North America
Land of opportunity and larger diameters
TBMs
Which is better – the bore or the bang?
Shotcrete
How to combat ‘bending moments’
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CONTENTS
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Light at the start of the tunnel
W
e start the year with a spark. Two sparks, in fact – one good, one bad. The good one couldn’t be better. The bad one could have been worse, but there were a million reasons why it wasn’t.
This month, the Channel Tunnel, the 50.5km (31.4-mile) undersea rail pass linking the UK to France, experienced its fourth fire in almost 20 years. One million litres of water sprayed out from the sprinkler system on January 17 when a lorry caught fire at the French end of the underground railway’s south tunnel. Carbon-monoxide detectors acknowledged the smoke and triggered the high-pressure water-mist sprays, which extinguished the flame and luckily resulted in little damage to the tunnel. As I write this, five days after the event, delays are expected to last at least one more day. From the tunnel with the longest undersea stretch in the world to Europe’s largest construction site: our second spark can be found on the Crossrail project. Crossrail’s goal of delivering at least 400 apprenticeships over the lifetime of the project has now been met. Ms Fatima Alghali, 23, now works for contractor BBMV as a commercial apprentice at Whitechapel and Liverpool Street stations.
“These schemes burn a bright flame for young people in construction but, more significantly, for young women in tunnelling”
News 3 Features North America 4 TBMs 10 Shotcrete 12 Contacts 19 Classified advertising
Next month (March)
“No two days are the same, and not only am I learning from some of the best engineers in the industry – I will end up with a qualification that will give me a great start to a career,” Alghali said. “It’s also a huge help that you earn a salary, as I’ll be debt-free when I qualify.”
Asia Safety Drill & blast
Around two in five (44%) Crossrail apprenticeships have been filled by people that were previously not in work; a figure that is double the UK average.
COVER
Terry Morgan, Crossrail chairman, said: “We have achieved this major milestone but we will not stop there, and will continue to create new apprenticeships as the project evolves.” There have been more than 8,000 enrolments in Crossrail’s Tunnelling and Underground Construction Academy, which opened in 2011. More than 10,000 people are working directly on Crossrail. Over the course of the project, it is estimated that Crossrail and its supply chain will support the equivalent of 55,000 full-time jobs across the country. These schemes burn a bright flame for young people in construction but, more significantly, for young women in tunnelling. LUKE BUXTON, EDITOR luke.buxton@aspermontmedia.com
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A new underwater pedestrian tunnel will link Canada’s Billy Bishop Toronto City Airport to the mainland when it opens early this year. Contractor Technicore Underground began excavation on the mainland and island shafts in May 2012 and used two TBMs. Once excavation was complete, Technicore approached King Shotcrete Solutions, which proposed the use of a dry-process shotcrete alternative that would provide similar properties to the steel-fibre shotcrete, but using a macrosynthetic fibre. King’s Technical Services Team proposed MS-D3 structural synthetic-fibre shotcrete, an accelerated dry-mix shotcrete that incorporates the use of macro-synthetic fibres to improve toughness (postcrack energy absorption), impact resistance, fatigue resistance and resistance to plastic shrinkage cracking. See page 17
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NEWS
Contract battles for Balfour Balfour Beatty’s construction profits will be lower than expected due to bidding with “optimistic assumptions”, accountant KPMG has reported. Profits for 2014 will be £70 million (US$106 million) lower because of contract issues that a KPMG report said were not managed effectively. KPMG criticised Balfour for tendering for contracts at very low margins with optimistic cost expectations. Balfour Beatty also endured high levels of employee turnover because of what KPMG calls a “com-
New CEO Leo Quinn
plex reorganisation programme” during a time of highly challenging market conditions. Balfour directors stated that they will assess the level of contract risk
provisions in the UK construction business and announce the outcome with the full-year results in March. “Balfour Beatty is a large organisation, which had become too complex and too devolved for adequate line of sight and financial control,” new chief executive Leo Quinn said. “The key is that these issues can be put right and we now have a clear action plan in hand.” Current tunnelling contracts for Balfour include Crossrail and the London Power Tunnels.
MTEW to work on Crossrail 2 Transport for London (TfL) has appointed a consortium to provide environmental and sustainability services for the proposed Crossrail 2 scheme. MTEW – Mott MacDonald, Temple, ERM and WSP – will provide input to the developing project plans and the funding case. If approved, Crossrail 2
will transport almost 50,000 passengers an hour between south-west and north-east London, creating a high-frequency, highcapacity rail line with shorter journey times in 22 miles (36km) of new tunnels. It will add 10% more rail capacity in London. MTEW will generate a sustainability and environ-
HNTB deepens bench of experts US-headquartered civil-engineering consulting and construction-management firm HNTB expanded its tunnelling practice with eight industry veterans in 2014. Mark Ramsey (HNTB’s tunnel practice leader in the western US) has two decades’ experience in tunnel design and construction. Raymond Sandiford, PE, F. ASCE, is HNTB’s tunnel and underground engineering group’s national geotechnical and foundation practice leader.
Heiner Sander (HNTB’s tunnel practice leader for the eastern US) has over 30 years’ experience in project, design and construction management for tunnels. John Anderson, PhD, PE, is HNTB’s geotechnical chief engineer with more than 35 years’ experience in tunnelling, geotechnical, foundation and seismic experience. Ruben Manuelyan, PE, is technical design manager for underground structures. He offers clients more than 40 years of experience with
mental framework for the scheme, working with other appointed consultants. The consortium will also work closely with stakeholders to produce a report on environmental aspects. Initial proposals have been consulted on publicly and the Department for Transport is deliberating on safeguarding the route. bored tunnels and immersed tubes. Thomas Richardson, PE, is tunnel construction manager. His three decades of expertise include tunnelling and underground engineering projects. Arman Farajollahi, PE, is a principal tunnel engineer and serves as senior technical specialist on complex tunnelling projects. He brings 25 years of experience. Jaidev Sankar, PE, is a senior project manager with extensive experience in underground structures.
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Parsons appoints P3 director Parsons Brinckerhoff (PB) has named Karen Hedlund, former deputy administrator of the US Federal Railroad Administration (FRA), as its director of public-private partnerships (P3s). Hedlund led the legal advisory team on P3 projects such as the Silver Line extension of the Washington, D.C. Metrorail system and the Port of Miami Tunnel. In her new position, Hedlund will work with federal, state and local transport agencies as well as private companies to facilitate financing and development of tranport projects through P3s. She will be based in PB’s New York headquarters. “Karen’s expertise will be extremely valuable to clients looking for innovative ways to finance and build transportation infrastructure with the help of the private sector,” John Porcari, senior vice-president at PB, said. Hedlund was appointed deputy administrator of the FRA in 2011, after serving as the agency’s chief counsel from 2010. During her tenure, she provided leadership for the administration’s US$12 billion rail grant programme, including $3 billion of investments in the California High Speed Rail Project, and $3 billion in improvements to the Northeast Corridor.
Karen Hedlund
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North America
Shrinking public dollars, growing diameters Tunnel-diameter records and a shift to private funding are just two growing trends in North America. Nasri Munfah PE, senior vice-president and chair of tunnel services, HNTB, reviews the market
T Nasri Munfah outside the Tom Lantos Tunnels at Devil’s Slide in California, for which HNTB provided final design Photo: HNTB
Expanding urban centres
systems. Most major cities are opting to add infrastructure underground due to the multiple benefits of and advances in underground construction. Impressive, complex and sophisticated, underground structures can help solve current and future urban congestion and development challenges. Therefore, we can expect demand to increase for skilled labour, specialty technologies, equipment and the industry’s ability to meet more challenging ground and groundwater conditions. Demands for increasing tunnel diameters are on the rise, as well. It should be noted, however, that funding availability and regulatory requirements will complicate the industry’s ability to meet those demands. Recently, US tunnelling and underground construction has been marked with the following four trends.
Urban growth is exerting increased demand for more efficient transportation, reliable power, water and wastewater conveyance and communication
1: Use of alternative delivery methods We have seen a transition from traditional design-bid-build
he worldwide tunnelling and underground construction industry is witnessing a historic boom as tunnels become viable solutions to traffic congestion, dwindling right of way, ageing infrastructure, population growth and rapidly expanding urban centres. North America has tremendous opportunities, with estimates of more than US$70 billion in tunnel and underground construction projects in the next five years. Expansion in transit systems and high-speed rail in major US cities presents significant underground opportunities in the decade to come. Canada has seen substantial growth in transit projects in Toronto, Ottawa, Edmonton and Vancouver. In addition, significant hydroelectric and mining projects demand underground construction.
The Crenshaw/ LAX Transit Corridor project consists of nine miles of light rapid transit and nine stations. Three miles are underground Photo: HNTB
procurement to design-build and/ or public-private partnerships (P3). In the US, local governments have relied heavily on federal matching dollars to fund their infrastructure projects. With that funding shrinking, many owners are seeking private investors. Maryland’s Purple Line, the Port of Miami Tunnel, Virginia’s Elizabeth River Midtown Tunnel and San Francisco’s Presidio Parkway tunnels are good examples of P3-delivered projects. HNTB is involved in the largest projects that follow this trend. The firm is the quality-assurance engineer of the Elizabeth River Midtown Tunnel project and the designer and engineer of record for the Presidio Parkway. To accelerate project delivery, many US owners are opting for the design-build approach. This includes the Los Angeles County Metropolitan Transportation Authority, the Virginia Department of Transportation, California’s high-speed rail initiative and the District of Columbia Water and Sewer Authority. For example, LA Metro recently awarded three mega design-build projects, totalling more than $3.4 billion. The first of these projects is the $1.2 billion Crenshaw/LAX Transit Line, for which a joint venture of Walsh-Shea Corridor Constructors (WSCC), two prominent US construction companies, was selected based on their technical approach and favourable price. HNTB is the lead designer and engineer of record for the project. The Crenshaw/LAX Transit Line project design is 85% complete and is in the early construction stage. It consists of approxi-
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mately 8.5 miles (13.7km) of transit line and eight stations, including three miles of tunnels and three underground stations. Project design challenges include minimising impact to surface traffic, adjacent buildings and properties in an urbanised area; constructing a facility in an active seismic zone; a complex geology of clay, sand and silt; and a varying groundwater table. The tunnels will be constructed using an earth pressure balance TBM (EPB TBM), which has been fabricated and is under testing. The cross passages will be constructed using the New Austrian Tunnelling Method (NATM) with ground improvements. The stations will be constructed using cut and cover. The Crenshaw/LAX Transit Line project is slated to open in 2019. The Chesapeake Bay BridgeTunnel Commission plans to construct the Parallel Thimble Shoal Channel Tunnel Project
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using design-build. In addition, Amtrak’s Baltimore and Potomac (B&P) Tunnel will be constructed using design-build procurement. Most of the tunnelling projects in Canada are being procured as design-build in order to expedite construction, reduce cost and manage risks. 2: Large-diameter tunnels New records are being set for tunnel diameter. The Washington State Department of Transportation’s Alaskan Way SR 99 tunnel in Seattle is the world’s largest machine-bored tunnel at 17.5m in diameter. Large-diameter tunnels are possible due to the advancement of TBM technologies and the ability to more accurately control ground and groundwater at the tunnel face. 3: Rehabilitation while maintaining operations Several New York City Transit tunnels and four Amtrak tunnels
in New York were flooded during Super-storm Sandy in 2012. To minimise interruption of service during inspection and assessment and to identify potentially hidden defects, HNTB introduced to the owners a multipurpose scanner (TS-3), produced by Spacetec Datengewinnung of Germany. The new scanning technology is capable of simultaneously taking 360º photogrammetry, laser and thermal readings as it advances slowly through the tunnel.
