canada Line will link downtown Vancouver to the Vancouver Airport and the city of Richmond.

cut-and-cover option, progressing on five rolling-program fronts between four open cut stations.

Within days of the first train test runs in 2008, a classaction lawsuit was filed by more than 100 business owners in the Cambie Village against the engineering, procurement, construction (EPC) contractor, SNC-Lavalin, and project owner TransLink, claiming that the cut-andcover disruption cost them hundreds of thousands of dollars in lost business by driving potential customers away. In 2016, the Supreme Court of British Columbia Province ruled that members of the class action could not sue for lost revenue but could instead sue for lost value of the property in which they ran their businesses.

Hatch Mott MacDonald splits its joint venture NOVEMBER 2015

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fter 20 years as a joint venture providing engineering and professional services to the North American infrastructure market, Hatch and Mott MacDonald announced in 2015 the separation of the Hatch Mott MacDonald (HMM) joint venture into two distinct businesses. HMM’s Canada business became part of Hatch while HMM’s US business became part of Mott MacDonald.

HMM’s Pipelines business, which operates in both Canada and the USA, also joined Mott MacDonald.

Since its formation, HMM had grown into a major engineering and infrastructure business, with 3,000 staff and 77 offices throughout the USA and Canada. In Canada, the JV was involved on the Spadina Line subway extension (see p11) and the Niagara water diversion tunnel (see case study p35), among other transportation, water/wastewater, and oil and gas pipelines projects. n

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The ruling came as planning for the Broadway extension of the Vancouver LRT system was advancing. The Mayor of Vancouver at the time, Gregor Robertson (2008 to 2018), committed to supporting bored tunnelling for the underground reaches of the new line stating that “as long as I am mayor with a council majority, we will not let cutand-cover happen.”

Evergreen Line

Ahead of that, in January 2013, EGRT Construction, a consortium led by SNC-Lavalin with Seli as its tunnelling partner, won the Can$889 million construction contract for the Evergreen Line. The 11km LRT project comprises elevated and at-grade guideways with a 2km bored tunnel section and seven stations. Caterpillar supplied a 9.84m diameter mixed face EPBM, plus back up, for excavation of the single-bore double track tunnel.

The TBM had a specification to withstand pressures of up to 5 bar. The Evergreen Line opened in December 2016. n

SNC-Lavalin takes over Atkins

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n 2017, Canadian engineering and construction firm SNC-Lavalin purchased UK design, engineering and project management firm WS Atkins in a cash deal worth Can$3.5 billion (£2.08 billion).

SNC-Lavalin was founded in 1911 and has offices across 50 countries. Its construction division has completed a number of tunnelling projects in Canada and North America and holds a share in the Can$9.1 billion 30-year design-construct-finance-

China acquires Aecon

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n 2017 CCCI, the international division of China Communications Construction Company acquired infrastructure group Aecon of Canada for an agreed Can$1.51 billion.

Aecon will be the second major international civil construction company acquisition by CCCI after securing ownership of John Holland from Leighton Group in Australia in 2015. The agreed deal, which the Aecon Board accepted unanimously, valued the Toronto-based company at $1.51 billion.

CCCI President Lu Jianzhong, who was instrumental in securing John Holland

maintain contract to build all 25 stations, trackwork and signalling for the Crosstown LRT project in Toronto, the central section of which runs underground (see p12). It is also involved in the construction of Ottawa’s Confederation Line (see p14).

WS Atkins and Partners was established in 1938 by Sir William Atkins in London. Floated on the London Stock Exchange in 1996, Atkins is involved in an array of rail and metro projects in Europe, the Middle East and Asia. n

NOVEMBER 2017 said Aecon is a pioneer in public–private partnerships (PPP) and concession operations. Beijing-based CCCC, parent company of wholly owned subsidiary CCCI, is one of the largest engineering and construction companies in the world with revenues estimated at $62 billion and a stated 118,000 employees (including 48,000 foreign employees) in more than 140 countries and regions. CCCC is publicly traded on the Hong Kong and Shanghai stock exchanges. Aecon is publicly traded on the Canadian and New York stock exchanges. n

Golder Associates acquires Alan Auld

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anadian consulting engineer Golder Associates purchased the assets and ongoing operations of the UK based Alan Auld Group in 2017. With headquarters in Doncaster, UK, and offices also in Canada and the USA,

APRIL 2017

OCTOBER 2017

the Alan Auld Group has a particular expertise in the design and construction of complex shafts. Acquisition by employee-owned Golder Associates adds to its business operations from 165 offices in more than 40 countries. n

Toronto Metro: New beginnings with Sheppard subway CASE STUDY: After constructing earlier subsurface works as either cut-and-cover or mined under compressed air conditions, plans for the new Toronto Metro Sheppard Subway in the 1990s specified its first use of EPB pressurised TBM excavation of running tunnels and a one pass precast concrete bolted and gasketed segmental lining. It also introduced the policy of the client purchasing the TBMs and segments for the project as a method of kick starting construction phases. Despite funding cut backs and a claim to cover much greater use of EPB operation conditioning agents, the project was instrumental in the early development of EPB technology, the application of DRBs and the future for owner-procured project purchases.

SITE VISIT REPORT: SEPTEMBER 1996

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the construction schedule. The same process was used on the recently completed St Clair River railway tunnel project (see case study p44). In Toronto, the policy would provide a jump start on the construction programme and - by eliminating two large cost items from the bidders tenders - was expected to result in closer, more competitive bids.

But this is the only expansion project remaining on what started in 1990 as an ambitious Can$7 billion programme to be realised over a 25 year period and funded 75%/25% by the Provincial Government of Ontario and the Metropolitan Government of Toronto. This was quantified in 1992 in a ten-year programme worth Can$3.2 billion and covering five separate projects, three involving tunnelling. Work on the subway would be the first significant construction of subway since 1978, some 16 years ago, and the programme was seen as a way of moving the Province out of a three-year recession.

When promoted, the plan was to purchase two tunnelling machines for all three projects, a total of 8.9km of twin tunnelling, with the prospect of a further 12-14km of twin tunnels under future expansion proposals. With only one tunnelling project left, the economics of the client buying the TBMs for 4km of twin tunnelling have been reduced.

Similarly with the client’s purchase of the tunnel linings.

A potential order for some 15,000 rings for three subway line projects has been reduced to a total of 5,550 rings for the Sheppard Subway tunnels only.

onstruction of for the Sheppard Subway extension of the Toronto Metro began early in 1997 with contract documents on the street, tenders from six prequalified bidders due back by early June 1996 and award of contract due by 25 June 1996.

In early 1994, funding was approved to allow construction of three of the five original projects, these including two of the original three tunnelling jobs. The 4.7km Eglinton West line from Allen Road to York City Centre was to start first, followed by the 6.4km Sheppard Subway line from Yonge Street to Don Mills Road (Fig 1). The 4.4km long Spadina extension to York University was shelved. The third project was expansion of the Wilson Yard storage and maintenance facility.

However, TTC had committed itself to the proposal in Fig 1. The original four projects of the Can$7 billion expansion programme for the Toronto Subway of 1990

Funding cut

In Summer 1995, the newly elected conservative government in the Province of Ontario cut back previous commitments to the programme further in efforts to reduce a soaring public spending deficit. Authorised funding was cut to Can$1 billion to cover only one or other of the subway lines and a smaller expansion of the Wilson Yard. At the time work on the Eglinton Line had been in progress since early 1994. Excavation of the cutand-cover tail track section had started and bids were in for the one large tunnelling contract for the project.

Despite this, further local political pressure had the Eglinton Line work terminated and the Sheppard Line was adopted as the sole project to go forward.

Lovat EPBMs prior to launch on the Sheppard Subway in early 1997

This programme reduction minimised the advantages of early decisions by the client, TTC, the Toronto Transit Commision, to buy the necessary tunnelling machines as well as the precast concrete lining segments for the approved subway lines and make these available to the successful contractors for the work. The idea was promoted by RTEP, the Rapid Transit Expansion Programme management team which included TTC staff and Delan-Hatch JV personnel and staff, as a longrange, cost-effective method of risk-sharing between client, contractors, and suppliers and to accelerate 27

late 1993 and has had to follow through. The order for the two machines went to local Toronto-based tunnelling machine manufacturer Lovat and a contract for the manufacture and supply of the precast concrete linings went to CCL, a Canadian JV between Concrete Systems Inc., ConCast Pipe Ltd, and St Lawrence Cement Ltd.

Tunnel design

The geology beneath Toronto consists principally of glacial till, glaciolacustrine and glaciofluvial sand, silt and clay deposits, and beach sands and gravels. The shale bedrock lies typically 40-60m below the relatively flat ground surface and well below metro tunnel alignment.

The metro is typically subsurface with relatively shallow running tunnels between cut-and-cover stations. Cover above tunnel crown is about 15m on average and the ground water table, close to Lake Ontario, rises to within 1m of ground surface decreasing gradually with distance from the lake edge.

Under its contract with Lovat, TTC ordered two convertible 5.9m diameter open mode/EPB TBMs and their backups and associated equipment. The order to CCL JV was for the 225mm thick x 1.4m wide bolted and gasketed rings, each 5.2m i.d. ring comprising six segments and a key.

The contract for the two TBMs was signed with Lovat in May 1994, after the first cut in funding but when the Eglinton and the Sheppard Lines were expected to proceed. The TBMs were eventually delivered in October and November 1995 and since then have remained in storage awaiting start of the Sheppard tunnels in early 1997.

Programme changes and delays have also affected the CCL contract. When signed in March 1995 the order was for 10,600 rings to line the twin tube tunnels for both the Eglinton and Sheppard Lines. The contract was worth some Can$50 million and was driven by what was then a fast-track project geared to the schedule of the Eglinton project which was to be the first. On this basis CCL embarked on the construction of a state-ofthe-art casting factory on a green field site about 50km west of Toronto. The new plant with its 84 steel moulds from Cleco of the USA, plus the carousel production line, steam curing tunnel and robot station capable of automatically bending, cutting, assembling and welding the reinforcement cages, was designed to fill the order for the 10,900 rings in two-and-a-half years. The cost implications of reducing the order by almost 50% to 5,550 rings for the Sheppard Line alone are currently under review by TTC. Production at the factory commenced in February 1996 when work started on a single shift basis. This moved to a two shift operation in May 1996 and the first rings for the Sheppard Subway were scheduled for delivery in the Fall of 1996. The order was expected to be complete by Summer 1997.

During a site visit to Toronto, despite continued uncertainty about funding, TCC was working towards awarding the tunnelling contract for the Sheppard Line in July 1996. Six groups led individually by Kenny Construction, Obayashi, McNally, and Traylor Bros of the USA, Savakka of Canada and Ingenieros Civiles Asociadas of Mexico, are expected to return bids having first met the prequalification criteria. These, in addition 28

to adequate financial strength and bonding abilities, included previous experience with EPBM tunnelling and one-pass lining construction.

The Sheppard Subway extension is envisaged to eventually extend in tunnel to Scarborough City Centre where it will join an extension of the Scarborough light rail system which is built at grade and elevated. The current scheme is for a 6.4km long section under Sheppard Avenue from the Yonge Station on the existing north/ south Yonge Street Line to the Don Mills Station. The project carries a current budget of Can$945 million and is programmed to be in operation by the end of 2001.

The civil work is divided into eight principal contracts: one (the largest) for all the tunnelling work; one each for the five stations; another for the 700m long open cut tailtrack facility west of the Yonge Subway Line which will allow trains to switch from line to line for access to the Wilson maintenance yard; and for a bridge over the Don River. The river divides the bored tunnels into two sections: the first a 3.3km long stretch west to the tail track facility and the second, a 650m length east to the Don Mills Station (Fig 2). To start tunnelling as soon as possible, the contract specifies that tunnelling will start at the Leslie Station excavation and will continue westward through the two station locations for the open-cut stations to be excavated subsequently. After completing the two 3.3km long drives, the TBMs will be relaunched at the Leslie Station excavation works for the two 650m drives east to the Don Mills Station.

The shallow cut-and-cover design and cost of Leslie Station forces the tunnels to surface on to a bridge over the Don River valley and maintain its primary function as a Subway link to the North York hospital. The bridge over the river also results in a 400m length of cut-andcover to the east where ground surface is too shallow to allow tunnelling to resume directly off the bridge.

The maximum cover along the 6.4km alignment is 15m to crown level and the shallowest is 4m to crown level.

The maximum watertable level is about 8m above tunnel crown giving a potential water head of 14m to the invert of the 5.9m o.d. tunnels.

Under the project’s administration, all contracts are signed with TTC as the owner. The programme management team appointed in 1991, consisting of an integrated team of TTC staff and Delcan-Hatch personnel, is responsible for construction management and supervision as well as co-ordinating the detailed design packages which are being completed by outside consulting practices. Section designer for the tunnels is the Hatch/Mott MacDonald joint venture.

In deciding to purchase the tunnelling machines for the programme, TTC emphasised the importance of an accurate geotechnical report. By buying the tunnelling machines, TTC has assumed some risk against which it too must protect itself as far as is possible from the expensive consequences of changed geological conditions.

To limit its risk exposure and prevent the contractor from taking advantage of the fact that it did not choose the machines should there be any problems, TTC has adopted the policy of a geotechnical baseline report (GBR). This report, prepared by the programme’s geotechnical consultant Golder Associates, sets out a

baseline by which both the contractor, the owner and any arbitrating body in a potential dispute, will judge the validity of a claim against changed ground conditions.

The GBR, as well as the pre-purchase of the TBMs, is expected to limit significantly the risk contingencies in the contractor’s tenders and result in lower bid prices.

To protect its investment in machinery, the TTC has specified a minimum injection of foam ahead of the machine to: • Keep the torque levels down; • Reduce the potential for abrasive wear on the tools, cutterheads and other machine components; and • Help protect the bearing seals by ensuring that they are not over pressurised during closed EPB operation.

The minimum amount of foam as specified however is not intended to prejudge the amount needed to facilitate EPB excavation and ensure control of ground movement and settlement. The type of foam used is up to the contractor provided it is environmentally acceptable.

The existing ground is not classified for any type of special disposal or handling.

Boulders

Before the TBMs go to work and before bids are to be returned, the contractors have been informed of a major modification of the design. When the design of the machines was finalised they were fitted with soft ground cutterheads. Based on geotechnical investigations, the risk of meeting large glacial boulders was considered low. Geotechnical cores had not identified any large boulders and the cobbles and pebbles of the glacial deposits could be excavated through the soft ground cutterheads and the screw conveyors without difficulty.

It was not until work started on the cut-and-cover tailtrack facility that the full potential of meeting boulders in the alignment became clear. Pile driving for the retaining walls was interrupted on several occasions by very large and very hard granitic boulders. Further boulders have been uncovered during excavation. Boulders were also identified during a recently completed enabling contract designed to support the surface railway which runs directly over the cut-and-cover works at the Leslie Station site and the launch site of the TBMs. Further risk analysis following these discoveries has convinced TTC experts that the TBM cutterheads must be fitted with disc cutters. Unfortunately, the heads already supplied with the TBMs cannot be modified effectively. It has been proposed therefore to design and build two new cutterheads, fitted with both picks for soft ground conditions and discs for hard rock excavation.

The muck ingress openings in the new heads will also be fitted with grizzly bars to stop ingress of stones too large for the screw conveyor. During the site visit in June 1996, recommendations for the purchase of the two new cutterheads were being finalised and an addendum to the contract documents informing the contractors of the situation was also being prepared for distribution.

One reason for missing the presence of boulders in the geotechnical investigation may be that small diameter core drills are easily deflected by smooth hard rock obstructions. Boulders also tend to lie in the deeply incised gullies cut by the advancing and retreating action of glaciers rather than being distributed randomly in the layers of more fine glacial material. Another reason why

Fig 2. Sheppard Line extension and its tunnelling works

boulders were not considered as a potential high risk problem, it was explained, is the low history of meeting boulders on previously tunnelled lines. These however run north/south and away from the glacial gullies. The Sheppard Subway is the first east/west bored tunnel alignment (the Bloor line in the south was constructed substantially by shallow cut-and-cover) and as such cuts across the north/south patterns of glacial deposits thus increasing the likely incidents of meeting boulders.

Although tunnelling on Toronto’s new Subway expansion programme has been significantly reduced, attitudes remain optimistic for a positive construction phase. TTC is confident that, with the new cutterheads, it has the right machines for the job; the prequalified contractors all have extensive EPB tunnelling experience; the contract includes a GBR; and the four-member team of the Underground Construction Technical Review Board established and retained by TTC brings to the project additional eminent tunnelling expertise. All will be put to the test when the contract is awarded and tunnelling begins.

Final account

While the construction of the Sheppard Subway project is an acknowledged success, the contractor for the TBM tunnelling works, McNally with partner Kiewit, did submit a $4.4 million claim for additional muck hauling costs, arguing that the use of foam was much greater than could have been anticipated in the contract documents and that the liquid muck had to be hauled to a more expensive disposal site than had been offered in the bid.

When initial settlement discussions failed, the parties agreed to a formal hearing of the DRB which unanimously rejected the contractor’s claim stating that it had not made a reasonable case against the actual terms of the contract. As the DRB’s recommendation was non-binding, the contractor took the case to court and after some 2.5 years, settled before trial began when it became clear that the DRB recommendation would be available to the court as part of the proceedings.

Since these early days of using surfactant foams for conditioning EPB muck, the technology has improved significantly, although many EPBM operations continue to struggle to condition muck for efficient, slop-free EPB extraction and disposal. There remains an opinion among many that using extensive soil conditioning for optimum EPB screw conveyor operation is akin to turning good ground into bad for the sake of having the method work.

The technique however does provide assurances to the owners and avoids extensive and expensive settlement mitigation measures that might be required otherwise. n 29

Congress Chair Rick Lovat (left) welcomed more than 1,000 delegates from 52 countries to WTC2010 and the 36th ITA General Assembly

WTC 2010 Vancouver

D

elegates from around the world were welcomed by the Tunneling Association of Canada (TAC) to the spectacular waterfront city of Vancouver for the ITA-AITES World Tunnel Congress (WTC) and the 36th General Assembly of its Member Nations. This was the second time the premiere tunnelling congress had convened in Canada, following the first in 1989 in Toronto.

In memory of Sir Alan Muir Wood of the UK (1921-2009) the first President and Honorary Lifetime President of the ITA, the Muir Wood Lecture was inaugurated as an annual feature of the congress programme with Professor Emeritus Dr Einar Broch of Norway giving the first lecture on the theme of Tunnelling for Hydropower Projects.

Topics for the technical program included Innovative Techniques and Advances in Geotechnical Investigations for Tunnel Projects, New Advances and Innovation in Mechanized Tunnelling, Tunnelling under Sensitive Structures, New Advances in Contract Practices and Procurement, and Commercial Aspects for Tunnel Projects.

Design, planning and construction of the Canada Line in Vancouver and tunnelling plans for the transit expansion in Toronto were the focus of keynote presentations, while the ITA session addressed Ground Reference Information for Bidding Tunnel Projects. Various practices on this subject are in place around the world and the open session provided a series of presentations from the perspective of the ITA, the client, the engineer and the contractor.

The associated exhibition at the event hosted the booths of more than 420 companies and organizations.

The conference technical tours included the Canada Line, the city’s new light rail system that was inaugurated in August 2009 in time to provide service for the athletes and visitors to Vancouver’s hosting of the 2010 Winter Olympic Games, and a day visit to Seattle’s $1.8 billion Brightwater conveyance tunnel project in the USA.

MAY 2010

In addition to the technical session program and the exhibition hall, there was ample opportunity for networking during the many social events that included the congress banquet and a sunset dinner cruise aboard a luxury vessel, enjoying the spectacular sights of Howe Sound and the city lights.

At the General Assembly of the International Tunnelling and Underground Space Association (ITA) Professor In-Mo Lee of Korea was elected as the President for the coming three years to 2013, taking over from the successful previous three-year Presidency of Martin Knights of the UK. Four new Vice Presidents were elected - Markus Thewes (Germany), Bai Yun (China), Soren Degn Eskensen (Denmark), and Ivan Hrdina (Czech Republic) - and five new members were elected to the Executive Council - Rick Lovat (Canada), Amanda Elioff (USA), Pal Kocsonya (Hungary), Ow Chun Nam (Singapore) and Daniele Peila (Italy). Three new member nations were also welcomed to the ITA family - Argentina, BosniaHerzegovina, and Montenegro.

The activity and productivity of the ITA Working Groups was a major focus of attention at the General Assembly. There are 13 active Working Groups and another seven that have completed their work. At the 2010 General Assembly the Working Group on Seismic Effects was revived at the request of the China Member Nation delegation and following several high impact earthquakes over recent months and years in China and elsewhere.

As well as the Working Groups, the ITA also hosts the activities of a foundation and three committees: •

ITACOSUF - Committee on Operational Safety of Underground Facilities

•

ITACUS - Committee on Underground Space

•

ITACET - Committee on Education and Training

•

Foundation for Education and Training in the field of Tunnelling and Underground Space.

More than 200 delegates from 32 countries attended a two-day ITACET training course. At its meetings during the WTC and General

Left: As the official media partner of WTC 2010 in Vancouver, TunnelTalk recorded several video presentations and interviews Right: Animateurs of three of the ITA Working Groups explain the process and challenges of progressing their work to publication

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Download a publication of tributes to Richard in recognition of his career

Career recognition for Richard Lovat

T

NOVEMBER 2017

unneling professionals at a gala dinner and awards night in Toronto, recognized the life-time career achievements of Richard Lovat. Two awards were presented; one by TAC, the Tunneling Association of Richard’s adopted home country Canada and the other by the ITA, International Tunnelling and Underground Space Association.

Members of the new ITA Executive Council at the Vancouver WTC

Assembly, the ITA-CET committee and Foundation sanctioned six new courses for the coming year. These included a training session on the planning design and construction of immersed tube tunnels to be held in Abu Dhabi in October 2010 and others for different venues around the world at different times on Planning, Construction and Operation of Common Utility Tunnels; Innovations in Tunnelling; Monitoring and Control in Tunnelling; Principles for Tunnel Design; and Underground Space Use. Plans were also outlined at this General Assembly for the formation of an ITA Technology Group. Specific details of the Group’s composition and objectives are to be presented ahead of confirmation of its creation at the General Assembly next year (2011) in Helsinki, Finland.

Some 129 papers were presented during the World Tunnel Congress technical sessions and a further 159 poster presentations were on display.

The ITA Open Session discussed the topic Ground reference information for bidding tunnel projects - current practice, shortcomings/benefits and future challenges. Martin Knights chaired the session and presentations were given by Joe Gildner of Seattle Sound Transit, presenting a client’s point of view, Marco Giorelli of Lovat Inc, presenting the experiences by the TBM manufacturer of ground reference requirements for EPBs, Ulrich Wadepohl of Hochtief providing the international experience of a contractor’s point of view, Markus Thewes of Ruhr-University Bochum explain the requirements concerning geotechnical investigation for the minimization of risks in shield tunnelling, and Arnold Dix, Animateur of Worlding Group 3, discussing the role of law in the apportionment of underground construction risks. Keynote presentations were delivered

by Jeff Hewitt of AECOM regarding the construction of Vancouver’s Canada Line Transit Project and Susan Reed Tanaka of the Toronto Transit Commission presenting tunnelling plans for transit expansion in the Toronto area. n

TunnelTalk references •

ITA 2008 news from Agra, India - September 2008

•

WTC 2009: A global view of the business - July 2009

•

ITA sets strategy for growth and development - June 2014

•

Steep curve ahead to keep ITA relevant - May 2016

•

A new era begins for ITA at WTC2019 - May 2019

In presenting the awards, Rick Staples, President of TAC at the time, described how, through the activity and business of the company, Richard placed Canada on the international stage as a principal designer, developer, manufacturer and suppler of modern TBM systems and technology, spearheading an early development of earth pressure balance excavation of soft ground and exporting the Lovat brand of mechanical tunnel excavation worldwide, from Canada to the USA, Russia, South America, Australia, across Europe and into China.

