Alpine
How to deal with difficult rock
TBMs
Could mechanised tunnelling work on the Fehmarnbelt?
Waterproofing Sealing Crossrail tunnels
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July / August 2014
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CONTENTS
1
Why did the woman cross the rail?
G
ermany has Angela Merkel, World Cup mascot and chancellor for almost 10 years now. The US had Condoleezza Rice, secretary of state from 2005 to 2009, followed by Hilary Clinton until 2013, who is about to say ‘Zip it, Bill!’ and possibly become the first female president of one of the most powerful nations in the world. The UK had Margaret Thatcher… almost a quarter of a century ago. In the mid-seventies Argentina’s Isabel Martínez de Perón was the first female president in the Americas. Since 2007 the country has been led by Cristina Fernández de Kirchner.
News 2
For 30 years now, Switzerland has regularly had prominent female figures as part of the country’s Swiss Federal Council that serves as the nation’s head of state. Between 1990 and 2011 the two Marys held the presidency of Ireland – Mary Robinson and Mary McAleese. Finland had a female president from 2000 to 2012 – Tarja Halonen. The Scandi-Baltic nation’s women became the first in the world to have unrestricted rights both to vote and to stand for parliament. Britain had suffragette proponent Emmeline Pankhurst… around 1900.
“The Mayor of London, Boris Johnson, whose hair can be seen from space, has finally said something useful”
Features 4 Alpine projects TBMs 12 Waterproofing 18 Contacts 21 Classified advertising
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The UK is clearly still behind the times when it comes to high-level career opportunities for women. In a blatant attempt to conceal his membership of the Old Boys’ Club, UK Prime Minister David Cameron has just reshuffled his cabinet and promoted more women to top positions within the government.
And the Mayor of London, Boris Johnson, whose hair can be seen from space, has finally said something useful too. He spoke at a Crossrail event to mark National Women in Engineering Day, where he stated: “There is much more to be done to encourage more women into what historically has been a male-dominated field.”
Next month
If you’re not blinded by his magnificent blondness, you can see he has a point that chimes across the industry.
Australasia
With the UK needing to double the number of annual university engineering graduates to 87,000 to meet demand, Crossrail is urging more women to become engineers to prevent a seizure of skills.
Shaft sinking & raise boring
Just around the corner, Thames Tideway bosses have also declared they want half of their staff on the £4 billion (US$6.9 billion) tunnel project to be women by the time the project is completed in 2023. And no, I’m sure they’re not talking about men going under the knife. Of course, a person should never get a job, or lose out on a job, based solely on their gender, sexuality, race or age, but it is evident we need to accept this expansion of our horizons sooner rather than later. LUKE BUXTON, EDITOR luke.buxton@aspermontmedia.com
Drill & blast Roadheaders
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NEWS
TBM Tiger ready to bite in Ontario In Canada, Robbins’ tunnel boring machine Celtic Tiger is gearing up to bore out the C$400 million (US$373 million) Hanlan water main in Mississauga, Ontario. The machine will begin at Mississauga’s Lakeshore area and drive 5.8km north. The Hanlan Water Project, needed to meet the water demands of future population growth, includes the installation of a 2.4m-diameter feeder main and a 1.5m Mississauga City Centre sub-transmission water main. The feeder main will run approximately 14.5km from the Lakeview water-treatment plant on Lake Ontario to the Hanlan reservoir and pumping station. The sub-transmission main will run approximately 6km from the Hanlan reservoir and pumping station to the intersection of Cawthra Road and Burnhamthorpe Road. Construction on the project began in 2011 and is slated for wrap-up by early 2017.
JV to sign $1bn Northern Line contract for London London Underground has selected the Ferrovial Agroman Laing O’Rourke joint venture as the preferred bidder for its £600 million (US$1 billion) Northern Line extension. The UK-Spain JV will build two new stations at Battersea and Nine Elms as well as undertaking tunnelling and track work, installing escalators and lifts, and providing power supply and station fit-out work. The contractor will sign in late August with construction due to start early next
The new stations could be open by 2020
year. The extension could be open by 2020. The joint venture saw off competition from Balfour Beatty and Bam; Costain and Sir Robert McAlpine;
and Bechtel and Strabag. Laing O’Rourke’s portfolio includes tunnelling and transport work in London, Hong Kong and Sydney (Australia).
Stockholm Metro awards tender for design of Arenastaden extension mmm$lcj#]cX^$Z[ Engineering consultant WSP’s Swedish outfit has won the contract to design a new subway route in Stockholm. The company will etch the line from Odenplan in central Stockholm to the new commercial and entertainment district of Arenastaden. The scheme will be the first phase of the largest public transport initiative in Stockholm in 40 years. A total of nine new stations and 19km of new subway will be built. The groundbreaking ceremony is expected to
“This is going to be a take place by mid-2016 challenging project from with the first metro train both technical and planexpected to roll on the ning perspectives,” WSP first leg from Odenplan to Sweden managing director Hagastaden in 2020. Two years later it will extend to Magnus Meyer comJ^[ j^_Yad[ii e\ W if_Z[hi m[X WdZ j^[ Z_ijWdY[ mented. Arenastaden. h[iebkj_ed e\ j^[ BWi[h ?dj[h\[hec[j[h ki[Z _d KBIÈh BdjaY VcY HZ\bZci BZVhjgZbZci ioij[c$
By 2022 Stockholm Metro trains should run from Odenplan to the new station at Arenastaden
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alpine projects
Dealing with difficult rock AlpTransit is offering innovative solutions for disturbed geology on the Ceneri Base Tunnel in the Swiss Alps Works at the Saré cavern of the Ceneri Base Tunnel
Crew using Dieci Pegasus telescopic elevators in the northern stretch
“We are crossing our fingers and we hope to progress quite comfortably until breakthrough by the end of 2015”
T
he Ceneri Base Tunnel is Switzerland’s second-largest rail-tunnel construction project. The north portal is situated in Vigana and the south portal in Vezia. Due to dense residential areas close to the portals, and crossings under or over important traffic routes, the two tunnel tubes are being excavated mainly from Sigirino, from which driving is in progress towards both portals. Excavation of both tubes is taking place by conventional drill and blast. This work began in 2010 and will continue until 2015. The main excavation phase was preceded by the preparation of site facilities (between 2006 and 2008) and excavation of the intermediate access at Sigirino by TBM, between March and November 2008. Due to the issues mentioned above, only a few hundred metres at the portals were excavated from outside (1km total). Excluding the excavation of the approach trenches, underground excavation started at the north portal by the end of 2008 and finished in January 2012; at the south portal underground excavation started in April 2010 and finished in May 2011. In the north, the contractors had to cross under the highway, with less than 10m clearance from the tunnel roof to the asphalt. This was addressed by using a jetgrouted system of columns over the roof of the future tunnel. In the south, engineers faced a similar situation. On one section they had a road tunnel crossing over the new alignment with a 4m layer of rock in between. Also, works entailed crossing under a few houses with a maximum distance of 10m from the basements. Not far from the approach trench in the south portal is a villa
of historical importance. Contractors had to minimise vibrations during excavation. By using vibration monitoring and slow excavation speeds, reduced lengths of excavation steps, excavation in subsections and reduced explosive quantities, they successfully avoided any damage to the building.
Rocky road AlpTransit had originally expected excavations to finish at the end of 2014 for the north stretch towards Vigana, and mid-2016 for the south section towards Vezia. “We encountered more difficult geological situations than expected; we now estimate to break through at the north by the end of 2015, but excavation works in the south are estimated to finish earlier – in the first half of 2015 – as progress has been quicker than thought,” AlpTransit project engineer Paolo Vicentini comments. “We excavated through several fault sets characterised by disturbed rock layers with variable thickness and orientation. Spacing between faults also varied highly in the different sections and we came across many disturbed sections where we had to slow down.”
Thanks to speeding-up measures explained below, this delay in the excavation toward the north will not affect the opening date of the tunnel by the end of 2019. The contractors encountered different kinds of gneiss (Ortogneiss, Paragneiss, Micaschist, Amphibole-bearing gneisses and Amphibolites). The gneiss rocks were metamorphosed by the pressure and heat in different orogenic cycles (the latest is the Alpine). During evolution the crystal grains became orientated parallel to each other. These bands in the rock define the main foliation (or schistosity). By mid-July this year the north drives will meet the next disturbed section, the Isone-zone. After this, no further major difficult sections are expected. “We are crossing our fingers and we hope to progress quite comfortably until breakthrough by the end of 2015,” says Vicentini. Another important disturbed area was found when excavating at Saré (in the south section of the tunnel), an underground diversion that will allow AlpTransit to begin running railway traffic while it excavates an extension of the tunnel towards Italy. “In this first project phase we provisionally exit the tunnel close to Lugano, but we leave underground the chance to go ahead in the future for excavation to Italy,” Vicentini explains. The Saré diversion comprises two big caverns heading towards the south. At the bottom are two exits, one for the first-phase tunnel and one in preparation for the future tunnel extension.