HNTB is providing construction QA/ QC, testing and inspection for the US$2.1 billion Midtown project Photo: HNTB
Delivering Solutions
Euclid Creek Storage Tunnel Cleveland, OH
New Irvington Tunnel San Francisco, CA
Eglinton Crosstown LRT Toronto, ON
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FEATUREAmerica North NAME
Presidio Parkway replaces the existing southern access to the Golden Gate Bridge and consists of multiple roads, bridges and tunnels within the Presidio Parks Photo: HNTB
By combining this sophisticated tool with a standard visual inspection, material sampling and on-site testing procedures, tunnel owners can obtain rapid, comprehensive and objective inspection findings. New York’s application of this technology is the first full-scale application in the US. 4: Demand for programme managers The need for programme managers for tunnels and underground projects is growing worldwide. This is perhaps North America’s greatest contribution to the global tunnelling community. HNTB has been performing programme-management services on several tunnel projects, including Amtrak’s B&P Tunnel and the Mill Creek/Peaks Branch Drainage Relief Tunnel Project in Dallas. Recently, HNTB was selected as part of the programme-management team
for the Chesapeake Bay BridgeTunnel Commission’s Parallel Thimble Shoal Tunnel project and for the Virginia Department of Transportation’s Hampton Roads District for various major projects, including several tunnels.
Advancing forward A mentor once told me that all the easy tunnel projects have been built. He was right. Many of the projects that were unthinkable just a few decades ago because of their complexity are under construction now. Much of the industry’s progress is due to advances in various tunnelling technologies. For example, when I began my career
36 years ago, ground loss of 1% of the tunnel’s face was the norm. Now, with new technologies and techniques, ground loss has been minimised to one-tenth of 1%. We now have remote sensing technology and the ability to replace cutting tools on the face of a TBM without exposing workers to high atmospheric pressures. Tunnels are larger, deeper and subjected to higher face pressure than ever before. All of these advances are reducing the risks of tunnelling and protecting overlying buildings, streets and utilities, which means that we will probably see more complex tunnel projects in the future. Nonetheless, technology alone cannot replace solid engineering knowledge, practical experience and good judgment. The need for an engineer’s ingenuity and problem-solving ability has never been greater. Those skills will always be in demand.
Recovery work at New York City Subway and Amtrak Tunnels following Super-storm Sandy Photo: HNTB
Current HNTB projects •A mtrak’s B&P Tunnel, Baltimore, Maryland •C entral Subway, San Francisco, California •C renshaw/LAX Transit Project, California • E lizabeth River Midtown Tunnel, Norfolk, Virginia • F our Amtrak tunnels post-Super-storm Sandy Assessment, New York
•M ill Creek/Peaks Branch Drainage Relief Tunnel Project, Dallas, Texas
•N ew York City Transit Super-storm Sandy remediation, New York
• P residio Parkway tunnels, San Francisco, California • S ound Transit’s University Link, Seattle, Washington January / February 2015 04-06,08-09North Am_WT1501.indd 6
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North America
Combating concrete issues Construction of the Midtown Tunnel revealed the challenges unique to unlined immersed concrete tunnels Main picture: transporting a tunnel element down the Chesapeake Bay Photo: Aerophoto America
Left inset: flooding of the dry dock before floating out the first six elements Right inset: finishing works before flooding the dry dock
“Unlined immersed concrete tunnels, such as the new Midtown Tunnel, rely on the external walls, invert and roof being free from cracks”
T
he cities of Portsmouth and Norfolk in Virginia, US, are separated by the Elizabeth River. Road links between the two are currently via the two-way, single-lane Midtown Tunnel, and the two tubes of the Downtown Tunnel, carrying two lanes of traffic in each direction. Both of these crossings are heavily used. After many years of study, the Virginia Department of Transportation (VDOT) has undertaken to add a second tube to give the Midtown Tunnel two lanes in each direction. The Elizabeth River Tunnels project also includes maintenance, safety and operational improvements to the three existing tubes of the Midtown and Downtown tunnels. In 2007, the weekday volume of traffic using the Midtown and Downtown tunnels was 41,600 and 103,300 vehicles respectively. Doubling the capacity of the Midtown Tunnel will allow for future expansion of traffic at this location and also help to reduce the volume of traffic using the Downtown tunnels. The new tube of the Midtown Tunnel involves the construction of an immersed tube tunnel (ITT), cut-and-cover and open-trough approaches, a new tunneloperations building, and approach-roadway modifications and relocations. The new tunnel will accommo-
date two lanes of westbound traffic, leaving the two lanes in the existing tunnel for eastbound traffic. The use of ITT techniques minimises the depth of the tunnel with the roof a few feet below the river bed at its deepest point, thus reducing the overall tunnel length. During the preparation of the procurement documents and the subsequent negotiation of the comprehensive agreement, engineering-design and consultancy company Capita assisted in preparing the technical requirements, particularly with reference to design and construction of the ITT. Engineering-services provider Southeastern Transportation Partners (STP), including Capita, also carried out a costing exercise to demonstrate that the agreement gave value for money. As the contractor’s design developed, Capita has assisted
The specialist for tunnelling equipment and logistic systems
STP in reviewing the emerging design to verify compliance with the technical requirements and with best practice. The construction proposals have also been subject to similar reviews, as have the QA/QC procedures adopted by design/build contractor SKW Constructors (SKW).
Feeling the heat Although there have been a number of immersed tube tunnels constructed in the US, these have generally been fabricated from steel or are concrete-lined with a steel membrane to make them watertight. Unlined immersed concrete tunnels, such as the new Midtown Tunnel, rely on the external walls, invert and roof being free from cracks. In order to achieve this, the heat of hydration needs to be controlled during the concrete placement so that early
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North America
age stresses do not exceed the tensile strength of the concrete. This was particularly challenging on this project as each element is continuously reinforced over its 340ft length and the summer ambient temperatures can exceed 35ºC. The high cement content needed to meet the durability criteria also increased the heat of hydration being generated. SKW adopted a series of measures to combat these issues, including pre-cooling the freshly batched concrete by injecting liquid nitrogen into the material, embedding pipes into the concrete members through which cooling water is circulated, and heating adjacent previously cast concrete. The ground conditions vary over the length of the ITT and the presence of soft alluvium beneath sections of tunnel invert needed to be addressed to avoid longterm differential settlement. Consideration was given to the use of timber piles over these areas, but this was ruled out due to the practical difficulties of installing them underwater. The solution adopted was to remove the alluvium, up to a depth of 30ft below the screed bed level, and replace it with a granular material vibro-compacted in place. To prevent movement of the existing tunnel during these deep underwater excavations, the
extent of the combined sheet piles supporting the dredged excavation had to be increased from that initially planned.
Current progress Construction of the new Midtown Tunnel is reaching a critical phase; the first of the tunnel elements has just been immersed. The first six elements, cast in a shipyard east of Baltimore, have been transported 200 miles (322km) down the Chesapeake Bay and are docked in the Elizabeth River, close to their final destination. The Portsmouth cut-and-cover tunnel has been built, the river end sealed with a temporary
bulkhead and the temporary sheet piles removed in preparation for its connection with the first element. Here the river has been dredged and the screed bed is being graded to level. Because of their proximity to the existing tunnel, the trench for the first three elements has been confined to a narrow slot. Land-based cranes can therefore be used during the immersion process. Further into the river, a specially equipped lay barge will be employed for this operation. The buoyancy of the elements will be controlled by filling temporary ballast tanks with water. The final batch of five elements is being constructed back in the Baltimore shipyard to complete the 3,774ft immersed tunnel. These will make the 200-mile journey down the Chesapeake Bay this spring.
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The immersion pontoon in readiness on the Elizabeth River
“Construction of the new Midtown Tunnel is reaching a critical phase; the first of the tunnel elements has just been immersed”
This article was written by Trevor Bone, associate director at Capita
Screeding rig operating in the narrow slot for the first three elements
Focus on the teams The developer of the project is Elizabeth River Crossings, which will serve as the concessionaire for the 58-year term of the comprehensive agreement – this includes finance, operations and maintenance. The design/build contractor on this US$1.5 billion contract is SKW Constructors, a joint venture of Skanska USA Civil Southeast, Kiewit Construction Company and Weeks Marine. SKW’s principal designer is Parsons Brinckerhoff. VDOT has contracted Southeastern Transportation Partners (STP) to provide professional engineering services for the project management and oversight of the design and construction phases of the works. STP is a consortium of consultants led by Parsons Transportation Group and Rummel Klepper & Kahl and includes Capita providing specialist immersed concrete tunnel design and construction expertise.
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TBMs
Top left: TBMs have some advantages over drill and blast in fault zones, as they are less likely to disrupt rock, better able to control water, and allow for faster installation of ground support Top centre: the Kargi hydroelectric project TBM was launched in early 2012 Top right: the crew at Kargi excavated seven bypass tunnels in the first 2km of boring and made extensive in-tunnel TBM modifications to combat ground conditions Lower centre: crews overcame severe fault zones and squeezing ground at Kargi Lower right: about 7.8km of the tunnel at Kargi was excavated using the TBM, and 4km by drill and blast
The bore versus the bang New innovations usher TBMs into a world previously occupied by drill and blast. Desiree Willis reports
D
rill and blast (D&B) and mechanised tunnelling with TBMs are the two most common excavation options for rock tunnels. As technologies evolve, so do the ground conditions in which they can be applied. TBMs are now capable of excavating in more difficult conditions, and projects are testing uncharted waters with great success.
Evolving methods Derek Zoldy, national programme director for URS in Canada, has conducted research into the different excavation methods and when they are best used, by compiling past data from research studies. “Data-acquisition systems have been the best innovation in the underground in the last 10 years, for both TBMs and drill and blast,” Zoldy says. “On drill jumbos, the design of the drift round can be loaded into a machine’s software, which can then do automated drilling and monitor the depth and orientation of the holes.” Zoldy believes these systems have made tunnelling more accurate and safer. “Data acquisition on TBMs can monitor positioning and operational parameters, and has greatly improved their operation,” he continues.
Despite obvious improvements in both technologies in the past 10 years, there are clear differences in the methods and advantages to using each depending on the conditions.
TBM vs D&B While both methods are effective, factors such as geology, tunnel length, project schedule and manoeuvrability can tip the scales in one direction or the other. Based on Robbins’ observations over decades of field data, TBM operations typically proceed at two to three times the advance rate of D&B operations. However, a TBM operation often takes longer to mobilise – one year or more. Modern drill jumbos with computer-aided systems may not take as long to mobilise, but from the date an order is placed, it can take half a year to one full year to mobilise that equipment as well. Once tunnels reach a length of 3-4km, D&B operations become less economical even with their faster mobilisation time because of their slower advance rate. The capital cost to purchase a TBM is significantly higher than for D&B equipment used for a large-diameter tunnel operation. However, overall costs during the project can be much lower when
using a TBM, particularly as tunnels get longer. The Stillwater Mine in Montana, US, employs both methods for its mine access tunnels, with TBM operations running at about 66% of the operating cost of similar D&B operations. Finally, manoeuvrability and tunnel geometry can play a role in the decision-making process. Hard-rock TBMs require fairly straight tunnels and bore circular holes. Invert segments can create a flat invert and shorter machines can be designed to make curved tunnels, but their manoeuvrability is far less than a D&B operation. D&B is capable of making sharply curved tunnels, multiple headings, and a variety of tunnel shapes including horseshoeshaped tunnels.
Geological considerations Much of the advance rate and other factors for these technologies depend on ground conditions. When deciding on whether or not to use a TBM, Zoldy looks to the geology. “The machine must ultimately have the ability to cut the rock before it. The torque of the machine must be able to generate enough base pressure to initiate cracking in the rock.”