For his second award of the evening, Richard’s son Rick, a member of the ITA Executive Committee and President-elect of TAC, recounted a history of the company he helped build with his father when he joined the team in 1986. Rick presented a personal account of his father’s life from a childhood in Italy to his emigration, first to Switzerland and then to Canada, to the start and development of company. The presentation guided the audience of Richard’s friends, colleagues, customers and fellow tunnelers through the development of the range of iconic Lovat TBMs, highlighting the milestone achievements and contracts including the ground breaking introduction of early EPB technology to the UK - an association that Richard remembers with respect and satisfaction - and the always close connection to the Canadian and USA tunneling industry until sale of the company to Caterpillar in April 2008.

In accepting both awards Richard received a rousing standing ovation and the warm and heart-felt congratulations of everyone in the room.

The link between Canada and the International Tunnelling and Underground Space Association (ITA) is long established and enduring. Canada was on of the original founding Member Nations of the International Association in 1974 and members of the Tunnelling Association of Canada (TAC) have contributed diligently to the ITA Working Groups, the General Assembly of Member Nations, its Executive Council and its Committees. In 1992, TAC nominated and supported Dan Eisenstein of Edmonton, Alberta, as the seventh President of ITA to 1995. Eisenstein was a leading technical tunnelling engineer and effective promoter of tunnel construction of all types in urban settings not only in Edmonton and Canada but also in the USA and across the globe (see p15 and p48). Visit the websites to become a member of TAC and to review the membership tiers of the ITA and the activities of its Working Groups. n

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In the evolution of modern underground infrastructure design and construction, Canada has played a leading role. From the undertaking and development of rock mechanics and soil behaviour to the application of cutting edge TBM, drill+blast and open face sequential excavation of extraordinary structures, Canadian engineers and projects have advanced the industry’s state of the art practices.

These achievements have been celebrated in the annual awards presented by TAC, the Tunnelling Association of Canada, and in the videos the Association has produced for each award winner since 2013. Congratulations to them all.

Library of TAC Award videos

2013

Canadian Tunneller of the Year: Dr Peter Kaiser Canadian Project of the Year: Niagara water delivery tunnel International Project of the Year to which a Canadian company made a significant contribution: McNally Construction as sponsor of the JV that completed the Euclid Creek Tunnel Project in Ohio, USA Dan Eisenstein Memorial Scholarship: Michelle van der Pouw Kraan

2014

Canadian Tunneller of the Year: Dr Evert Hoek Canadian Project of the Year: Billy Bishop Toronto City Airport Pedestrian Tunnel Dan Eisenstein Memorial Scholarship: Jennifer Day

2016

Canadian Lifetime Achievement Award: Dr. Raymond Benson Canadian Innovation Project of the Year: Port Mann Water Supply Tunnel Project Canadian Infrastructure Project of the Year: La Romaine 3 Hydro Power Project Dan Eisenstein Memorial Scholarship: Sarah Cain Photo of the Year: Scott Marshall and Tony Dell for the John Hart Hydro Generating Station Replacement Project

2015

Canadian Tunneller of the Year: Brian Garrod Canadian Innovative Project of the Year: Mayo B Hydroelectric Enhancement Project Canadian Infrastructure Project of the Year: Toronto-York Spadina Subway Extension Twin Tunnels Project Dan Eisenstein Memorial Scholarship: Josephine Morgenroth Photo of the Year: David Blackwell: Port Mann Water Supply Tunnel

2017

Canadian Lifetime Achievement Award: Boro Lukajic Canadian Innovation Project of the Year: Upper Lillooet Hydroelectric Project Canadian Infrastructure Project of the Year: Confederation Line of the Ottawa LRT Dan Eisenstein Memorial Scholarship: Timothy Packulak Photo of the Year: Giuseppe Gaspari for the picture Confederation Line LRT Multi-Dimensional Underground Space

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C A N A D I A N

A C H I E V E M E N T

AWA R D S

2021

Lifetime Achievement Award: Frank Policicchio Canadian Innovation Initiative Award: Virtual TBM factory acceptance test during a pandemic – Ashbridges Bay Treatment Plant Outfall Canadian Project of the Year Award up to Can$100 million: Rangeview Sanitary Trunk – Phase 1 Calgary, Alberta Canadian Project of the Year Award more than Can$100 million: Burhamthorpe Water Project Contract 1/2 Canadian Young Tunneller of the Year: Michael Mains Photo of the Year: Kemano T2 Project TBM cutterhead inspection

2018

2020

Canadian Innovation Project of the Year: John Hart Generating Station Replacement Project

Canadian Innovation Initiative Award: McLoughlin Point Wastewater Treatment Plant Cross Harbour Force Main and Outfall

Canadian Infrastructure Project of the Year: Eglinton Crosstown LRT Tunnels for the Toronto Subway

Canadian Project of the Year Award (Up to Can$100 million): Riverside Stormwater Interceptor

Dan Eisenstein Memorial Scholarship: Pasquale Basso Trujillo

Canadian Project of the Year Award (Over Can$100 million): Eglinton Crosstown LRT Mined Stations (Laird, Avenue and Oakwood)

Canadian Lifetime Achievement Award: Garry Stevenson

Canadian Lifetime Achievement Award: Richard Staples

Young Tunneller of the Year Award: Connor Langford and Andre Solecki Dan Eisenstein Memorial Scholarship: Madison Kennedy TAC Undergraduate Scholarship: Graham Swarbrick Photo of the Year Award: Ashbridges Bay Treatment Plant Outfall Shaft and Starter Tunnel

2019

Lifetime Achievement Award: Enrique Fernández Gonzáles Canadian Innovation Initiative Award: Ottawa LRT Construction Sequence and Tension Tie Support for Shallow Urban Caverns Canadian Project of the Year (up to Can$100 million): South Surrey Interceptor: Johnston Road Section Dan Eisenstein Memorial Scholarship: Antoine Gagnon Photo of the Year: Eglinton Crosstown LRT Project

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Lovat: History of a global Canadian brand APRIL 2008

I

t was something of a bombshell when news came through in 2008 that Lovat had been sold. A brand that personified Canada’s place in the international TBM tunnelling industry and a family business that was passing from the founding generation to the next had been sold to the giant construction equipment manufacturer Caterpillar. TunnelTalk interviewed the owners of the company to know the reasons for the change of direction.

“Acquisition by Caterpillar secures our future without compromising our legacy,” is how Rick Lovat described the move announced in April 2008. “As President and CEO of the company, I could see that within five-ten years we would need to be twice as big, if not bigger, to keep pace with demand, in terms of capacity, resources and staff. This was going to be difficult from our footprint here in Toronto, and would take substantial capital. With Caterpillar we gain these resources. What is there not to like about this deal?”

Richard Lovat, founder of the family business in 1972, is also pleased with the change. After emigrating as a mechanical engineer from Italy to Canada, Richard built the company to a world-recognized name with a loyal customer base and a reputation for sticking with the toughest of projects to a successful end. Lovat Senior said: “I could see things coming for the market, for the company, and to be selected by the industry leader as their tunnelling partner is the highest recognition of our efforts. They wanted the best and we have joined with the best.”

Globally, the TBM supply business is estimated at US$1 billion plus per year (in 2008). With no slow down in sight, this could double over the next five years and could continue to grow to multi-billions or trillions. Getting a slice of this lucrative action prompted Caterpillar to begin investigations about how to enter the market. According to Rick Lovat, “they approached us about 18 months ago saying that, of the investigations they had made, it was us they wanted to partner with.” And there is much to credit the union. The two companies are North America based and therefore operate under the same basic ethos and business management model; they are under similar legal systems; they speak the same language; they will operate their international efforts from the world’s leading economy; they have the same experiences and evidently share a common goal. “With Caterpillar, we can draw on the company’s dynamic R&D department; on its purchasing power; and on its international servicing network,” said Lovat.

As a private company, Lovat did not publish annual accounts, but with more than 250 TBMs delivered globally and support companies in Europe and China, Lovat employed today more than 450 and

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“our order book through 2008 reflects the demanding state of the business”, said the CEO. Publicly-traded CAT accounts reported sales and revenues of $45 billion for 2007 with expectations to increase that by 5-10% in 2008 and increase profit per share by 5-15% on 2007. In the acquisition statement, Mining and Underground Products Vice President Chris Curfman said, “we intend to leverage our global business with continued investment in the Lovat product line”.

This however was not to be. Five years later, in May 20013, Caterpillar announced it was to phase out of civil tunnelling, explaining that the tunnel boring business no longer represented a strategic growth opportunity.

Over the five years of its ownership Caterpillar found out that the TBM tunnelling market is highly competitive and unpredictable. One of the Caterpillar sales was the machine delivered to the troubled New York Harbor Crossing water tunnel project for the OHL/Tulley Spanish/US Joint Venture. In a disastrous set of circumstances, the starter shaft of the project, along with the beginning of the undersea drive by the TBM, were completely flooded out during Superstorm Sandy in November 2012. Flood water has since been pumped out, but rehabilitation of the saltwater damaged TBM became part of wrangling between the contractor, the client and the project insurers.

A strategy to standardize TBM components and sizes to promote a more cost-effective range of off the peg TBMs by Caterpillar also failed to take shape. The unpredictable nature of tunnelling and the particular features needed on a TBM to cope with varying geological conditions continually defeats efforts to standardize machines as Atlas Copco found out to its cost after its failed attempt at owning the USA Robbins TBM manufacturing company in the 1990s.

Then in February 2014, Caterpillar announced sale of substantially all of its assets to its Chinese manufacturing partner Liaoning Censcience Industry Co Ltd (LNSS). “For the past year, LNSS has been a

manufacturing partner for the sale of TBMs in China,” said Paul Clark, Caterpillar General Manager with responsibility for tunnelling.

“Given the relationship, this was a natural next step for both sides.” Financial details of the transaction were not released.

One of the first TBM delivery contracts for Lovsuns, as an overseas subsidiary of LNSS based in Toronto, was a 3.9m diameter EPBM for two wastewater tunnels in Istanbul, Turkey. Confirmed one month after Caterpillar sold the tunnelling assets to LNSS in November 2014, the machine was designed by experienced ex-Lovat engineers and was manufactured in the Chinese facilities of LNSS. “We designed and engineered the tailor-made TBM for Istanbul in Toronto and produced it completely in the facility in Liaoyang China,” explained Hongyu Xue, Managing Director of Lovsuns Tunneling Canada Ltd. “In doing so, we successfully united the best practice, knowledge and technology of both companies for the highest advantage of our customer.”

In 2017, Lovsuns closed manufacturing operations in Toronto to concentrate on strengthening production potential in China and improve logistics worldwide. Hongyu Xue explained that the company will continue to hold a base in Toronto to strengthen its engineering, sales and after sales services for international customers with orders for new or refurbished Lovsuns TBMs fulfilled by the company’s headquarters and factory facilities in China. Since then, Lovsuns has continued to straddle both markets, gaining new orders in North America, the Middle East and beyond.

“From a global perspective the China/ Canada synergy will allow us to grow faster both in China and overseas. Global customers are looking for cost-effective, high-quality TBMs and the LNSS strategy offers safety of operation and productivity.

We will continue to innovate, broaden and improve our product line, offering machines for special applications to help our customers overcome their challenges” said Xue. n

Toronto TBM homebase first for Lovat, then for Caterpillar and now Lovsuns

Niagara hydro diversion project

Robbins TBM ready and set to go

CASE STUDY: Had things gone to plan geologically, the 10km long Niagara TBM water diversion tunnel to increase the generating capacity of the Sir Adam Beck hydro complex on the Canadian side of the famous Niagara Falls, should have been completed by Fall 2009. As it was, the 14.4m diameter heading being excavated by still the world’s largest ever main beam gripper TBM was slowed by unfavourable geological conditions, conditions in which perhaps the original shielded machine concept with a precast segmental lining, rather than the adopted alternative, might have been the better choice. Site visits and reporting through the five years of TBM excavation, records exactly how geological conditions caused such havoc.

Plan of attack

SITE VISIT REPORT: DECEMBER 2006

A

n open gripper TBM; an in-situ concrete lining; on-site construction of the largest ever, 14.4m diameter hard rock TBM; and lining operations concurrent with excavation: these were some of the

• Client: Ontario Power Generation • Consultants: Hatch Mott MacDonald & Hatch Acres • Design-build Contractor: Strabag/Dufferin JV • Contract Engineers: ILF and Morrison Hershfield alternatives Strabag AG of Austria adopted to secure the competitive edge for the Niagara hydro power water diversion project.

Figs 1 and 2. Plan and geological section of the TBM drive around the famous Falls

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The driving force behind the Can$600 million design-build contract for the 10.4km long tunnel is early completion.

Every extra day of power production through the Can$985 million upgraded and increased generating capacity of the Sir Adam Beck hydroelectric power complex at the foot of the famous Niagara Falls constitutes significant operating income. To maximize the revenue, project owner Ontario Power Generation (OPG) and its project engineers Hatch Mott MacDonald and Hatch Acres, prepared contract documents that encouraged prequalifiers to present alternatives that would compress the construction period, maximize the tunnel’s flow characteristics, and have the project commissioned as soon as possible. Efforts by the project’s three prequalified bidders to achieve this were further concentrated by the contract’s schedule of Main technical data of the Robbins TBM Cut diameter with new cutters 14.44m Cut diameter with worn cutters 14.41m Main bearing three roller (three axis) Bearing life >13,000 10hrs @ 224kN cutter lead Individual cutter load 311kN Recommended cutterhead thrust 18,426kN Maximum thrust 27,900kN Maximum gripper force 71,500kN VFD cutterhead drive via 15 x 315kW electric motors Total installed drive capacity 4,725kW Cutterhead torque at 2.4rpm 18,670kNm at 5.0rpm 8,960kNm Breakout torque 28,000kNm Thrust cylinder stroke 1.82m Transformer for TBM drives 2 X 2,500kVA Transformer backup 1 X 1,000kVA Transfer conveyer capacity 1,600tonne/h Belt width 1,400mm TBM weight approx 1,900 tonne

incentives based on liquidated damages of Can$250,000/ day maximum for any delay beyond the contracted delivery date and a bonus of 50% of that for every day earlier. There is also a bonus or penalty for flow of water through the tunnel above or below the guaranteed 500m3/sec.

In a truly bold move, the proposal presented by Strabag AG of Austria countered nearly every construction assumption in the bid document and presented a completely different approach that proved convincing to the client and its engineers. The defining differences of the alternative are to use an open gripper TBM instead of a shielded machine; to finish the tunnel with an in-situ concrete lining instead of a precast concrete segmental lining; to build the TBM and its backup on site rather than reassemble a shop commissioned and shipped machine; and to install the final lining concurrent with TBM excavation.

In 1998 Obayashi with JV partner Kenaidan Contracting and designer Harza, was lowest of six bidders for a precast concrete segmentally lined drive and was in the process of procuring a 13.9m double-shielded gripper TBM from Herrenknecht when the bid was caught up in protracted re-organisation of Canada’s power industry.

With no official commitment to the estimated Can$400 million proposal its validity was permitted to expire.

These are daring variations between the two proposals.

The geology as well as the required diameter of the delivery tunnel at 14m or more, suggested that shield tunneling would be favored, The criteria for a watertight lining and for it to be completed within the incentive-driven time line suggested that a one-pass bolted, gasketed, and backfilled precast segmental lining erected within a shield would be the only way to go. As for building a TBM on site, that is a high stakes undertaking, as is solving the technical demands of installing an in-situ final lining concurrent with TBM excavation.

In preparing its proposal, Strabag with its local subcontractor Dufferin Construction, had to have the confidence of its major suppliers that these alternatives could be achieved. For design issues, the committed engineering partners are ILF of Austria and its office in Virginia, USA, and Morrison Hershfield of Toronto. For the equipment systems, the principal suppliers are the Robbins company for the TBM, Rowa Tunneling Logistics of Switzerland for the trailing back-up, and Bystag of Germany for engineering of the in-situ concrete lining operations.

A watertight finish

Engineering a watertight finish is essential to the minimum 90-year design life of the infrastructure. Some 80% of the 10.4km tunnel lies in the shale and mudstone series of the Queenston Formation that are known to exhibit swelling and squeezing behavior. These are induced by relief of relatively high in-situ horizontal stresses and the potential of the shale units to swell when in contract with water.

Two drill+blast tunnels built in the 1950s to feed water to the exiting Sir Adam Beck hydro station provided valuable data for the current undertaking.

To achieve a watertight lining, ILF proposed a pre-stressed in-situ concrete lining with a fully closed polyolefin waterproofing membrane behind. A program of contact grouting will fill any voids in the crown of the 600-700mm thick lining and provide a tight interface to the rock mass.

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Rowa backup looking forward to the cutterhead (left) and back across the gantries (right) with a crane system fixed to the tunnel’s crown

A final program of high pressure interface grouting, injected at up to 30 bar through grout hose rings installed between the initial lining and the waterproofing membrane, will pre-stress the lining and place the entire structure under a state of compression. This will help contain the internal water pressure without the need for reinforcing steel and eliminate the long term corrosion risk.

TBM procurement

One of the longest lead-time concerns was procurement of the proposed 14.4m diameter TBM. Under a conventional machine order, with fabrication, shop assembly and testing followed by delivery to site, site assembly and commissioning, to start of TBM excavation would take upwards of 15 months. A principal factor in securing the job for Strabag was agreement from Robbins to build the machine on site. “This probably cost us an extra three or four weeks on a shop build, but saved three to four months in overall delivery time,” said Lok Home, President of Robbins. “Site construction of TBMs has been undertaken in the past, and the process does have its own set of pitfalls, but we were confident that a site build for this machine was doable.”

Several points worked in favor of a site build. The TBM is an open, main beam, hard rock gripper machine and assembly of the major components is less complex than for an shielded machine. In addition many of the main components, including the drive unit, the 6.6m diameter main bearing, and the gripper assembly, are similar or identical in design to those used on the 10m rock machine supplied by Robbins to the Dillingham/Fletcher/ llbau (now Strabag) JV for the second tailrace tunnel of the Manapouri hydro scheme in New Zealand about six years ago. That was the previous largest ever hard rock TBM and Strabag’s Project Manager at Niagara, Ernst Gschnitzer, was Tunnel Manager at Manapouri. He and the Strabag team know the machine characteristics and have worked with Robbins in the past both at Manapouri and on other international rock TBM projects.

“The significant difference between the Niagara machine and the Manapouri TBM is the extra 4.4m in diameter,” said Home. “That has a major influence on machine performance. Our greatest concern was to build a rigid superstructure to prevent vibration in the 14.4m diameter cutterhead and ensure constant and uniform contact of the discs to the face. The rock formations at Niagara are not especially hard, ranging in compressive strength from 19MPa to about 45MPa for the majority of the drive

through the Queenston shale and mudstone, and up to 150MPa through the upper limestone layers, but any sustained vibration of the big, flat rotating cutterhead will over stress its structure, interfere with uniform penetration and in turn cause tool breakages, excessive wear and reduced advance.”

Along with its other record setting statistics, the Robbins machine will be the first to use the company’s new 20in (508mm) cutters. “Although only one inch larger in diameter than 19in cutters, these 20in cutters have significant benefits”, said Home. “They weigh about 3% more than a 19in disc but have 35-40% more ring wear volume which increases cutter life significantly. This reduces the number of changes needed and in turn increases TBM availability.” With a cutter spacing of 89mm, the 14.4m diameter cutterhead is dressed with 85 x 20in cutters. Robbins has a cutter consumption contract with Strabag for the project.

A core team of eight Robbins technicians were on site during the four-and-a-half months it took to build the shop manufactured and tested components of the machine. In what was described as an unprecedented achievement for a machine of its size, the TBM was ready for an official cutterhead turning ceremony on 8 August 2006, some three weeks ahead of the penalty-driven 1 September contracted start-boring due date.

Trailing backup

Behind the TBM are the four gantries of the systems’s 105m long logistics backup. Designed, manufactured and assembled on site by Rowa Tunneling Logistics, the first of the four gantries is supported on hydraulic legs while the remaining three are towed on rollers running directly on the tunnel invert.

As well as all the necessary workstations, workshops, power supply installations, storage areas, and ancillary equipment, the back-up provides the platform from which the immediate support elements are installed. These comprise mainly rockbolts of up to 6m long, steel sets where needed, wire mesh, and layers of shotcrete.

“The principal requirement of the installation was to prevent backup caused delays of TBM production,” said Jost Wenk, Managing Director of Rowa. “This demanded efficient movement of supplies and materials and required a certain independence of movement between TBM advance and immediate support application stations.”

37

To streamline management of materials, Rowa installed several crane systems through the four working levels (including the tunnel invert) of the 14.4m tall structure. The most innovative of these is a mono-rail crane system that is attached to the tunnel crown. Operating completely independently of the backup, the system provides a full length uninterrupted supply line of materials from the trailing gantries to directly behind the cutterhead.

Monorail sections are moved forward from the back as the machine advances.

“This suspended gantry crane guarantees smooth operations”, said Wenk. “It allows materials needed for tunneling to be put to use immediately behind the cutterhead without any interim storage. With a swivel and telescopic boom on the crane, this is a highly mechanized delivery system, which is a further trump card in the tough battle for performance and cost efficiency.”

On the backup there are two immediate support platforms both of which can move independently of the TBM. The first is located directly behind the cutterhead. From here full ring sets, or partial arch channels held by 2.4m rockbolts, can be installed, wire mesh can be placed and layers of shotcrete can be applied as necessary. These immediate support elements are expected to be needed in particular at the start and at the end of the drive where the steep tunnel gradient cuts obliquely through the horizontal layers of the upper strata (Fig 2). The alignment is governed by the need to pass beneath a deep buried gorge at the start of the drive at the tunnel’s outlet portal.

Shotcrete is used throughout the drive as an element of support and as a method of sealing sensitive rock types against the degrading affects of contact with water and air.

Two newly developed shotcrete robots, one for each primary support work station, provide all-round 360° shotcreting of the 14.4m diameter tunnel. They can travel through a longitudinal displacement of 8m for the forward installation and through 20m for the main shotcreting station. Each of the two moving stations is also equipped with two independent drill rigs for installing rock bolts of up to 6m long.

From the second working station, all elements of primary lining are installed within 40m of the face. The longitudinal displacement of the working decks and the full round shotcreting robots is designed so that the heaviest class of prescribed immediate support can be applied without holding up TBM advance.

onto the H+E shoulder-suspended continuous conveyor.

At the portal the H+E conveyor rises up the access ramp, past the site’s concrete and shotcrete batching plant (where more than 400,000 tonne of concrete will be batched for the project) for relay to a transfer conveyor that carries material to the muck storage site. Through its operating time, the conveyor system will haul more than 1.6 million m3 of rock from the 10.4 km long x 14.4m diameter tunnel. On the alignment, the conveyor will negotiate the steep inclines at either end of the drive and the minimum 600m radius horizontal curve.