Choosing the tools In some sections main contractor Società italiana per Condotte d’Acqua (Condotte) and its partner Cossi Costruzioni did not need to excavate with drill and blast as the rock was so disturbed that they were able to excavate it
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with the bucket of the excavator. “In some places we needed only hydraulic hammers,” Vicentini says. “In the Saré diversion’s west cavern the situation was troublesome: we had to divide the excavation phase into sub-section phases. We had three sub-sections for the top part for about 60m of excavation, only after excavating the big invert.” In the original plan, it was agreed to excavate two-thirds of the tunnel with drill and blast due to geology; the south would have been built by TBM. The winner of the tender was able to offer both solutions, but drill and blast promised a lower price.
Lining and recycling Excavation and lining works for the two small sections near the portals were awarded to joint venture Matrosud (main contractors Pizzarotti and Implenia) for the north section and the joint venture CPV (CSC Lugano and Pizzarotti Bellinzona) in the south. The critical path in the north caused general delays in the schedule. The way AlpTransit is dealing with this problem is to start lining the tunnel while excavating – this began in the middle of last year to accelerate works, rather than excavate and then line, as in the original plans. Concrete for lining is provided by sub-contractor Holcim, which installed a double batching plant underground. Holcim also provided the site with aggregates, but since some of the tunnel’s excavated material excavation is usable as gravel, AlpTransit is also
recycling part of the muck. “An important thing for us is excavation material management,” says Vincentini. The good material from excavation is kept in a stock pile, then crushed. This provides about 30% of the sand and gravel to produce concrete for the site.
Innovations on the job Contractors are also using a hanging platform to keep the surface at ground level free for works and traffic. “TBMs have a long backup train; we have a similar thing called a hanging platform provided by Rowa. It is a steel construction, about 300m long,
hanging on the ceiling of the tunnel, using anchors. On it we place all equipment needed for excavation, including transformers, ventilation coils, pipes and containers for people. “By using this, you keep the floor free to pull traffic from loaders, to move drilling equipment and for people to pass, and it should be helping to build the concrete invert. I have come across examples of these systems used during TBM operations but not in drill and blast before,” Vicentini says. Opening of the Ceneri Base Tunnel is scheduled for December 2019.
5
Above left: in the Saré west cavern the excavation was divided into smaller phases because of disturbed rock Above: looking south from Sigirino. Excavation works in the south are estimated to be completed in the first half of 2015
Focus on safety “During excavation along particularly delicate zones and despite the applied safety measures, we had three situations where the roof collapsed (one in the south and two in the north stretch), which we faced efficiently, and could resume work shortly afterwards,” Vicentini explains. “In all three situations working teams reacted readily and took the right measures by pulling behind the equipment and waiting for the collapse to come.” AlpTransit works to the highest safety level. The contractor has initiated a safety
The specialist for tunnelling equipment and logistic systems
programme called Behaviour Based Security System (BBS). The principle is that workers on the site are stimulated to take care, to implement and suggest safety measures. “BBS is working well and gives good results,” Vicentini adds. Despite the careful application of safety measures, it was not possible to avoid a fatal accident. One worker died in the tunnel in September 2010 at the start of excavating the north stretch from the intermediate access.
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Life on the long rail Final breakthrough in the east tube took place in October 2010, followed by the west tube in March 2011 Route of the Gotthard and Ceneri Base Tunnels
World Tunnelling reflects on works at the Gotthard Base Tunnel as it approaches its grand opening
T
he Gotthard Base Tunnel, at 57km the world’s longest railway tunnel, will go into operation in 2016, five years after final breakthrough took place. Since 2009, installation of the railway systems in the tunnel has
proceeded in parallel with final excavation and construction work. The first pilot train runs took place in mid-December 2013 at speeds of up to 220km/h on a 13km section between Bodio and Faido. In 2019, the flat route through the Alps is scheduled to be completed with the Ceneri Base Tunnel. More than 70% of the 15.4km under the Ceneri has been excavated so far.
15 years’ driving The Gotthard Base Tunnel runs from Erstfeld in the Swiss canton of Uri to Bodio in Ticino. The tunnel was designed with two single-track tubes, linked to each other every 325m. At the onethird points at Sedrun and Faido are multifunction stations, which contain emergency-stop facilities. The tunnel was therefore divided into five sections, which for part of the time were constructed simultaneously: Erstfeld, Amsteg, Sedrun, Faido and Bodio. Eighty percent of the Gotthard Base Tunnel was excavated with TBMs (Erstfeld, Amsteg, Faido and Bodio) and 20% by drill and blast.
The northern approach comprises a 5km-long overground track south of Altdorf railway station in Uri. At the southern end, there is a 7.5kmlong overground section from the south portal of the Gotthard Base Tunnel to Biasca. The northern overground section was handed over to the railway systems contractor in September 2013. In the same month in the south, the new main line was already inaugurated.
Setting the trend Some of the sections were completed ahead of schedule. The Erstfeld section is 7.8km long. Here, the first 600m of the Gotthard Base Tunnel was
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constructed by cut and cover. Branch-offs in the tunnel ensure that a future extension of the tunnel to Brunnen, in the canton of Schwyz, is possible without interruption of operations. Driving began in December 2007 and was completed in September 2009, half a year earlier than planned.
battling the blockage
enormous quantities of materials had to be transported through the two shafts. To the north, the difficult Tavetsch Intermediate Massif and Clavaniev Zone had to be penetrated. To absorb the large squeezing movements of the rock, deformable steel rings were installed. Thanks to the construction method used, excavation work was completed half a year
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A diagram of the Gotthard tunnel system
Before driving could begin on the 11km Amsteg section, a 1.8km access adit had to be constructed. A 1.8km cable tunnel was also created, which leads directly into the underground centre of the Amsteg power station. The two TBMs started out from Amsteg in October 2003 and January 2004 respectively. Breakthrough in the east tube took place in October 2007. In the west tube, however, water ingress in June 2005 washed loose material into the cutting head and blocked it. In parallel with 2,800m of injection bores, a reverse drive was cut from the east tube. In mid-November 2005, the miners succeeded in releasing the cutting head, and in mid-December 2005 the TBM could resume driving. Despite this delay, breakthrough to Sedrun took place six months ahead of schedule at the end of November 2009.
tough Rock The 8.5km Sedrun section was only accessible through a 1.5km access adit and two 800m-deep supply and hoisting shafts. This situation presented a special challenge to construction operations and logistics, since
A train carrying concrete in the tunnel
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Tough application, ingenious solution
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alpine projects
ahead of schedule in the autumn of 2007. When driving to the south, numerous fault zones were more extensive than expected. Here, too, deformable steel rings were used in some cases. Final breakthrough in the east tube took place in October 2010, followed by the west tube in March 2011. Later this year construction work in the Sedrun section will be complete. The large storage halls and numerous container buildings on the installations site have already been removed. Part of the present installation site will be turned into wetland. The final projects in Sedrun will be completed in 2016. Similar geological problems hit the 15km Faido section. In the area where the multifunction station was originally planned, the steel beams that were installed could not withstand the pressure from the rock. In the areas of heavily squeezing rock on the northward drive, extra-strong supports were used. Despite these measures, in January 2008 in the west tube, the backup train of the TBM became trapped. Equipment had to be removed or relocated, and in some places shotcrete had to be chipped off laboriously by hand and steel rings had to be partly removed. In October 2010, the first final breakthrough could be celebrated between Faido and Sedrun in the east tube, and in March 2011, the last final breakthrough of the Gotthard Base Tunnel took place in the west tube.
Deformable steel arches were installed in the tunnels in zones with squeezing rock
In September 2013, all of the underground built structures were handed over, and by the end of January 2014, the construction site of the tunnel-construction contractor was closed. In March 2006, an unexpected fault zone caused the TBM in the west tube of the Bodio section to become jammed. Driving could only continue after 10 days, while the cutting head was roofed over. The high rock pressure caused deformations in the excavation support, which made extensive reprofiling work necessary. In the autumn of 2006, breakthrough to Faido took place in both tubes.
Spoil processing For the Gotthard Base Tunnel, a tunnel system with a total length of almost 152km was excavated. This produced around 28.2 million tonnes of excavated rock. Around 33% of the excavated rock was suitable for use as aggregate for concrete and shotcrete within the tunnel. Unsuitable material was used for embankments, landfilling and renaturing, as well as further projects such as the creation of bathing and nature-reserve islands in Lake Lucerne.