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TBMs
At Kargi, NATM work proceeded from the opposite end of the tunnel to the TBM operations
“Despite slow initial progress, a TBM advance rate of 600m in one month was achieved in March 2013 and a project best of 723m per month in spring 2014”
When choosing D&B, Zoldy says method should be looked at in smaller-diameter tunnels that approach the power limits of a small TBM. “If you can get fragmentation of the rock with blasting, the production schedule is tolerable, blasting can meet strict vibration tolerances, and any damage can be mitigated, then D&B is worth looking at.” In difficult conditions such as fault zones, TBMs may have the edge. “When blasting through fault zones, there is the possibility of creating large wedges of unsupported rock. Sometimes the frequency of the blast creates a wave in the rock mass, which can unlock some of these wedges. These areas are also prone to inrushes of water. With a TBM, those problems are mitigated and water control is easier.” Zoldy points out that with D&B, multiple operations occur simultaneously, with much equipment being moved in and out. A TBM has a lot of that equipment on board. The project location also makes a difference. “Blasting in tight urban areas is not recommended [due to peak particle velocity, noise and vibration],” Zoldy adds. “TBMs have a much smaller zone of influence.”
The changing landscape in Turkey Turkey’s Kargı Kızılırmak Hydroelectric Project (HEPP), completed in 2014, is a good example of employing both D&B and TBM methods in difficult ground conditions. The HEPP scheme, for Norway-owned Statkraft, will generate power for about 150,000 homes. The 11.8km tunnel will source water from the Kızılırmak River, sending it to a new generating station operated by Statkraft. A Robbins 10m-diameter double-shield TBM excavated through 7.8km of complex geological conditions. The machine was launched into poor geology. In the first 2km a
total of seven bypass tunnels were needed to free the TBM from collapsed ground. The cutterhead stalled on numerous occasions as the conditions varied widely from solid rock to running ground. Small and wide faults along the alignment added another level of complexity, as the excavation was located very close to the North Anatolian fault line. Contractor Gülermak, with Robbins field-team assistance, installed a custom-built canopy drill and positioner to allow pipe-tube support installation through the forward shield. Drilled to a distance of up to 10m ahead of the cutterhead, 90mm-diameter pipe tubes provided extra support across the top 120º to 140º at the tunnel crown. Injection of resins and grout protected against collapse at the crown while excavating through soft ground. Gülermak was now able to measure and back-fill cavity heights above the cutterhead in some fault zones to over 30m and, in addition, was able to help detect loose soil seams and fractured rock ahead of the face. Despite the slow initial progress, a TBM advance rate of 600m in one month was achieved in March 2013 and, more recently, a project best of approximately 723m per month was achieved in spring 2014, including a daily best of 39.6m in April 2014. Due to the geology-engendered TBM delays, D&B operations began from the inlet portal in July 2012. The plan was to reduce the length of the TBM stretch of the alignment by 4km.
Advance rates in the NATM D&B section were expected to be relatively high due to the competent rock of the Beynamaz Volcanites (including basalt, agglomerates and andesite) along this section of the alignment. While a direct comparison cannot be made for the full tunnel length, after about 2.8km of excavation the ground conditions became comparable to the D&B geology. The TBM outperformed the D&B heading progressing from the opposite end of the tunnel. Crews at the D&B heading progressed in relatively good ground conditions for 4km, where they achieved advance rates of nearly 300m per month – still less than half of the maximum TBM advance rate. It took the D&B operations 23 months to complete 4km of tunnel, whereas it took less than eight months for the TBM operations to complete the same length of tunnel.
Knowledge gaps The changing nature of technologies leaves certain areas with a lack of information. One of these areas is in large-diameter operations. As tunnel machines grow in diameter, more R&D work is required to determine optimal materials, Zoldy notes. There is also a lack of current research in the D&B arena, Zoldy goes on. “The means and methods of conducting a D&B operation have been around much longer than TBMs [and] it seems the D&B industry is sitting back on its heels looking at old technology and hoping that because it’s been around for a long time people will be more accepting of it. There haven’t been new admixtures for blasting agents [since] water-gel explosives in 1958.” “Most young designers now are not up to speed on drill and blast. There should be a standardised certificate programme [for various tunnelling methods] in North America for operators.”
Desiree Willis is a technical writer for The Robbins Company January / February 2015 10,12-13TBM_WT1501.indd 12
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TBMs
13
Heavy-duty dam works Hard-rock double-shield TBM to complete Laos hydropower project
T
he Xe-Pian Xe-Namnoy Hydropower Project is located in the southern part of land-locked Laos in southeast Asia. It is on the Bolaven Plateau, around 80km east of Pakse and 35km northwest of Attapeu. Two central cored rock-fill dams, waterway tunnels with a vertical shaft and a power house with 410MW generating capacity make up the project. The main contractor is Korea’s SK Engineering & Construction (SK). SK has subcontracted the construction of the low-pressure head-race tunnel by TBM to Italian company Seli Overseas. Seli Overseas contracted Terratec to design and build a Ø5.74m hard-rock double-shield TBM to complete the 11.5km tunnel. Following successful factory
tests, the new Terratec machine was delivered to the contractors on December 6. The TBM will bore through mudstone, siltstone and sandstone and, for that purpose, the cutterhead was designed by the Australian TBM maker with a robust and versatile concept, mounting heavy-duty 17in (431.80mm) disc cutters and keeping four large bucket openings. The 2,000kW electric VFD main drive will allow the cutterhead to cut the hardest rock zones efficiently at the maximum speed of 7RPM and also to deliver an exceptional torque of 8,000kNm to cope with fractured parts of the alignment. The TBM also includes a high-speed regripping system,
The TBM will start the 12km drive early this year
single-shield advancing mode and high-pressure emergency thrust. The key parts of the TBM were produced in Australia and Japan. The assembly of the TBM was performed at Terractec facilities in China. The machine has been transported via ship to a port in Thailand from where it will be conveyed via road to the project site. The TBM is expected to begin assembly in the field early in 2015. Terratec is celebrating its 25th anniversary this year.
“The 2,000kW VFD drive will allow the cutterhead to cut the hardest rock zones efficiently at the maximum speed of 7RPM”
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shotcrete
Careful lining design for new mine drift A change to the tunnel lining design helped combat ‘bending moments’ on a mine-access project
I
“Due to the 1.15km tunnel being on a 1:8.6 downhill gradient with a final depth of 170m below ground, the bending moments developing at tunnel knee level became very high”
Left to right: secondary lining spraying with Meyco Versa; view from breakthrough cavern up the drift; completed concrete floor
n 2012 Irish Salt Mining & Exploration (ISME) engaged UK-based tunnelling specialist Joseph Gallagher (JGL) to construct a new access drift for ISME’s existing salt-mine workings at Carrickfergus, Co. Antrim, Northern Ireland. The existing mine produces approximately 400,000 to 500,000 tonnes of crushed rock salt annually for the de-icing of roads during the winter period. The crushed rock salt products are supplied to the Department of the Environment Roads Service in Northern Ireland, and to local authorities and motorway maintenance contractors in the UK and the Republic of Ireland. The principal aim of the new drift project is to provide the access, egress and ventilation requirements to permit the development of a recently gained 280-hectare (2.8 million m2) mine-extension area. Before construction of the new no.2 drift, access to the mine had been through a 10m2 adit constructed in 1965, which contains the mine conveyor system, or the no.2 airshaft, which contains a rack-and-pinion lift. The limited access meant larger plant that needed to be moved in or out of the mine had to be broken down into smaller component parts for easier transportation. The construction of the new no.2 drift is part of ISME’s ongoing programme of investment in the mine with the drift being planned over a period of seven years from geotechnical and mineral investigation, budget and feasibility, route refinement, planning authority
approval, and finally contractor design and construct engagement.
Tackling bendy knees ISME provided JGL with a minimum space envelope requirement of 6m wide by 5.5m high. JGL appointed Alan Auld Engineering (AAE) to design the tunnel to meet these requirements. Initially, a classic shotcrete profile consisting of a circle with a flattened invert was considered, as this profile is usually the most economical, especially when the invert requires backfilling to support traffic. However, due to the 1.15km tunnel being on a 1:8.6 downhill gradient with a final depth of 170m below ground level, the bending moments developing at tunnel knee level became very high. This would have required a much thicker tunnel lining of 600mm as opposed to the 285-350mm originally shown in conceptual designs. The problem was solved by reverting to the most efficient load-bearing capability of a 7.5m ID circle, associated with nominal hydrostatic pressure relief beyond 650m. The final designed lining consisted of a 185-250mm-thick steel-fibre reinforced primary lining with fibre dosage ranging
from 10kg/m3 to 30kg/m3 dependent on tunnel depth and ground conditions. This was followed by a 100mm-thick non-fibre secondary lining reinforced with fabric mesh. A Meyco Suprema pump and Oruga spraying robot were used to apply sprayed concrete to the excavated profile for the primary lining, with a Jacon spraying robot and second Meyco Suprema pump on standby at all times in case of equipment failure. JGL used a new Versa combined mobile spraying unit for the secondary lining works, supplied by Meyco as part of the testing and development of its new product. The Versa provided JGL with extra reach during spraying, allowing secondary-lining bay lengths to be increased and reducing the amount of repositioning required.
Plant on site Power was supplied by ISME. Specialist Plant Associates, part of the Joseph Gallagher Group, provided ventilation – four-stage 1,200mm fans mounted in a silenced 40ft container to ensure minimal disruption to surrounding residents – and related tunnel services. FP McCann supplied concrete from a batching plant approxi-
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mately four miles (6.4km) from the site, with two wagons on turnaround constantly. FP McCann worked with JGL during the mix-development stage, including advising on cement types available in Northern Ireland and modifying the existing batching plant to allow steel-fibre dosing of the shotcrete. FP McCann also worked with JGL to ensure proper safety training Concrete admixtures were supplied by BASF, which undertook reactivity testing to ensure that the right admixtures were specified for the works. Through the glacial tills JGL used its Terex Schaeff 312 tunnel excavator to excavate and load away, being ideally suited to the 7.5m ID tunnel. Excavated material was removed from the tunnel using Hydrema 912 rear-tipping dump trucks with a capacity of 10t. Larger dump trucks were considered, but 25t 6x6 dump trucks were too large for the tunnel profile, raising concerns about safety to operatives working in the tunnel. It was known that the ground became competent 250m from the start of the tunnel, and at this point the Schaeff 312 was replaced with a 45t, 110kW roadheader, which worked until approximately 600m, where the
rock strength exceeded 25Mpa and the 110kW cutterhead power was not sufficient to maintain progress. A Volvo 220D with a 1,500kg rock breaker was used to break out the advance with a rotary cutting-head attachment to trim to tunnel profile, and a small loading shovel to load material into the dump trucks as the Volvo was too large to slew inside the tunnel. The last 25m of the tunnel was in solid halite rock. The client installed 2.4m resin rock bolts and JGL fixed mesh and applied 150mm of shotcrete lining to an area 10m around the breakthrough point to maintain cavern stability.
Gliding through the ground The tunnel was driven through a wide range of ground conditions; glacial tills containing boulders up to 1m in diameter and a fault plane infilled with a hydraulically active vein of Hibernian Green Sand, the full range of Mercia Mudstone with banding of anhydrite and finally halite (rock salt). Excavated material was used for an on-site engineering function on land adjacent to the drift that had previously been prone to flooding. This saved nearly 150,000t of material going to landfill, and removed the need for approximately 7,500 wagon movements on local roads. The tunnel was divided into a top heading and double invert sequence to ensure that the face was kept at a size that was manageable in terms of safety and stability, but also tailored to suit machinery and supply of sprayed concrete.