Transport to and from the TBM will be via a fleet of rubber tired vehicles supplied by Plan and Techo of Germany.

The ventilation system is supplied by Cogemacoustic of France and includes one ventilation fan stationed at the tunnel portal, 10.4km of 2.6m diameter flexi ventilation ducting and one booster fan to be introduced as the tunnel lengthens.

Concurrent concreting

Perhaps the most technically demanding aspect of Strabag’s alternative is proposed casting of the full in-situ concrete lining with its PVC waterproofing membrane, concurrent with TBM advance. The challenges of making this work logistically have been taken up by the team at Bystag in Germany.

“Both the invert and the arch lining will progress concurrent with excavation,” said Kurt Usel, Owner and Managing Director of Bystag. “The invert will progress first, starting about 400m behind the TBM. About 400m behind that, the arch concreting is planned to follow. Each concreting installation will have two 12.5m long forms that will cast in leap-frog sequence to provide 25m of lined tunnel/day. That is the plan.”

Designing concrete casting systems for a 14.4m diameter circular tunnel that will, at the same time, keep all excavation services and supplies operating without interruption is a tall order. For the invert, the shutters are incorporated into a 87m long bridge with a ramp each end for a total 87.5m that will allow rubber-tired TBM supply vehicles to travel over the invert casting operation (Fig 3).

The forms will cast the invert lining to just below spring line. To prevent up-lift, the two 12.5m long forms on the bridge will be braced against the tunnel crown and via hydraulic braces against the tunnel wall. The single traffic lane for the transport vehicles through the bridge structure is between these braces. The crown vent duct In addition to the immediate support systems, Rowa also hangs from the centre line between the crown braces and supplied other items of equipment on the backup including grout Fig 3. Bridge formwork for the concurrent invert lining the conveyor remains on its initial shoulder brackets pumping equipment, compressed air installations, industrial and “For the arch forms, things get cooling water plants, dedusting more tricky”, said Usel. “The equipment, ventilation duct transport vehicles are now storage, and transfer conveyor. traveling through the forms on the concrete invert but both the vent In providing the backup system, duct and the continuous conveyor Rowa worked with Robbins on have to come off the tunnel walls the interface with the TBM and onto diversions through the arch with H+E Logistics of Germany, forms and be transferred back supplier and installer of the onto the new concrete lined walls contract’s continuous conveyor at the back end.” muck hauling system. From the TBM transfer conveyor, muck As part of both the invert and travels on the Rowa feeder arch casting processes, the conveyor through the backup and 38

PVC waterproofing system and the grouting rings for prestressing the lining have also to be installed. “Integrating all activities on a smooth running rolling program and establishing familiar routines for the crews will be key to maintaining optimum production,” said Usel.

Eyes on the alternative

The implications of the Niagara approach for compressing tunnel construction times by allowing contractors, with consultants and system suppliers, the space to innovate, may provide the springboard needed to elevate tunneling from an unavoidable necessity to the preferred option.

Following the Niagara experience, Robbins has adopted on-site build of two 10m gripper TBMs to fill a $135 million order for a large water diversion project in India.

For Rowa, Wenk said that “the improvement of the interfaces and the reduction of the transloading sites are the deciding success factors.” For Bystag, the Niagara order adds to a list of innovative solutions it has offered since its business start up in 2000. For Strabag the prize is ahead. Within its 51-month design-build turnkey contract, to December 2009, excavation of the 10.4km long tunnel is programmed to take 23 months starting on 1 September 2006. Concurrent casting of the final lining program is to finish not long after TBM breakthrough.

Scale of the 14.4m diameter TBM bore with crown trouble evident

In late November 2006, the complex tunneling system was into the tunnel drive but still had a ways to go to reach optimum performance. Once all systems are synchronised, debugged and running smoothly, it will be all systems go for the 24/7 tunneling crews. With the invert concrete lining system scheduled to launch in about February, the full tunnel production line will be heading towards an excavation breakthrough in about September 2008.

Accounting for slow progress SITE VISIT REPORT: JULY 2008

B

y 2008, progress on the Niagara TBM water diversion tunnel project was seriously delayed. One 1.9m stroke of the mega 14.4m diameter Robbins TBM should be taking no more than 40 minutes. In fact it is taking twice as long. The machine is capable of better but a lack of standup time and the resulting overbreak of the host rock was retarding progress. Modifications to the machine backup and its ancillary equipment had been incorporated and there were plans to optimize the tunnel’s vertical and horizontal alignment, but managers realized that breakthrough would be well beyond the original plan.

This had major contractual consequences and raised several questions, one being the selection of an open, main beam, gripper TBM and concurrent casting of a secondpass in-situ concrete final lining over the original plan for a shielded-TBM drive with a one-pass precast concrete segmental lining.

Grand scale

A drive into the heading realises the megascale of the tunnel. At more than 14.4m high and 14.4m wide, the 2.6m vent duct in the crown, the continuous conveyor attached just above springline on the left-hand side and men and equipment in the invert look positively miniature. At about 163m2, there is no escaping the upgrade in scale from the more usual 6-12m diameter bored tunnels.

All traffic in and out of the tunnel is wheel based, running directly on the wide shallow invert and passing each other by driving onto the low sloping walls. This is ahead of gravel infill passing bays being installed at about 500m intervals as the tunnel advances and concurrent casting of the final invert concrete

lining progresses. Approaching the back of the TBM is like coming upon an ocean oil-drilling rig at night, the lights gleaming in the dark and identifying the various working decks of the backup. It is impossible to take in details of the crown, sidewalls and invert in one shot. Scan of the tunnel confirms that every inch of the surface is covered with a shell of shotcrete to create a smooth circular profile with shadows indicating local irregularities.

We park high on the invert slope behind a 50m long x 10m wide deck that advances with the TBM to allow for easy turning of service vehicles for the journey back out.

A walk across the turning deck and intervening invert reaches the back end of the trailing gantries and a chance to climb to the top deck where the perspective takes on another dimension. From here, at almost eyelevel with the enormous ventilation flexiduct, the view is down to the vehicles some 14m below and to the trundling conveyor belt slung between its anchor chains attached to the crown and shoulder of the diameter.

A canopy of grouted spiles and layers of mesh and concrete installed to contain overbreak

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From left: Severe overbreak leads to alignment change; Securing a section of high crown overbreak behind the TBM

From this distance, still some 130m from the face, there is no evidence of the huge cutterhead turning at up to 3.25rev/min against the rock face and there are few workers to be seen. Each TBM shift comprises a crew of 20 so they are here but on this huge machine not readily spotted. The walk forward passes backup equipment in the luxury of ample space, with ladders and stairways rising and disappearing between decks and around the full sized shipping container modified and fitted out to provide a minimum three days survival for the full crew should they need refuge for any reason.

Everything wears a film of fine red dust, evidence of high oxidation of the hosting Queenston Shale mudstone.

Continuing the walk, past large openings in the first, second and third decks through which supplies are lifted to the different levels, and banks of transformers, electronics and power packs, brings us to the operator’s cabin. We are now about 20m from the face but still no evidence or view of the sharp end.

Here we meet Tommy Day, one of three operators trained to control this monster machine. When asked how it compares with operating other TBMs Tommy replies: “I don’t know. This is the first machine I have ever worked on.” That is truly starting at the top.

Crumbling crown

This scaling is vital to the safety of the workers. Before comprehensive scaling became part of the excavation cycle, a massive block of rock, weighing some 30 tonne, fell out of the crown and came to rest on the railings of the working deck. It took several shifts to consider a plan for safe breakup and removal of the block. Scaling of the crown with the boom of the rockbolting drill rig as well as with hand held spiling bars became part of the routine.

In zones of weakest rock, project contractor Strabag and its design-build engineer ILF, introduced cycles of grouted pipe spiling to presupport the crown. Grouted spiles of 9m long and on 4.5m overlaps created the strengthened layer to limit overbreak and ensure crown stability.

As rock strengths improve, spiling ends, but a zone of persistent overbreak to as deep as 2m forms in the left haunch of the profile. This is due most likely to the rotation of the giant rock cutterhead, explained Erich Kapeller, Senior Construction Manager for Strabag. “In production the cutterhead rotates clockwise and removes loose rock as the head pulls up towards the crown leaving larger voids at the haunch.”

Forward of the operator’s cabin we come face to face with the center of activity, about 7m behind the cutterhead.

Discussions in the office beforehand could not prepare anyone for the reality of working in this tunnel. The hive of activity has little to do with TBM advance and everything to do with lining and support. It also explains why Tommy had nothing to do for the 35-40 minutes of our visit in the operator’s cabin.

Weakness is manifest predominantly in the crown and not seriously through the invert slopes or through the gripper zones of the sidewalls where conditions remain reasonably competent. The Queenston Shale is dense with an RMR (rock mass rating) of up to 70 but unconfined compressive strengths are soft at between 19-45MPa. The maximum 21,694kN thrust of the giant machine is unlikely to be needed with 60% of that being applied on average.

Just as the invert is notably wide and shallow, the crown of this mega-tunnel is wide and almost flat, which causes considerable trouble. Several sedimentary layers are cut through at the shoulders and even the thinnest of these hosts a wide arc of the 14.4m diameter cutterhead. This causes the weak sedimentary layers to want to break back to rock of greater confining strength. The TBM is making at least one stop through a stroke to allow for some serious scaling to induce weak rock to fall and for workers to deal with the broken rock that collects on the TBM’s finger shield.

Once scaling establishes a sound base and immediate support of rock bolts, channels, wire mesh and shotcrete is installed at the front work station, every part of the exposed tunnel, including the invert, is covered with its minimum 130mm thick layer of wet mix shotcrete from the main shotcreting station on the backup. The shotcrete shell is a vital primary lining element of Strabag’s designbuild alternative to protect the Queenston Shale from its known behavior of swelling in contact with water and moisture. The 24h/day, 7-day working week comprises two 10hr boring and support production shifts/day and a 4hr maintenance shift every morning.

What looked like competent self-supporting rock was coming away with the touch of the drill steel. Hand scaling was bringing down rock from off the finger hood, the length of which has been shortened by 2ft to provide earlier access to the exposed crown and allow rock to fall to the invert through the gap between the back of the cutterhead 40

and the leading edge of the working platform. In the invert, gangs spend the shift loading the rock onto a feeder to the main muck-hauling conveyor.

Geological influences

Rock behavior is influenced also by the steep 8% decline of the tunnel over its first 1,400m to pass under a deep buried gorge. On this steep decline the heading cuts at oblique

Figs 4 and 5. Revised plan and vertical alignment of the TBM drive, closer to the famous Falls and higher into more competent rock

angles through the predominantly horizontal bedding of the sedimentary bedrock layers. This caused instability in the crown through several reaches and ground water inflows from different layers. A sump at the lowest point of the tunnel ahead of the more gentle 0.1% incline for the next 8.5-9km of the drive toward the intake structure in the Niagara River, just above the rim of the famous Niagara Falls, is fitted with a 4,000gal/min pumping capacity. Once into the uphill alignment the crown stays for some distance in each band of the horizontal bedded layers exacerbating the stress relief spalling in the crown.

Rock quality is also influenced geologically by the gouging of the deep buried glacial gorge and by drill+blast excavation in the 1950s and 1960s of two existing tunnels that deliver water to the Sir Adam Beck hydropower complex, the capacity of which is being increased by the new feeder tunnel. The new tunnel passes about 35m beneath what is believed to be the bottom of the buried gorge, creating the alignment’s lowest point at 150m below ground surface, and is 40m to 60m below and between the two existing tunnels that are up to 90m below the surface and about 80m apart.

The original timeline for tunnel excavation was 28 months.

It is now 22 months since the TBM began boring in September 2006 and it has completed 2,140m of the 10km long drive. Conditions were expected to improve as the tunnel progressed passed the buried gorge but they remain unchanged. The design-build contract carries a heavy penalty for delayed delivery of water to the power station, and a shielded TBM with a one-pass precast concrete segmental lining was considered by the owner’s project engineers, led by Hatch Mott MacDonald. A precast segmental lining behind a shielded machine might solve the immediate problems of instability in the crown but the tunnel must sustain an internal pressure of 200+ psi or 14 bar through its specified 90-year design life. This requires the tunnel to be in direct contact with sound, competent rock. The advantage of the open gripper TBM is that the rock can been seen explained Kapeller. Weak rock in the crown is removed and the pre-stressed final lining will be in contact with sound rock. The open method, it is argued, can guarantee no voids behind the shotcrete primary lining or behind the secondary in-situ final lining.

A full round waterproofing membrane will be applied to the primary shotcrete-lined tunnel and a program of high pressure interface grouting injected at up to 20 bar through grout hose rings installed between the initial lining and membrane will pre-stress the lining and place the entire structure under a state of compression. Due to the

slow progress the concurrent final lining operation is on hold and postponed to October 2008 for start of the invert operation, with the arch operation planned to advance at a 400m distance.

Conditions as encountered are said to be far more problematic than envisaged and major modification of the TBM’s work area has been necessary. The L1 work area gantry immediately behind the cutterhead has been redesigned to accommodate the spiling cycles and to allow for the scaling operations. As well as cutting the finger hood back by 2ft, the wire mesh erector and the ring beam erector have been removed. Two cherry pickers on the top deck provide raised access to the crown. Underneath the TBM, extra mini excavators in the invert work loading the scaled debris onto a Haggloader type feeder to the tunnel’s main haulage conveyor.

In the 2,140m of tunnel completed to 2 June 2008, 92 umbrellas or cycles of grouted pipe spiling had been installed in different sections. Steel ribs were installed in short sections at the start of the drive but have not been used since introducing spiling. “In these conditions, it is crown support we need and not just at intervals but in the longitudinal umbrella-type application,” said Kapeller.

“Grouted pipe spiling using 25 x 9m long x 2in diameter spiles at 40cm centers across the crown and on 4.5m overlaps, provides that presupport.”

Immediate support comprises rockbolts, wire mesh, steel channels and flash coat shotcrete ahead of the primary shotcrete lining. Swellex bolts are said to be best suited to the conditions and “we are using 4m and 6m long bolts in different arrays,” said Kapeller. In addition, 3m long Swellex bolts are installed in the crown to anchor the continuous conveyor, the ventilation duct, and the monorail crane attached to the crown over the full length of the trailing backup and advanced in sections from the back to the front.

Alignment modification

To improve progress and mitigate the delay, the chosen plan is to alter the tunnel alignment. The alignment is to be changed, to rise more quickly into a band of competent rock encountered at a higher level on the decline at the start of the drive. To do this, the alignment will first move horizontally away from between the two existing tunnels and to the inside, closer to the Niagara River (Figs 4 and 5). This will be achieved over the coming reaches of the drive and will allow the vertical alignment to rise when determined.

Once committed to elevating the vertical alignment there can be no going back. The gravity fed tunnel operates as a 41

siphon under the buried gorge and into the supply channel on the surface to feed the power station penstocks. An added advantage of the intended alignment change is a slight shortening of the drive, which is in the benefit column of the move. Permits to authorize the changes were in the applications process during the site visit of 2008.

While discussions continue on how best to proceed, the feeling is that all involved are committed to staying the course; that the TBM will get through; that the tunnel will get finished; and that Strabag will complete and hand over a finished, fit for purpose, specification and performance criteria compliant facility.

Breakthrough ends tortured journey

SITE VISIT REPORT: MAY 2011

T

he world’s largest hard rock TBM received a hero’s welcome on 13 March 2011, following a long and tortured drive that tested the resolve of all involved. No shortage of dignitaries, media and invited guests were present to witness the massive TBM’s breakthrough, marking the end of excavation on the 10.2km (6.3 mile) Niagara Tunnel for Ontario Power Generation (OPG). The TBM connected with a grout tunnel about 300m (984ft) from the intake structure and ended its drive with a final stroke of 1.3m (4ft 4in) to complete a total 10,143m (33,277ft) excavated.

Ontario Premier Dalton McGuinty, OPG CEO Tom Mitchell, Strabag CEO Dr Hans Peter Haselsteiner, and Robbins CEO Lok Home were among those present at the celebration as well as hundreds of workers. Guests also included Rick Everdell who began his career with OPG’s predecessor, Ontario Hydro, right out of college on the project. He began on the feasibility studies to expand capacity at the hydroelectric complex in 1982 and has remained with the project almost 30 years through its various incarnations, and rising to the position of Project Director for the client.

“It is terrific for a civil engineer like me, having started out on such an ambitious project, to see the excavation come to a successful end,” said Everdell. “The project has certainly had its share of setbacks, including an economic downturn and reorganization of the power industry in the late 1990s that forced the cancellation of an earlier tender process and reduced the project from its original two tunnels plus a new powerhouse, to the single tunnel.

Then there were challenging ground conditions once we got into excavation. Still, after four and a half years of tunneling, the TBM is finally at the finish line.”

Strabag won the design-build contract in August 2005, but almost from the get-go the excavation was hijacked by extensive overbreak, requiring the removal of large amounts of material that slowed advance rates to a crawl.

Dark days

“The most challenging days were in 2007 when the TBM entered into the Queenston Formation before the St David Gorge and at a maximum depth of 140m (459ft),” said Everdell. “Significant overbreak meter after meter, essentially blew out the schedule.”

John Tait, Project Manager for Hatch Mott MacDonald, OPG’s representative on the project, summed up the mood in those dark days. “Depressing! Absolutely depressing. The Robbins TBM was capable of doing a 1.4m to 1.8m stroke in about an hour but advance was lucky if it accomplished that in a 24-hour cycle. It went on like that day after day for months and months.” Things hit bottom that year when the strain and uncertainly threatened the project. Strabag’s original Can$600 million fixed price contract included a penalty of Can$250,000/day maximum for any delay beyond the contracted delivery date and a 42

bonus of 50% of that for every day earlier. With the original Fall 2009 completion schedule completely out of reach, tensions rose between the stakeholders and came to a head with a dispute resolution hearing.

Dispute resolution

A resolution was reached at the end of 2008 to move the horizontal alignment further east to avoid the exiting two tunnels and change the vertical alignment to move the TBM out of the Queenston Formation. The contract was also changed from a fixed to a target price contract with the completion date pushed out to 2013 and at a revised cost estimate of about Can$1.06 billion.

“I think reaching that agreement, to find a way forward and finish this project, was a highlight,” said Tait. “Nobody liked it and everyone compromised. We had our disagreements and our arguments, and said a few harsh words, but the day it was over we shook hands, respected each other as professionals and got on with the job.”

Progress rates improved in the higher ground of the new alignment and 2009 saw the best advance rates of the entire project, including best shift: July 5, 14m (46ft); best week: July 12, 153m (503ft); and best month, July 468m (1,535ft). The best day came on May 1 the following year (2010) with a record 25.4m (88.5ft) in 24 hours.

“Conditions were much better in the overlying rock formations compared to the Queenston Shale,” said Everdell. “Several kilometers of the tunnel have virtually no overbreak, so getting out of the Queenston Shale with the realignment was the right decision.”

Even so, average advance rates remained lower than expected in some sedimentary strata as overbreak continued to dog the excavation, including a rockfall in September of 2009, where about 25m3 or 100 tons fell from the two o’clock position in the crown some 2km (1.2 miles) behind the TBM, and about 3,600m (2.2 miles) into the drive.

The TBM

There were plenty of small, frustrations too, including one that initially delayed delivery of the TBM, much of which was trucked from the Robbins plant in Ohio for the on on-site assembly. A section of the massive cutterhead was waylaid at a Pennsylvania Turnpike weigh station for two weeks because it was over the weight limit by 91kg (200lbs) and required a special permit, said Mike Kolenich, Project Manager for Robbins. “The thing is, when the load was re-weighed it was actually under the limit. Either the scale was off the first time, or our driver lost a heck of a lot of weight in the two week layover.”

Despite the delay, the onsite build was completed within the 12-month deadline and the massive 14.4m (47ft) diameter TBM performed as specified. “With all the challenges of the project, it is very satisfying to know the machine was not

one of them,” said Kolenich. “Strabag also took great care of the TBM. It adopted a maintenance schedule and really stuck to it.”

The TBM, dressed in 20-inch disc cutters, was modified slightly in the early stages of excavation due to the excessive overbreak. The work platforms behind the cutterhead were replaced with several man lifts to more easily manoeuvre workers around the crown. Additionally, more protection was added to some of the vulnerable systems as a safeguard against the falling overbreak.

While the TBM’s work is done, there is still much to do, including the crown profile restoration work and completion of the concrete lining installation that has been underway since December 2008. The invert installation has progressed beyond 7km and the arch installation that began in May 2010, has progressed more than 2km.

Each concreting installation has two 12.5m long forms that cast in leapfrog sequence to complete 25m a day. A peak workforce of about 400, working in three shifts/day across the 24hr/day, 7 day/week schedule are assigned to the several concurrent lining operations.

Awe-inspiring

The shear magnitude of the operation and the size of the TBM and its trailing gear never fail to impress even the hardest cynic. “Everyone is awed by it,” said Everdell. For the arch installation and membrane placement there is a train of work platforms that are about five stories in the air and about 450m long. “We are almost a tourist attraction,” said Tait.

“Everyone wants to visit. I remember one colleague visiting, who, according to him, has seen it all and done everything. I walked him into the tunnel early in the excavation right under the TBM and he looked up and said ‘Oh, holy cow!’ and that is the best way I can describe it.”

For most involved, the Niagara project is a career high. At 67, it comes near the end of Tait’s career. He should have retired two years ago, but is committed until the end of the project. “There were times, back in 2008, when we had the worst rock conditions and the schedule kept slipping that I questioned if the excavation could be finished, but here we are, we made it, and give Strabag its due, they stuck it out, and kept at it, when another contractor might have walked away.”

“In hindsight a target price contract with incentives and disincentives might have been a better way to start out the project, rather than a fixed price with incentives,” said Everdell. “OPG actually adopted that model on another project and would probably use it on other significant projects. You can get a better base price to begin with and it really does promote working together as a team that can respond quickly to challenges as they arise. I think it is a better fit for these major infrastructure projects.” Tait and Everdell have little time for reflection with the project still two years from completion, but for the moment they are enjoying the successful completion of excavation. “There is a powerful sense of accomplishment,” said Tait, “so it is a great day everyone involved.”

Niagara opens

After more than seven years of construction, the challenging Niagara Tunnel Project was commissioned in March 2013. The outlet gate opened and water was allowed to flow through the 10km water supply tunnel near the famous waterfalls on the Niagara River. “Thanks to the years of commitment by the Strabag team the project could be concluded as both a technical and financial success months before the contract deadline,” said Strabag CEO Hans Peter Haselsteiner. The construction contract was awarded to Strabag as a Can$600 million design-build fixed price contract in 2005, and tunnelling works commenced in September 2006.

Following the encounters with extremely difficult geological conditions and after a successful dispute resolution process, a revised contract and schedule was negotiated in 2009. Project completion was finally delivered Can$100 million lower than the revised Can$1.6 billion and nine months earlier than projected. “Congratulations to our contractor Strabag and the hundreds of men and women who safely completed this engineering marvel,” said Tom Mitchell, OPG President and CEO. The experience also encouraged engineers in Canada to adopt dispute resolution boards as a condition of contract. n

TunnelTalk references • • •

Tracking the world’s mega-TBMs - September 2020 Advocating for more DRBs in Canada - August 2010 Road to litigation and possible bypasses - January 2020 43

CASE STUDY: With EPB technology in its early development, and with compressed-air, hand-excavation of the first rail tunnel under the St Clair River one hundred years earlier as their guide, engineers were convinced that pressurised mechanised TBM technology with a modern bolted and gasketed precast concrete segmental lining was the choice to be made in the early 1900s for the new larger diameter replacement subaqueous rail link.