Commissioning In mid-December 2013, commissioning of the Gotthard Base Tunnel began with the first pilot runs. An approximately 13km pilot section in the west tube between the south portal at Bodio and the multifunction station at Faido has already been fitted out with the necessary railway infrastructure systems. The purpose of the pilot-operation phase is to obtain preliminary confirmation that the entire tunnel system meets the specified requirements. Between December and June trains travelled over the pilot section at speeds reaching a maximum of 220km/h. From October 2015, the full length of the tunnel will be opened for test operation at speeds of up to 280km/h.
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Truck loads built up heat with intensity in the 1999 Mont Blanc Tunnel fire
Fire under the White Mountain The Alps are no stranger to tragedy and the tunnels traversing them are no exception
A
snowy peak 4,810m (15,781ft) above sea level is the last place you would expect to find fire. In the rocky core of Mont Blanc a road tunnel runs for 11.6km (7.2 miles) connecting France and Italy, reaching an elevation of 1,395m. It opened 49 years ago. Its history had been charred by truck fires on 35 occasions before a fatal incident in 1999. The previous blazes were detected early and extinguished, but March 24, 1999, was a black day.
Author: Mark Tansey, FireVu’s business development manager
Fuelling the fire Drivers in the tunnel attempted to alert the driver of a Belgian truck carrying flour and margarine that smoke was coming from under the cab. Finally he stopped and tried to manage the problem. Two minutes after the driver had attempted to put out the fire, tunnel employees raised the alarm. There were at least 10 cars and vans and 18 trucks in the tunnel, which became trapped because of the airflow direction. Combustible loads on the trucks
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The aftermath of the Mont Blanc Tunnel fire
trapped in the tunnel prolonged the disaster: the flour and margarine cargo alone was equivalent to a 23,000L oil tanker. The inferno burned for 53 hours and claimed 39 lives, as temperatures exceeded 1,000°C (1,830°F). Repercussions included €13.5 million (US $17.5 million) in compensation paid by the Italian tunnel operator and a custodial sentence for the head of tunnel security. The tunnel was closed for three years for renovation and fire-safety upgrades. Within two years, further fatal tunnel disasters struck other Alpine regions, namely Tauern and Gotthard.
“The inferno burned for 53 hours and claimed 39 lives, as temperatures exceeded Fast burn 1,000°C” Fires in a tunnel present particular
dangers. Vehicles burn far more vigorously in confined spaces owing to High Heat Release (HHR) rates. The HHR is four times as powerful in tunnels as in the open air. While a car fire produces 3-5MW of heat, tankers produce
as much as 200MW. In 1999 the Mont Blanc tunnel had a number of tankers and trucks with combustible loads. Dense smoke can be highly poisonous. Mont Blanc’s fumes contained cyanide and carbon monoxide. The speed of the smoke outpaced people who left their vehicles and ran; those who attempted to escape using their vehicles found that the smoke choked off the oxygen to their engines, which ground to a halt. A fire a tunnel poses specific challenges to firefighters: intense heat; thick, toxic fumes; poor or no visibility; confined operating space for emergency services; and airflow that generates aerodynamic disturbance affecting smoke behaviour. Further problems come with communications. With international tunnels, authorities might speak different languages and encounter difficulties working together under pressure.
Fire-detection measures It is essential that fire detection and prevention systems enable fires to be contained and extinguished before developing into unstoppable infernos. Indeed, a new EU directive came into force at the end of April 2014 that should help reduce major fires immensely. Incidentand fire-detection monitoring systems need to be implemented for tunnels over 500m long. For those over 3,000m, video systems are mandatory. Good progress has
• high flexibility and elongation at break • long life expectation • calendered with a bright signal layer • project-optimised widths from 2 up to 4 m • no toxic fumes in case of fire • simple installation with hot air
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been made in implementing the directive. Many countries have exceeded the requirements. However, others are lagging behind and might need more time to meet their obligations.
Fire suppression in practice Many fires start with a smouldering phase. At this stage fires can be dealt with, even by non-emergency staff, contained and extinguished. Fire-detection systems need to recognise danger early. Heat-activated solutions (such as cable that short-circuits when the thermoplastic melts) generally take too long, and provide no visual information to help tackle the blaze. Other systems that can be considered include infrared, air sampling and optic sensors. Visual smoke detection (VSD) uses changes in its wide field of
view to alert operators, remotely or on site, to potential fire danger. Its effectiveness is not affected by car fumes or vehicle movements. During tests at Sydney Habour Tunnel on a controlled vehicle fire generating temperatures in excess of 500°C, FireVu’s VSD solution generated an alert after just 14 seconds with a further 30 alerts. Other fire-suppression methods, which can be used effectively in conjunction with fire-detection solutions, include: • S prinklers, standpipes, hydrants; •D eluge, possibly with foam; •W ater curtains – efficient at blocking flames spreading and good for compartmentalising fires, protecting tunnel structures and facilities and cooling temperatures; and •W ater mist. Steps such as those introduced
by the Mont Blanc authorities (checking trucks before they enter the tunnel and educating tunnel users) are to be commended. There needs to be co-operation towards finding the best solution for each tunnel from fire engineers, emergency services, governments, workforces, owners and other parties. Fire-detection and prevention systems should not be seen as extras, but essential tools to protect tunnels and their users from catastrophe. The potential cost in lives, property loss and disruption means that investing fully in fire protection is a sound use of funds. Tunnel fires can be tragic, terrifying and costly. Technology has matured, is proven and available to provide very early warning of fire, which ultimately saves lives.
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“Tunnel fires can be tragic, terrifying and costly. Technology has matured, is proven and available to provide very early warning of fire, which ultimately saves lives”
This article is an edited version of FireVu’s business development manager Mark Tansey’s article ‘Tunnel fires: why they are vulnerable to disaster, consequences and possible 10.04 solutions’ Belloli inserzione inglesethe New 178x124_Layout 1 23.06.14 Pagina 1
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TBMs
Flexible solutions for Fehmarnbelt? Though initially rejected as being too costly, an optimised TBM solution could be a viable option for the Fehmarnbelt Fixed Link
“The TMG and TMF concepts for railway and roadway tunnels allow for a single tunnel to provide the capabilities usually offered by two parallel tunnels”
I
n January 2011 the Danish authorities took the preliminary choice of an immersed tunnel as the preferred solution of the 18km Fehmarnbelt Fixed Link between Denmark and Germany. This recommendation, following consultation with project manager Femern, was based on a comparison of a cable-stayed bridge and an immersed tunnel, with the latter being selected because of its lower environmental impact. The tunnel group also developed a three-tube TBM tunnel proposal, which, despite having lower environmental impact than an immersed tunnel, was rejected because of its higher cost. A new optimised TBM tunnel solution, based on two innovative and cost-effective concepts for the construction of tunnels, has been proposed by Silvino Pompeu-Santos of SPS Consulting. In the optimised TBM solution, the link is formed by two tubes, one for rail traffic and the other
for road, both provided with separated and isolated directions of traffic, and adopting advanced and reliable safety means for the evacuation of the users in the event of an accident or fire.
TMG and TMF concepts The Tunnel Multi Gallery (TMG) and Tunnel Multi Floor (TMF) concepts for railway and roadway tunnels respectively allow, with a suitable arrangement of the cross-section of the tunnel and the adoption of additional specific measures, for a single tunnel to provide the capabilities usually offered by two parallel tunnels. This reduces costs and improves safety.
Optimised TBM solution The proposed railway tunnel is 20km long and has an interior diameter of 11.50m, being provided with an intermediate floor slab and a central wall, creating two independent and isolated railway galleries (ballastless), one for each direction of
A cheaper choice The cost of the optimised TBM solution was estimated on the basis of the cost ratios (the global cost divided by the excavated volume) of railway and roadway tunnels built around the world employing TBMs. In five cases concerning railway tunnels, cost ratios between €234/m3 and €328/m3, and an average value of €287/m3 were obtained. In seven roadway tunnel cases, cost ratios between €286/m3 and €545/m3 and an average value of €395/m3 were obtained. On the Fehmarnbelt Fixed Link, the costs of the tunnels will be €1.15 billion
for the railway tunnel and €2.4 billion for the roadway tunnel, bringing the total cost of the link to €3.55 billion. These figures admit cost ratios of €450/m3 for the railway tunnel and of €650/m3 for the roadway tunnel (values that are 50% higher than the average values above). They also take into account the excavated volumes of the tunnels as 2.54 million m3 and 3.63 million m3, respectively. Therefore, the cost of the optimised TBM solution represents less than two-thirds the cost of the immersed-tunnel alternative, which was estimated as €5.5 billion (2008 prices).
travel. Each gallery offers about 38m2 of cross-sectional area, and a service gallery below. The railway galleries are provided with 1.4m-wide emergency walkways on the outer side. The exterior wall of this tunnel is about 0.5m thick, so that, allowing about 0.1m clear space to be injected, the diameter of the excavated tunnel will be 12.7m, a common size for TBM tunnels. Both emergency walkways have escape doors at 400m intervals that give access to vertical access galleries. The service gallery is equipped with emergency monorail electric vehicles that are parked at the portals of the tunnel and run suspended from the slab, to provide local access and the evacuation of people in the event of accident or fire inside the tunnel.