Through the soft glacial tills the tunnel was constructed in two top headings followed by a double invert to ensure early ring closure for stability and hence minimising ground movements. On entering the competent Mercia mudstone, the advance sequence was changed to a top-heading advance only for the remaining length of the tunnel, followed by invert construction. This allowed advance rates to be improved, saving time on the programme. An AAE representative was on site during the entire tunnel construction and advance length was tailored to suit prevailing ground conditions. The works were undertaken on a 24-hour, five-day-a-week basis, with weekends occasionally used for plant maintenance as required. Advance rates varied throughout the project as ground conditions changed. Typical advance rates in the glacial tills were 35m/wk, 25m/wk in the mercia mudstone, and 15m/wk when halite was encountered as the tunnel neared the breakthrough point in the mine. On completion of the tunnel, the invert was backfilled with Type 1 crushed rock provided by FP McCann and compacted to the designer’s specification. Other backfill materials were considered, including stabilising the excavated material with cement and lime, pulverised fuel ash or furnace-bottom ash from the neighbouring power station, or lower-grade backfill materials. However, while all these were acceptable and met the designer’s specification, JGL decided that Type 1 would provide a road foundation that would give the client a top-grade, maintenancefree, long-lasting road. Overall, the project took nine years from early contractor involvement to final delivery. Collaborative planning for the project meant that during the two years of construction the client was not required to issue a single instruction for additional works.
15
Left to right: Terex Schaeff 312 excavating top heading advance through glacial tills; tunnel breakthrough into cavern; removing rebound and overspray during spraying of invert advance
“During the two years of construction the client was not required to issue a single instruction for additional works”
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ITA CROATIA Croatian Association for Tunnels and Underground Structures
ASSOCIATION INTERNATIONALE DES TUNNELS ET DE L’ESPACE SOUTERRAIN
AITES
ITA INTERNATIONAL TUNNELLING AND UNDERGROUND SPACE ASSOCIATION
41st General Assembly and Congress of International Tunnelling and Underground Space Association ITA-AITES
SEE TUNNEL
PROMOTING TUNNELLING IN SEE REGION
LACROMA VALAMAR CONGRESS CENTER DUBROVNIK, CROATIA
MAY 22-28,2015
www.wtc15.com ITA/WTC 2015.indd 1
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shotcrete
17
Synthetic versus steel New shotcrete solutions suggested on the pedestrian tunnel at Billy Bishop Toronto City Airport
I
n order to improve passenger flow, a new underwater pedestrian tunnel will link Billy Bishop Toronto City Airport to the mainland. It will feature a modern, mechanised walkway, powered by renewable energy. To provide access to the tunnel, a new pavilion will be constructed on the mainland while an extension will be added to the airport terminal building on the island side. Technicore Underground began excavation on the mainland and island shafts in May 2012. Once the shafts were excavated, tunnel boring machines dubbed ‘Chip’ and ‘Dale’ were launched to bore the seven interlocking tunnel drifts, forming the unique arched crown design of the main tunnel. Three of the tunnel drifts were built to include new City of Toronto sanitary and water mains, which saved Toronto taxpayers an estimated C$10 million (US$8.28 million). Excavation of the tunnel was completed in October 2013, during which time shotcrete, waterproofing and reinforcing steel layers were installed.
Spray time The original shotcrete specification called for a steel-fibre reinforced wet-mix shotcrete. For various reasons Technicore investigated alternative options for shotcrete supply. The most critical of these factors included the availability of a pumpable steel-fibre mix, product workability and compatibility between the waterproofing membrane and the steel-fibre reinforced shotcrete. Technicore approached King Shotcrete Solutions, which proposed the use of a dry-process shotcrete alternative that would provide similar properties to the steel-fibre shotcrete, but using a macro-synthetic fibre. King’s Technical Services Team
the material properties of each filament and provides enhanced structural properties to concrete. Over 1,200t of shotcrete were applied throughout the 550ft (152.4m) tunnel, using an Aliva AL.252 shotcrete machine.
Two machines bored seven interlocking tunnel drifts
The next step
proposed MS-D3 structural synthetic-fibre shotcrete, an accelerated dry-mix shotcrete that incorporates macro-synthetic fibres to improve toughness (post-crack energy absorption), impact resistance, fatigue resistance and resistance to plastic-shrinkage cracking. To meet the specification, flexural toughness results were required. The ASTM C 1550 Standard Test Method for Flexural Toughness of Fibre Reinforced Concrete was performed at Laval University. Three panels were shot on site, and after 24 hours were taken to the university and tested after seven days. The average corrected energy absorption at seven days was 280 joules. The main benefit of a macrosynthetic fibre-reinforced shotcrete was the compatibility between the shotcrete and the waterproof membrane. From the perspective of hardened property performance, the macro-synthetic fibre is able to achieve exceptional bond strength between the cement matrix and the fibres because of its unique ability to partially fibrillate on mixing. After mixing, each fibre is transformed into a fibre with fibrils at each end that act as anchors. This fibrillating action provides a bonding capacity that optimises
Next phases of the tunnel project include construction of connecting terminal structures, installation of moving walkways, escalators and elevators and landscaping, as well as electrical, mechanical and final finishing work. The pedestrian tunnel will have four moving sidewalks travelling at 2.3km per hour. From a bank of six elevators on the mainland side, travellers will go 100ft down to access the tunnel and travel along the passageway to escalators, which take travellers to the airport’s check-in area, all in less than six minutes. This is not the first attempt at building a tunnel to the island airport. On October 8, 1935, a long ditch was hollowed out along what is now the Eireann Quay roadway towards the seawall of the Western Channel, while another ditch was burrowed on the island side leading to the north seawall. Steel sheet piles were hammered into the ground to shore up the seawalls and enable excavation. But work on the project ended as quickly as it had started, when the federal government issued an order to cease all work, and fill in the holes and ditches, shortly after construction began. In August 2012 steel pilings from the 1930s attempt were found at the end of a tunnelling drill bit. The drill bit needed to be replaced, but the pilings were soon removed and construction resumed. Tunnel construction is due for completion before spring 2015.
3-D cross-section of the planned pedestrian walkway
King Shotcrete Solutions proposed macrosynthetic fibre for the tunnel walls
This article was written by Matt Croutch, technical sales representative for King Shotcrete Solutions January / February 2015 14-15,17-19Shotcrete_WT1501.indd 17
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shotcrete
The concrete, the cold and the cure Variability in shotcrete compressive strength in tunnels is influenced by a number of factors Above right: poorly trained nozzlemen oversprayed the middle of the cores before being shown better practice
Below: the compressivestrength ratio results for 28 days to seven days, for Stage I and Stage II shotcrete respectively
T
he compressive strength of concrete and shotcrete is mainly controlled by mixture design parameters, including the water-cementitious material ratio (w/cm). Other factors, including the skill set of nozzlemen, can also affect compressive strength, as can wet- versus drymix and accelerator addition at the nozzle. At a tunnel project in western Canada, over 5,000m3 of accelerated wet-mix shotcrete was applied and over 700 pairs of cores were tested for compressive strength at seven and 28 days. This article provides a statistical analysis of the shotcrete compressive-strength test data and shows that the variability is influenced by numerous factors.
Introduction The tunnel was lined with shotcrete strengthened with one or more types of reinforcement, such as rock anchor bolts, depending on the ground conditions. Wet-mix shotcrete with accelerator was added at the nozzle. The project design required shotcrete to be applied to an average thickness of 4in (100mm), with a minimum 2in cover over steel sets or ring beams. The compressive strength was: 1,450psi (10MPa) at three days, 2,900psi at seven days and 5,000psi at 28 days, tested to ASTM C1604/C1604M. The wet-mix shotcrete design used 10% silica fume by mass of cement to achieve durability requirements. A hydration-controlling admixture was used to extend the plastic life of the shotcrete for up to eight hours. For overhead applications, an alkali-free accelerator was added at the nozzle at dosages of 6% by mass of cement. The higher dosages of accelerator were used in wet ground conditions and where thicker shotcrete encapsulations were required.
Quality-control testing Each American Concrete Institute (ACI)-certified nozzleman was qualified to shoot underground reinforcement, a vertical test panel and an overhead test panel. During the construction stage, one QC testing panel was shot per nozzleman per day. Four cores with diameters of 2.75in (70mm) were extracted for every test panel. Two cores were tested for compressive strength at seven days and two at 28 days. Stage I
was applied to upper walls and overhead and Stage II to the tunnel’s lower half. Over 1,000 cores were extracted from QC test panels and tested during the entire construction stage.
Strength results Generally, shotcrete cores develop about 70 to 75% of their 28-day compressive strength at seven days if properly cured. The compressive-strength ratio is defined as the ratio of compressive strength at 28 days versus the compressive strength at seven days. The ratio ranges from 1.5 to 2.5 for both Stage I and Stage II shotcrete. This variability could be attributed to the following reasons: •C uring of testing panels: the shotcrete QC test panels were typically shot in the tunnel and left for two days, then transported to the surface testing laboratory. The moisture content in the tunnel was generally above 80%, which is considered to provide natural curing. But the temperature in the tunnel was 40 to 50°F (5 to 10°C); •H andling the QC test panels: some panels were left outside for a few days without proper curing before cores were extracted for testing; • An alkali-free accelerator was added but the dosage was inconsistent during shotcrete production: this was largely due to the challenges of properly operating the accelerator dosing pump in the underground environment. •N ozzlemen’s shooting
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technique: hand nozzling requires proficient operation. During QC testing, shotcrete core strength from one nozzleman was 725 to 1,450psi lower than for other nozzlemen as he was overspraying in the middle of the cores.
Variability of strength
•C oefficient of variation (COV) for
•
Stage I and Stage II shotcrete for seven-day strength is 20 to 21%, and 15 to 17% for 28-day strength. This shows that the seven-day strength tends to have higher variation than the 28-day strength. T he actual average strength for seven days and 28 days for Stage I and Stage II are slightly lower than the average Canadian Standard Association (CSA) requirements for cores drilled from a concrete structure. This is because several compressive-strength tests did not meet the specified compressive strength of 2,900psi at seven days and 5,000psi at 28 days.
Based on the testing data from this project, the COV of shotcrete core
strength should be less than 20%. The least variation can be achieved by proper mixture design, rigorous quality control, proper curing and handling of test panels and shotcrete core samples, proper shooting skills and a QC testing programme to test compressive strength for daily shotcrete production.
19
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Summary Underground shotcrete QC core strength depends on mixture design, nozzleman skills, equipment, curing conditions and test-panel handling. Variation in compressive strength of shotcrete cores at 28 days was found to be less than that found at seven days. When accelerator was used, the variation of the core strength tended to increase. With proper QC, a minimum of 96% of the shotcrete cores tested met the specified minimum compressive strength of 2,900psi at seven days and a minimum of 96% of the shotcrete cores met the specified compressive strength of 5,000psi at 28 days. Tunnel shotcrete cores show a standard deviation of 870 to 1,160psi for compressive strength, and a COV of 16 to 21%.
Lihe (John) Zhang (right) is an engineer at LZhang Consulting and Testing and a committee chair of the American Concrete Institute. This article is an edited version of ‘Variability of compressive strength of shotcrete in a tunnel-lining project’, reprinted with permission from the Fall 2014 issue of Shotcrete magazine (www.WhyShotcrete.org)
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CONTENTS
1
The nose for the job
W
e have an extended feature about cured-in-place-pipe replacement on pages 15 to 21 in this edition of Trenchless World magazine. One case study reveals the challenges in treating severe corrosion on a storm sewer under a busy street in Colorado (US). The other record feat takes place under a muddy sugar-beet field in Germany. Fully prepared and trained personnel attended each site to face the expected obstacles that underground works on such tasks bring. When working on the sewers, every contractor knows that the unpleasant reality is the smell.