SITE VISIT REPORT: MAY 1994

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n 1 March 1993, a joint venture led by Traylor Bros of the USA started work officially on the railway project under the St Clair River between Sarnia in Ontario, Canada, and Port Huron, Michigan, in the USA (Figs 1 and 2). On 1 November 1993, the JV launched a 31ft 2in (9.52m) diameter EPB TBM manufactured by Lovat Tunnelling Equipment of Canada from the Sarnia portal. The schedule for excavating the 6,000ft (1.8km) long x 27ft 6in (8.4m) internal diameter tunnel was 8.5 months and at planned rates of about 240m/month or 10m/day.

“Experience to date [March 1994] has proven that an EPB TBM is the right tool for the job,” said Neville Harrison, Construction Manager for the Design and Project Management team, Hatch-Mott MacDonald, a joint venture between Hatch Associates of Mississauga, Canada, and Mott MacDonald of the UK, which also completed detail design for the scheme. “Through careful operation of the TBM, it is possible to limit ground movement to extremely fine increments with the relatively impermeable clay till responding to changes in ground pressures within one or two hours. Face loss has been limited typically to less than 1%.”

The 100m3 of unbulked material for each 1.5m wide ring of precast concrete lining is excavated in about 30-35min and transported by three trains of 4 x 18yd3 muck cars.

Only about 5% water needs to be added to the plenum for effective EPB extrusion of the clay till through the 1.2m diameter x 12.6m long screw conveyor of the EPBM. Once through the initial learning curve, progress reached a best to date of 12 rings (18m) in a day of three 8h production shifts. “We hope to improve this to a steady 14 rings (21m) a day,” said Michael Roach, Project Engineer for Traylor Bros.

With Traylor Bros as lead (40%), the JV includes Foundation Co, Canada; Frontier-Kemper, USA; and Wayss & Freytag, Germany (20% each).

Figs 1 and 2. The new St Clair River rail tunnel across the Canada/ USA border (below), is aligned in a narrow band of soft material (right)

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St Clair River

TBM purchase

In a departure from more normal practice, the TBM and the tunnel’s precast concrete segmental lining were purchased by the client, the Canadian National (CN) North America railway company, owner and operator of the existing 100-year old railway tunnel between its Canadian network and the network operated by Grand Trunk Western, its USA subsidiary.

Pre-purchase of the TBM and the lining through what is known as a Negotiated Compressed Schedule (NCS) contract, was adopted by CN to help ensure completion of the Can$200 million facility within a tight planning, design and construction schedule of just 33 months (in March 1994 Canadian dollar values Can$1 = US$1.35). Delivery of a new TBM within the construction contract would have required at least a further 12 months in the contract period. Preorder of the lining reduced the risk of segment production holding up tunnel progress.

As part of the NCS procedure, a short list of seven prequalified construction groups was required to join round table discussions about the special demands of the project and choice of machine and the tunnelling method. Only those groups participating in this Technical Committee and accepting Committee proposals could bid the project. Among the most significant developments, these discussions led to adoption of the EPB technique for tunnel excavation and provision of a backup compressed air facility in the tunnel to avoid potential inundation.

Following the bid process, the Traylor & Associates joint venture of Traylor Bros (USA), Foundation Co (Canada), Frontier Kemper (USA) and Wayss & Freytag (Germany) was awarded the contract in October 1992 after submitting a price of Can$52.8 million, the lowest of three received.

The owner also agreed to partnering as a feature of the contract management, following a proposal from Traylor.

After an international tender, CN placed a base price EPB TBM order of about Can$17 million with Lovat. This is machine number 125 manufactured by Lovat during its 20year history and is the largest TBM built by the company to date. The 9.5m diameter x 10.25m long tunnelling shield weighs about 524 tonne. The 72m long trailing backup adds a further 200 tonne. The cutterhead is fitted with 6 pairs of flood control doors and is dressed with 200 spade type teeth and 53 backloading ripper teeth or 53

rail connection backloading twin disc cutters. Eight 300hp electric motors are coupled to variable displacement pumps for a total cutterhead power availability of 2,400hp. Cutterhead rotation is reversible and provides a minimum rotation of 1.5 rev/min and a maximum of 2.5 rev/min. The 30 thrust rams have a 2.25m stroke and deliver a maximum thrust force of 6,000 tonne. Twenty four x 200 rams across the shield’s articulation joint have a stroke of 305mm and provide an articulation angle of 1.8°.

The 1.2m diameter x 12.6m long screw conveyor passes through the bulkhead just below axis level into the 60m3 excavation chamber. The end-drive central shaft screw has a 318m3/hr material carrying capacity and a reversible rotation of 0 to 18 rev/min. From the horizontal discharge gate in the underside of the conveyor casing, muck extrudes onto a 1.2m wide conveyor belt system and back to the muck train.

Man-entry into the excavation chamber is achieved via the machine’s three-man air lock located in the upper part of the bulkhead. After closing the cutterhead flood doors, the chamber is emptied halfway via the main screw. The remainder is removed, if necessary, via a small auxiliary screw located in the shield’s invert. Man entry is then achieved either into free air if safe conditions can be secured by the flood doors, or into compressed air if required.

As the TBM advances, the precast concrete segments of the single pass lining are lifted into place by the 100° Lovat segment erector. The rings of the 400mm thick bolted reinforced lining are 1.5m wide and comprise six segments and a key, the largest segments weighing 7 tonne. Production and supply of the required 1,236 rings was pre-contracted to the Pre-Con/Sehulster JV of Woodstock, Ontario, for a contract price of about Can$16 million. The segments were cast at Woodstock and transported by rail to the site. Segment production started in April 1993 and the last segments of the order were delivered in January 1994.

The segmental lining, designed by Hatch-Mott MacDonald, is secured across both joints using a straight bolted system, and is fitted with an EPDM sealing gasket supplied and imported from Phoenix of Germany. As the TBM pushes forward off each new ring, the nominal 150mm annulus is filled immediately with a sand and cement mortar grout injected through the machine’s tail skin to the rear of the three-row wire brush tail seal. Three 160 ltr/min rated Schwing pumps inject 7.5-8m3 for each 1.5m wide ring through the 13 x 50mm diameter

circular grout pipes recessed into the tail skin. Grouting is controlled automatically and only two or three of the grout pipes are needed to fill the annulus using about 110 Itr/min of the pumping capacity. A stainless steel spring collar is fitted around the rear of the tail skin to prevent grout migrating forward along the shield skin toward the cutterhead.

Tunnel logistics

By choosing a bored tunnel instead of an immersed tube or bridge alternative, both of which involved several difficult planning and environmentally sensitive issues, the alignment was almost self-selecting. With an existing operating tunnel it was logical for CN to locate the tunnel portals on its own property and between its existing land based facilities.

Following early feasibility and preliminary design studies, concluded by Canadian consultant Klohn Leonoff Ltd, this places the new tunnel parallel and about 26m to the north of the existing tunnel. The 6.15m i.d. existing tunnel needs to be replaced to provide a facility large enough to accommodate modern double-stack freight cars and multistack car transporters. In the 10-15 or so years since the introduction of these vehicles, they have been uncoupled from standard-sized trains and transported across the St Clair by CN-operated barges. When the new tunnel is commissioned, the old facility and the barge operations will be decommissioned and remain available for times of emergency or maintenance shutdown intervening requirements in the new tunnel.

With the horizontal alignment fixed, vertical alignment was also largely self-selecting. The new tunnel portals are located along side those of the old in an enlargement of the existing open cut approach ramps. This gives the tunnel a fixed length of 1,844m with the 600m under the river matched by another 600m under the landfalls to each portal. To maintain the 2% rail gradient limit, the new tunnel depth was effectively fixed but this was also influenced significantly by the geology.

A comprehensive geological design report completed in 1990/1991 by Golder & Associates of Canada indicated that the soft saturated silts, clays and tills of the river bed overlie the uneven topography of the shale bedrock which is between 20 and 50MPa in unconfined compressive strength. With desire at St Clair to avoid a mixed face situation as far as possible, taking the alignment deep into a full face of shale would have extended the landfalls and tunnel length considerably.

Staying with the 1,844m length sandwiches the tunnel’s 9.52m cut diameter between the river bed and the shale interface leaving a limited cover of about half a tunnel diameter (4.6m) in the tightest points (Fig 2).

Left: The 31ft 2in (9.52m) diameter Lovat EPB TBM and its precast segmental lining was procured for the project by the client Right: The existing 100 year old tunnel on the left, the new tunnel portal on the right and the Esso research building behind

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The interchangeable disc cutters have been incorporated to cope with large boulders known to exist in the lower glacial river tills and the possibility of intercepting the shale in the invert. A bead on the leading edge of the TBM helps resolve the possibility of meeting squeezing clay.

With a shale bedrock, the potential to encounter methane and other hazardous natural gases is high. Oil was first discovered in North America at Oil Springs in Ontario about 30km away. For this reason, the TBM is designed and built to meet Class 1 Division 1 explosion proof regulations and all tunnel personnel have been issued with, and trained in the use of self-rescue equipment.

Given these onerous geological conditions, excavation of the existing tunnel in the late 1880s and early 1890s was a major civil tunnelling achievement. It was hand excavated under compressed air from within an early tunnelling shield and lined with cast iron segments. Welldocumented records kept by the project’s Chief Engineer Joseph Hobson proved useful in the planning, design and execution of the new project.

While geological conditions remain the same, activity on the surface either side of the river has changed significantly over the 100 years. The west bank is relatively sparsely developed but in Sarnia the zone between the tunnel portal and the river is now home to one of the largest refineries and tank farms owned and operated by the Imperial Oil (Esso) company. From launch, the TBM passes directly beneath a busy main access road, a main trunk line sewer, many storage fuel tanks with their many pipelines and overhead pipe racks and, perhaps most sensitive of all, the 40 year old Esso research building. This three-storey building houses banks of hi-tech computer and laboratory equipment and lies about 150m from the tunnel portal.

With no possibility of moving out or suspending operation, underpassing the research building presented a significant challenge for the TBM and its crew so early into the tunnel drive. The tunnel passes under 13m of ground cover to surface and within 10m of the building’s basement and foundations. To prevent settlement damage, permitted movement under the building was set at a maximum 10mm with a maximum settlement trough slope of 1 in 1,500.

During design of the protection works to adjacent structures, settlement calculations were based on a conservative face loss figure of 4%. “This gave us a field of influence of some 30m either side of the tunnel’s centre line and for about one to two tunnel diameters in front of the advancing TBM,” said Ian Ward-McNally, Deputy Construction Manager for Hatch-Mott MacDonald. “In addition, we expected a response time of about 24hr to any change in pressures. As it happens, the elastic behaviour of the material results in much faster response times. The actual settlement trough extends typically to 10m either side of the centre line and face loss is well within the design limit of 4% and less than 1%.”

The most significant part of the protection works for the Imperial Oil research building was achieved through a programme of compensation grouting carried out by geotechnical engineering contractor Hayward Baker of Odenton, Maryland, USA, with assistance from Keller Colcrete of the UK. To complete the work, two shafts were sunk close to the building and a cement/bentonite grout was injected through horizontal fanned arrays of tube-a-manchette injection pipes (Figs 3 and 4). This reduced heave to the maximum ground movement target of 10mm and created a reinforced mat of grout beneath the building which spread the settlement effects. As the TBM passes through, any settlement is compensated for as the induced heave comes back to ground zero.

If excessive settlement is recorded by the array of real time geotechnical monitoring instruments, more grout is injected. If extra heave is recorded, the TBM EPB variables (screw conveyor rotation and discharge gate operation) are altered to reduce the operating pressure. The HatchMott MacDonald project management team, responsible for communication between the grouting crews and the TBM operators, ensured tight ground movement control.

As it happens, passage through the zone of influence of the research building (a total of about 35m) took less than four days working continuously 24hr/day. The foundation grouting programme, designed and controlled in detail by Hayward Baker was completed several days before the TBM approached and only nominal regrouting was required. The research building has long since been passed and while a comprehensive array of field instrumentation will continue to monitor ground movement for a total of 24 months, there has been no need for further fracgrouting to date and little likelihood that any will be needed in the future. Hayward Baker remains associated with the project to continue protection monitoring works for the tank farm and pipe racks, movement under which is being compensated by using jacking techniques rather than grouting.

During a site visit to the project in early March 1994, the TBM was on stop after low levels of microscopically fine clay particles were found in a routine check of main bearing lubrication oil. The contamination was first noticed on 29 December after completing about 250m of tunnel using up to 4.8 bar maximum EPB working pressures.

Initial inspection by Lovat representatives indicated that the 6m diameter three row roller bearing from Hoesch Rotha Erde did not appear to have suffered any damage and that partial failure of the bearing sealing system had occurred. Inspection of the sealing system showed the inner seals in good condition, while a number of the external seals had been damaged. Unfortunately, while access to the main bearing is possible in-situ, the only way to fully inspect and replace the seals is by removing the

Figs 3 and 4. Plan and section of the compensation or fracgrouting system to limit ground movement under the research building

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cutterhead. “In other circumstances, the TBM could have continued to the end of the relatively short 1.8km long drive,” said Rick Lovat, “but as part of a responsible project engineering team, we agreed that since the opportunity was available, a shaft should be sunk and the situation rectified as a preventative measure before heading out under the river.”

On 9 January 1994, following temporary repairs to the sealing system, tunnelling at lower EPB pressures resumed towards a 15m diameter x 28m deep shaft located about 136m from the St Clair River sea wall on the Sarnia side. According to reports from the site, the shaft is expected to be complete by mid to late May 1994 and the TBM underway Installation of the bulkhead as part of the again by mid-June 1994. drive’s compressed air back-up system

TBM performance

To this point, the TBM was performing exceptionally well according to Michael Roach of Traylor & Associate. A comprehensive computer-controlled data logger linked also to a terminal in the project office monitors key TBM operating functions including the eight earth pressure cells located inside the excavation chamber. From the data, operating pressures are right within a band of half a bar either side of the pre-calculated value. At times, working pressure changes have been needed on a ring by ring basis and the TBM was said to have responded with controlled speed and accuracy.

Since detecting the sealing problem, the TBM has operated at about 1 bar, or just enough pressure to feed the material into and through the screw conveyor. This is less than half the 3.5 bar EPB pressure needed to control surface settlement and up to 100mm settlement has been recorded behind the TBM during this period. Fortunately, the tanks and pipe-racks being underpassed at this time can tolerate some ground movement and this is quickly compensated for using the jacking techniques.

Location of the rescue shaft well ahead of the TBM was required for several reasons. First, a convenient space for a shaft working site was available within the Esso refinery and secondly, tunnelling could continue during shaft sinking and stoppage at the shaft was planned to coincide with a scheduled shutdown to prepare the tunnel and the TBM for the challenging 600m drive under the river.

During this preparation period, the in-tunnel bulkhead and air lock will be built into the completed section of tunnel at ring 155, about 132.5m from the portal. The tunnel’s one California switch must go in also ahead of the bulkhead. TBM advance to the shaft allows just enough space for the California switch, the bulkhead, and the end of the trailing backup of the TBM. During shutdown, the TBM muck chamber will also be emptied to allow man-entry to check and replace any worn cutting tools ahead of the river crossing. “Although we cannot guarantee TBM performance, we did commit to an undertaking that construction would not require any operations out on the river,” said Roach. Many of the environmental issues overcome by choosing the bored tunnel option would be revived if, for whatever reason, construction activity is needed from barges in the middle of the river.

While much has already passed, more awaits the TBM under the river. The St Clair clay till is not abrasive but the shale bedrock presents a real threat. Also the over-

consolidated lower till contains more sand and hosts a confined aquifer. As such the TBM may well have to cope with water pressures from below tunnel alignment as well as above. Under 10m of water and with only half a tunnel diameter of cover, ground treatment may well be necessary if man-entry is needed during the under river drive. To meet these possible requirements, the shield is fitted with a series of bulkhead ports suitable for forward grout injection or ground freezing equipment.

In the meantime, while the impact of the current situation on the project’s construction period and its budget is still under review, the TBM in its optimum EPB operating mode has proven itself well capable of meeting the special challenges of the job. The TBM achieved breakthrough on the USA side in December 1994 and the new link opened to rail traffic in April 1995.

Supreme court finds for the engineers NEWS REPORT: DECEMBER 2008

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ollowing completion of the project, a long litigious battle ensued with the project insurers who were refusing to cover claims for losses caused by the TBM sealing problems and consequent delays. Project owner CNR (Canadian National Railways) took the case to court in 2004 and won. Royal and Sun Alliance Insurance Co of Canada, as head of the insurance syndicate, appealed and had the Ontario Superior Court ruling overturned in March 2007. In taking the issue to the Supreme Court, CNR won a final ruling that found once again in favour of tunnel engineering and ruled that the insurer must pay more than Can$30 million in claims, plus pre-judgement interest and costs.

The core of contention was the definition and scope of the exclusion clause ‘faulty or improper design’ within the context of the policy that insured CNR against ‘all risks of direct physical loss or damage ... to ... [a]ll real and personal property of every kind and quality including but not limited to the [TBM]’ but excluding both ‘the cost of making good ... faulty or improper design’ and ‘inherent vice’. The syndicate of project insurers rejected a claim to cover the cost of sinking the emergency shaft to remove the cutterhead and inspect suspected failure of the TBM’s main bearing sealing system, denying coverage on the basis of the ‘faulty or improper design’ exclusion.

The original trial judge in 2004 found that design of the TBM “accommodated all foreseeable risks within the then limits of engineering knowledge”. The 9.25m diameter Lovat TBM was one of the largest EPB machines in the world at the time, and one of the first EPBMs used in North America. The judge acknowledged that the design proved, in the result, to be defective, but found that it was not ‘improper’ or ‘faulty’ according to the state of the art at the time and therefore held the insurers liable for the $29,582,638.91 claim, including pre-judgment interest, plus $1,150,837.35 in costs.

In 2007, the Ontario Court of Appeal, by majority, allowed the appeal, stating that, in its view, a design error may, but need not, depend upon designer negligence and that since the failure was attributable to ‘design’, the exclusion clause 47

applies since the foreseeability standard also mandated that the relevant design succeed in withstanding all foreseeable risks.

In writing for the seven to three majority in the Supreme Court, Judge Binnie allowed the counter appeal, stating that its ‘all risks’ policy “afforded the CNR greater protection than that which the majority in the Court of Appeal was prepared to allow. The policy did not exclude all loss attributable to ‘the design’, but only loss attributable to a ‘faulty or improper design’”.

“In my view,” he continued, “the insurers did not meet the onus of bringing the loss within the exclusion. …..The design exhausted the state of the art but left a residual risk.

Failure is not the same thing as fault or impropriety. ….The insurers make a beguiling argument but I do not think it

should prevail. The CNR was entitled to insure against the possibility that a design might fail even though not improper or faulty according to the state of the art. The insurers cannot rely simply on the benefit of hindsight to discharge their onus of proof. ….It was for the insurers to demonstrate that the exclusion applies.”

Conceptual design of the under-river tunnel project to connect Sarnia in Ontario, Canada, and Port Huron, Michigan, USA, started in August 1991 and despite the delay to sink the temporary shaft and repair the cutterhead sealing systems before advancing under the St Clair River, TBM manufacturer Lovat confirmed that at no time was the integrity of the machine’s main bearing compromised. Repair of the cutterhead sealing system by Lovat was at no cost to the project and did not in itself result in an insurance claim. n

McNally ownership and ISO registration

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n July 2011, and after three generations of family ownership, McNally became a 100% subsidiary of Weeks Marine another family-owned business. Ahead of the takeover, Laura McNally, Vice President Corporate Development and a third-generation of the McNally-family management said: “Weeks brings opportunities to grow the McNally brand and expand its marine operations.” Rich Weeks, President and CEO of the New Jersey-based firm at the time said, “With this purchase, Weeks secures an entrance into North America’s tunneling industry and establishes a significant presence in Canada.

MARCH 2011 AND JULY 2011

quality processes that all our employees could buy into.” ISO, the International Organization for Standardization, is the developer of international practice standards with its Secretariat in Switzerland.

Among McNally’s many tunneling projects through the years are the Sheppard Subway in Toronto (see p27); the South Light Rail Transit System in Edmonton (see p19); the Region of York sewer tunnel network near Toronto; an interceptor sewer tunnel contract in Columbus, Ohio, USA, construction of the river intake structure for the Niagara hydropower water diversion project (see p35); the Toronto Subway Spadina Line extension in JV with Aecon and Kiewit Laura McNally and Ray Hutton, a grandson of the McNally founder, (see p11); and the Can$150 million Port Mann water supply tunnel were appointed Managing Directors of McNally while Patrick under the Fraser River in Vancouver in JV with Aecon. n McNally and John Hutton, who built the company into an international operation and managed the Video: Canada recognises a long and rewarding career in tunnelling collaboration with Weeks Marine, stepped down from day-to-day operations to serve on the McNally Board of Directors and in an advisory role to the management team.

In 2011, McNally became the first North American tunnel and marine contractor to achieve ISO registration for Quality Management Systems, Environmental Management Systems and OHSAS certification for Health & Safety Management Systems. “It just made sense,” said Pat McNally, President of the company his father in founded in 1949. “Our operations have quadrupled in the last decade and the ISO registration has established

Dr Zdenek Dan Eisenstein, 1936 - 2009

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n June 1st 2009, the industry lost a top class promoter of tunnels and the underground space dimension when Dan Eisenstein died in Vancouver, Canada.

Dan was well-known in the international industry, bringing confidence to city planners and politicians for developing underground infrastructure.

As Professor Emeritus of Civil Engineering at The University of Alberta in Edmonton, and as Past President of the ITA, International Tunneling and Underground Space Association, from 1992 to 1995, Dan’s special brand of geotechnical and civil tunneling expertise was in demand the world over. He promoted the use and introduction of new tunnelling techniques from Europe for the Edmonton Metro (see case study p15) and was a member of the expert advisory panel for the twin-bored tunnels excavated under the center of Vancouver for the Canada Line metro link to the city’s international airport (see case study p20). Prior to that, he was

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instrumental in lifting a ban on any further tunneling for development of the Los Angeles metro, making way for progress and successful completion of twin running tunnels and an underground station on the Gold Line of the LA Metro into East Los Angeles.

Also in Los Angeles, he promoted the use of closed mode EPBMs for controlled excavation of the East City Interceptor Sewer (ECIS). This was necessary after serious incidences of ground loss and surface settlement on the earlier NOS sewer project in the same area.

As a native of former Czechoslovakia, Dan received his Undergraduate and Graduate Geotechnical education at the Czech Technical University in Prague between 1959 and 1965.

Following a period of postdoctoral work in London, he accepted an academic position at the University of Alberta in Edmonton in 1969, becoming a Full Professor in 1974 and a Professor Emeritus in 2001. From 1972 to 1983, Dan completed four Visiting Professorships in Brazil, South Africa and Germany. In 1990 he became an Honorary Professor at Pontificia Universidade Catolica in Rio de Janeiro and in 1991 he received an Honorary Doctorate from The Czech Technical University. Through his career, Dan’s prime research and professional interest was soft ground tunneling, especially in urban environments. He was a pragmatist about the art of tunneling. n

CASE STUDY: Only once into excavation are specifications and construction estimates of a project tested. Only then do the best laid plans of a keen lowest bid award and the contract terms come under pressure and perhaps require a drastic change of plan as the only way forward. The Seymour-Capilano project in Vancouver had all the drama on the road to completing the twin 3.5m diameter x 7.1km long deep rock tunnels, taxing the resolve of the owner, its consultants and its contractors.