Roadway tunnel The proposed roadway tunnel is 19km long and has an interior diameter of 14.2m, provided with two intermediate slabs, creating two stacked roadway galleries (independent and isolated), each for one direction of traffic, and a service gallery below. Each roadway gallery has two traffic lanes, an exterior emergency lane and emergency walkways on both sides, in a total width of 12.6m. The exterior wall of the tunnel is about 0.6m thick. Considering about 0.1m clear space to be injected, the diameter of the excavated tunnel will be 15.6m. The road tunnels also have escape doors from the emergency walkways every 400m, giving access to vertical galleries. The traffic galleries of both tunnels are equipped with longitudinal ventilation through jet fans. On the extremities of the roadway tunnel, polluted air will be extracted to treatment plants. For fire safety, the traffic galleries are fitted with active devices for detection and attack, acting jointly. Heat sensors and smoke-detection systems will
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TBMs NASTT’S TRENCHLESS TODAY | SUMMER 2014 pumped out of the tunnel through pipes placed along the top of the
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NASTT.ORG Cross-section of rail tunnel in the
Batilla terivato et; in adhui conost rei siconsu lintro Quiu erebefe ripteris etifecre, que teri senatus Marit grae quam ditea service quemoerus, gallery. new TBM plan: tam in di sensintem quam inium suncum ad condessa me tum nesimis nocut con ste es comnem ide et; hos separate gallery publis hil vocributus. re cum eo, C. Ad atquemplina, note, nictu it firis nequidepos, nonsid Environmental impact for each Resse fir que quam non addum dertere scerris et senitea ina consultiu mantium et Catuam practe etiam hos ocridem newtaleger TBM solution will not is se direction, pere pl. Vertemedo, nora num. sendacr The entiam cerurni hilicaela nihintrae with traessed disturb the natural seabed, which escape gallery Es hae cus, nocchus et co inam nosto iam sin numenam in sentere stiam, convoli cipior linterit, quod mei sentraet includes a large area of thecerimil issinclus. and monorail nem publici endeori tiestu vivid re con inem estribus et; inceserum, efericae tat vit nicendu German Natura 2000 iam quit, quemo huc tellestor quodium vis cerevid Nenihilin vium publissus, duc (protected mus sestandem below. me rei Plain scidientiam tunnel section condacii prit, suntemque es sedo, untereh ebatur. permis. national heritage) site. only possible disturbance and publiquas section Enitum perobsendius nontela ia invessime pernirmihil Ne pultusThe se comni scent. Omnicae tiaelis inat L.(left) Asdam of natural habitats would withconsulius escape intrur. vid cus consulos vilis alesseriu quidestrus nertem hocus, consum omne istari publi illemoccur publiculla vit, in-shore, placingnos theat, bored staircase que (right) pulares Catum, sil veriam. Sulariumus itimorum porum horum mente Maremulium factus on confirmihi, cae egit dicultuidet nihilic material in nos the et reclamation actam publinirid prorus. Quid rectoraet, nos, cone paticas est ingulic onvoculiciis cutus ex dem ia terraareas, in tuus audam Romne quita, onvivit, the nonere, boring vehebunumCross-section of venderehemus pultus, nonvere, nos ca in tescem pora quam. Soli quium ur.depending Epopora, clut quo etil huconfere technology used. earthCateret; pres- Catiquam road tunnel: pore conscerfir qui ses consis, quod serferc endaci tam nequide num sessultis aus fortum ia If remus us co te non balance-type TBM machines separate level for ffrehem sulistissis aucissu piorum aperum inatquos et; num et; et que Etrum autsure foratuusquod iam tem conte manum. eris. are used, the bored material will in each dicidin vistra? Ita, consum nium locaeque terei pra dum iam ocatuis Hen antra ne opoptil us ocurbi egernum viris, direction, opublia pos, need treatment, because with escape derioraelus et? Nos consignos, C. Us tatam Patuis opulto Catiferis. Catrorumnot consu stisany oma, ut venatero vidines modient ifecta cler in it is ‘virgin’ underground gallery/monorail Solis viviri pulego vis, Patabes! Erbit; hum ommo publiisqua dii si patil actante moraet; horterions id ad nosmaterial. co mo vivilieniu quem incum, If slurry or mix-shield below. Plainserbem tua nonte is. Sena, nos se patiem obsenat inpraci tum publingulem vermilica nox no. Ublicae toruro hicitype sedeTBMs mentebem in inum are rem used, it will be necessary tunnel section Med iumus hae inam movessensus pracipio conferi, cotastrora mius acrei esiliu quem quost L.just Catus, C. Entem esillartes caveres? to separate the bentonite fromcomnihi(left) and section sen neri, obus non se conloct aribus con patquit re cure, que noximpr demurbertiam unum essilicae rei stodiu licissici consupe the excavated soil,ego which is a idessus? int vese abem, highteredeffre publi distributed peceps, sesalong bonessultus, one side, sissign oximum automatically activate withmoverum escape sent. in hi, pero viricauciam, sultora no. Cupio water-mist pertili civit. nozzle Sp. Ad renis ponsultior ubliissum intem placed sa Muliuris. common Vive, quitus senam consuntesi unul ure poendam and reliable process.pra inat, staircase discharged into tubes pressure (right) egilina riurit? Nostempl. Viviurniam iaciem ensum inequis intus Thefit. volume of bored material along etreo the underside of the slab toad in Etre systems to Ubit? reduce temperature. pules? Untis et cutemquam sendeferidet actum nihilis, fit aceris senatus simanulius eorunt. placedintractore, in the reclamation wells installed alongMae, the tunnel Pio etiatoreibe Each traffic gallery is provided publincus sedo,drains quamregularly la dit? Andessul vit perum The esit;effluent C. Arisulint. cepon maximan areas noc, is about 6.2sid million m3, dacchum rem neme tur, bottom. is then Decienique with effluent nocum prae, Ti. etravocupio, et vil hus essente conferum autes egit. Vere con is ad faciis notiquonsu estande nericon clernum eore que nos, ment in redo, que consisu ltorununtem et; nosta, cla iustam lisses! Sere, aucomne querid consule gerfit Catum etis simorente, SPECIALIZING IN ALL facerdiem. Us. Onsus, nostem pro coenimis, conosti linamenat, UNDERGROUND ponsciem potiend uconosu lvidiculi perente dientea in haet, ere novenatu manum nius fit Cuperitister in ta menem. EQUIPMENT AND Aper quitabit patam inatil hocrum diis catuit is lossa novir peri, ANCILLARIES quem pere co mis nihicau conlocuperis mius; nit, adhuius diero mo TBM, EPB, MTBM, GBM, atilineque ninatus, side audefex nihicum sim tiem dem intis, Cupions Pilot Tube, Road Headers, upiocuppl. Dit. Saticior ad morum ubliisse pore estrarisul hem Auger Boring,Pipe Jacking, untesse ndacta, vent. Imor adhui co Cat, conerfessua perra, niam Segment Forms fur, nox num publibus publis; et vivereb aturbis. Gered nonsumena, sena, se nonsulego hosus; hostuiu quam, que coterit vis? Na, vituam interei sernihil hi, vius. Udacibuntem ves obse etio, num ina, nosulego LET US HELP YOU…. es et; num revivis vir ipiocris, sesta re, occiam orte mus, no. Quitis • Market your et; Caticas Muliumust? 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TBMs
Location map of the Fehmarnbelt Fixed Link
“This new solution presents a low cost of €3.55 billion, less than twothirds of the cost of the immersedtunnel solution”
smaller than the volume of dredged material that would be involved in the immersed-tunnel solution. The TBM tunnels would consume 1.9 million m3 of concrete and negligible rock and sand; the resources needed are less than for a immersed tunnel.