Our story takes place in the aptly named Dogtown in St. Louis, Missouri (US), well known for its annual St. Patrick’s Day Parade; now perhaps known for its smell. In December last year, residents of the quaint neighbourhood identified a new odour: toxic, almost like the heady personality of a permanent-marker pen. The smell was even detected inside homes. Its origin was soon traced to the sewers, but nobody looked at the diaper on the baby in the room. It was something else. The Metropolitan St. Louis Sewer District (MSD) is working to repair and upgrade parts of the sanitary sewer line system beneath the western region of Dogtown.
“This is a very large sewer, so it will have more of an odour impact than we usually see”
The smell is in fact epoxy-infused liner used in the cured-in-place-pipe replacement scheme. The heating/curing process is known to release smells that, while noisome, are not a hazard to health, MSD spokesperson Lance LeComb commented. “Odours do come off sometimes, and we certainly apologise for the inconvenience. This is a very large sewer, so it will have more of an odour impact than we usually see,” LeComb remarked. The smell can snake its way up through dried-out sink traps or basement drains in people’s homes, LeComb added, and went on to suggest that if a smell is detected, inhabitants should pour a few cups of water in the sink or down the drain to flush the smells away. While the repairs were scheduled to finish on December 18, recent wet Dogtown weather conditions mean that the repair time is likely to be protracted. MSD has assured the local population that it is using vented sewer lids and flushing the lines regularly in an effort to dissipate the smell more quickly. LUKE BUXTON, EDITOR luke.buxton@aspermontmedia.com
News 2 Features 4 Middle East HDD 9 CIPP 15 Contacts 21
Next month (March) North America Pipe ramming / bursting Microtunnelling NASTT preview
COVER In 2014, Michels completed a 9,038ft (2,755m) crossing of the Mississippi River, installing a 36in (914.4mm) steel pipe. The company pushed the limit of HDD technology, particularly at this diameter, for this impressive crossing that stretched from Missouri to Illinois. This project presented many unique challenges and required an extreme amount of experience, ingenuity, planning and construction expertise. Projects of this length and diameter had previously been thought of as unachievable, so Michels is extremely proud of its success. See page 9
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NEWS
Morgan Tucker marks decade in business
UK-based consulting engineering company Morgan Tucker marks 10 years in business this year. The firm, whose competencies include trenchless options on sewer utility projects, has UK offices in London, Newark and Leeds, and recently opened its Nottingham office. Further expansions and acquisitions are in the pipeline. Morgan Tucker has overseas offices in the Czech Republic and Oman. From the first project worth approximately £2,000 (US$3,026) for Wolverton & Greenleys Town Council, Morgan Tucker now manages approximately £1.2billion of construction schemes each year. “We are delighted to reach this significant milestone,” managing director Matthew Tucker commented. “The construction and property sector has been decimated by the recession, so to make it through unscathed has been an achievement in itself. “The fact that we have achieved our targets and expanded in the process is a real accomplishment and testament to the hard work of the whole team at Morgan Tucker. “We have worked on some significant projects since winning our first contract in 2005 and this year will see us start work on further high profile schemes.” Morgan Tucker managing director Matthew Tucker
Chelmsford effluent project takes 8km of concrete pipe Utilities and civils material supplier Keyline has delivered almost 8km of concrete pipe to Essex & Suffolk Water’s Chelmsford Effluent Pipeline site. Civil-engineering specialist contractor Roadbridge used pipe jacking to install 7,900m of 1.4m-diameter concrete pipe to upgrade the capacity of the existing outfall from Chelmsford. The duplicate pipeline runs from the Chelmsford (Brookend) Sewage Treatment Works to Langford Water Treatment Works. Essex & Suffolk Water to increase the capacity of an existing dual pipeline that carries flows from the Chelmsford sewage-treat-
The Chelmsford Effluent Pipeline is one of the largest installations of its kind in the UK
ment works to the Blackwater Estuary. Roadbridge’s contract involves the design, supply and installation of the underground gravity pipeline, which runs in parallel with the existing pipelines, crossing numerous roads and watercourses. Contractors and suppliers The new release can cater for pipes up to 48in in diameter
McElroy offers larger pipe-fusion machines Manufacturer McElroy has expanded its offerings from small-diameter pipe-fusion machines to large with the release of In-Ditch 48. The In-Ditch 48 packs more power into a smaller package with 3,000psi (207bar) maximum pressure to serve in-ditch applications for 16in OD to 48in OD (450mm to 1,200mm) pipe, the company said. The new machine features a top-loading heater and facer providing greater flexibility in tight spaces with minimal site excavation
required. Removable jaws and clamp cylinders make it easier to load, and the four-jaw carriage converts to a three-jaw configuration, making it possible to fuse short pipe stubs. The In-Ditch 48 provides ease of mobility with multiple lifting points, a carriage spreader bar and skidded carriage. The In-Ditch 48 is compatible with the McElroy DataLogger, which provides joint recording and added jobsite accountability, McElroy added.
faced logistical difficulties as the drivers had to navigate around various sites including residential areas, schools and bridges. The project was also challenging due to its intense timescales. The client moved the delivery date of May 2015 forward six months to November due to the area’s high water table, avoiding the likelihood of winter flooding. In the end, completion took place in October 2014. The tighter timescale was of significant concern for pipe manufacturer Stanton Bonna, which had to lift production significantly, working double shifts, as well as storing around 4,000m of pipe for the project.
Pierson launches advisory group Former Parsons Brinckerhoff president and CEO George Pierson has launched the Pierson Advisory Group to advise and assist senior executives in streamlining projects by identifying and eliminating the obstructions. Pierson’s background is in engineering, operations, law, business and leadership. Pierson added nearly US$1.4 billion of shareholder value while president and CEO of PB, culminating in its sale for nearly three times the value of the firm when he assumed leadership five years earlier. Pierson also led a team of experts in crisis response to PB’s role in Boston’s Central Artery/Tunnel project (“the Big Dig”), negotiating a resolution of issues with all involved parties. PB also works in microtunnelling and other trenchless technologies.
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Moving out from the middle Trenchless technology is slowly shedding its ‘specialist’ shell and entering more mainstream underground construction and engineering works in the Middle East This year’s Trenchless Middle East show will feature a larger outside area than in previous years for demonstration of machines
F
igures from the United Nations Population Fund in October 2013 reveal that all the nations in the Middle East are experiencing gradual population growth. Three of the region’s five largest nations – Egypt, Saudi Arabia and Turkey (with numbers
of 82 million, 75 million and 29 million respectively) – are facing an average annual change of 1% to 2%. Israel, Kuwait, Lebanon, Oman and Qatar are swelling at speed with a 3-4% boost to yearly population digits. Since the start of the new millennium, certain emirates cities have emerged as modern showcases of architecture, design and transportation links. Dubai hosts the Palm Islands and the tallest engineered structure in the world – Burj Khalifa. Qatar, whose growth rate is 5.9%, is an oil-rich nation that is set to open up to the world stage when it hosts the 2022 FIFA World Cup. Massive infrastructure projects are currently under way.
Futuristic visions
Population growth in the Middle East Country
Annual growth rate
Egypt
1-2%
Israel
3-4%
Kuwait
3-4%
Lebanon
3-4%
Oman
3-4%
Qatar
3-4%
Saudi Arabia
1-2%
Turkey
1-2%
There is a constant stream of development here to rehabilitate or build new pipelines and tunnels. Over the last few years the share of young people in the Arab Middle East has expanded, pushing demand for high-speed fibre-optic internet connectivity, opening doors to non-disruptive installation methods in densely developed urban areas. Government departments are slowly getting behind less-invasive ground-engineering and construction techniques. For instance, Dubai Electricity and Water Authority (DEWA) and the Roads and Transport Authority (RTA) have announced intentions to support trenchless technologies in their current and forthcoming portfolio of construction programmes. To support its sustainable development, in September 2014 DEWA began work on a 25km water-transmission network across Dubai. At a cost of Dh170 million (US$46.3 million), the project will connect
17 locations with the main transmission lines. The project includes extending glass-reinforced-epoxy main water pipelines in different diameters, in addition to a remote-control and monitoring system. Work on extending and launching the main water-transmission network is expected to be completed by the end of 2015. The geology is one obstacle to the adoption of trenchless techniques. If the hot working conditions were not tough enough, the ubiquitous sand poses challenges for stability when it comes to HDD and other trenchless methods and it can be expensive to import appropriate technology and draft in experienced engineers, but these nations have the finance and the spirit to endorse new, more environmentally friendly means. In particular, several large European, North American and Australasian engineering consultancies and equipment manufacturers, from pipe-bursting machines, HDD and microtunnelling to plastic-pipe and cement suppliers, have offices or distribution and sales partners in this region. UK-based contractor Kier has just announced a £150 million (US$ 227 million) contract for a mixed-use civil works project in Dubai.
Yielding more young Oman has experienced the region’s highest population growth rate by far with a 7.9% yearly hike, one of the highest in the world. This is due to an increase in the birth rate and improved healthcare, which is prolonging life. Higher-quality sanitation methods and more effective
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systems are coming into place. Haya Water (Oman Wastewater Services Company) has contracted Parsons on the US$1 billion A’Seeb Wastewater Project in Muscat. Parsons is providing design, project management, design review and construction supervision on the project that started in 2006. The collection system includes a new main sewer, 1.45km of gravity sewer and 212km of vacuum sewer, which will be one of the largest in the world and the largest ever constructed in a single project. The project runs along 21km of the Sultan Qaboos Highway, which is the city’s main traffic route and could not be closed for construction works. Trenchless solutions were therefore required. Microtunnelling took place near the coast line, with project design taking into account sandy soil and a high underground water table. The contract was worth US$140 million to construct a 23km gravity sewer main collector sewer, 21km of which was bored with microtunnelling machines with a maximum diameter of 2m. “Microtunnelling was complete in 2012,” Martyn Harris, contracts manager, A’Seeb Wastewater Project, Parsons – Environment and Infrastructure, tells TW. “General works on the wastewa-
ter network are still ongoing.” A fibre-optic network duct was also installed along the sewage and recycled water lines, connecting Seeb residents. There are six contracts on the project, each managed by a different contractor. These are both local and international companies, including a JV between Gulf Petroleum Services and Greenline Trading. Parsons (headquartered in California, US) has a significant presence in the Middle East with offices in Bahrain, Israel, Oman, Qatar, Saudi Arabia, Turkey and the United Arab Emirates (Abu Dhabi and Dubai).
Getting close Very few projects in this region call for trenchless methods and, even when those methods are inked on tender documents, there are no guarantees. In December 2013 Istanbul Water and Sewerage Administration opened a tender to local and international companies for CIPP rehabilitation (total length: 40,000m) and HDD installation of HDPE pipeline (total length: 3,300m). CIPP works were outlined for three sewer pipelines comprising: 35km at Ø300mm, 3.5km at Ø400mm and 1.5km at Ø500mm. HDD works were composed of five potable-water pipelines ranging from Ø125mm to
Ø500mm in length, and from 50m to 1,500m in length. “I visited Istanbul Water and Sewerage Administration [and] was told that, due to some financial reasons, the rehabilitation technique has been changed and another technique is being used in the project instead of CIPP,” Yasin Torun, chairman of the Turkish Society for Infrastructure and Trenchless Technology (Altyapi ve Kazisiz Teknolojiler Dernegi), informs TW. In the region generally, several successful projects that utilised trenchless solutions have been concluded recently. These include: Transco’s installation of gas pipelines in the UAE using HDD; Italian company ICOP’s work on the longest multi-curve sewer pipeline in the Middle East; Esfahan Water’s rehabilitation of old sewer pipes with excess sedimentation in Iran; and International Aramoom’s employment of CIPP-UV on a pipeinspection and rehab programme in Saudi Arabia.