Vancouver drives towards better drinking water

OFFICE VISIT REPORT: MARCH 2004

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Project area is close to the Cleveland Dam spillway at Capilano

ew federal and regional water quality standards and future demand are the forces driving the Seymour-Capilano Filtration Project for the Greater Vancouver Water District. Twin 3.5m (11ft) diameter tunnels will connect a 1,200 million litre/day (ml/day) pumping station to an 1,800ml/day filtration plant more than 4 miles away. The pumping station at the Capilano reservoir will send raw water through one tunnel to the filtration plant in the Seymour watershed. Gravity will then feed the treated water back through the second parallel tunnel to Capilano

and into the distribution network (Figs 1 and 2). Within the overall project budget of Can$600 million, tunnel excavation is estimated at about $100 million.

The Toronto office of Hatch Mott MacDonald (HMM)carried out preliminary studies for project definition and confirmed the preference for deep tunnels in bedrock for conveyance.

Brian Garrod, Project Engineer for Mott MacDonald, said: “the tunnels will lie at a maximum depth of 640m (2,099ft).

The high quality granite bedrock means substantial portions of the tunnels will be unlined. The deep glacial deposits at each end Fig 1. Plan of the parallel of the tunnels will require deep water tunnels access shafts and reaches of in-situ concrete lining.”

Fig 2 (inset). Geological section of the deep alignment

Working with SNC Lavalin, overall program manager for the filtration project, HMM has also completed the geotechnical site investigation and final design for the twin tunnels and will provide engineering services through the construction phase.

The predominant rock type on the tunnel alignment is a strong granite/granodiorite with unconfined compressive strengths in the range of 80 to 250MPa. This is reflective of the mineral assemblage and the degree of alteration. The geotechnical report describes the rock quality as good to very good with a rock quality 49

designation (RQD) generally greater than 75%, which is typical of good quality granite.

While the ground water table is near surface, initial borehole packer testing indicates a low rock mass permeability. Phase II of the geotechnical study however raised serious questions about the location of the proposed 12m diameter Seymour shaft. High groundwater flow rates in about 100m of water-bearing overburden were found. “We initially considered ground freezing,” said Garrod, “but this proved too costly, so we looked at alternative shaft sites. After evaluating 10 different sites we decided on a location about 250m (820ft) from the original site. The bedrock at this location is about 30m (98ft) below surface and pipelines will be installed to connect to the filtration plant.”

Selection of the vertical alignment is driven by the requirement to pass with adequate rock cover beneath two buried valleys. Geotechnical studies showed significant variability in rock surface profile with bedrock depths in excess of 600m (1,968ft). The tunnels will run in bedrock between 160m and 640m deep. Sections of steel lining are specified for zones in which the measured stress levels in the host rock are found to be inadequate to prevent hydraulic leakage.

Because of significant restrictions on construction at the environmentally sensitive residential Capilano end, the Seymour end will serve as the working site and launch shaft for the two TBMs required to meet the project schedule.

The shaft will be about 185m deep x 12m diameter and

the tunnels will be driven on a 2%+ downhill gradient.

A minimum 3.5m excavated diameter was selected for the tunnels to provide sufficient clearance for the installation of initial support in poor quality rock. This diameter will also accommodate a minimum 3m i.d. final lining. At the Capilano pumping station end, two 3.5m diameter raise bored shafts of at least 220m deep to pass under the buried valley will link the water conveyance tunnels to the new filtration plant. As work on the new plant gets underway, tree clearing and site grading started near the Capilano Reservoir Cleveland Dam in late January 2004.

The tunnel construction contract will contain risk-sharing provisions including a geotechnical baseline report, a differing site conditions clause, and a disputes review board.

“Completion of the design phase is only days away now,” said Goran Oljaca, Senior Engineer with Greater Vancouver Water District, and award of the excavation contract is scheduled for July 2004, with project commissioning achieved by 2006.”

Following an international invitation to tender, three bids were received in early August 2004 for the twin 3.5m o.d. x 7.6km TBM-driven water tunnels: • Bilfinger Berger/Frucon JV - $99.65 million • Frontier Kemper/AECON - $186.24 million • Peter Kiewit & Sons - $237.54 million In August 2004, Andy Saltis, Project Manager for GVWD, confirmed the design-build contract award to the Bilfinger/ Frucon JV.

Facing the challenges of Seymour-Capilano SITE VISIT REPORT: DECEMBER 2006

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n September 2006, on the first of two site visits by TunnelTalk to the project, both TBMs were launched and were ramping up towards full production. Success on the project will depend on mastering the demanding logistics of the project, maintaining optimum production, and preparing for the unpredictability of the geology.

From the bottom of a single 180m deep x 11m diameter access shaft, both 3.8m o.d. headings of the twin water tunnels, must advance 7.1km on a 2.3% downhill gradient through what is predicted to be sound granitic and metavolcanic bedrock but with recognized unpredictability beneath the maximum 640m overburden.

The greatest of these uncertainties is the depth of two known glacial valleys - one at the start of the tunnel drives near the access/working shaft at Seymour and the other at the far end close to the site where the two tunnel drives dead end and are connected to the surface via two 275m deep x 4m diameter raise bores (Fig 1).

“Everything about this job is driven by these challenging logistics,” said Christian Genschel, Project Manager for Bilfinger Berger. “From the method of excavation, to the management of muck haulage and the safety measures required, everything is dictated by the long, deep, small diameter, downhill, dead end specifications of the design and the uncertainties of the geology. At the end of the drives we must dismantle and retrieve the TBMs back through the finished drives, excavate a large chamber in which to 50

• Client: Greater Vancouver Water District • Programme Manager: SNC Lavelin • Tunnel Consultant: Hatch Mott MacDonald JVX • Contractor: Bilfinger Berger/Frucon JV progress the Capilano raise bores, and muck everything out through the Seymour shaft. At the end of excavation, we will install steel liners and steel pipes as designed and backfill everything, including the Seymour shaft and its working chambers.”

Bilfinger Berger (Canada) Inc was awarded the 49.5-month, design-bid-build contract in August 2004 as the lowest of three bids and as the first major contract for the North American operation of the Bilfinger Berger GmbH parent company of Germany. The tunnels are a major component of the new Can$600 million filtration plant project by the Greater Vancouver Water District to convey raw water from the Capilano Reservoir to the new filtration plant at the Seymour Reservoir, and return treated water back to the head works of the Capilano distribution system.

These are the first tunnels undertaken by the Water District and there are no existing bored tunnels through the mountains of the Vancouver region on which to draw previous experience.

Pacific Liaicon-SNC Lavalin is the appointed construction managers for the tunnel contract and Hatch Mott MacDonald, completed final design of the tunnel project and is providing on-site resident engineering services through the construction phase. Golder Associates completed

Working shaft tower crane set to get the first TBM assembled at the bottom of the access shaft and ready to go

geotechnical investigations and assisted Hatch Mott MacDonald with writing the contract’s geotechnical data and geotechnical baseline reports (GDR and GBR).

Construction began on site in mid-January 2005. The end date of the contract is March 2009. Bilfinger Berger’s bid of Can$99.65 million was substantially below the two competing bids of Can$186.24 million and Can$237.54 million. With no bonus for early completion, there is a Can$30,000/week penalty for any time overruns.

Project mobilization

In gearing for the project, Bilfinger Berger mobilized with largely new, topof-the-range equipment. Two new high-performance series TBMs from Robbins have been procured. “One, with a cutterhead diameter range of 3.5m to 5.2m, the company has bought, and the other is on a rent agreement,” said Genschel. With the TBMs, Bilfinger Berger also concluded a cutter consumption contract with Robbins and service agreements for three Robbins technicians during TBM assembly and a full time on-site Robbins technician and cutter service technician through the drives.

Behind the TBMs, and despite the 150m in 7,100m downhill gradient, Bilfinger Berger (BB) has elected to use a rail-bound mucking system.

“The length and diameter of the tunnels ruled out the possibility of using a continuous conveyor,” said Genschel. “We would have required more than 15km of horizontal conveyor for the two tunnels and the diameter is really too small. Within the 3.8m diameter we have to fit rail tracks in any case and provide clearance for manriders and supply trains, as well as fit the 1.2m diameter ventilation duct to deliver the specified 8.5m3/sec of fresh air to the headings at all times. In addition, as the drives lengthen we have to install a California switch, power and ventilation booster stations, and intermediate sumps and pumping stations. Add to that all the necessary pipelines and power and lighting services and there is little room to spare in the small tunnel diameters.”

Rail-bound mucking is based on muck trains of five 5.4m3 capacity Mühlhäuser side-tipping muck cars pulled at the front by one 35 tonne diesel GIA loco. Each train will muck away one TBM stoke of 1.5m and BB has mobilized with enough rolling stock to operate seven muck trains, three for each drive as the headings lengthen, plus one spare.

Through the shaft, muck management is based on a BB-patented fully automated hauling system using two 30m3 kibbles. “These buckets are on the center line of the shaft and are inline with the tunnel headings and the shaft’s tail tunnel,” said Josef Messner, Construction Manager for BB. “As Excavation of the short drill+blast starter tunnels 51

one of ten alternative sites where seismic survey and core drilling indicated a buried bedrock hump rising above the main water-bearing members of the glacial stratigraphy, to within 30m of the surface, and consisting of reasonably competent granitic rocks, excavation proved different.

After using NATM as an alternative to grouted corrugated liner plates through the glacial overburden, much of the lower shaft was excavated by drill+blast in reasonable rock with pattern rockbolts, welded wire mesh, and 150mm minimum thickness of dry-mix shotcrete. According to construction face mapping however, several reaches were through mixed conditions comprising hard granite rock to one side and metavolcanic rock to the other. This threw the effectiveness of the drill+blast cycles and caused sever delay as well as higher consumption of explosives and support materials. The conditions and their consequent impact are the subject of the first issue to be heard by the contract’s dispute review board.

Shaft bottom assembly and working area with the first Robbins TBM assembled and ready to launch

the trains arrive the side-tipping cars empty into which ever of the kibbles is available. It then passes into the back tunnel and returns on a set of tracks to the other side of the offloading bays. This allows us to handle two loaded trains at once (one from each heading) without any hold up’’.

When filled, electronic sensors activate hoists to lift the kibbles to the surface where they are emptied into muck bins either side of the shaft. From arriving at the shaft bottom, the cycle time for off loading a train and returning the empty kibble through the 180m deep shaft is less than 16 minutes.

The head frame of the shaft is a substantial installation built of Leiberr tower crane components and fitted with two 70 tonne hoists, one for each kibble. The shaft excavation progressed using a 150 tonne mobile crane and constitutes the first major vertical shaft sinking operation in British Columbia in more than 20 years and one of the deepest excavated using a crane as the primary hoisting system. The permanent gantry crane, hoists and head frame was needed also for lowering the TBM components.

Ahead of TBM assembly, BB excavated the necessary working chambers. These included a 30m long back chamber plus a 50m long tail tunnel, as well as a 14m wide x 6m high assembly chamber at the headwall of the drives. An 8m deep pit below the shaft’s working level houses the two 125m3 recesses for the kibble bays and a 400m3 water sump.

Inundation of the works is a low probability risk, but one that needed to be taken seriously. “The GBR states that we must anticipate ground water inflows of up to 65 litre/sec in some reaches,” said Genschel. “The contract specifies a continuous overlapping probe drill ahead of the face and a minimum 220 litre/sec pumping capacity through the shaft.”

The TBMs are fitted with pumps and pipe-work to meet a minimum 115 litre/sec horizontal capacity back to the shaft sump. They are also fitted with two permanently mounted drill rigs and pumping equipment for probe-drilling and perexcavation grouting if that should prove necessary.

Although good quality rock is anticipated for the tunnel drives, the unpredictability of the geology was illustrated during excavation of the shaft. After moving the shaft to 52

The delay also set back delivery and start up of the TBMs. Robbins held the machines at its workshops in Solon for several months beyond the contracted shipping date. Shaft excavation finally reached bottom in November 2005, after starting in mid-January, and the components of the TBMs started arriving in a convoy of 72 trailer-trucks in May 2006.

Furnishing of the shaft and its head frame was well advanced by then and the first piece of the first machine went down the shaft on 21 May.

TBM specifications

For the most part, the GBR predicts hard granite/granodiorite bedrock at tunnel horizon with compressive strengths of up to 285MPa and an RQD of generally more than 75%.

To get best production in these conditions, each 3.8m diameter Robbins TBM has an installed power of 1,260kW, a maximum thrust of 10,700kN and a maximum cutterhead torque of 885kNm. Each cutterhead is dressed with 26, 19in backloading Robbins cutters.

The trailing gear for each TBM is some 250m long. These long trailers are designed to accommodate two muck trains at once, one being loaded while a second waits on the backup. “Maximizing production is the key to completing the drives on program,” said Messner. “We cannot afford to lose any time in the excavation cycle. The long backups will prevent delays waiting for muck trains and will allow us to optimize the shaft hauling system.” Two California switches will be installed in each 7.1km long tunnel at about 2.4km and 4.8km.

Emphasis on production also demanded that both TBMs start and advance at the same time. Early works at the bottom of the access shaft did include drill+blast of starter tunnels but in efforts to mitigate some of the shaft excavation delays, BB excavated shorter starter tunnels by drill+blast and had the partly assembled TBMs excavate the rest, stopping as advance allowed to add gantries of the long backup.

“Had we excavated full length starter tunnels of 250m-plus, we would have taken a further three months or more before we could begin TBM assembly,” explained Messner.

“Instead, we excavated a 60.5m long starter for the first TBM and had it advance, fully assembled, to a chainage of 500.4m where it was stopped while the second TBM was assembled’’. It too went through a staged assembly and was launched from a short 70.5m drill+blast starter tunnel.

“For the second machine,” said Messner, “we had the

advantage of extra room at the back of the first tunnel which we used for assembly of its backup - the trailing gear stretching back around the corner and backwards into the first tunnel.” During that period there was no space in the first tunnel between the end of the first TBM and the last gantry of the second TBM. All the electric cables and hydraulic hoses of the second TBM were strung umbilically back through the tail tunnel, waiting for the second machine to move forward and allow the cables to be attached to the gantries as they came in line.

This was an unusual approach but not a first, according to BB, for launching two TBMs out of a single working shaft at the same time, and it did have its challenges, including some interference in the sensitive electronic frequencies, and umbilical power cables. But these were overcome by the team and the Robbins technicians, who agreed the process could be achieved.

Plans and expectations

“When rock conditions are in the favorable range - and according to the GBR that should be for some 86% of the drives - we anticipate TBM production rates of up to around 28m/day working 24h/day, 7 days/week,” said Genschel.

“We will operate the machines on a 20hr production and 4hr maintenance cycle/day and maintain a three swing-shift pattern per machine, each crew working eight days on, four days off. As we progress we will also install the contract’s specified systematic support ranging from rockbolts as required in the best quality rock to steel sets, wire mesh and 50-100mm of shotcrete in suspected zones of fractured material.”

One fortunate break for the team is that a suspected fault zone at the start of the tunnel drives did not materialize. The feature, anticipated to be linked to the Lynn Creek feature on the surface required probe holes to be drilled before breakout of the shaft and into the horizontal excavations of the assembly chamber and starter tunnels. Fortunately, while there was some water ingress, it decayed readily and both TBMs launched into good quality competent, dry, granite bedrock.

In operation the twin tunnels will be pressurized, raw water pumped from Capilano to Seymour and treated water gravity fed from Seymour to Capilano. Separation of the parallel tunnels by 100m will prevent cross flow between them and a total of about 1,900m of steel linings in each tunnel will prevent leakage where they converge at their east and west ends. The remainder of the tunnels, through anticipated competent rock, are designed to operate unlined. An energy recovery facility and pressure-balancing tank at the Capilano end will produce hydropower to drive the scheme’s operating systems.

In considering the options for meeting filtration regulation standards for the drinking water in Vancouver, many different schemes were considered explained Andy Saltis, Project Manager for program managers Pacific Liaicon-SNC Lavalin. These included building a smaller filtration plant at each reservoir as well as installing the water conveyance infrastructure as buried pipelines or combinations of opentrench and shorter, shallower lengths of tunnel. “These were all rejected on economic, environmental, and social concerns,” said Saltis, and despite the evident challenges of the deep-tunnel option, it exhibited itself as the “most economical, least environmentally damaging way to go.”

As a value engineering proposal, Bilfinger Berger offered

Unlined gripper TBM drive in good quality, competent granite

a contract alternative to sink a larger diameter shaft at the Capilano end of the tunnels, instead of two raise bores, which would have saved seven, eight, nine months on program but the option was rejected. There were several reasons for this according to Saltis, for program managers Pacific Liaicon-SNC Lavalin. “Environmental, logistical and social considerations dictate that both tunnels advance from the Capilano end,” he said. The site at the Capilano Reservoir, close to the Cleveland Dam spillway, lies within a residential zone of high-value real estate and heavy construction within the neighborhood was unacceptable.

“Also, the site is on a narrow strip of public land at the edge of the deep spillway ravine. There is barely space to establish the necessary pumping station and raise boring operation for the two connection shafts. There was no space at the site to establish a work site needed to sink a shaft or advance tunnel headings. All had to progress from Seymour where the Water District owns tracts of land and could site the project’s new filtration plant.”

“The contract specified a shaft of not smaller than 11m diameter and the drawings indicated a shaft of 12m diameter,” explained Genschel. “We selected 11m diameter which saved on the excavation and lining and on the subsequent backfilling of the deep shaft.”

Within the 11m diameter space, the 180m deep, shotcretelined shaft provides clearance for one-at-a-time operation of the 3.2m diameter, 30m3 kibbles and accommodates the three 1.2m diameter rigid ducts of the forced ventilation system from the two 150kW rated vent fans on the surface into each tunnel heading, as well as operation of a 2,400kg/23-people rated Alimak elevator. It also houses all other service lines and the four 8in diameter pipes of the water pumping system. “In some way, the downhill gradient is an advantage,” said Genschel, in that “should there be a major inundation at the far end of the tunnels, the headings will fill from the bottom up, chasing all back toward the shaft bottom.”

As well as winning one of the most challenging tunneling projects in North America at the moment, Bilfinger Berger has faced other hurdles in establishing its first project in the region from its European base. Finding labor to work the 24/7 swing-shift schedules and willing to learn the specialty of working underground with different methods 53

such as NATM and shotcrete has been a frustration.

There are few experienced tunnel workers in the Vancouver region and keeping trained workers against a competitive regional mining industry, offering attractive wages, is a struggle. Another frustration has been mobilizing according to North American standards. Many health and safety at work standards in Canada are based on working in mines. Ventilation systems are based on powered extraction, and introducing a forced ventilation system, with exhaust through the tunnel cross section, required special exemption permits. Operation of the

Alimak elevator in the deep Seymour shaft also required special permit as a point of non-conformity according to prevailing work safety standards.

Despite all, BB has taken on the challenge of the SeymourCapilano Twin Tunnels and is gritted to see it through. “We are anticipating about one year of TBM operation to reach the end of the 7.1km long drives,” said Genschel, “but it will be the complex logistics, the unpredictable edge of the geology, and the ability of the workers, that will ultimately determine actual progress rates’’.

Seymour-Capilano geological encounters SITE VISIT REPORT: MAY 2007

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y early 2007, both TBMs on the project were more than 1,000m into their 7,100m long drives, with TBM1 at chainage 1,765m and TBM2 at 1,179m.

“We are moving - not as expected but as well as is likely through the rest of the drives,” said Josef Messner, Construction Manager for Bilfinger Berger who has taken over as Project Manager from Christian Genschel. “TBM2 is going better than TBM1 at the moment. TBM1 hit water last week and the Engineer instructed us to stop and grout off the inflow.” It was not a lot of water at about 3 litre/sec, but in the 7.1km long downhill drives water inflow

is taken seriously. Production was down for a total of five days while seven 40–45m long holes were drilled and some 3,400 litres of grout was injected to reduce inflow to about 1 litre/sec. The TBM2 heading coming up behind is about 100m parallel and, as it is unlikely there will be a grouting benefit for the parallel heading and it too will run into water at the same chainage.

This is the second phase of instructed water control grouting to date. The first was in TBM2 tunnel and comprised a similar grouting program. TBM1 tunnel was already ahead and water was not encountered when TBM1 passed that particular chainage earlier and there was no grouting required. Systematic probe drilling is a

Top from left: Grouting equipment railcar assembly ready to go into the headings as needed; Each TBM is fitted with two drill rigs. Bottom from left: Water ingress through a drill hole; Grouting injection pressure gauge

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contract specification and a 40m probe with a 10m overlap is maintained. Each machine is fitted with two Atlas Copco 1838 drill rigs, one either side of the main beam.

Chips and fines

A more persistent time losing factor is the amount of fines generated by the boring process. “The rock is a particular mix of harder and softer zones and frequent changes from hard to soft conditions,” said Messner. As a result, rather than producing well-defined chips, the TBM is grinding a lot of fines that lead to excessive sedimentation and causing various problems. It interrupts operation of the TBMs’ transfer conveyor back to the muck skips; blocks the water pumps at the TBM heading; clogs the dewatering tanks on the TBM; and creates trouble at the main water sump-pumping station in the bottom of the access shaft and at the water treatment plant on the surface.

A small feeder belt has been installed under the TBMs for clearing fines by hand onto the main belt. Pumps, dewatering tanks and sumps also need regular cleaning.

The fines are said to settle and pack like concrete that takes some shifting. Cleaning the main shaft sump means shutting down shaft activities and TBM production to get at the sump.

“The rock is not as consistently hard or strong as predicted in the geotechnical report and it has these pockets or lenses of softer material that create a mixed face that does not require high power, which rather grinds down into the fines which are a pain,” said Messner.

Conditions were said to be similar to the mixed conditions encountered during excavation of the access shaft that caused problems with the drill+blast cycles and “cost us much extra time.”

For the two high performance Robbins machines dressed with 26 x 19in cutters, power is not an issue for the 3.8m-diameter headings. “Achieving optimum availability from the machines is more the concern.” Cutter ware is also influencing the fines phenomenon. “The biggest ware problem is a face of mixed hard rock and pockets of softer rock,” said Messner. “Disc ware is unusual compared to more normal chipping ware and cutter changes in the small diameter tunnel are taking longer to complete.

Although only two inches bigger on diameter and 50kg heavier than 17in discs, 19in discs, at about 200kg each for face and gauge cutters and 335kg for center cutters, take special handling and you would not think it but this really does make a difference.”

All things combined, progress is usually between 1718m/day working two 10hr production shifts and a 4hr

Tight fit in the 3.8m diameter tunnel

maintenance shift/day. “We are running TBM1 seven days/ week,” said Messner “but only have crews at present to operate TBM2 from Monday to Saturday afternoon. This will change when another 15 workers arrive from the Philippines. Permits were issued recently by the Canadian authorities and we are just waiting for clearance in the Philippines.”