Fresh conclusions The optimised TBM tunnel solution generates a lower environmental footprint, avoiding any disturbance of the natural seabed along the tunnel. The TBM solution presents an innovative and reliable safety concept, which represents a step
forward for the safety of tunnels, in particular long tunnels. Emergency rescue relies on dedicated unmanned electric vehicles that circulate inside a service gallery, so it is completely independent of conditions inside the traffic galleries, which reduces the risk of loss of lives in the event of an incident inside the tunnel. This new solution presents a low cost of €3.55 billion, less than two-thirds of the cost of the immersed-tunnel solution, allowing for an equivalent reduction of the tolls to be paid by the users. The proposed optimised TBM solution was presented to the public consultation on the project in Denmark in the summer of 2013 and to the similar public consultation recently held by the German authorities of the state of Schleswig-Holstein.
This article was based on on the paper ‘Optimized TBM Tunnel Solution for the Fehmarnbelt Fixed Link Based on TMG and TMF Concepts’ by Silvino Pompeu-Santos, civil engineer (PhD), SPS Consulting. Contact: pompeusantos@sapo.pt
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TBMs
A practical approach Tunnelling experts David Green and Andrew Hindmarch from Mott MacDonald discuss some of the practical design and construction considerations that may affect TBM performance
T
his practical discussion is intended to raise the awareness of those wishing to learn more about the general issues surrounding the procurement and use of TBMs. There is no TBM that can cope with all eventualities at the flick of a switch. A TBM needs to be specified and designed to deal with most of the conditions expected, as well as facilities that can be used to change driving mode or configuration. This involves forward planning and robust risk management. A fire-safety strategy for tunnel construction needs to be agreed early on in the TBM procurement process, as this will affect the design of the TBM, associated
backup and rolling stock. It is often said that the best ground investigation for a tunnel would be a horizontal borehole the same size and dimensions as what is being built. In reality, the typical method of interpreting geological profiles is a cross-section of the route, with geology and ground-water interpolated from ground investigations such as boreholes and core. The anticipated ground and groundwater behaviour will influence the TBM- and tunneldesign requirements. A geotechnical baseline report is useful to assist during the procurement process and provide a riskmanagement tool during construction.
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Identifying hazards Where hydrogeological conditions may change or obstructions may be present, it is essential that the TBM has the equipment to allow the contractor to identify, prove and deal with these. Gases can be detected in samples of groundwater from monitoring wells during site investigation. The water can release the gas in the tunnel during construction, so it needs to be managed with ventilation. An example is radon, which can be encountered in granite. Radon is inert but in the presence of dust it can decay to produce carcinogenic radon daughters. Gas sensors can be installed on the TBM and in the tunnel with an interlock and shut-down system. Although physical probing is not always preferred by contractors, it can be useful to give advance warning of conditions and allow better planning of interventions.
A slurry TBM (Herrenknecht Mixshield), from the Stormwater Management and Road Tunnel in Kuala Lumpur, Malaysia
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TBMs
Linings and muck handling The TBM must be designed to be compatible with the linings that it will build. Apart from the obvious lifting issues, the TBM may have to build different types of lining in one tunnel. Issues that affect the safety of the workforce such as ring-building platforms, protective railings, exclusion zones and remote-controlled erector arms are fundamental. Having chosen a suitable TBM and lining, it is important to remember that the tunnel construction can only reach expectations if the supply and muck-away chain is properly designed, operated and maintained. If a TBM is driving from a deep shaft, the production rate is generally controlled by the speed at which the arisings can be lifted out of the shaft, which is known as the winding speed. TBMs operating from headings will be slightly different but the same principles apply. Similarly, if a surface drive site is small, muck handling will be restricted and any interruption of surface haulage
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Herrenknecht TBM designs: double-shield rock (top left); single-shield rock (top right) earthpressure balance (centre left); unshielded gripper (centre right); slurry (bottom left)
may impact significantly on tunnel construction. A minimum muckstorage facility of two days’ mining is prudent for such sites. Broadly speaking, there are three ground scenarios that a TBM may have to deal with: hard/ soft rock; soft ground; and mixed-face conditions. There may
or may not be a need to deal with water. Ground conditions may change along the route of a tunnel. A TBM may be required to operate in closed or open mode. Carefully chosen facilities and forward planning will be required for this. Though the judgements in selecting the TBM assume the use of appropriate means, methods and workmanship, ultimately the behaviour of the geologic materials in the excavations will influence the tunnelling contractor’s choice of machine.
Types of TBM TBMs come in different types to suit different ground conditions and lining designs: • S ingle-shield rock TBMs are mainly used in unstable conditions where there is a risk of ground collapse. A single-shield machine can be converted to a closed mode if high water ingress is likely to be encountered. •D ouble-shield rock TBMs (also known as telescopic machines) combine the functions of a gripper and single-shield TBM. This allows for the installation of concrete segments parallel to tunnelling. •U nshielded gripper-rock TBMs are used in stable rock where there is low water ingress and no risk of ground collapse. Before each stroke, the TBM is braced against the previously excavated tunnel using gripper shoes. • E arth-pressure balance TBMs are suitable for soft ground and some rock applications. They use the excavated material to support the tunnel face during excavation. • S lurry TBMs are appropriate for granular soils and some rock conditions and use a pressurised fluid to stabilise the face during excavation. The muck is transported in the slurry created and pumped away to the surface, where the fluid is separated out and recycled. •M ulti-mode TBMs can operate in a number of different modes, such as slurry and open face, earth-pressure balance and open face, and a combination of all these.
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FEATURE NAME WATERPROOFING
Delivering watertight solutions The BBMV JV successfully waterproofs Crossrail C510 tunnelling works
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“A waterproofing system was required to provide the 120-year design-life guarantee”
n the heart of East London, BBMV (a joint venture (JV) encompassing Balfour Beatty, BeMo Tunnelling, Morgan Sindall and Vinci Construction Grand Projets) is constructing a vast series of underground tunnels at both Liverpool Street and Whitechapel as part of Europe’s largest infrastructure project, Crossrail. Set to transform the transport network across London and the southeast, the Crossrail project includes the creation of 42km of tunnels. To protect the tunnels from water ingress, and with maintenance and repair extremely difficult, a waterproofing system was required to provide the required 120-year design-life guarantee and to satisfy the clients specification. For the £250 million (US$427
million) C510 contract, located beneath the densely populated Whitechapel and Liverpool Street area, BBMV has developed and implemented an innovative combination of sheet and spray-applied waterproofing to ensure approximately 2km of new underground tunnels are kept watertight for over a century.
Rising to the challenge Faced with a busy location, challenging site conditions and industry spotlight on every aspect of construction, BBMV required a team to push the envelope in terms of tunnelling and waterproofing expertise. To achieve this, they combined a fully integrated core team drawn from previous tunnelling projects with expert staff from
DUAL ISSUE iPAD EDITION
+ Waterproofing work underneath Whitechapel
their various business streams. In the construction of the larger tunnels, BBMV utilised a twostage process starting with a pilot tunnel excavation at 1m increments. A Liebherr 944 excavator completed the enlargement, before a 300mm-thick sprayed concrete lining stabilised the tunnels and formed the permanent tunnel lining. For the waterproofing specification, BBMV trialled and tested numerous products and systems for suitability in the ground conditions. Although the majority of the tunnels are within London Clay, the tunnels do encounter areas of sand and silt of the Lambeth Group, which presented the site team with groundwater issues. As a result, Crossrail’s original complete spray specification was replaced with a combination of sheet and spray to counteract the additional water in the invert. “Spray waterproof membrane bonds together the primary lining and secondary lining producing a composite structure,” explains Peter Coppenhall, one of the JV’s tunnel engineers. “However, as the wet lining made a full spray application unsuitable, the combination of spray in the crown and sheet in the invert guaran-
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WATERPROOFING
teed us the watertightness required.”
Laying the foundations Following the shotcrete application to form the primary lining, a regulating layer is applied to provide a suitable substrate for the membrane to be applied to. A bespoke connection detail, consisting of re-injectable tubes and a waterproof sealing tape, is first installed. The connection detail ties together the sheet membrane and the spray applied membrane. In the invert a protective layer of geotextile fleece is fixed, followed by the sheet waterproofing membrane installation, which is undertaken by Austriabased specialist subcontractor IAT. A series of double-welds, connecting the sheet membrane to one another, and single welds, connecting the sheet membrane to the waterproof sealing tape and the waterbars to the membrane, is used. Testing of these welds is crucial to ensure watertightness in the sheet membrane. The doublewelds form a hollow channel between two parallel welds which is tested by its ability to hold a given pressure over a 10-minute period and the single welds are tested mechanically to prove it is one continuous weld. Water bars, re-injectable tubes and contact grouting are also being installed as additional measures onto the PVC membrane. BBMV follows the application of the sheet membrane by pouring the secondary lining cast in-situ invert and sidewalls to allow access for the spray-application of BASF MasterSeal 345. Such a crucial element of the process, the application and inspection of the sprayed waterproofing requires careful planning, co-ordination and training to ensure a quality product.
spray/sheet combination, BBMV had to ensure the highest quality application. Only fully-trained BBMV employees who had attended a two-day BASF Applicators Course were permitted to complete the BASF MasterSeal 345 spray-application. With work carried out from an elevated working platform, the MasterSeal product was mixed and sprayed using a Meyco
Quality control is key As the first Crossrail tunnel site to use spray-applied waterproofing, and the first tunnel site to use this
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Piccolo pump in two coloured layers and in stages of just 4m at a time. This systematic approach provided the team with a simplified and more accurate method for applicators to complete initial visual inspections. “When compared to the sheet membrane, we understand that the spray-applied system being used as a composite lining is a relatively new concept in the UK
ELIMINATE WATER PENETRATION
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WATERPROOFING
and will be under scrutiny,” Coppenhall adds. “With just a 3mm-thick layer after curing and the structural bond being absolutely key, we have to ensure the waterproofing reaches the required bond strength of 0.5 N/ mm2 and 100% coverage.”