Time for TME It has been two years since the eighth Trenchless Middle East (TME) took place in Dubai. This edition of the exhibition and conference was the largest event in its history, with a variety of trenchless technology showcased by over 100 companies. Exhibitors included companies from the Gulf Cooperation Council (GCC) countries, Russia, the United Arab Emirates and the US. There was an additional contingent from Europe in the German Pavilion. The conference programme attracted a record attendance of 285 delegates. The 2015 conference programme will have a strong focus on rehabilitation and new innovations. This year, the event features an extended outdoor area where HDD rigs and other large machinery will be displayed. There are about 60 companies from 14 countries exhibiting at TME. “The booming construction market and infrastructure
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International co-operation is a major mover of projects in the right direction
“Due to financial reasons, another technique is being used in the Istanbul Water and Sewerage Administration project instead”
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development in the region is growing the sector and provides a continuing demand for practical knowledge of trenchless technology,” Caroline Prescot, managing director of organiser Westrade Group, says.
Vorsprung Durch Technik German engineering enjoys worldwide renown. It is no surprise that there is a healthy cluster of German companies imparting their trenchless expertise in the Middle East. The German Society for Trenchless Technology (GSTT) has organised the German Pavilion at Trenchless Middle East for its members for a number of years. The pavilions are supported by the Federal Ministry for Economic Affairs and Energy. “In addition to policy and budgetary issues, the active involvement in the Trenchless techniques are finally spreading to a wider audience
“The problems in a lot of Middle East municipalities are frequent blockage and damage in sewers due to population growth and the small size of the sewer and supply system”
Shop window Exhibitors at TME represent a wide range of countries from Middle Eastern nations, Europe, North America, Asia and beyond. Companies from the region include Abu Dhabi Sewerage Services Company. Tatco Trading and Abu Dhabi Trading has been the authorised Ditch Witch products dealer for the UAE and Saudi Arabia for 37 years. W T Burden Middle East sells iPEK pipeline inspection systems. Heitmann Middle East provides its suction-excavator services all over the UAE as well as in adjoining countries. German companies include Prime Drilling, manufacturer of HDD rigs with pull force ranging from 30t to 600t. MTS Perforator supplies thrust-boring, pipe-jacking and segmental-lining machines from 100mm IDto 3,000mmID. IBAK Helmut Hunger is a large manufacturer and supplier of inspection systems for surveying pipes and water
wells that are difficult to access. Herrenknecht is well known for its mechanised tunnelling systems ranging from 0.10m to 19m in diameter. Arthur Habermann develops, designs and distributes durable solid pumps. Amex specialises in the trenchless rehabilitation of gas and potable-water mains and pipes. A large number of Chinese companies are also displaying their products and services. Unionchem provides speciality chemicals to the industry. Jiangsu Dilong Heavy Machinery provides HDD machines from 5t to 450t. HHJX also produces HDD rigs. Zhenjiang Anda Trenchless Engineering & Machinery researches and develops the production of pipe-jacking equipment. Xuzhou Xugong Foundation Construction Machinery was established in January 2010 and sells non-excavation machinery.
presentation of German companies at international fairs and exhibitions is of prime importance to back the export activities of German industry on international markets,” Jens Hoelterhoff, chairman of GSTT, comments. GSTT also organises German Pavilions at Trenchless Asia and other International No-Dig shows. The German Society for Trenchless Technology publishes a yearbook including the latest GSTT standards, a directory of who provides what, and offers industry professionals information on state-of-the-art-trenchless construction techniques and products. In addition, the association supports professors of universities with teaching material. GSTT gives lectures entitled ‘Trenchless Innovations from Germany’ at international no-dig events. These activities will be conducted in the future and will be updated. The Middle East can learn from Germany’s catalogue of experience on non-intrusive underground works. “In Germany trenchless technologies are used in all utility areas. So far, reliable statistics are only available in the range of sewers: more than 64% of all activities are done trenchless. The proportion of trenchless renewal and renovation is decreasing while the uses of repair methods are increasing,” says Hoelterhoff. After many years of leadership and partnership in this area, GSTT members are able to confidently identify and solve issues germane to the locality. “The problems in a lot of Middle East municipalities are frequent blockage and damage in the sewer systems due to population growth and the small size of the sewer and supply system,” Hoelterhoff notes. “In cities with difficult space conditions and high-density traffic, trenchless technologies and the rehabilitation of supply and sewage lines offer technical, economic and ecological opportunities.”
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24/07/2014 15:18
HDD
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Michels owns a fleet of 17 large rigs, which have worked all over North America
In familiar ground From legendary long distances to greater technology and green thinking, Michels is pushing the boundaries of HDD
M
ichels Directional Crossings, a division of Michels Corporation, has successfully completed horizontal directional drilling (HDD) crossings in all 50 states, Canada, along the US-Canada and US-Mexico borders, and internationally. Design engineer Greg Goral started his trenchless career at Michels and has more than 25 years of experience. He talks to TW.
q
Can you describe recent progress within the HDD industry? Longer distances allowed through the use of HDD pilothole intersect technology. HDD has become a more accepted and preferred method of installing underground utilities.
Advancements have also been made with large and small equipment for providing a greener footprint at an HDD site and more technologically advanced systems.
q
What type of equipment is being purchased by the market? Rigs, equipment and tooling that have been evolving with the help of creative suppliers and manufacturers that have been in the industry from its infancy. These industry experts have the greatest experience in evolving the rigs, equipment and tooling to meet experienced HDD contractors’ needs and to help to advance the tools and equipment in the industry. Michels has custom-fabricated
many of our rigs from the ground up to make sure they are capable of supporting the rigorous demands of the industry. Michels currently has 17 large-capacity drill rigs, nine of which have capacity of 1.2 million pounds (5,338kN) of drilling thrust/pulling power.
q
What is the biggest challenge HDD contractors face? The number-one issue we see challenging the HDD industry is the ability to dispose of environmentally safe drill fluid/cuttings, which is a combination of bentonite mixed with native ground formation. Michels complies with all rules and regulations regarding disposal of drilling fluids/cuttings as well as
“HDD has become a more accepted and preferred method of installing underground utilities�
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Greg Goral has a quarter of a century’s worth of experience in the trenchless sector
“The HDD industry has seen some dramatic evolution within the last five to 10 years”
all environmental and safety topics. Negative perceptions of our industry may have been influenced from publicity created by and directed toward a frantic influx of oil-fracking projects and operations. However, this perception is far from the truth for HDD operations, as the bentonite brands used by Michels are NSF-60 approved and not harmful to the environment when properly disposed of. As most in the industry know, bentonite is a nitrite (clay) in powder form that when mixed with water is an essential part of the HDD process. Drill fluids serve several functions: •C ooling the drill bit and its cutters; •C reating static pressure within the annular space, holding open the hole while carrying drilled cuttings to the surface; •A dding a clay-like cohesiveness in the form of platelets to the surrounding formation, which in turn stabilises the drilled hole from collapsing; •A iding in eliminating friction for the down-hole-assembly (pipe) and providing a smooth, flowing pullback for the product line when installed.
q The Toro 2024 is powered by a 74hp Cummins B3.3 diesel engine
Can you talk about a recent significant project?
In 2014, Michels completed a 9,038ft (2,755m) crossing of the Mississippi River (the 2,320-mile (3,730km) long river running from Minnesota to Louisiana, US) installing a 36in (914.4mm) steel pipe. We pushed the limit of HDD technology, particularly at this diameter, for this legendary crossing that stretched from Missouri to Illinois. This project presented many unique challenges and required an extreme amount of experience, ingenuity, planning and construction expertise in order to complete it. Projects of this length and diameter had previously been thought of as unachievable, so we are extremely proud of our success.
q
What has the oil and gas industry’s growth meant to the HDD market? It has meant that trenchless technology contractors can maintain a solid backlog of projects and expand operations in preparation for handling an influx of work from the public sector. This will have a noticeable effect on the industry, increasing the need for new equipment and larger quantities of better tooling.
We are seeing an increase of several projects for replacement of old deteriorating lines. However, most of the long-haul mainline projects with mileage are new lines. It has levelled out a bit, but there might be a small influx in the coming years. There are several factors affecting growth, which are all tied to the US and world economy.
q
What is on the horizon for HDD?
Advancements are being made in all facets of the HDD market. Trends for HDD equipment are for providing greater efficiencies in handling stem, tracking the drill head and operation of the equipment. Electronics, electro-hydraulics and telematics are making their way from the smaller drill rigs into new designs for the larger drill rigs, creating a more efficient and operable machine. The HDD industry has seen some dramatic evolution within the last five to 10 years with changes in equipment, tooling and technology. With the ever-changing world of HDD, it is going to be interesting to see what the next five years will bring to the industry and what will be the drivers for continuing advancements.
Drilling into global markets The Toro Company makes its drilling debut in the trenchless market
T
he Toro Company celebrated 100 years in business in 2014, and attributes a healthy portion of its century of success to innovation. The company is evolving through technological advances in manufacturing and an emphasis on service towards helping customers deliver superior results with Toro’s products. One such step forward is Toro’s increased presence
worldwide with its construction and utility equipment. Toro is known around the world in the turf and landscaping industries with its offering of mowers, irrigation and turf-care equipment. The company is excited to build on its core and expand its product provision in the global market of utility products, including the Toro Dingo compact utility line, along with
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two horizontal directional drill (HDD) rigs – the DD2024 and the DD4045.
The 4045 drill is Toro’s most powerful HDD rig offering with 40,000lb of thrust and pullback, and 4,500ft-lb of rotary torque
Reviewing the rigs With positive outlooks for utility sectors worldwide, the company is confident that it is the right time for Toro’s HDD equipment to debut on the global stage. Both horizontal directional drills offer innovative features that will be productive in global markets, such as the quad rack-and-pinion carriage design to spread machine load evenly for smooth and stable thrust and pullback, and an open-top vice system for increased visibility and safety when breaking apart tool joints. The DD2024, in particular, combines a compact design with 20,000lb (88.9kN) of thrust and pullback force and 2,400ft-lb (3,254Nm) of rotary torque. Powered by a 74-horsepower Cummins B3.3 turbocharged diesel engine, the DD2024 delivers consistent and reliable performance in all operating conditions. The upper end of the horizontal directional drill offering is the Toro DD4045, which packs a powerful 40,000lb of thrust and pullback, and 4,500ft-lb of rotary torque. The DD4045 features a 160-horsepower, Cummins QSB4.5 diesel, liquid-cooled engine and an on-board, infinitely variable drilling-fluid pump that delivers a flow of up to 70gpm. The multi-function colour LCD display provides a clear view of the drill’s performance and functions. For hard-rock drilling conditions, an air hammer easily integrates and is controlled from the DD4045 display. An optional enclosed cab keeps the operator comfortable no matter what the weather may bring. Both HDD rigs feature forward-mounted track drive motors with planetary gear reduction to provide superior traction in all types of ground conditions. The rear dual
11
stabilisers adjust independently to secure the unit safely during operation. Selection of single or dual joystick mode offers flexibility between operators who traditionally prefer one system vs. another. For operator safety, a remote exit side lock-out system disables hydraulic functions via remote control, and the Zap Alert system notifies the operator in the event of an electric line strike.