These extra workers will increase the number of expatPhilippinos on the project to 48, or about 40% of the work force, and will increase TBM2 production to 24hr/7days/ week. “We are still behind the original schedule,” said Messner, “and there is little chance that we will be able to make up any time lost during the shaft excavation and assembly and start up of the TBMs, but we might yet reach program advance rates of 27-28m/day - not as an average but as a regular daily rate. Our best advance to date was slightly more than 30m/day recorded by TBM1.

Average progress is now being influenced by the fines situation, by grouting cycles required, by rock support installation, and by the frequency of cutter changes.”

The 49.5-month contract by Bilfinger Berger to create the water transfer connections between the Seymour and Capilano reservoirs for the Greater Vancouver Water District (GVWD) started in January 2005 and is currently projected to finish in June 2009. Pacific Liaicon and Associates (part of the SNC Lavalin Group) is undertaking project and construction management and Hatch Mott MacDonald is supervising construction. Golder Associates completed geotechnical investigations and contributed to preparation of this demanding contract’s geotechnical data and geotechnical baseline reports (GDR and GBR).

Vancouver’s twin tunnels contract terminated NEWS REPORT: MAY 2008

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n May 2008, the contract with Bilfinger Berger was terminated and the process to appoint a replacement contractor to complete the works was underway.

In a statement, Metro Vancouver, the regional utilities provider, said that by refusing to continue work on the Seymour-Capilano tunnels Bilfinger Berger had forfeited its right to perform further work on the project and had forced termination of the contract. The Canadian division of Bilfinger Berger of Germany brought the two tunnel

headings to a standstill in early January when a zone of weak rock raised concerns for worker safety.

The lead heading was 4.1km or 57% into its 7.1km long drive when it was stopped on 7 January. The second was at 3.8km or 55% through the parallel tunnel when it was halted on 10 January. The two 3.8m diameter Robbins TBM headings were just past the deepest part of the alignment and under a cover of between 500m and 550m when they came to a stop.

It was reported that ten rock fall events were reported 55

by Bilfinger Berger to the health and safety authority in January and that it was WorkSafe BC that closed down excavation until the safety hazard was resolved.

Doug Neden, Project Manager for Metro Vancouver’s Greater Vancouver Water District, said in a telephone interview that it was said to be a combination of rock weakness and the release of in-situ stresses that caused rock falls from the crown. He said that although the term rockbursting had been used, there had been no explosive spalling or slabbing of the rock. “The signs of stress relief are evident in the profile just off the vertical, at the 11 o’clock and 5 o’clock marks,” he said. “Had the rock been stronger, it is said the falls would not have occurred.”

Conditions were said to be stable since the lead TBM was stopped in early January. The second TBM in the parallel drive, about 100m distant and about 300m behind, was stopped before it entered the weaker zone.

Metro Vancouver said that its tunnel designer and construction supervision engineer Hatch Mott MacDonald had prepared a plan that addressed the safety concerns and allowed for safe resumption of work. Bilfinger Berger did not accept the plan and high-level talks between contractor, client, designer, WorkSafe BC, and the client’s overall program and construction manager Pacific Liaicon/ SNC Lavalin, failed to resolve the stalemate.

Development of the plan included Robbins since technical solutions involved modification of the machines. The 3.8m diameter tunnels, for example, limit bolt holes and bolt lengths without using couplers. A larger diameter would allow for longer bolts but would require modification of the machines in-situ.

In the interview Neden confirmed that 40m long probe holes drilled into the face of the lead heading had been surveyed with endoscope cameras but that these had provided little useful indication of conditions ahead. After stopping excavation, the front 60m of the lead heading was taped off for safety and crews applied shotcrete to the tunnel walls behind.

In its statement Metro Vancouver said that “the world’s foremost experts in rock mechanics and tunnel engineering” endorsed the plan as “safe and viable” and that Bilfinger Berger claims “are without merit”. In the statement Johnny Carline, Chief Administrative Officer for Meter Vancouver, said “Bilfinger Berger’s refusal to move forward.......is a great frustration” adding that “the contractor has provided us with no practical alternative in terms of completing the work”. Bilfinger Berger has not been available for comment or interview.

The contract’s GBR (geotechnical baseline report), prepared by Hatch Mott MacDonald and project geotechnical engineers Golder Associates, predicts granite/granodiorite bedrock of 80-285MPa with an RQD of generally more than 75% for the majority of the twin 7.1km drives. The maximum 640m deep alignment between the 180m deep access shaft at Seymour and two 275m deep x 4m diameter raisebores at the Capilano end, is determined by the need to pass beneath two glacial valleys infilled with waterbearing sediments.

The tunnels are designed to remain largely unlined with support behind the two Robbins High Performance main beam gripper TBMs comprising mainly rock bolts and wire mesh with shotcrete as needed and steel sets provided for the worst Class 5 conditions. Sets were not being installed when the lead TBM was stopped. Water ingress, a major concern in the two 2.3% down gradient TBM drives working from the single 180m deep x 11m diameter access shaft at Seymour, was said to be lower than anticipated at 16-18 litres/sec.

Suspension of tunnelling caused layoff of some 30 tunnel workers, many brought in by Bilfinger Berger from the Philippines for the contract.

Bilfinger Berger was awarded the twin tunnels contract in August 2004 after submitting the lowest of three bids. Its Can$99.65 million bid, was below the Engineer’s Estimate and more than Can$86 million below the second bid. The contract is now reported as a $200 million project.

Early delays excavating the 180m x 11m diameter access working shaft set the contract back by more than six months. Subsequent delays launching the TBMs and downtime to install water control sumps and replace motors and gearboxes on the machines had the 49.5-month contract running up to a year behind schedule before tunnelling halted in January. Rock conditions in the shaft and the impact on excavation was the first issue heard by the contract’s dispute review board (DRB).

Bilfinger Berger had planned average rates of 28m/ day working 24h/day, 7 days/week to complete both tunnels in about 12 months. The machines had recorded rates of 20-22m and a peak of +30m in a day of two 10hr production shifts and a 4hr maintenance shift. The contract was originally to be completed by March 2009. There can be no reliable prediction now of when the remaining 3km+ of the two tunnels, plus the two Capilano raisebores and all finishing works, will be complete, nor how long the ensuing legal battles will take to resolve.

Seymour-Capilano continues at a high price JANUARY 2009

• Client: Metro Vancouver of city utility suppliers including Greater Vancouver Water District

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hree prequalified consortia were invited to return proposals in January 2009 to take over excavation of the twin Seymour-Capilano TBM drives. The prequalified groups prepared to take up from where the previous effort came to a standstill are: • The McNally International, Obayashi Corporation, and local contractor Procon Joint Venture; • The Seymour-Capilano Partnership of Frontier Kemper, JF Shea and AECON; and 56

• Programme Manager: SNC Lavelin • Tunnel Consultant: Hatch Mott MacDonald JV • Rebid Contractor: Frontier-Kemper/JF Shea/Aecon •

The Seymour-Capilano JV of Dragados, SELI and Schiavoni

“Once proposals are received, the technical and financial merits of each will be evaluated and the contract awarded to the selected group,” said Bill Morrell, media spokesperson for Metro Vancouver of regional utilities providers that includes the project client for the twin tunnels, the Greater Vancouver Water District (GVWD).

The prequalified consortia have been asked to submit a schedule of time and a fixed-price and a target-cost proposal for completing the project according to the detailed design specified by project engineer Hatch Mott MacDonald. The successful group will take possession of the construction site and all the equipment mobilized by the previous contractor to build the two 7.1km long x 3.8m diameter rock tunnels and their deep operating shafts at each end.

When the GVWD terminated the Bilfinger Berger contract in May 2008, it “exercised its contractual right” and “claimed access to all the equipment” said Morrell. This Left top: Rock instability in the crown; Bottom left: Support applied as needed; includes access to and continued use Right: Fractured rock in a side wall as part of instability that brought the of the two new 3.8m-diameter hard-rock contract to a halt Robbins TBMs procured by Bilfinger The Regional Director for Construction for WorkSafeBC, Al Berger for the contract, one bought Johnson, told TunnelTalk that Bilfinger Berger had already

by Bilfinger Berger and the other rented from Robbins. stopped work when it asked WorkSafeBC to inspect the Through the intervening year, GVWD has maintained the situation and that, while WorkSafeBC found no violations to site, ensuring that the sump in the single, 180m-deep cause it to shut down the works, it did agree to work with working shaft for both tunnels at Seymour and all both parties to develop a method for progressing the works intermediate pumps on the existing headings continued in a safe manner. Johnson could not recall if any of the to operate, and contracted maintenance of the equipment workers in the Bilfinger Berger tunnelling crews exercised and of the TBMs. “We are confident the TBMs will be fine,” their right to refuse to work in the headings as being unsafe. said Morrell. “They have been maintained and inspected for operational readiness by Robbins. As part of the new “WorksafeBC hasn't received a Notice of Project of bidding process, the short listed proponents were given Construction for re-commencement of the project by a new time as required to review the condition of tunnels and contractor,” said Johnson. “Once that is received, officers the equipment.” There was no indication from Morrell of will initiate a pre-job meeting with the contractor to review an Engineer’s Estimate for the continuation contract. and discuss its health and safety program. Procedures will be reviewed to ensure work is done safely and in Looming trial accordance with the regulations." Morrell told TunnelTalk As work on resuming the works draws closer, Bilfinger that there has been “no redesign” of the overall project Berger and Metro Vancouver prepare for the court cases ahead of awarding the continuation contract. that arise from the original contract’s termination - Bilfinger Berger alleging “unlawful and wrongful” dismissal along Arriving at the doors of the courtroom is the result of with other claims, and GVWD claiming refusal by Bilfinger hardening of uncompromising positions by all parties.

Berger to progress the works according to the design and The original contract did have a DRB facility but when supervised by Hatch Mott MacDonald.

Bilfinger Berger says it requested that the situation of its perceived unsafe conditions in the tunnels be taken to the DRB, GVWD declined to participate. The contract’s Termination of the contract followed concerns by Bilfinger DRB clause required both parties to agree for an issue Berger for the safety of the workers in light of instability to be addressed by the DRB panel. The dispute revolves and rock falls in the unlined TBM tunnels. Subsequent around the specified consequences of meeting claimed inspection by WorkSafeBC confirmed some safety issues unexpected, unforeseen or differing conditions. that needed attention and requested the employers to delivery an investigation report and a method for In the 55-page GBR there is no reference to the terms ensuring safe continuation of the works. Hatch Mott rock bursts or high horizontal stresses. It does state MacDonald and GWVD report that they addressed the that the “quality of the granitic bedrock is expected issues, and that a design to cope specifically with claimed to be predominantly “Good” to “Very Good” with rock bursting behaviour in the tunnels by Bilfinger Berger NGI Q-system values greater than Q’=10” and that it was submitted. This was not considered adequate by is “expected that the TBM tunnels will be largely selfBilfinger Berger and GVWD, stating that Bilfinger Berger supporting, and will require only nominal levels of local or “declined to progress” the works, resoved the impasse by pattern rock bolts over large portions of the alignment.” terminating the contract.

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Five initial TBM drive support classes are provided with Class V support comprising “Steel Ribs (+ Shotcrete)” in “Extremely Poor” rock, described as that with a Q rating of <0.1, an RMR of <25, and predicted for a total 240m of the total 7,100m of each TBM drive. In the 214m of “Very Poor” rock, with a 0.1>Q’ <1 rating and a 25 <RMR <45, the support is for “Full Pattern Bolts (+ Shotcrete) using 2.5m long rock bolts as per the design specifications.

The GBR also states that “risks associated with subsurface conditions consistent with, or less adverse than, the baseline conditions represented in the Contract Documents are allocated to the Contractor. Those…. more adverse than the baseline….are accepted by the GVWD”. Under the terms of the original contract Bilfinger Berger claims that “GVWD is responsible for providing a safe, viable design” and that it is “responsible for all risks arising from encountered conditions being different than those set out in the project’s GBR”.

Regarding GVWD’s repossession of the site and access to all the mobilized equipment, Bilfinger Berger reports is has placed a lien against the property of Can$22.5 million for labour and material used to date, and a return

of all assets. This totals more than $35 million in value including the two TBMs. While resolution of the differences between Bilfinger Berger and GVWD are now for a judge to decide, the experience by the new contractors to advance the tunnel headings is yet to be seen. Morrell of Metro Vancouver would not be drawn on any steps taken by GVWD or by its project designer and supervisor Hatch Mott MacDonald as to changes made to contract design, specifications or methodology in coping with rock conditions as they exist where the two TBMs came to a standstill in January 2008 at 4.1km and 3.8km or about 55% into their 7.1km long drives.

When TunnelTalk visited the project at the start of Bilfiner Berger’s contract in September 2006, Project Manager at the time Christian Gentschel explained that the greatest risk to the success of the tunnels lies at the far end of the two downhill drives where they pass within a close distance beneath a deep glacial valley in the bedrock that is infilled with waterbearing sediments. A confident prediction by anyone is that things are not going to get easier as work on the two long, dead-end headings resumes.

Continuation contract reaches contract conclusion NEWS REPORT: APRIL 2009

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ired in a legal battle that left them idle more than a year, the TBMs on the project were set to restart after Metro Vancouver awarded the completion contract to Frontier-Kemper/JF Shea/Aecon for a lump sum, fixed-price bid of $181 million, just $5 million less than its original 2004 bid for the entire project as one of the original bidders.

Back then the client anticipated the 7.1km twin tunnels would cost $200 million and take three years to build.

That included the original $99.7 million contract with Bilfinger Berger for construction of the tunnels as well as the job’s design engineering, the tunnel lining and other associated costs. Overall costs are projected to double under the new contract to $400 million.

Inflation is partly to blame for the ballooning cost said Bill Morrell, spokesperson for Metro Vancouver. “First of all, there’s a five or six year separation in time and of course Celebrations after completing the second drive, holing through on an angle into the first

escalating construction costs contributed to that. But at its root, this is what the industry said it would cost. This was a competitive process, and based on the best determination of the folks capable of completing the work, that is what it is going to cost to finish this project.”

A second bid was also received from original bidder Dragados/SELI/Schiavoni JV but the bid price was withheld. Morrell said it was “not the policy of the GVWD’s purchasing department to release the value of bids contained in proposals.” A further bid, from original bidder JV McNally/Obayashi/Procon was non-compliant. “We required all submissions include a target price and a fixed price and that particular bid only entered one price,” said Morrell. He didn’t say which.

Dave Rogstad, President & CEO of JV lead partner Frontier Kemper, confirmed that the JV will proceed using the original engineering and the two Robbins hardrock TBMs currently in place, but directed all questions concerning the specifics of the contract to the GVWD. These questions included if and how the JV might be planning to modify the TBMs to better handle the ground conditions. When pressed on the issue, engineers with the GVWD said in a written statement, “we cannot discuss the details of the contractor’s proposed means and methods.”

Rogstad also confirmed that Frontier-Kemper’s tunneling team would come from the contractor’s challenging but successfully completed TBM drive on the region’s Ashlu Creek hydro project in the mountains north of Vancouver near Whistler. JF Shea’s TBM tunneling team is also available, having recently completed the grueling five-year Arrowhead water tunnels project in Southern California through exceptionally difficult ground conditions.

John Penner, Contracts Manager for Bilfinger Berger Canada, said the recent award supports the company’s claim that ground conditions were fundamentally different than as described in the GBR. “We believe that the recent budget increase for the project by Metro Vancouver represents an acknowledgement that tunneling conditions

58

are more adverse than those contained in the initial geotechnical baseline report, and reinforces Bilfinger Berger’s position, that enhanced tunneling equipment and procedures are required to safely complete the project,” said Penner. According to Bilfinger Berger, tunneling in the current conditions could not be performed safely using an open-type TBM as specified by Metro Vancouver and that the steel ribs, rockbolts and welded wire mesh support elements, as specified in the contract, were “not sufficient, safe or viable in the changed conditions.”

With the overall cost of completing the project now at an anticipated $400 million, the utility has sued to recover these additional costs from Bilfinger Berger. In return, the German contractor is suing to recover its loses, including more than $38 million of equipment confiscated by Metro Vancouver, and more than $22 million in unpaid labor and materials supplied to the project prior to termination.

The new JV is now mobilizing and if all goes to plan the TBMs will resume their drives within the month (April 2009) and head towards a new anticipated completion date of late 2012 or early 2013.

Excavation complete

In the year after resuming the works, the Frontier-Kemper/ JF Shea/Aecon JV advanced the two Robbins rock TBMs at a steady pace and by about 1.75km. “In the last two or three weeks progress has averaged about 15m a day, which I think is very good progress,” said Metro Vancouver spokesman Morrell in an interview in mid-April 2010. Work has been hindered by varying ground conditions including some soft rock which had slowed progress, however, he said the feature was not a surprise and was included in the geotechnical baseline report.

Morrell said there have been some minor modifications to the Robbins TBMs including changes to the trailing gear so they could pass through the steel supports installed as per the contract. The finger shields were also replaced on one of the machines.

Morrell said TBM excavation should be complete by Fall 2010 and that water should be flowing through the tunnels by early 2013. “We have a very strong working relationship with the new JV. At 15m a day, I think that is showing that they are doing a very good job and we are satisfied with that. We are confident that this work is continuing well and we can meet our current completion schedule.”

By October 2010, despite warnings of dangerous conditions ahead, the first of the two Robbins HP gripper TBMs had completed its 7.1km long raw water tunnel and the second machine, about 200m behind in the treated water tunnel, was expected to hit its end point in midNovember.

The two 3.8m diameter rock TBMs will end their drives at the location of the shafts at the Capilano end which will be excavated as 270m deep x 3.5m diameter raise bores.

Once the TBMs have been dismantled and the components withdrawn back through the tunnels they have completed, the dismantling chamber will also be used for attaching the reamer to the pilot string to complete the shafts.

Rock conditions for the second part of the twin tunnels have generally been better than anticipated according to Morrell. “Higher groundwater inflows were encountered within the last hundred meters of the

drives,” he explained, “and this was managed readily with a program of grouting. Completion of the drives is a substantive milestone for the project.”

According to information sent to TunnelTalk by a credible source, “conditions were much better then those portrayed at the change of contractor. After pushing through the so-called bad section and installing 33 ring sets, the rock became very stable. From that point on, and using appropriate support measures, [very few] additional ring sets were required in the drives. The last 40m were the hardest, after hitting 200psi of water on the last probe hole. The next week and a half was spent injecting grout before starting up again and reaching the end of the first TBM drive. With all said and done, it was a great project to be a part of and a thrill to finish,” was the comment.

Set against warnings of unstable rock conditions ahead, both tunnels are reported to be complete earlier than expected.

After removing one TBM completely, the backup of the other was separated from the machine and backed up to the entrance of the Capilano chamber. From there it will be used for power delivery, pumping of water ingress and mucking out of the chamber and raise bore excavation back to the muck skips. Muck trains will carry excavated rocks back to the working shaft at Seymour for disposal.

“We are quite pleased with the breakthrough. The success of this project can be attributed to having an excellent crew of knowledgeable people, good pre-planning of the work and very good TBMs,” said Frontier-Kemper Project Manager, Serge Moalli. Since re-start of the two TBMs in July and August 2009, the machines achieved rates of up to 29m (95ft)/day. The second Robbins TBM holed through at an angle into the parallel drive.

The completion of the project will mark one of few examples of TBM tunneling in British Columbia. “I think we have proven here that you can tunnel through the hard granitic rock of British Columbia, even with all its quirks and stress releases. We have shown that this is an effective alternative to drill+blast,” said Moalli.

Ironically, successful end of the twin TBM drives comes just as mediation talks get underway to resolve the differences between Bilfinger Berger and Metro Vancouver. Metro Vancouver filed suit to recover from Bilfinger-Berger the additional costs of completing the tunnels. Bilfinger Berger filed a suit against Metro Vancouver in attempts to recover funds lost as a result of the termination of contract and recovery ownership of equipment confiscated for completion of the tunnel, including one of the TBMs. An inevitably lengthy and costly litigation court case was the chosen procedure and after hearing from many experts and reviewing thousands of documents, the issues were resolved by the parties shortly before the commencement of a trial that was set to last for two years. Instead a two-day mediation process resolved the issues. The details of the settlement remain confidential. n

TunnelTalk references • • • • • •

Geotechnical concerns for deep mountain drives - May 2012 TBM drive done at Ashlu Creek - April 2009 Clawing success from the extreme at Arrowhead - December 2007 Advocating for more DRBs in Canada - August 2010 DRBs-knowing and playing by the rules - August 2008 Enhancing the success of DRBs - October 2008 59

CASE STUDY: Exploitation of new reserves is key to a prosperous mining operation. Towards this end, mine operators are looking more to the tunnelling industry for rapid and economic methods of excavating access roadways and shafts for new projects. In the mid-1980s, a full face TBM was used for the first time by the mining industry in Canada to develop a vast coal deposit extending out under the Atlantic Ocean off Cape Breton Island, Nova Scotia.

SITE VISIT REPORT: MAY 1985

O

f the traditional heavy industries, as manpower has become more expensive, the future of deep seam coal mines worldwide depends heavily on rapid, economic development of new deposits. This has forced, rather than encouraged, the introduction of labour saving methods, which in turn has radically changed the design and operation of new developments. On Cape Breton Island, Nova Scotia, unemployment, in a once major coal producing area, is high. Developing a vast coal deposit that dips in a 7-8% declining wedge out under the sea, was one positive way of solving the problem and increasing the productivity of the community.

It was decided to drive two 3.5km-long drifts to intersect with the seams at approximately 200m below sea level and 150m beneath the sea bed. To excavate these in the shortest possible time, the operators, the Cape Breton Development Corporation (CBDC), established by the Canadian Government, looked for the most economic tunnelling methods. After visiting and examining various European coal mine expansion projects, particularly the modern Selby development in Britain, CBDC was convinced of the inherent advantages of driving circular roadways with a full face TBM, and decided to apply a similar concept.

This ambitious project, named the Donkin-Morien Mine Development, is stratigraphically situated within a unit that consists of 425m of interbedded sandstones, siltstones, mudstones and shales within which are located nine major coal seams, four of economic importance.

lnterbedded sediments

Difficult site investigation, requiring an offshore drilling programme, indicated that mixed ground would be encountered, with compressive strengths varying between 10MPa and 100MPa. The tunnels are designed to follow the dip of a sandstone layer before levelling out at -176m for intersection with the Harbour Seam at -200m. Site investigation data suggested a homogeneous sandstone formation with no faults. It was the drive through the interbedded layers, after leaving the sandstone that could pose problems due to possible faulting. A TBM capable of handling all eventualities and rock types was required.

As a government-funded project, CBDC wanted to keep it a wholly Canadian operation and it was with the cooperation of the National Research Council of Canada (NRCC), the Department of Supply and Services (DSS), and Lovat Tunnel Equipment of Toronto, that the first Canadian-built full face TBM for medium and hard rock drilling was designed. Development costs of more than Can$l0 million were shared by the NRCC, DSS and CBDC. In July 1981, CBDC invited tenders for development of the Donkin-Morien Mine and awarded the contract to Beaver Underground Structures of Canada. Beaver was already the owner of a Lovat 4m diameter soft ground TBM, and it was agreed that this would be used as an experimental 60

TBM treatment for machine. The cutterhead was modified by Lovat and following successful field trials carried out on the site by Beaver, the 7.6m diameter prototype rock machine was officially ordered by CBDC. As Lovat is a designer and manufacturer of fully shielded soft ground TBMs, the rock machine is quite different from the more familiar hard rock TBM grippers. The prototype, Model M-300, is a fully shielded, open face machine equipped with 45 interchangeable roller disc cutters and 55 carbide ripper teeth. Since either type of cutter can be used, the TBM can excavate hard rock or softer ground. To control shield rotation, it is equipped with antiroll devices and the cutterhead can rotate at variable speeds clockwise or anti-clockwise. The excavated rock is directed by a series of scrapers through the open face of the cutterhead where it drops onto the central primary conveyor which extends through the bulkhead of the machine. A rubber curtain and controlled ventilation system prevents dust entering the crew’s work area.