Testing the water The testing process throughout both spray and sheet applications has been a vital element in the project’s success so far. From wet film thickness tests and Shore hardness testing to operators assessing their own work, regular testing has ensured waterproofing and bonding standards are exemplary. “From inspectors to engineers and nozzlemen to project managers, the challenge has been to ensure everyone has a thorough understanding of what we are doing,” site agent Peter Leyton said. “Through methodology submissions, inspection
testing and training, and working closely with our supply chain and subcontractors – we have made sure everyone is on board.” “Due to the level of surveillance this project and system is under, it’s vital that everyone knows the criticality of the waterproofing process,” he adds. “It is inevitable there are issues, but with our stringent design, planning and application process there have been no issues, so far, with waterproofing integrity.” Set for completion in 2018, Crossrail will transform train travel across London and the southeast, delivering faster journey times and boosting rail capacity by 10%. With vital waterproofing works going virtually unnoticed beneath the pavements and buildings of one of the busiest locations in East London, BBMV is providing hidden strength and watertightness that will protect these underground tunnels for generations to come.
Island tunnels free of water Keeping tunnels dry on a mega-link project in Asia is a mammoth task
T
he 49.9km Hong KongZhuhai-Macau Bridge (HZMB) is a combination of bridge, tunnel and artificial island. The project, overseen by the China Communications Construction (CCCC) joint venture, is a critical part of the overall construction work, and involves some of the most
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WATERPROOFING
difficult to construct immersed tunnel in the world and two artificial islands. The project has been divided into four phases. The two artificial islands were built during the first phase. The second phase involved the construction and installation of the first tunnel section, which was completed in May 2013. The third phase involves installing the remaining 32 tunnel sections, some of which are at deep-sea depths of 40m. This will be the most difficult and time-consuming phase, and will take around three years. The fourth phase will involve engineering work inside the tunnel, as well as some construction work on the artificial islands.
Sizing it up Zhuhai, in Guangdong province, China, stands on the west bank of Pearl River Delta (PRD), which feeds into the South China Sea. It borders Macau and faces Hong Kong on the other side of the delta. CCCC started work in 2009, and has been continually working since. The duration of the contract for the island and tunnel project is six years. CCCC has finished installing the first two tunnel sections, using half of the duration of the contract. The first two are 112.5m in length and weigh 50,000t respectively. From the third one on, the tunnels are 180m long and weigh 80,000t. “Given that we were working on the open sea and the high risk involved, we spent two years studying complex marine issues, preparing for the
installation,” said Lin Ming, general project manager and chief engineer. “We’ve done a great job in terms of the installation of the first two, and until now, everything has gone as planned.”
Guarantee for a century The expected service life of the HZMB is 120 years, and it is designed to withstand a magnitude 8 earthquake. As a result, the tunnel sections need to remain watertight for well over a century. “The island and tunnel project is sophisticated and risky. We can’t allow imperfect sealing products to ruin the entire project.” Trelleborg won the bid, becoming the sole supplier of sealing solutions for the immersed tunnel, with the Project Management Department taking a variety of factors into consideration, such as product performance, product design and corporate performance. The products ordered included Gina gaskets, Omega seals, waterstops and a variety of sealing accessories. The order placed by the Project Management Department is Trelleborg’s biggest ever in terms of tunnel infrastructure business. The four types of sealing products used in the HZMB immersed tunnel were designed and manufactured by Trelleborg Offshore & Construction’s infrastructure operation. Two of them were produced at the Trelleborg’s facility in Qingdao, China.
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.world-tunnelling.com Advertising production Sharon Evans T +44 (0)20 7216 6075 E sharon.evans@aspermontmedia.com
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sales@bmcdowell.com
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North America
Novel pipe repair in New York
Microtunnelling
Casablanca’s comprehensive water programme
Pipe bursting Potable-water pipe replacement in florida
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CONTENTS
1
While the ink’s still wet
W
e love the subject of leaky pipes, but it looks like the US government doesn’t and that’s a good thing for two reasons. Firstly, the political parties actually agree on something that actually leads to something happening; and two, it means consistent business for the trenchless sector for a long time to come. US President Barack Obama signed the Water Resources Reform and Development Act (WRRDA) into law during a ceremony at the White House in June 2014. The House had voted 412 to 4 and the Senate voted 91 to 7 to approve the legislation and send it to the White House for President Obama’s signature. The WRRDA amends how the federal government chooses and pays for critical water-infrastructure projects throughout the 10 million km2 of space in the country. It also refines the environmental review and permitting process to slash waiting times to get vital projects off the ground. This finally paves the way for much-needed improvements to US water infrastructure over the coming years. The April 2011 American Water Works Association (AWWA) Inside Insight ‘Infrastructure: It’s Not All About the “M” Word’ by Marcia Lacey estimates that the cost in the US of replacing aged infrastructure ranges from triple-digit billions to more than US$2 trillion.
“This finally paves the way for much-needed improvements to US water infrastructure over the coming years”
The bill passed this summer comes with a tag of $12.3 billion. Reported quantities of wasted water vary but, in 2009, the American Society of Civil Engineers’ Infrastructure Report Card stated that every day leaking pipes lose an estimated 7 billion gallons of clean drinking water. About the same time it was also reported that the annual shortfall to replace ageing water facilities had reached $11 billion. Aside from contributing to economic growth, the new bill should mean the country will be better prepared for natural disasters, such as heavy rain storms, hurricanes and the general diurnal strain on water and wastewater systems. Although the bill authorises the United States Army Corps of Engineers to undertake the projects, a Congressional review process for approving projects has been attached to the bill. This means that instead of letting the Army Corps of Engineers have the final say on decisions about which project to pursue, Congress can liaise with external consultants, associations and contractors, thus widening the information pool and reaching out directly to the growing trenchless community. In particular, it’s good news for trenchless-equipment manufacturers in North America and beyond. LUKE BUXTON, EDITOR luke.buxton@aspermontmedia.com
News 2 Features North America 5 Microtunnelling 12 Pipe bursting 16 Contacts 19 Classified advertising
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Next month UK Auger boring No Dig UK preview HDD
COVER Large-scale pipe replacement by No-Dig United: in 2012 No-Dig United launched its global projectexecution service. Handling logistics, mobilisations, project executions and general consulting, this has really put the supplier on the map this year. With projects in most parts of the world, handling pipe replacements in diameters up to 1,500mm using static pipe bursting, it has found a new niche in the trenchless industry. The picture shows a T400 pipe burster and its operator, on a site in Doha, Qatar. Email: info@nodigunited.com. www.no-dig.dk
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NEWS
Vermeer releases more powerful HDD rig Vermeer has introduced a new horizontal directional drill. The new D20x22 S3 Navigator HDD was designed to cater for contractors who desire a small-footprint machine yet one that is able to increase productivity when working in urban or tight jobsites. “Compared with its predecessor, the D16x20 Series II, Vermeer has added power and improved precision control for those customers who work mainly in fibre/telecom and gas-service installation,” said Jon Kuyers, global product manager for underground business at Vermeer. The D20x22 S3 features 19,550lb (8,875.7kg) of
thrust/pullback with 2,250ftlb (3,050.6Nm) of torque. The 74-horsepower (55kW) Deutz engine is capable of 12% greater power than the D16x20 Series II. All new models that feature the S3 label are Tier 4 Final (Stage IV) emission-compliant in North America and Europe. The D20x22 S3 features a new hydraulic system design with enhanced rotation, thrust and tracking performance over the D16x20 Series II Navigator. The hydraulics increase the system’s efficiency, allowing better use of engine horsepower and helping to increase the drill’s productivity. The D20x22 S3 has a faster carriage speed, which can lead to an increase in
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Vermeer’s new D20x22 S3 Navigator HDD offers more power and precision control than its predecessor
the amount of product installed per minute. The 167ft (50.9m) per minute now exceeds competitive
models in the same class, Vermeer says. Tracking power and speed has increased as well, improving the drill’s ability to make sharper turns, climb slopes and track up to 3.3mph (5.3km/h) to travel to jobsites in less time than previous models. Operator comfort has remained an area of focus, most notably through reduction in the level of noise from the drill. The D20x22 S3 has been upgraded to the common control system currently used on larger drills. The system features a digital display and improved onboard diagnostics, which allow operators to customise the available drill information.