Global expectations These two innovative products have been well received in the US, and Toro anticipates that customers outside the country will also appreciate the quality of Toro’s directional drill product line. As a manufacturer of construction and utility equipment, Toro sees opportunities in global markets, including many areas in
Latin America, Asia and across Europe. These are regions where key indicators in the construction industry point to a healthy future, and the company wants to make sure that it is helping drive economies in those regions by providing top-quality utility equipment for infrastructure projects. As far as Toro’s plans for expanding the product offering in the global marketplace: the company is excited to make these products available through existing and future distribution partners. The company wants to consistently make significant steps forward by gradually rolling out Toro horizontal directional drills to these key markets over the next few years. Right now, The Toro Company is establishing relationships with distribution partners whose values align and have a strong focus on customer service and
“The company is confident that it is the right time for Toro’s HDD equipment to debut on the global stage”
Toro sees high demand in utility and construction sectors in the years ahead
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“2015 is expected to be a promising one for the utility industry”
support. From there, the company wants to let the equipment do the talking. Once utility contractors have the opportunity to operate Toro equipment, they will quickly see the benefits against their current HDD equipment, the company believes. At first blush, 2015 is expected to be a promising one for the utility industry within many regions, and The Toro Company is keen to be playing a part in the success of the construction and utility segments worldwide.
About The Toro Company New York Stock Exchangelisted The Toro Company (NYSE: TTC) is a worldwide provider of inventive solutions for the outdoor environment including turf, snow and ground-engaging equipment, and irrigation and outdoor lighting solutions. With sales of US$2.2 billion in Fiscal Year 2014, Toro’s global presence extends to more than 90 countries.
The company’s products have helped customers on golf courses, landscapes, sports fields, public green spaces, commercial and residential properties and agricultural fields. The company first engaged with the trenchless sector at the No-Dig Madrid show in Spain from October 13 to 15, 2014, where it exhibited its HDD rigs.
This article was written by Mike Brugh, business manager, international site works, The Toro Company
A Forward RX33×120 rig was used to bore a 225m wastewater pipe in the Netherlands last November
In the right direction It’s a promising year ahead for Russia-based drill rig manufacturer Forward, which is
“During expanding its international dealer network. Ildar Nizamiev, manager of the company’s the last business development department, talks to TW two years to this, Forward HDD rigs are Have you introduced any Where are your main Forward suitable for operations in new rigs lately? markets? has been freezing Russian winter conditions. During the last two years At the China Mining exhibition Without any doubt, Russia has actively Forward has been actively in October 2014 Forward the most demand because expanding presented a horizontal direcexpanding its dealer network Forward drill rigs are unique its dealer tional drilling rig with 12-60º worldwide with rigs in such counequipment, which meet the tries as China, the CIS countries, demands of national customers, network drilling angle for super-viscous India, the Netherlands, Turkey oil extraction and coal seam such as 24-hour high-quality worldwide”
q
q
degassing. The company has a line of seven HDD models for different sectors.
service, a big warehouse with all necessary equipment, drill tools and spare parts, training and consulting services. In addition
and Ukraine.
q
What countries are you targeting?
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In November last year in the city of Weesp (in the Netherlands) contractor O&S International Drilling Company used a Forward RX33×120 to bore a hole for a 225m-long, 500mmdiameter HDPE wastewater pipe in sandy soil. In the same month, HDD Muhendislik Company used a Forward RX11x44 to install a 125m, 300mm-diameter steel drinking-water pipe in sandy soils in Bursa, Turkey.
Contractor HDD Muhendislik Company used a Forward RX11x44 on a water-pipe installation job in Turkey
q Last year the company successfully signed an agreement to open representative offices in North Africa, the Middle East region and Mongolia. The company is interested in the Middle East, African and European regions most of all. Forward already has partners in
these regions and has held further negotiations with potential customers and signed preliminary contracts to purchase HDD rigs.
q
Can you talk about any recent projects that used your rigs?
What are your expectations for 2015?
In 2014 Forward participated in international exhibitions and conferences, which gave it an opportunity to enter the biggest main markets of the world. Forward expects that 2015 will be very promising and successful for the company as a result of potential work and active attendance at these events.
5-DAY BASIC DRILLING FLUIDS WORKSHOP • Designing the Right Drilling Fluid
Cebo Holland produces and delivers high quality industrial minerals and additives, from stock and according to customer specifications. Every year in November Cebo Holland organizes, together with Baroid and Herrenknecht, a 5-day basic drilling fluids workshop = Mudschool.
• Laboratory Tools and Exercises • Instruction by Industry Experts
Last year people came from 15 different countries to follow the HDD or Micro Tunnelling course. Hands-on laboratory exercises, practical demonstrations and interactive lectures are the main topics of these workshops.
In cooperation with
Next Mudschool will be held on the 2 - 6 November 2015
Industrial Minerals, Powerful Logistics
mudschool@cebo.com - www.cebo.com 1433854_CBH_adv_178x124.indd 1 09-12,14HDD_Trench1501.indd 14
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Practical solution: pulling in a 354m-long liner in one piece
The long line New record length for rehabilitation of a wastewater sewer using UV-cured CIPP technology
T
he municipality of Nordstemmen in Germany has for years implemented the scheduled rehabilitation of its existing wastewater, stormwater and combined sewers using liner (CIPP) technology. In 2012 and 2014, a total of 2.7km of the municipality’s old wastewater network was made fit for future generations. The 354m-long sewer section of wastewater pipeline rehabilitated on February 11, 2014, was particularly demanding as it crosses under a field. This field could only be driven on with lightweight machinery. Working under difficult conditions, Arkil Inpipe rehabilitated the section of the combined water sewer using the Berolina-Liner system. As the typical cable length of the UV-curing equipment, around 250m, is not long enough for this, curing was planned from both ends. An Arkil Inpipe 9 x 1,000W curing unit was used. The five intermediate manholes were crossed with the Berolina liner and remained closed. Following the rehabilitation, a special mortar was used to join the two liner ends onto the end manholes. With the lining of this sewer section, the whole rehabilitation project in the
municipality of Nordstemmen was completed successfully.
the around 16-hour installation in two shifts.
Preparation
Rehabilitation of pipe run
Due to the soil conditions, the rehabilitation work could only be carried out during the winter period. In the summer, the field is planted with sugar beets, so that the intermediate manholes are not accessible. The manhole covers, which are located up to 1.5m below the ground, could only be exposed using a lightweight mini-excavator. Unfortunately, the weather did not play along. The frosty month of February was chosen during planning as the most suitable one. But mild temperatures and enormous quantities of rain softened the soil severely. Wooden planks were laid up to the start manhole to prevent the installation vehicles, weighing up to 18 tonnes, from subsiding at the manhole. The sewer section to be rehabilitated was disconnected from the network using an inflatable plug. The wastewater that built up was extracted by a suction vehicle with 18mÂł capacity and pumped back into a main ID 700mm (28in) sewer 500m away. This procedure had to be repeated several times during
Due to the soil conditions on the field, the manholes could not be approached directly and the pipeline was not rehabilitated in the usual way, from pipe run to pipe run. The practical solution was to pull in a 354m-long liner in one
Contractors used a lightweight mini-excavator to access the five intermediate manholes covers, 1.5m below the surface of the field. These manholes were crossed with the Berolina liner
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Wooden planks were laid to prevent the 18t installation vehicles from subsiding in the soft soil of the field
“BKP Berolina and Arkil Inpipe have again succeeded in setting a benchmark for the installation of UV-cured liners”
A crew member operating the suction vehicle to collect wastewater that had built up
piece, via five intermediate manholes. Theoretically, BKP Berolina Polyester, based in Velten near Berlin, can produce infinitely long GRP liners. The 4mm-thick Berolina-Liner, weighing around 2.6t, was delivered on a 3m-long wooden pallet with a total height of 2.50m. This packaging unit required special transport to Arkil’s storage area in Hanover. On the day of the rehabilitation, the Berolina-Liner was loaded onto a flatbed truck and delivered to the construction site just in time. Before the liner was pulled into the start manhole, all the pipe runs were cleaned with the help of a flushing vehicle to remove coarse deposits. The pulling-in was carried out using a controlled winch. To protect the liner, gliding foil was pulled into the sewer along the whole length so that the outer film of the liner remained intact. After the pulling-in process had been completed successfully, the curing vehicle was positioned directly over the manhole.
The so-called “knee” was lowered through a hole in the floor at the rear of the vehicle. This is a device that is connected with the liner, which is already located in the pipe run, and is used to provide air in a controlled manner using compressor technology. The calibration process is carried out in all sub-steps precisely to the specifications, so that the liner has time to “unfold” and to nestle up against the pipe wall so that it is close-fitting. To ensure that the liner does not over-expand in the intermediate manholes during this phase, the installation team installed a “jeans cap” with zip around the Berolina liner in each of these areas, to act as a support sock. This precaution prevents the liner from overexpanding and is not removed after curing has finished. After the Berolina-Liner had been expanded successfully by means of air pressure, the team leader, Michael Wollenhaupt, while maintaining the internal pressure, pulled the light source through the knee 200m in the direction of the start manhole. The first part of the BerolinaLiner was then cured using UV technology. The installation vehicle was moved together with the light equipment and the same procedure was repeated at the other end over a length of around 160m.
In this way, it was ensured that the entire 354m were cured with sufficient overlap in the middle section. With a curing speed of 60m/hour, the liner was cured successfully within around six hours. The experienced and wellcoordinated installation team of Arkil Inpipe, in co-operation with the applications technicians of BKP, ensured that no problems or delays occurred during the calibration process and curing.
Follow-up work After the two curing operations had been completed, a leak test was successfully performed. The liner ends were joined onto the respective end manholes. Due to the exceptional length of the sewer and its location under a field, it was decided not to cut open the liner in the intermediate manholes, but to seal the manholes with concrete covers at around 1.5m below the ground and to backfill the pits properly in the field. Before rehabilitation, the intermediate manholes were already up to 1.5m below the field and that is the way they will stay in the future. The subsequent CCTV inspection documented proper installation for all those involved and a fault-free rehabilitation result. Through exact preparation, innovative production processes and many years of experience in installing such extraordinary liners, both BKP Berolina and Arkil Inpipe have again succeeded in setting a benchmark for the installation of UV-cured liners. Arkil Inpipe is currently equipping a UV unit with a new, 320m-long UV curing cable so that it will be able to cure particularly long rehabilitation lengths more easily in the future. “This measure enables us to cure up to 600m sewer pipe in one go using UV technology,” Torsten Schamer, managing director of Arkil Inpipe, says.
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Figure 1: map showing the location of the corroded twin 72in corrugated Dunkirk metal storm-sewer pipes
Critical CIPP in Colorado Severe corrosion on a storm sewer under a busy street called for emergency repair
E
ach year, utility Aurora Water replaces a significant amount of ageing water line pipe throughout the city of Aurora, Colorado (US). During a routine pipelinereplacement project, contractors discovered severe corrosion on the adjacent Dunkirk Storm Sewer. The system comprises dual 72in (1,828.8mm) corrugated metal pipes (CMP), each 1,200ft (365.76m) in length. The dual pipes were installed as a new development nearly 25 years ago. The storm piping is located under a divided, four-lane street. City authorities initiated the immediate evaluation of several trenchless installation options for an emergency repair project due to its location. Cured-in-place pipeline (CIPP) replacement was selected as the preferred choice. This article will discuss project specifications, inspection and quality-control protocols; the method used to repair a tear in a large CIPP liner; how this repair
methodology can be modelled for future repairs on liners of this size; and lessons learned.
Determining the problem Further investigation revealed that the corrosion was consistent along the length of the storm sewer and was restricted between the eight and eleven o’clock positions. A closed-circuit television (CCTV) inspection of the storm sewers was conducted to determine the extent of pipe degradation. Soil testing was also done to determine the cause for such rapid, advanced degradation. The Corrugated Metal Pipe Design Guide states the service life expectancy for aluminised steel as over 75 years when installed in a soil/water environment with a pH range of 4.0-9.0 and a resistivity of 500ohm-cm or greater. The in-situ bedding material had a resistivity of 300ohm-cm. It was concluded
that the main culprit for the corrosion was the pipe-bedding material. Therefore, it was determined that the repairs must be designed for fully deteriorated conditions.