The operator can watch the removal of the rock from his position on the right side of the conveyor, and has quick access to the face if necessary. The cutterhead is thrust forward by hydraulic cylinders which can be retracted from the face. Forward thrust of the 6.3m long x 350 tonne The Lovat rock TBM is fitted with either 45 discs or 55 carbide teeth with a steel set expander and probe drill in the rear

Canadian coal

machine is provided by 24 x 1. 7m stroke hydraulic jacking rams, which provide a total thrust of 1,088 tonne and thrust off the systematic steel arch support system.

Because the machine has to work in a potentially gaseous environment, the 2,050hp is supplied through intrinsically safe electric and flame-resistant hydraulic systems to Canada Centre for Mineral and Energy Technology (CANMET) certification and Labour Canada standards.

Cutterhead rotation is limited to a peripheral speed of 92m/min to minimise the possibility of a methane explosion initiated by sparks created by the cutters.

In September 1983, the prototype M-300 TBM arrived on site. Unlike the Selby project where the decline was excavated first and the TBM assembled in a chamber at the bottom, CBDC decided to start the Donkin-Morien TBM drive at the surface and excavate the 20% decline by TBM. A short portal tunnel was excavated with drill+blast techniques and the TBM which had been assembled in sections on the surface was lowered down a short shaft onto a launching pad. The first of five x 15m trailing platforms was also set in place. For the first 170m, the TBM had to follow the line of the 4m diameter test tunnel, enlarging it to the full 7.6m diameter (Fig 1).

Vertical curve

During the site visit, the TBM had successfully excavated 2.7km of the first 3.5km long drift. This included the successful negotiation of a 950m radius vertical curve to decrease the 20% decline to 10% and further transitions to the majority gradient of -1.1%.

As in Selby, mucking-out is via conveyors. The primary 11.5m long x 1.2m wide conveyor tips onto a secondary 170m long conveyor. A full length conveyor then transports the muck along the tunnel, up the drift and discharges just outside

the portal. The conveyor has a 600 tonne/hr capacity.

Maximum cutting capacity for the TBM is between 180-200 tonne/hr with about 145 tonne/hr being excavated at the time of the visit. To make a flat working invert in the circular profile, the required amount of excavated material is allowed to spill off the end of the diverted secondary conveyor and is compacted into place. In the decline, a deck of prefabricated steel grids is used.

Ground support consists of W150 x 23 circular steel sets or rings erected within the tailskin of the shield. Once clear of the tail shield, the ring is expanded by a hydraulic expansion device and bolted firmly into place. At mid point of the circular profile, 15mm space bars are inserted once the ring leaves the tail skin to provide approximately 25mm clearance between the rock and the steel set at the crown. This allows for the insertion of wire mesh. Depending on the ground conditions, the sets are erected on 1m or 1.5m centres and the mesh covers the crown to about the tunnel shoulder. Rockbolts are also inserted although the need for these has been limited.

Ventilation in this potentially gaseous environment was a considerable concern. At the portal, two 300hp 23.6m3/sec rated fans force fresh air to the face via 2 x 1.2m diameter flexible ducts. A secondary ventilation system at the face consists of a forcing fan supplying 4.7m3/sec into the cutterhead area and a dust scrubber/fan unit exhausting 7.1m3/ sec from the cutterhead. To help suppress the dust, a water spraying system operates within the excavation chamber.

Geological conditions were continually monitored by systematic probing. A 100m long probe hole was drilled into the face of the drive, usually at weekends to avoid interrupting the TBM boring schedule. Twice a month, a second probe is drilled at a +35° angle, into the crown. As it happens the geology has proven very suitable to the TBM drive.

Progress considerations

During the site visit, CBDC was not entirely happy with the progress rates being achieved. The specifications called for a penetration rate of 3m/hr in rock strengths of

Top left: Fig 1. Longitudinal section of the route under the Atlantic marking progress rates, cutter wear/m and gradients; Top right: The TBM followed the line of the experimental pilot tunnel; Bottom left: Fig 2. Average operating and time-delay charts for average between 9 January to 17 March 1984 (left) and week ending 13 October 1984 (right); Bottom right: View of the face through the cutterhead

61

A fleet of DJB dumpers mucked-out up the 20% grade and the profile then had to be secured with rockbolts and shotcrete and the invert concreted. Each round took 10hr to complete. With the overbreak of a drill+blast operation included, this proved expensive. The decline was taken to the bottom of the 10% portion. When the TBM was shipped to the site, CBDC took over the tunnelling operation.

Drill+blast vs TBM

Grid floor in 20% decline with thrust blocks between steel sets

100mN/m2 and 1.5m/hr in strengths of 140mN/m2. “That means in the rock we are encountering, we should be getting between 120m to 130m/week working the two 8hr cutting shifts/five day week,” explained Coady Marsh, Project Manager for CBDC. “As it is, our best week’s progress to date has been 100m with a weekly average of about 80m.”

One reason for this slower than expected progress is the interruption to erect the steel sets. The rings are spaced with HSS-101.6 x 101.6 x 7.95 steel thrust blocks inserted at each TBM thrust point. The TBM must stop boring at the end of each stroke until the steel set is properly installed. This takes between 10 and 12min/ring and accounts for much of the lost boring time. As Richard Lovat, designer and manufacturer of the machine explained: “Boring time is seldom more than 40%.” He went on to explain that the original design included a gripper system to allow the machine to thrust off the tunnel walls where rock conditions permitted. “Advance could then have been independent of the ring erection, adding about 15% to cutterhead time.” However, for a combination of reasons, this facility was dropped at design stage.

A fundamental reason for initial low progress rates was inexperience of working with TBMs. At one point the gauge cutters were allowed to wear down too much before replacement. It took a week to free the shield and get it under way again. This was blamed on the original method of monitoring cutter wear. “Maintenance has been a problem,” said Lovat. “The machine is stopped with problems that could have been avoided with a thorough preventative maintenance programme.” As part of the contract, Lovat trained three TBM operators for about three months in its Toronto factory and a Lovat engineer is despatched to site whenever necessary.

Another problem seems to be a lack of community support for the project. Earlier in 1984, a serious fire occurred in one of the few operating pits in the vicinity causing complete closure for the 1,200 miners who worked there. Present labour requirements on the Donkin-Morien Development comprise 12 men/8hr shift and 15 men for the 8hr maintenance shift between 8am and 4pm each day for 5 days/week. It seems to be too far in the future and too much in the hands of others for the community to have total confidence in the hundreds of jobs the Donkin-Morein mine will bring once in operation. But CBDC is fully committed to the present strategy. It is also still convinced that the TBM is the best possible means of driving the development tunnels.

During the development stage of the TBM, CBDC gave notice for Beaver, the engaged contractor, to get the project underway driving the parallel decline with drill+blast techniques. A single 3 boom jumbo, drilling 80 charge holes in the 7m wide x 5m high face achieved a pull of 3m/round.

62

The 1,027m completed by drill+blast has proved helpful in comparing the cost of each technique. Records show that at current progress rates, the TBM is three to four times faster and requires about one third of the manpower. With drill+blast, Beaver was achieving 3m/10hr shift. The TBM is achieving 1.9m/hr in two 8hr shifts. Cost comparisons show that the drill+blast operation was costing approximately Can$12,000/m tunnelled while the TBM costs were Can$4,800/m tunnelled at October 1984 prices. In addition, the machine driven tunnel is expected to cost much less in structural maintenance over its lifetime than the equivalent drill+blast tunnel and to provide significantly better ventilation characteristics.

With the start of the TBM operation, CBDC awarded a TBM tunnelling contract to local contractor Finlay Walker Mining and Tunnelling. While the owner of the firm has worked with a full face TBM for a different contractor before setting up his own company, his workers have not. This inexperience has much to do with slow progress rates.

However, with time, marked improvements in advance rates have been achieved. In December 1984, at the end of its drive the highest excavation rate for the TBM was standing at 31m/day with a best week’s rate of 122m. Before coal can be mined, the second drift will have to be completed to provide the necessary ventilation. The proposal is to re-assemble the TBM at the abandoned face of the drill+blast decline and complete the second drive on a 50m centre from the first.

Because the TBM is required to dead end, the entire machine can be dismantled into pieces within its own tunnel, the heaviest weighing approximately 27 tonne. No large chambers are required for assembly or dismantling and not even the skin of the shield is sacrificial. Oversized gauge cutters were fitted to the head for the final few metres to provide only the 50mm overcut required for complete dismantling and removal from the tunnel. Although no definite start date for TBM continuation of the second drift has been announced, it is expected to begin in May 1985 and take approximately nine months to complete. Future funding commitments from the Canadian Government and predicted world market prices for coal, have caused some re-scheduling of the development programme with a third and fourth drift into the mine currently on hold.

Despite getting off to an unsteady start, the Donkin-Morien Development will certainly attract much interest from a technical point of view. It is Canada’s first TBM drive under the sea for coal development, and could establishes Lovat’s full face rock TBM as a keen competitor to existing models. n

TunnelTalk references • • • •

Selby coal mine development, UK – Roadheader vs TBM, an investment in speed - UK Focus and Case Studies Developing a blueprint for TBM mine access - October 2014 TBM first for Australian coal seam access - November 2013 Mobile Miner squares up to the task - April 2010

External reference •

Alternative excavation methods in underground coal mining, University of Wollongong - 2014

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DEC shaft RT: for the of twin tube construct the Nancy p station is Comm siltsayand was built and EMBdER e freew sinking ram. tion, of thefrom secti sizeable of sche underwayof the WRC rado start ranges ent plant t-lanfine Creek m) ion of distinc 1987 a second way. cobbles shaft and us which treatm eigh dule in (6.5k path 3.5 miles elps of Colo bridge over the capital city e grew, the proje High site dubio the gravels the to st at the mom mile of being sewag of the the region dloose WCS thealluvial deep mobilizat accept ct. At the new, dedi new under element and oston, a 200ft ’s first primary the 4ukee, shares As Northwe . From ess the LRT forMilwa tts,lishe Boston ion, but estab from each Hensel-Ph ent with 1952.

MassAna O project will anticipated cated succin has arethe chuse 1968. After outlets nd d TBM etunnel are look to build street we ation Seattle’s groun andboulders mining by the Quincy Massa been treatmen other end, begin. authority, dfrom olarge beyocharge inthe Island in the shoreline, just Chicag answe is the criticthe Island the contract buses ing and futur h short Deer the At the the seco is sinking the to for d Transitalong at rpor for was withit has cities by inco rema do 1 mile back ning Formation 60-70ft ess tly built toplan Parallel 1.3 TBMrs to WRC site, t plant for about network, Diego rged throug in on only set ront rounurban al Sanifican was een procwaterf thesign Discharge s Area Rapirated LRT y (EPA) traffic (18d-the-cloc week plant “Ideall schedule betw an uphi nd WCSO TBMClayton acce mile , thethrough pass under the Agenclace largeg US 21m) to , tion belowisofdischa y,/day an long maximum.

(2km) rge with a closed 230ft frustratin the waste designed those T, the Dalla ss shaft Obayashi/ encedand integ among stion.. We will ll gradient k onconge about in been ing,1986 a fulllong discha street Protec will exca influ , pressu allems the expectation tunne At Cityp seabed isionone mile the ions s of be better For DAR manage an g prob day for rece the d bybelow from whic and often nment ls, three to 50% of week theends rized tunnel ent is operate prov to s. otiatscreen than up 8hr dulin vate ing afternoon in the ption . cause 158ft centra the Enviro to in to to have main on l nsive Neg up lopm shifts the more the course 45ft lead sche at harbor 23,0 s, the buses shaft. The ing215ft l district, tenance water bearin the little federa expe . Part deveits water /day, and is a main 00ft (7km h ages of ed in 1983 Station the polluti shield Shaf 2).on. theT agre (65m day inay. stati n issue present 4 1 and offtena In the waste out of the 6 days about ,” said John t will adva would e into (FigsLRT g ground thence ) deep Jim once a essw first TBM Budget arduous, the will takeon desig ve hing und pass streetof sea level mile/h place ded. d sewag dissol and somet rgro North Aven) in of anand rs tech takes a long, at this point. r comm Atkinson, / rding to MacDonald, nce 20,5south , laun and DAR to its 148ft will carry eme upeach mach conts and agre of mile/hr in unde increa nician uter tide Pionee accotreate sive and that this is ill-foun chedr at the Expr ciently planning e with Herr ine on“but there DART: to dilute lope 00ft ofebbing traffic ract Projec comprehen helme on each peak with ue with onesentthe lace athe ond.with rand insuffi (45m) deep ys, but of proves period t Manag (6.2k er flows overw the side to arriv with complex that many are deep Citypes dela ent forl abilityatsincedeve enknsky mach been s. to about und statin studies full-ti12 Herr r’s natura beach nce investigatio er of eithe Parsons echtscrapers infor sitergro tie backs Clear Cree m) me Herr an uphi Rockdale on the designer Intensive n light long and time The , own Managem n on better unde excavatedenknecht. We ine. We also have has convenie together rs, onethe Waste anchoring by project with ion harbo gree “Twoalong pany enkn ll gradient Tunneling these ically k theption prepared m TBMs the high costof Constructwaste can be echtwe need reporttowe finishbased the solutio To date, in biolog will pay the LRT and they n ofas7-11 a majori both began in as far to prick ural CDM route and rece are atunnel er systegeological hland Com to re that, chai easy access caused shaft. the WCS itectof ms, r cont a fixed cutte minim indicate n Atkinson/Dil November will tyract to t outfall. arch been given of the start dateual the Sout Science proble and of the tunnel s Director g group .” or pressu reaches national rdfour to theum n, thethe ities cost/yd Asse requirem deal 1986 supp ventilatio effluen ly all the 3 inter face. ed outfall retur author Martin, excited to have construction chose Knowing by the isOintunn when pass through individ Engineerin 1996 towa s and lowest of linghammbly of rock JV the public complete Also, long-d two open-f dry,elscompe ent the Guy of thewill as the cutte to lie istance14 long sea tunnel the work said and duledan consent oving pare nt tunnel to get exca an avid ribute 1 and it takes are under 3 ent eight compe ofwon theTBM predicted, first F r need aced machin y to get byOften case, cont tentdground r civil contra “We are hold treatm and the, the sche s.” the upper said othe below the are about t currently ct with vation of Bostons,’s of large, slow-m wouldforReaches geology.

Ken Johnesdecr at Rock are read only inn. which there water . In we millio withee facility different h, with deading the part material $61.6 million ting bids at $44.2 the larges theaction quite breast 1980s, dale Shaf store sible operation conscience into last and t $40 whicand lineplates the in WCSof ston, the are taking on the more sandy d y respon of 7 Nove abou ingravelly be ide, ated lia. worldw O the stati and into contface ionmust to mbeoperation softer wet ationcost scale tunnels much sea usual 30-to- Engineer’s Estima million, well t, theOf the porous City’ in agenc ract.in“As of the gripp operat ofgranular Found force ingthem rolling , will anaestim s Proje the State y, Austra in condit pressure Law er the runn a a te. ents sued 36 r y was on. job Sydne ions.” secti variou Instea in hydrostatic 2007 well month in its The rvation on be ct of bar irem to 7 jogger Agencare anticipated this scale, lace d Man as the ,” me.Conse and ent and the full requProtectionand nd secti , going edown beachved Citypuction constr was “techn sonmachin s. The Seattle Metroconstruction period of proposals, TBM drive ager for the tight 17 month all treatm me, station mnmentalReaches 2 Water4Act the sche now invol undercing costs undergrou ically forservice syste the one from sewer for s plan has with flow from , the client, expected. silty material nal sche s, the cont andosals program Cityplace nd sections prop only is also Seattle superior andwith starterl Enviro redu origipermeable by early n competent l 7-mile CBD ,with inches Robbins , less m)Federa CDM facilitie imposed ated Federal Clean to have the r r the ract the ntow in a (32k 1972 sued -based makin most econo 1990.

A Federa Deer Island to spar ged the on more dowthe Unde turnmile an elevon ay Boston undergrou on of earlie 20 mical.”

In char n part of by e (right) t reliable machi To meet this, the system in servic a the State. in the ing g delivery Robbin to Deer Island dary pressure. not )enforc the (EPA) for(11km T was taking place s moderate by suing at abou rge on Atkinson easy and e more an order the harbor $218 millio nes, one down versi osal for ed, whe n DARrity rundischa d Expressw atedded this secti The machin y and secon and delive quick. respon t 7 miles neede esse ever for each prop was1986 impos EPAestim 3, thereunder es are quite 1989rces meMay andcarried red quickl 1depr tube, design d two Island ns how . After primar 8-10 miles out to InResou was to of ian and thewas original rground for abou reaches schein of the nAutho Nut open-faced y. finding different and conditions long tunnel estio (CBD) andt expe nsive The the ed, built sugg)estio med gravelly Water ent be e excavation discharged of water where (7.6km porous, rectify district a sugg found.tts Distric e theTBM artmwill In the an CourtMassa ran unde Thesor plenum, 5 mile m to abov the backh shields. To provid from the more familia be chuse The geolog such 110ft progra effluen business In t using a no ture into the way e median. the the Dep oe paddle man had to freezing. ent ent, ade can y be High strucentry central n. Approval for which limits in about can naturally dilute of ground on the implem treatm -type excavaoptimum face access r tripod of natives ) hadallytoat-gr clay with the is mostly over-consolid n. thee assistance a the harbor inter-re the State tanti ocean at grad without to drequire 1999. per alter (MWRA millio water table $1.1 billio ated sands, is expected e of the seat.beyon built two other acting hydraulic tor is mounted on , ted by later.7thanchamber, or 4, safe men entry 14 of Pionee runs subsn by 47 (Fig 1). no$828 toalign and chea rejecman d at silt and cylinders. a ruling LRT lines 2 and r Square Stationrising close to the machines face. ical balanc ing waste were gtothe theecolog situatio denied now being built and reaches court Theremain is price holdthe Washin the Robbin help alon e water to surfac the the air hed. with d this by gton y s has (Fig 1). North of rade Ther table is e south design, one will reac DC Metro compl of compresse residents -of-ways biodeg todegree scheme r side Coordinated andwas of the Station Caracas Metro worknd. in 1974 and used on the ay Deer Island facility s/ over conso well below the tunnel thergrou rail right s eithe Expresswsed promise unde time to lose. newly ,formed , the the other scale busin be of noess lidated materi in 1978. gallon existing elevation The to ral left used on the n, the 1989 a comts dated in boxeparteted, has centne of thethe propo and the dry als can be 1,200 million thedeadli ion cost esswaydivisioIn 37 June a short nsultan system such compl consity mmo truct very hard.

From Exprement sub-co of more than integral The 21ft (6.4m) its ld manag mral be acco) and lace the g anWhen native.own progra atedcapac ts engaged mercialers and wou a peak (HNTB North Cent At Cityp ptable alter its ng. Bein r comEngine an estim a thrust capac diameter, 140 tonne, ndoff ey ed Kaiser ws the consultantruction was ctions, withhave a majo way cutti engag en & Berge ity of 2,400 onstru 600hp shields high multistor is no acce route follo Cityp lace, MWRA e boxe designed by mme/cthes twoTamm g es the tonne via Needl their cons have itsa progra dsprisin project, million, were through Howar the 20 thrust have district, com . Both as ent and 62 built1988 April 19 passes development st to in be rams program.

Departm of $189 which Geoteyet essway ential Highway which is plans. by the ted in the Expr and resid second of ay the 7 DART LRT incorpora towers, Expressw se on the ral ct inten h Cent major impa of Nort nt, and nstruction way Departme d reco State High “Propose Texas by the

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It prov iding investiga different con structure one of the many. establish At 18km -1999 ay. Dec the infra n, Ger and long, the k railw comprises and of in 1996 on of water Storebælt Puttgarde study ble trac options two bridg realisati strait of and rail pe. A a dou road and bored) es and decks on roval and such a wide y and d and rail fixed and Euro the 6.6km a twin bored ent app link span (immerse -lane motorwa tunnel, west bridg ons to Governm tunnel the road a four e from link opti ational struct Knud of fixed rds bi-n to con parison ney towa the jour y and cost com of the world. s CASE ibilit STUDY: corridor a feas loped After the shipping the Seik deve est A/S, busi Channe an Tunn Femern for a four-lane l Tunn el linki Storebæ el betw the nisation, ng the lt rail link across er orga cost estimates een islan n own the UK ds ectio sh in Den tube tunnel proj and Fran mark (con of Honshu the Dani al designs and railway conn immersed the ects of and Hok an d ce (con 0 the era. these struction and in conceptu and a two-track kaido technolo considere . struction The proj BER 201 1988-199 bridge in Jap gies to ect emp had been favoured plan betw 1988-199 highway cable-stayed an (con 7) was D NOVEM een the their limit bridge a loyed one of 4), and struction nose. fore the mber 2010 dete the late sea on Of these, the parties MAY AN s. A set the mos it by a 1971-198 and there ates in Nove st in TBM almost el has for a of con d tube rminatio t dem STUDY: tunnel. nsive option 8), the to the the tunn Fehmarnbelt any anding tech founding immerse CASE n did the cost estim point of in, and technolo subsea the calamitie nology with Germ less expe ment of the result with the e. effort surv collapse. bers are across bored gy and the exp ark and n or €5 s taxe bridge ive to com he num Only thro the bridg to the erience with und Announce a surprise d the -stayed between Denm 7 billio ss the develop ate than pletion, ugh prof s takin contrac ersea A cable ut US$ produced a lower estim g acro ection ment of and und contribu the man tual rela essional n (abo y of the contrac aling ons with ting a fixed conn 38.5 billio ersed tube ergroun tionship dedicat eing the es reve ructi imm agre grea ntag und an DKK ts obst d exca s ion and to anti n for ersea After t deal on whic in at hannel ipal adva cipate, vations. and suba collective to the estimate 37.9 billion. two teams withi comes h thos shipping-c manage advanc of its princ It is on , DKK e to com while the queous (page e are no option - one the eme less at er 2008 billion) and tly bore e, Ther exp emb nt 43), including share of TBM sligh erience tube d tunn will profi all risks ss the strait is concept in Sept el proj s of the the plan with the immersed t by. The associat ects of link acro Storebæ ned TBM assistanc reporting fixed link recent ed -rail fixed any lt drive the e road ente time of the of the project s for the rprise s Storebæ undersea ark and Germ project that parties proposed have been a e of the through Denm lt Public and their success HelsinkiFig 1. Rout elt to connect the con Relation and fran Tallin k, up-f struction s team underse Fehmarnb ront and and with years a link honest was mad access inter view e poss to the ible s. senior manage rs of

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TBMs and needed to The shed sen of machines, Denmark, MT Group of Fran handle “We alwa ce, Dyck such Campeno comprises with the Kiewit machine ys intended Monberg n Bern Constructerhoff & Widm ard and ann of ion of USA Nielsen, s with the to place the West Germ Sogea same order .