Qatar’s power project to use trenchless methods HDD rigs will be employed on the Qatar General Electricity & Water Corporation’s (Kahramaa) US$108 million expansion project of its power-transmission system. The contract comprises engineering, procurement, construction, installation and commissioning services for extra-high-voltage underground cable systems provided by Prysmian Group. The project entails a total of 173km of 220kV cable and related network components, as part of stage 2 of Phase XI of the Qatar Power Transmission System Expansion project. The project is aimed at strengthening the main transmission networks and securing power supplies to
the industrial and residential sectors. The upgrade also includes replacement of an overhead line with an underground cable system. Installation of the first circuits will start in 2014 and the scheduled completion date is during 2016. Besides the Qatar contract, Prysmian Group has a portfolio of other projects completed or currently ongoing in the Middle East region. These include the first-ever submarine power transmission link serving Doha, the GCC Saudi-Bahrain submarine interconnection and the 400kV power-transmission system for Transco connecting the Bahia and Saadiyat grid stations in Abu Dhabi.
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NEWS
Tracto-Technik helps Wessex Water out of a tight spot UK utility Wessex Water has recently completed a pipe-bursting job on sewer-pipe replacements in a domestic setting with limited access in Broughton Gifford, Wiltshire. Traditional equipment was too large to negotiate the narrow back alleyways of the terraced properties. Wessex Water used a Tracto-Technik Grundoburst 400S rig to burst out 6in pitch-fibre sewer pipes and replace them in 2m lengths with 180mm screwed Demco SDR11 polyethylene gravity-sewer pipe. The job ran through the
The Tracto-Technik Grundoburst 400S proved useful in confined spaces on the Wessex Water sewer-replacement job
conditions of sandy clay was completed in record time of only two and a half hours from start to finish. Before using the smaller equipment on this job, traditional hand-dig methods were utilised in nearly every case where space was confined. Situations like this meant that in some cases outbuildings, garages and greenhouses needed to be dismantled or demolished and then re-assembled at some cost.
property owner’s back garden and into the neighbour’s back garden, where the exit pit was dug out. The pipe bursting of approximately 55m in soil
3
Change of scene for Steve Vick Steve Vick, products and services provider to the gas distribution, water and civil-engineering sectors, has moved to its new headquarters in Bradford on Avon, UK. The company decided to move from its previous Bath location following growth into industries such as nuclear decommissioning and water. At the Bradford facility staff are involved in making the fabric components used in its resin foam kits, assembling and packaging the kits and assembling pipehandling equipment. Product development and testing areas, customer training facilities and contract services, sales and customer care teams are also at the site.
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40ft deep and about to fail Angus W Stocking reports on a tricky pipe repair in New York
T
omhannock Reservoir, in the state of New York, is more than five miles (8km) long and holds 12.3 billion gallons (46 billion litres) when full. Parts of the reservoir’s earth-filled dam date back to 1900, which means that repairs are often needed. The reservoir is the only water source for the nearby city of Troy, so repairs will always be complicated and draining the reservoir is impractical for many reasons. This was especially true in 2012, when the dam’s bottom outlet began to fail. This is a 60in (1.52m) riveted steel pipe, surrounded by earth, 310ft (94.5m) long – the pipe was leaking at all seams and threatening to give way entirely. On the reservoir side, the inlet is about 40ft below the reservoir surface, and closed off by a gate that can be opened to release water. On the downstream side, to prevent erosion, the 60in pipe opens into a diffusion chamber that diverts water to four short 30in pipes. This difficult configuration effectively ruled out most pipe-rehabilitation techniques. Since there was no access from the reservoir side, all work would have to be done from the diffuser chamber. This is a small space, about 4.5ft wide, 5ft high and 12ft long, so there was no room for staging CIPP equipment, and
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the 30in pipes prevented the use of HDPE sliplining. Ryan Arold, vice-president of trenchless at Arold Construction Company, had a solution. “We did the initial inspection for CDM Smith, the city’s engineers, [and] it seemed like CentriPipe was the only solution that could possibly work in this situation.” CentriPipe, pioneered by AP/M Permaform, is a relatively new centrifugally cast concrete pipe (CCCP) technology that repairs failing pipe by inserting a spincaster into a pipe, and withdrawing it while it sprays thin layers of high-strength cementitious grout onto the pipe interior. The new pipe is structurally sound and waterproof, and since it adheres tightly to the old pipe, no annular space is created for water to move along. Staging areas are minimal, bends are no problem, work can be interrupted and resumed without leaving
seams, and flow reduction is minimal (final cast pipe thickness can be as thin as 1in, and rarely exceeds 2in).
The right solution The minimal staging area made CentriPipe the right solution for the Tomhannock project. Arold realised that he could set up the spincaster’s withdrawal winch in the diffusion chamber, and run in power, and air and concrete hoses from outside the dam and through the 30in diffusion pipes. It was conceptually simple, but complicated in practice. For one thing, the 30in pipes exit the dam about 10ft above ground. Arold Construction built substantial scaffolding that gave operatives safe access to the outlets. Since the spincaster and withdrawal winches were both too big for the 30in pipe, they had to be disassembled, taken through the diffusion pipes in pieces, and
Above left: the original riveted steel pipe Above: workers putting the grout hoses together and installing them into the pipe before grouting
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Above: the labourer on top is pumping grout to the spincaster while his colleague pulls hoses out as the sled approaches Above right: inside the diffusion chamber, in which workers set up the retraction winch to pull the sled
reassembled inside the diffusion chamber. To ensure good air quality throughout the project, blowers were used periodically. Aside from the low ceiling, space was not a big issue. Dewatering was a bigger problem. At the upstream end, “I’d say 20-25 gallons were coming through the gate every minute,” Nathan Baldwin, Arold’s operating superintendent and onsite foreman for the Tomhannock project, commented. “And the steel pipe was leaking at every seam.” Pipe rehabilitation began with
seam repair, using oakum and hydraulic cement – this did not prevent leaks, but it did slow down the leaks enough to work in the pipe. Invert repair is needed on many CentriPipe projects, to provide a smooth surface for spincaster withdrawal, but was not needed here because the thick steel invert was corroded but mostly intact. The upstream gate could not be effectively repaired. Baldwin therefore installed a sandbag and poly sheet cofferdam that would hold back water for about five hours – long enough for one
CentriPipe layer to be applied. With the 60in pipe repaired and dewatered, the CCCP process was relatively straightforward. CentriPipe applications are usually engineered by AP/M Permaform designers, based on factors such as pipe diameter and cover depth. In this case, the design called for a 1in application of AP/M Permaform’s PL-8000, a cementitious grout mixed with fibres for high tensile strength. That would have been more than sufficient, but Baldwin went a bit thicker. “We ended up taking five passes, and applying a little over one and a half inches,” he explains. “Coverage or structural integrity wasn’t a problem, but the riveted pipe has thick bolt heads, and we wanted to be sure we were covering them completely – on some projects, we want to be extra sure we won’t be coming back.” To check coverage and provide
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. Last year people came from 16 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.
• Laboratory Tools and Exercises • Instruction by Industry Experts In cooperation with
Next Mudschool will be held on the 3 - 7 November 2014
Industrial Minerals, Powerful Logistics
mudschool@cebo.com - www.cebo.com 0000000_CBH_adv_178x124.indd 1 America_Trench1407.indd 6
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quality control, one crewmember stays with the spincaster, and talks with the winch operator – by adjusting withdrawal speed, the spincaster operator can make sure that coats are applied evenly, with no slumping or thin spots. Coverage can also be checked with depth gauges before the grout cures, and by monitoring the amount of product being applied. Normally, Arold Construction has a four- or five-person crew on hand for CentriPipe projects, but on this project there were seven – additional hands were needed to move hoses through the 30in access ways.