“The pipelines were located in a busy urban intersection, so it was decided that only trenchless repair options would be evaluated�
Streamline specifications The affected pipelines were located in a busy urban intersection, so it was decided early in the design process that only trenchless repair options would be evaluated. Also, because the consequences and likelihood of failure for these lines was high,
Figure 2: the main culprit for the corrosion was the pipebedding material
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Figure 3: the liner vacuum impregnation
and the impact to public safety and property in the instance of a failure would be extensive, Aurora Water implemented a streamlined procurement process for both the design and construction. Swirvine Nyirenda, the city’s project manager, selected Parsons Brinckerhoff, with Joe Barsoom as project manager, to provide design services for this project. Barsoom and his team review-
ed the available trenchless technologies for large-diameter pipe rehabilitation. Several different technologies/products were evaluated, namely polyurethane-based products, CIPP products, spray-on cement-based products, slip lining and spiralwound PVC products. The recommended system needed the following minimum characteristics: •N o reduction in hydraulic capacity when compared with the existing system; and • F ully deteriorated design imparting an expected 50-year life for the installed pipe. The CIPP system was recommended for use. The CIPP liner was designed as fully deteriorated, per ASTM 1216-09 standards, so that the liner could withstand all external loads, including live loads, soil loads and hydrostatic (groundwater) pressure (assumed to be one foot
below the street’s surface). The existing pipes were 15ft deep, to invert at the deepest point. Given these considerations, the required thickness of the liner was determined to be a minimum of 37.5mm. Storm flows had to be maintained while repairs were being made, so only one of the two pipes could be out of service at a time. All flows were diverted from the storm sewer being repaired (west line) into the adjacent pipe (east line) until the western pipe was lined and restored to full service. Lining of the pipe was designated to occur during a period identified as low probability for heavy rainfall. The hydraulic capacity of the existing Dunkirk Storm Sewer was analysed and compared with the expected carrying capacity of the system after rehabilitation. Based on its HY-8 model, the analysis showed that the capacity of the proposed CIPP lining improved
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Figure 4: the liner vacuum impregnation Figure 5: the pipes were accessed by removing the concrete lid on the influent vault under the asphalt. This shows where it had to be cut to reach the twin corrugated metal pipes
the capacity of the existing CMP system, due to improvement of the roughness coefficient of the CIPP in comparison with the CMP.
Inspection, quality control The specifications dictated at a minimum the following qualitycontrol measures: •A sample of 1in diameter was cored from the crown of each pipe approximately 2ft from the upstream ends. Testing for the specific gravity and thickness was conducted by a local certified lab; • R estrained plate samples had to be prepared and tested in accordance with ASTM F1216-09. The lab tested for the physical properties of the restrained samples (i.e. flexural modulus and flexural strength). An additional “degree of cure” test was requested to compare the energy required to fully cure a raw sample in laboratory conditions with the energy required to fully cure a field sample in the same laboratory conditions. This test gave an indication of the degree to which the field-cured pipe was actually cured; • T he contractor was required to provide its calculations showing the theoretical inversion head to hold the tube against the existing conduit and not damage the tube; • I nspectors had to make sure wet-out was properly done by calculating how much resin was
•
•
•
applied for each shot (153lb/ft) and ensuring that each parameter was in compliance with the specs. The contractor was responsible for keeping a log with the amount of resin applied for each shot and cure temperature readings; T he contractor elected to work 24 hours a day, from the start of resin impregnation until the liner was installed and cooled. Seven inspectors were dedicated to the project to ensure adequate round-the-clock coverage; T he contractor employed its own quality-control measures that included closely monitoring the resin-catalyst ratio and the activation temperatures; B oiler and liner temperatures were monitored and recorded to ensure that heating, holding and cool-down occurred as per their theoretically prescribed plan.
Installation of CIPP liner Aurora Water selected the low bidder, Insituform Technologies, as project contractor to install the recommended CIPP liner. The contractor elected an “over-the-hole” inversion method for installation. The contractor set up an onsite wet-out facility in the staging area shown in Figures 3 and 4. No resin was stored on site, so the contractor developed a schedule by which resin was delivered in tankers as needed. Access to the pipes was
achieved by removing the concrete lid on the influent vault located under the asphalt. Figure 6 shows the location where it had to be cut to access the twin 72in CMP. Insituform also elected to execute each line as a single “shot”. Inversion was accomplished using a minimum head of 15.6ft. The host pipe was thoroughly cleaned before insertion of the liner. The contractor used “neat” resin (without any fillers) to ease the impregnation of such a large and thick liner. The measured specific gravity for the installed system had an average of 1.23. Once the wet-out of the liner began, the contractor worked 24 hours a day until the liner was fully installed and cured. Once the inverted pipe was fully cured and adequately cooled, the end was cut and all the impounded process water was pumped into a nearby sanitary sewer, again ensuring that no process water was discharged to the creek downstream. Rehabilitation of the west line proceeded without a hitch and the full extent of the 1,200ft pipe was installed in the allotted five days. However, during the installation of the east line, the inversion head could not be maintained beyond the inversion of about 1,000ft. Additionally, the contractor and onsite inspectors noted that process water was coming
Figure 6: cut end of the cured liner
“Rehabilitation of the west line proceeded without a hitch and the full extent of the 1,200ft pipe was installed in the allotted five days”
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Figure 7: tear in east liner
“Investigations revealed a tear in the liner, which was attributed to the pullback lines’ hooks puncturing the liner”
Figure 8: sample cores were taken around the tear to determine the extent to which the resin had washed away. The tear was then reinforced with three bars on 12in centres
out of the adjoining storm inlets and cracks in the street. To address these challenges, the first order of business was to ensure that all the process water was impounded so that it could be pumped into a nearby sanitary sewer. Investigations revealed a tear in the liner, which was attributed to the pullback lines’ hooks puncturing the liner. The contractor developed a procedure to save as much of the inverted liner as possible. The “turn back” was pulled back until the inversion pressure could be maintained and no process water was leaking, either from the road or adjoining storm sewer inlets. Once achieved, the contractor proceeded with the curing process. Due to the excessive “turn back,” extra care was taken to ensure uniform curing of the liner. This process took twice as long as originally scheduled. However, on completion, the major task of cutting out and removing the turn back was executed. Once the “turn back” was removed, the contractor inspected the pipe and the tear was exposed and evaluated to develop a repair strategy.
Repairing the tear Sample cores were taken around the tear to determine the extent to which the resin had washed away. The cores were tested for specific gravity and the results were compared with the theoretical specific gravity values. The outer cores had specific
values equal to the theoretical values. Based on this information, the extent of the tear and the necessary repair was determined. The tear was then reinforced. The steel reinforcement comprised three bars on 12in centres. This reinforcement ensured that the patch had sufficient strength to withstand all the loading. Next, the contractor proceeded to remove the torn liner and replace it with a patch, using its patented procedure. The process included an ambient cure of the patch. To line the remaining pipe, approximately 120ft of CMP, the contractor elected to use its Air Steam Inversion Cure setup from the downstream end. The repair design called for a minimum 10ft of overlap between the two liners. The end of the interior liner was bevelled to provide better hydraulics at the flow line. On completion of the repair, the annulus between the liners at the overlap began to leak. The contractor repaired this leak by injecting a low-viscosity hydrophilic grout, DeNeef Flex PURe LV. Next, the contractor removed the torn liner and replaced it with a patch. The process included an ambient cure of the patch. CIPP samples were prepared and tested in accordance with ASTM F1216-09. Testing for cured liner thickness, flexural strength, flexural modulus and degree of cure were performed by a local independently certified laboratory.
The contractor also monitored the inversion head to ensure that there was no excessive stretching of the liner. The engineer was provided with all the resin wet-out sheets for review and verification that the correct pounds of resin per foot was being installed. The contractor monitored process-water temperatures. They also employed some of their own QA/QC procedures with regard to the resin/catalyst ratio and the reaction temperatures. The installed liner exceeded the specified design parameters.
Measuring degree of cure For this testing, two samples are needed, an uncured sample and a sample representative of the finished CIPP. Both should include the same felt and resin as that being installed. The uncured sample needs to be chilled immediately in dry ice following wet-out, and delivered to the laboratory (still under cold temperature) within 24 hours of wet-out. Sample size does not have to be very large: 1-2 grams will be sufficient. On the cured sample, it is recommended to test the exterior as well as the interior. A differential scanning calorimeter is used to calculate the degree of cure. It measures heat flow going into a sample as its temperature is raised. (The instrument measures the energy needed to increase the temperature of a sample at a constant rate, in this case 10ºC per minute. This energy will increase or decrease due to the sample undergoing events such as phase changes and chemical reactions. During an exothermic event, the machine does not have to add as much energy to the sample, whereas during an endothermic event, the machine will have to add more energy). This gives peaks during exothermic events such as curing, and valleys during endothermic events. On arrival of the uncured sample to the testing laboratory,
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a small portion is immediately inserted in the machine for testing. The temperature is ramped from -50ºC up to 250ºC. This gives a curing peak. The energy under this peak (measured in joules/gram) represents 100% uncured. The same method is used on the cured sample. Compare any residual peak with the uncured peak: if the sample shows no peak at all, it will represent 100% cured. Test results correlate with previous work relating the degree of cure to ultimate physical properties. These showed that specimens that had a degree of cure over 85% had achieved their maximum flexural and tensile properties.
Lessons learned Four key observations were taken away from the project. When dealing with large-diameter water-inverted CIPP, care must be taken to ensure that a robust system is developed to impound/ control the discharge of the process water. The specifications must have clearly defined QA/QC procedures. In this case, the degree-ofcure test, which compared the in-situ liner cure with the fully
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cured laboratory sample, was included. The average measured degree of cure was 97.5%. The project team (i.e. the contractor, the owner and the engineer) has to be a cohesive unit in order to deal successfully with unforeseen circumstances. Due to the proximity of a creek, extra effort was taken during the design phase to develop a procedure for impounding the process water. This had huge rewards when the tear occurred.
A tale of teamwork Projects tend to challenge even the best-laid plans; one barrel was installed with ease and the other presented challenges. In order to deal effectively with unforeseen circumstances, it is imperative for the project team to be cohesive. In this case, Insituform, the engineer and the City of Aurora worked together to overcome the challenges presented by the second installation. The project risks were identified early in the design process and the plan to identify and allocate risk was deeply embedded in the city’s project-delivery procedures (eg. development of
a risk register, prequalification of contractors, etc.). The project deck was further stacked for success because the specifications dictated a robust QA/QC plan, which was further augmented by the contractor’s own QA/QC procedures. Allowing sufficient time to resolve issues can significantly benefit a project by enabling each team member to offer his/ her ideas for the successful delivery of the project. In conclusion, CIPP was a successful repair method for the Dunkirk Storm Sewers. It delivered a full structural repair to the storm sewers with minimum disruption to City of Aurora residents.
Figure 9: liner sample
“The project team has to be a cohesive unit to deal successfully with unforeseen circumstances”
This article is an edited version of the paper ‘An emergency large-diameter CIPP repair’ authored and presented by Joe Barsoom PE, senior associate, Stantec, at No-Dig Madrid 2014 Editorial Editor Luke Buxton T +44 (0)20 7216 6078 E luke.buxton@aspermontmedia.com Head of production Tim Peters Senior sub editor Jim Adlam Sub editor Woody Phillips Editorial enquiries T +44 (0)20 7216 6078 F +44 (0)20 7216 6050 www.trenchless-world.com Advertising production Sharon Evans T +44 (0)20 7216 6075 E sharon.evans@aspermontmedia.com
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