James for the manufac considereProject Man any and Howden ager four turer d more conv last mom ,” said for of machine ent one Glasgow, Scot Olav enient the MT Grou single Training from the same land, was to have p. “It TBM man of the large was and the awar man st same main orders ufacturer ded at ufacturer operators 17 ever tenance type of the . Worth on all could wou it redu more thanplaced with ces the be interchan ld be easier the drives. £45 millio a and quic finally, ged as necessary simp n, ker; could spare order beca lifies the TBM use it had administrationparts inventory parts; . How the nece and, ssary hard den won rock expe the rtise

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collapse it not back ty Construction Manager: under control after Authori• in now why was in-depth of an Water subjectTrent works at Heathrow is theSevern The to•that Taylor Woodrow station excavation &Safety l being Client:the sites.answer UK Health G portal H Hill & Sons tunnelling dnow REP Eurotunne Contractor: investigation by ting Engineofer:which is about October 1994. •The The geology shafts for transport the t:intende the UK. The storage facility is ners: faultless. ofClien • Design-build ENT:Engine its Desig Consulthe report projectoflooks vicinity of men and 1983 •(HSE), Geostore £20 million & Co of the site for the depth andtunnels in simple”, out JULYer:199 uced from rthe materials and for kept million yet.

• Contra carried the undertawhen and Ltd and)Executive Mowlem 78m deep project, m Contand introd racto (TML Balfour Beatty £15.1 is “amazin machinery ed ventilation, with John months taken king of ctors: for several according as awere maximu a joint 4 AND of • men s wereLink gly Calor Gas,x 1.8m diameter bore hole coal interest (6.5fissur started brought to the application Contractor: being collected firms to•appear sample to Tom The Residen hatlling systems a gh -Mancheby eight unlikely and) the 10.5km the wet FEBRUAR surface via two • Thyssen , and reamed is still Paterson, Wirtha reamer Trans 160m. Core is impressive Conoco with a with 60% consists t Mining Enginee tion (p56the the start 14.5km 40% t to build tunne were complete /Pigott Consor l throu Carsing resources atton Material evidence highly likely long spine roads examina Y 1996 contrac of legalthe tunnel r. The top ortium contracDesig formeticulous. ners: t. readythe ct atr chalkproject ngs. to tunne possibility share, has and, with constructed in as a result remains of alluvial tium: Shafts to remainin view, the drop coal d, causing l • Boldon 20m site and the identifie proceedings detail isCons headi in the ls) production onto cal hard planning to store g the the and glacial long aquedu rock well below the uppe geologi Tunne moved through the tunnel Tunne attention ethe mile) ct Japan was Drilling: Service point of that from ofd thed’Étud a conveyor g foron next 200m the coal bearing deposits and ble event landward the scale ortium in the crossthe itions of into severe slightly to avoid stages and instability indicate availatenderin technical Tunnel to conne e cond for the parties involved. made clear toA conveyor adit chalk strata. remarka is the Upper an for transferring boreholes adjusted • Cons • Fairclo While (Bureau through ire has run sea andofnotexcavat borings struts and readilyion onto aon nt to be or to constru rom a system will bring which stretche conveyor ugh: Cavern hen Cretaceous mostly bly quickly. e: BETU whalings tion in Derbysh alignme d need for in either their under Channel Calais in Franc Therefore, it was ction the of driven onal the coal the spine the early The Francbe comple nisedup the two 1-in-4 ng props, s east under tunnels Jubile theunderlyi ms were for the roads and hauled Seae and to of be used to behind area. es, andsyste McD would undersea avoiding s In January not nd shaft drifts to emerge ared years with have Lineinto the North difficulti attending an all-party-orga June to Proje affected Mottseries tunnelsrescue the surface Denmark ct team, as two UK: Grit at the was updiameter Exten in Engla at Gascoigne1981, contractor Gascoigne Wood 60m water h would much ean end construction. anglesthe 8kmFullface TBMs could t, as comp ing in beThese From six explorat of journalists as Europ sion and West German Dover briefing in late granted by Woodplanning Frenc (Fig Ashover the London site where all the permiss andthemay at shallow may to l and lt projec When JLE budg It is also gh the excavation visit and technical allionUnde large amount site five that appo was inted ory borehol Glanford const2). y. natural coal mines are producing throucore handling, storage ease Strait cross causes of to the pt and g tunne a difficu these dipping e, planned date et as well rgrou e of the by sched es, it was main series the ground water necessary to use the at Boroug runninThe ls. NATM becaus full ructio and loading facilities for the excavat Seikan of access 1996, that questions about the schem passing ment h nCouncil capacity originally1970s attem etunnel. ndchalk was not mudstones, marin n found ary contains lack of lty for by ion tunne to much. by exten equip n late as the of mana would nes d as the of 1980s, are located (Figs ule. Applic mpor thedeliver chose pressure theonLPG.” difficu t, with ls bands the 115,000m 3 Selby will two approxi sion, awarde new of ge several its progr pre-grouting. lengths landwardof mudstor fashio expected, and the costs thereof 1 and 2). aquifers and to contain g tunne costing twice 10 million Theamm set the conte example. The cover the 16marl caverns under mately ation ground contrac and very hard principle specified tonne had greatgcond the collapse and ded strataspectacula nes, x 21.2m a 53-m tor along d interbed itions of coal a year, long UK km-lo for more isolated e for Conoco startowned is mostlyfrom assoc journalists however As soon as spine roads reached ng i.d. rail runnine tunnel,The tunnellin land When choosin sandstolong to do the onth water for use red Authority to contrac nts are: (Fig for the storage except in not ally used ins and 164km Japan face bytothe public pressure, • that a higher funds programm g a madeflint be answered. The Central UK fractuWater the andElectricity setofitself by open first mine at Wistow, time. tunnels, two 7.6m thensiltstone n) one containe on the to the 2). iated cost l servic drill+blast, the survey 2was in acts to veme with storage m, Clien that this briefing of Generating site of Trent rising specific sectio x ded increa against at case liquid ing, e a butane use centra thorough for achie n ter coal production two t: JLE Board tough facility, the of Trans an UK Severn chose , calls for 285psi, comp The propane it knew thewere ses Govepropane at nearby gas (Fig the 14 treated to a LPG 100psi needed was was also geophysical Marl stratu task. As diameinterbed were from it began with excav notable power stations.

A ation rnment ted by high (252m of the 4.8m i.d. it had geology is port throu confirm the Lond to Management work and to a visit large Chalk ber. It tances, soon tunnelling of the weak, Mowlem most began immedi 1). Site investig or thertmen 15.4m time tocham large 55m 1).

Depa Two other4.8km, civilation and a liquefy the projec perhaps Frenc and hvice versa. current progress as theimporta Unde theconnec bids. In view project's 30psi to liquefy on gh contain spine team for constructio let in late short d in the impermeable, John wide the continuing to overthe design of circums at xthe same In the interim the rground ately on the first nt conside the other out due to success from the t ation ofr pipeline sections of roads t’s public which • Cont and later the connect the remaining million contrac butane, shaft(Fig ingmajor conveyors 1993 ation n contrdepend of sea cross excav it. The 3.6km and was aligne excluded Ltd expected underground into various le for rapid also scarried under ally an in the ractorsthus a, signs t to sinkand • Excavdiamete spineof ng acces Itsfundin £2 access “Oneration. four mines. acts s ity ofpresence how borings. During at the ation, ls under e problems for investigtunne shieldwill transport aquifers a great natural is gener fourconst g is grant tworoads deep 140m of the most and tunnel of substan access for each highly suitabzones awith major geologi was to modifi both Knowing exactly pal worki r aspects engin ructio 3km of the 1.6km x 1.6m specify aon-going is ed. extent 66m which from essential. shafts, rail more extensiv the cavern, was n work tial their desig main site eers: See cal propert cation minesalong startecoal us rock on impor used again ute to red as they come andThe south drift decided to ader works. a shorterthe princiing .

“Unlike almost and three enginee gases, excavation d. n-bu on line andawarde ies. Petroleu tunnellin All following the longto land By from tunnel is being drivenThyssen . Roadhe current quality of workmanship clauses other tant explore inclay en-ro faulting, it was /Pigott Consor muck homogeneoalthough fractu be anticipated There is also side as consult sea of sever the contr dtheto end stage, g jobs, we all following page ild behind alignmeasily const the of form, themore m we 500m ion method best the the tunnelling the site. what the 5.8m diameter borings soft in gault end. The headings. to al of introdseeping option, three under from with stored welcom tium.ructio the ent 5th Januaare ster.

Nine s Hill t to two lofterminal based excavat in act es for eachmachines tunnel document water takes sump entaryCastleadjacen tunnelling, inflows were Robbins TBMborehol uced into surface e the sight downstream for itsof Manche supervision differs in ntheir liquefied workdeadservices ry liquefied red the total 230-w Tunne construction with be was was in a large supplem neveran average of stratum headings. The will based cavern landward tempera 1996, the by eithercond workscorrid and end itions levelH Hill & Sons continue!” into the were conside need to cased about 100m/wk. the collapse may Channel was moved and or were orted to the scheme eek corrid longation it was the ground high waterthe Chalk Marl contr lowering , their is a fortransp on confess Strathclyde drilled or by compre programm week ture 117 of of Anderson Theconven below seais G or beingprayofit up to 90m the UKOne portal y booms equipment would was going on before Boldon north where detail were made.

ICE ed Paterso conveyor by also is: included surface originall the imple actor in the Drilling ationartthat under explained in some tunnel, some 70m parallel, itsion ssion.would be stipulThe Souththe and shaft out e and,excav Site investig l Coal Board n. equivalent three muck was wide, the Tunnel Following a maximum 115m d. Tunnelling it is usual from of site andentall using portals grounad 1979 incorporates oil well type al ment is being 57 xtional 75% comp m of the the pump known, but it was boun be ment On the excavated using line ed to Nationa plishm theselectio times the during to appro to ation to store 16mm stratum through progressed this out in familiar sectio d to accep of speci area of surface steel ropedrilling ydistance m3 l some the seabe ng incarried a Titan 134 roadheader The the botto es water along and accom flamepr alignm themanin accel for thet caverns nOflies in finding e oofed lete. refrigerated provid cords rig. n was tunnels are going detail how work now being ximately downhil across the full Worthwhen an the eratio beneath making about half and ing width£4.5 ity of the abou tanks rather 4.5 ,million the manya ent depth. the tunnels The JLE to worki available. of deep borehol whose water is sufficien of themillion d withly at a1mlarge intervals tunnellin pressure logistical necessary servic site n progr 30mm thick the rate of progress was awarde slurrie and 75m suited belt.g The UK ds as strata, with the possibil t amm vessels. tCheape and that it was sinking y ce. standar contrac planned • The to containfor contr Proje thanshow inflow meth from the original. d to Fairclou in Anderson constructio general different the long in readil at the is about sal t highly n ct distan ct, Strathclyde in g e olling es to 50m/wk. so the team the and them ods five was great gh, the three Coal be pract r still is cost Cable Belt Coal cannot be LPG but groun t 1km tenders. Geosto Measur tried nlowest the aquedufor dispo minimising as to is under pressur as reaso systems conveyor shallow holes to estim whilein UK side, of runnin ularly the extracted North make the not d move available contractor icable of appo remarkablyof ed until the cross theundergrsupervising continued e being encountered. the grouting were well additiongalpond abou e in larger seepag nable,”store ates Tunnel is are, on the scheme French compan a licencee were partic of adit connecting ment inted of settle e accep steel These ment water from usedcost ound geology Robbins pumpin changed ropes reinforced Project NATMAqueductation with several settlin methan capacit from said or specified Giant shaft rescue trains, of the the two conveyor comp which allow facilities on JLE. technTBM and g , nearly y Geosto doubles y Mike belt spine roads and ted the cavern consu excav oir and tunnels.

Mana on ation of ground In some the letedwhich access The . Liquefie ical have extensive designed speed with ls all have Engineer also What had al advances ck, most Reserv lting sea Smith two the lling rapid of stable ger prohibit bore time steel been Applic cases ton ed the roadheader obvious, canno d tunne hole ropes and for under , JLE’s connecting diameter supervis for Cons tunne gases • of origin been success and y sealed, this may To comp ive.

57mm allow has pressur engineers excavation and start,tothe most ologic the mine above is 1. Carsing To and prepa allow grouting fully tstored the same for thethe ed a of several require extensiv supporting tunnel regime to ensure modification tructio /week the detail Selby ensate red thection al in tunnel completed. constru predic high speed 428mFig used initialllex chambers operatio the techn spine be jeopa lightweight ede indesig LPG caverns On leached cavities n. cross while at cing service roads projecgroundw alling area which to ted settle 1in-thick contr e for areas clearly most expensive, is the The um and breaking 8h 60mWistow mine t progr ater “Wens and rdised under ground The steel act fordocu of the chalkbelt. ns our , includin a projec of ns through many in salt ropes in northern high,alteratio the comp ground marsh record came online in April by event ammregime n ofment are formed years but g one deposit conditio of a maxim a maximum spliced the advan excavation where d amount to the original scope of works t oftogether ment almost there the may contr e grout At this in s This France, be its side around finding ation. to under expecte to final the ng s with to thethat are ol. The size still prove have advance 14.5km forand engineer.form an endless isrope built in suitable the caverns injection Cliff. a purpose and buildi the consult with the methods of the the UK 7 days/week provelength, been the AssociatedOne ction dealtwo acceleratio constru geology comp concurrent ber, which had of the conveyor at withinof water -built undergr each x 30m deep cofferdam in three stages:diameter too ing n its contr will station espeare groun side. unfor be lexity, come intoby of the most shift/week) entally the contrac and nwater no easy l construction galleries eseen the tunnel; of the airport This is done ound of its clause grouting at Shak pal working (24h/day, maintenance kindfacility mont task, as longest used to curtains segm water. ation inactua their own. d treatment over cham before arriva operation of driving Central in Octob ts include of a new adver Terminal Area (CTA the se in difficu has betwee isl usefu Europe. excav methoabove, TBMs lties.Paterson hs when South Killingho e River Humbe LPGerjetty concrete and radial Two effect explaine was“The n caverns m. The ds. used 1994onof permeation the princi of the six downtime 3) to almost totally ure in advance Similarly, the collap over the grouting geology were being d:the recov lness complete e servic are built; Terminals r, on the lme, neither At the ive NATMenough ed. 1, 2 and site non-bolted l of o.d. 8,036 on JLE on ery progr of the se must be compet connect the and pipeline machines. ges and press negotiated. water as the rings the marin grouting, grouting sunrelated, excavation gallery strengthen launch a fully to include remove the extent grouting tunnel amm muck will also km each is es has been complet nor Airport which facility to expecte sea tunne 22km of 179m/week ent ” concu work extensiv encompass and TBM allow the Conoco loose a to stabilise Express but ofrrent, Only by cross passa had to share cing after the lining vs be necessa course and 18.77 excavat Settleeme andd to complete lined under ll average was l south. water disturbed ground. grouting of the the roadhead refinery Rail er ion and the Because the geologic Heath compensat an imme and ry.

17.36km collapse and the rowmore ducts also with the advan Since limited thent con requirem diate and Link tunne al propertiion grout bearing groun l site are so introduction Groun the effect tunnel, best overa e running tunne rn slurry and ent, the drivesstanding at the edge of this huge excavation relieving projec support es A Titan E205 trolthe of the Jubile d move the more responsible l progress l to porta n times TBM, ngs. marin t. As of predic of ing for mitiga d, bay has been importa nt, a sgeotech ment induc roadheader e project side, mode pressurised econom consecutive interc job, Mowlemscale be appreciated. "The upper the UK in the from porta reaction, ratesbeen ted transportatio g tunnel headi Four which South ic its contr one French establis excavatingteam volun Tunnel the ed its that bid the couldWork by excav Tunnel have hed,ept ground nical volume losses ting and piezome work ce (EPB) runnin On the actors the 9m wide tarily instru the JLE projecof the most critica eight firms tender. ters ation has Channel cross marine water-bearing ground Ofl the to measur equippedmove Waterloo mining to ure balan withments x l t team. ctedtop benea was soft outer lowest 20m second as they and e ground four hand 53km long and Lond stop NATM 5m high thethe and through and The Line, concerns for the earth press many latera Com stabilized by 1.2m heading with occur. ducts won of the water integrity th ,some work at ber 1981 gravels d the rescue shaft • The x plishe with visible pen is supported and running relief 30m deep central Septem section and safetyon Bridge to of the oldest ure in shaft, bands important access as it does 60m diameter Compensat sation grou in four years.Secant piles which interlock on the gical ls. of press accom diameter ted review of started 1km Trace marl 19m 1.

Fig Geolo and , historicallyand flint present of the and original of NATM stages of diameter the is ion grout one to ting ges ed on the bored tunne different d to be comple works. a comp Alan Powderham, under and subjected prestigious, the only work had most designe for JLE in the chalk which were ing is About centres," explained all ofmain access shafts superimpos passa areas of plan was 1.06m tunnels, and to the techniques Mowlem portals the three at that e platform limitation principally managemelex exercise London, linking of the Foundations time and been completed NATM The surveying from the four to ensur tolerances most stringent concourse and outer dersDirector Managing work collapsed MacDonald advanced s employed drive a tunne ngmain tunnels lyde roadhea decision-m nt and co-op in multi-level the damage the works restarted although revise the delay headi Division of Mott lling projec ever before • The excavation when Strathc system Geotechnical tunnel d or Steel in imposed had a t in the Anderson provided aking based erative all-pa representative on guidance Asses In fact using ct sea and Grosven damaging due course, on city. rty lead sea. in designer's six under Aquedu and Markham tonthe convened predicted sments of all PortaltheC instrument by extensive on information effect on under the mounte that Carsing Compens servicdein Solutions Team started at the so-called 1mm settle buildings within lly meet the the French geotechnic ation grout s of the 10.5km Tunnelling B and D in analysis. ation and collapse to engineer m on did actua the UK and the 12.4km shields. ment conto the al 350m cross section ing array computer-b and at Portals immediately following the “The of undergroun dinal and Harris, ur along aim,” s unde way forward. "The junction was within February 1982, at A in April. ased d route a Direc explained and r the West in economic Fig 2. Longitu a safe headings level. tor of stage, e finally by 900mm defines and the princi tunnel minster David marin on March, at an early a Clay below is supported the pal geote the company 60mm area insta London d decided conditions, on comp which step in GCG as It was line and ents of create lled from d ground diameterplan contiguous piles ensation chnical advis the establishmUK side which a predicte the below, five er of 20m grout hensive to The cliffs temp further view JLE • ing, “is compre from, andion, continue a orary grout chalk on the ing to keep m3 te a capping beam at of excavat lagoons the white el head ing shaft to formula the With "A substantial foot of 3.75 million rating the method Secant piles. ce Tunn s at the tightly ent lining. surface forms a rigid concrete collar incorpo for some UK Servi and perman site the and ground the main re for disposal what is an small roof support Employer, in all the 79piles together. manufactu linking ent of the were Report site. of muck TBM in in both the recovery ideas ies agreem of CIRIA working s’ "Originally, Howden a large endations t Practice high confined ent casting factorrecomm based on excavating ands of ing - Improved Contrac instinctively segm approach Fig 1. Plan of the ‘Tunnell x 65m," said Powderham.

• The ries where thoussegm ents were Gascoigne Wood and the general nts. 65m box of about y drifts and the five mine followed lining count shaft sites; UK factor contract documewere to tunnel Thewere tial in the Inset: Fig 2. Main rated precision at high rats. incorpo design features a poten h sections of the tunnel for day the need produced Grain had Althoug per ent rock, Isle of d near in compet segments on the driven755 was expecte be 4,42, of 1,152 required ate roof support output ced the .immedi and produ within 3.5 years on of the 37 42 segments ation now goingand lengths install units • The thousands of and other track g, many ical cablin of electr

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SPEC A ED T ON FOCUS DENMARK CASE STUD ES

CASE

STUDY: Application of a TBM for developme in North Yorkshire nt of one of the was the first use twin spine roads of a TBM on a demonstrated to link five coal mining project the significant mines in the UK. The 5.8m advantages of Robbins went on diameter Robbins the technique to supply TBMs to over traditional mine CASE operations the roadheader excavation TBM non-circular TBM STUDYworld for excavating over. Most recently : Excava rectangula Robbins has developed and r cross sections. an estima tion of the ted half the first a new cost of creatin ever purpose built also provid SITE VISIT REPORT: LPG storag ed greate g the same r security e cavern JUNE 1983 storage capac s in the UK for these CASE STUD vital infrastr ity in tanks in on the surface the 1980s were built Y: JLE, the ucture facilities.

SITE VISIT turbulent at . Underground REPORT: MARC times.

London storage Excavatio including Undergrou H 1984 n the Big nd Jubil and Lond Ben cloc progressed ee Line under on Bridg k towe Extension or alon services r and the gside project, to area e mainline railw Houses lived limits of s of south of Parlia some of the ay statio the Unde most impo through excit ment; and east ns; and created excavatio rground ing as rtant land London, passed well as new system. n work under the mos s colla Controllin which until the River metro stations marks of the pse then he Selby coal t critic g city, unde on exca Thames had rema labyrinth al chal mine complex the conc vation of unlined in lenges four time r the Waterloo Yorkshire was ined and settle urrent tunnels, driven designed by the together s to Heathrow circuit and • Client: UK National ment and outside the SITEclosedUK National Coal with man VISI190m loading termina technica bring metro Express beneath the in chalk Coalsome Board managin Board (NCB) TS AND agin to connect five Rail Link ls for rail flatland on tankers • Consultant: bank g the impa l construct ABRatIDG separate mine sites of the River and roadg the budg National Coal the Immingham. project south ion - at Board Wistow, Stilling Fleet, Humber, ED FRO ct of the in Octo • Client:et and the will be used first mined Riccall, Whitemoor as• the Contractor: statio ber 1994 M TWO Calor Gas M&E insta Cementatio and North Selby. underground n Geology petroleum Ltd were amo n JLE SUP• Consul llations.

Each would have liquefied gas (LPG) a pair of PLEM ting ng

UK F

1994 Rail Link in October the Heathrow Express prosecution excavations on world. The criminal of the NATM station UK and across the works and ramificatio years ns made had high impact d engineer four and its design-builence of how decisio s in the shields experi trial of the contractor to injury. roadheader anticipated insult a salient added ted that the the project, uct was than complete gton aqued for the project predic more water last. The g rock and long Carsin or drill+b nts ctors biddin The 10.5km when harder a to hand mining large amou turn ided CASE STUDY: seriously wrong. Contra as. They were right s and 1996 air to keep , prov JUNE eader go essed Christm 1998 Its REPORT: can roadh in VISIT compr cts. before SITE theirces design upservi under cedproje to giverail on the hillside advanture was four drives would be against public infrastruc out of the ed to eadere shield, hmarks mega forced three dwhich kept its roadh of futur d as benc and open face, funding ingplete lems, stan remain l. el, com ion and ted prob contro nizat under nnel Tunn water , orga documen ofning The Cha e plan its well well as STUDY: vativ H 1983 CASE el for the inno successes, as RT: MARC VISIT REPO the project in truction SITEkes.

• Client: BAA role mod that occurred on ar mista ing cons for the owner: d simil job in the collapse focus the mind, outstand rs will avoi 1994 will always • Consulting Engineer hatever jinxed the achieved to be well October othe h appears all remains - if it is being Mott MacDonald whic beginning, 9 of the question then? The the CASE STUDY: Collapse ns for the tunnelling industry in the later, after working on to recover during

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