Working in the deep end CCCP work is a new initiative for Arold Construction, and this was one of the more complicated projects the firm has taken on – limited access at one end of a
pipe, and 40ft of overhead water at the other end, guaranteeing some complicated logistics. “CentriPipe is a relatively new infrastructure technology,” Arold says, “and we were happy to have an opportunity to really find out what it can do.” CentriPipe is cost-effective compared with cured-in-place pipe, especially at larger diameters. It also has a number of
advantages compared with sliplining, including the relatively small staging area needed and CCCP’s relative indifference to bends in pipe or even mid-run changes in pipe diameter. Because it works well in tight situations where trenching is ruled out, CCCP use is likely to continue expanding as a superior trenchless rehabilitation technology.
7
Above left: sled used to support the spincaster inside the pipe to be coated Above: the steel pipe after coating with 8,000psi fibrereinforced concrete
Angus W Stocking is a licensed land surveyor who has been writing about infrastructure since 2002
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Reducing risks and increasing safety Sewer lateral inspections can prevent and identify cross bores – preventing danger and saving time and money
F
A Peer crew member checks as the CCTV camera enters the sewer via a manhole
or the past two years, environmental engineering firm Peer Consulting’s Field Services discipline has been performing sewer lateral inspections for contractors that are responsible for placing new gas lines on behalf of the gas utilities in the US Mid-Atlantic region. These contractors may use any of the following techniques for these placements: open trenching, horizontal directional drilling (HDD), or a mole-push technique, in which the contractor pushes the new line through a sewer cleanout (an accessible opening or manhole).
In this paper, the term contractor applies to all three methods, though HDD is used in the vast majority of cases. In any of these three techniques, the contractor does not want to cause damage to an existing lateral through penetration, scraping or breakage. It has been noted (Kennedy, 2010) that systems may not be submitted to the local Dig Safe data base, so independent verification of lateral location is essential. Water and sewer utilities have very stringent requirements for non-utility employees that need to enter their assets. Peer’s
long-standing relationship with the water and sewer utilities in the region helps the Field Services discipline easily obtain the necessary permits to enter the required assets, thus facilitating the process.
trenchless methods When Peer works with a contractor as a client, its task is to locate laterals so that the contractor can avoid them when placing gas lines. This process entails the CCTV camera moving along the main sewer line until a lateral is reached. Then, a smaller, robotic camera moves along the lateral. This smaller camera uses Sonde technology to send a signal. At the same time, a crew member is walking the ground surface with a locating wand, following the signals. When a signal is received noting the depth below ground surface to the lateral, that depth is recorded, and the lateral location
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9
A close-up of the CCTV camera used for the sewer lateral inspection, as soon as it came out of the manhole
is marked on the ground with spray paint. It is important to note that this is typically a ‘real-time’ operation in that the contractor is in the field at the same time, close behind, placing the new lines. Lateral inspections are typically
completed from the sewer mainline, but if the inspections cannot be completed from the mainline, inspections are conducted using a push camera, which allows the crew to manually ‘push’ the CCTV camera from the cleanouts on a person’s property to (rather than from) the mainline. For the work completed so far, for the most part, it has only been necessary to mark above-ground the locations of the sewer laterals, and then perform CCTV inspections of the laterals after the gas lines have been installed. Based on the contractor’s judgment, Peer might be asked
to immediately inspect the sewer lateral after the gas line is placed to ensure that no cross bore has been created. In rare cases, the consultancy may detect a penetration or breakage, and the contractor can make repairs immediately. This procedure reduces environmental damage and decreases total costs.
Existing cross bores Peer’s Field Services team is also working with gas utilities in the performance of their abatement programmes to identify any existing cross bores in sewer laterals in their system for
Preparing to pull out the camera from the manhole once the inspection is complete
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The TV screen inside the truck that displays the view inside the sewer pipes in real time
“Field experience suggests that there are two to three cross bores per running mile of installed distribution pipe”
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immediate removal and repair of the gas line. This effort began when a utility saw the work that the consultancy was performing for the gas contractors and realised the potential benefits. This process is only slightly different from the work done for contractors, since the information to be reported is simply whether a cross bore exists or not. When one is found, the location is noted and reported. This reporting should improve safety. In the event that a clogged sewer lateral occurs and a plumber goes in to clear a line with an existing cross bore, a gas explosion may very well take place, causing fatal injuries and severe property damage (Kennedy, 2010). Other challenges include the following: dirty and root-ridden sewers; the cost of using and maintaining the necessary equipment and personnel to
perform the job; the need for control traffic in certain locations; and co-ordination with other companies and agencies.
Final thoughts Field experience suggests that there are two to three cross bores per running mile of installed distribution pipe (Wallbom and Grade, 2010). In Peer’s experience thus far, after inspecting over 95,000 linear feet (approximately 18 miles/29km) of mainline sanitary sewer and over 1,500 laterals, only two or three cross bores have been found during the course of the inspection work performed in the last
year. When Peer has performed an advance inspection of the laterals, prior to the gas line being pulled, no cross bores have been detected. The company is not aware of any other firm (in the area) using lateral inspections to pre-emptively locate the laterals prior to placing new gas lines, which makes this project and the work being performed unique to Peer. Using the same techniques to detect cross bores in existing locations further enhances safety. Included is reduction of the risk of someone accidentally sending a root cutter up a lateral to clear a blockage when it is in fact a cross bore, causing a potentially disastrous gas leak. Peer’s experience has shown that use of these techniques does indeed not only reduce costs, but can also substantially improve safety. Its successes also indicate the value of locating laterals prior to placing new gas lines.
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Microtunnelling
decided to divide the outfall into two sections: • a first section of 1,057m from the shore to a reception pit to be excavated by microtunnelling; and • a second section, from chainage 1,057 to chainage 2,400, to be carried out by conventional marine works (dredging, underwater rock excavation, sinking a pipe fitted with concrete ballast blocks and backfill).
An Atlantic endeavour
On the North Atlantic’s eastern edge, utility company LYDEC has embarked on a comprehensive water programme to improve sanitation in Casablanca, Morocco Retrieving the Herrenknecht MTBM out of the sea
“The Atlantic Ocean’s rough sea conditions (waves, current and wind) did not allow the use of conventional marine works”
Lowering the tunnelling machine into the shaft
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he Lyonnaise des Eaux de Casablanca (LYDEC) project, from the port of Casablanca to the town of Mohammedia through the municipality of Ain Sebaa, started in 2010 and was carried out in several stages. Designers planned two coastal interceptors to collect domestic and industrial wastewater discharge throughout the coastal strip and transfer it to a central point of the Sidi Bernoussi anti-pollution project: the Port Interceptor (Roches Noires – Sidi Bernoussi) and the Mohammedia Interceptor (Mohammedia – Sidi Bernoussi). Other works include: several pumping stations with capacities up to 6m3/s; a central Sidi Bernoussi pre-treatment plant with an overall capacity of 11m3/s; and an ocean outfall to discharge pre-treated effluent into the sea. This project aims to make the beaches and coast attractive again for residents and tourists. CSM Bessac (France) was awarded the execution of the ocean outfall in early 2013, in a €35 million
(US$47 million) joint venture (JV) with Somagec (Morocco), Geocean (France), Etermar (Portugal) and Solsif (Morocco).
Project blueprint The aim of the structure is to transfer the water from the Sidi Bernoussi pre-treatment plant into the Atlantic Ocean, 2,400m away from the shore. The hydraulic design resulted in an outfall with an inner diameter of 2,100mm. At tender stage, the JV
The Atlantic Ocean’s rough sea conditions (waves, current and wind) did not allow the use of conventional marine works in the first section. Moreover, in order to withstand the 6bar internal pressure, the JV selected steel-cylinder concrete pipes for the first section and HDPE for the second. An existing Herrenknecht AVN 2200 microtunnelling machine, already used in Morocco by CSM Bessac for another sea outfall in Rabat, was adapted to the specific characteristics of the project (diameter of the pipe, geology and subsea recovery procedure) in the workshops of CSM Bessac in Saint Jory, north of Toulouse, France. The microtunnelling machine, with a total weight of around 77t, had an excavation diameter of 2,750mm. The steel-cylinder concrete pipes have an internal diameter of 2,100mm and 2,670mm outside diameter. Geotechnical and geophysical investigations were conducted during the preparation stage of the project (bathymetry, seismic reflection and refraction, boreholes and mechanical tests), in order to understand better the key parameters that are of critical importance, especially on this type of subsea works. These parameters included: development of the final longitudinal profile along the tunnel; definition of hyperbaric interventions zones at the front for cutterhead inspection; formulation of lubrication and mucking out
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slurry; and choice of the number and capacity of intermediate stations. The 12m internal-diameter working shaft was excavated between June and September 2013 by conventional methods. Temporary support was achieved by shotcrete in the lower part of the shaft.
Lifting the MTBM from the ocean, and an overview of the site installation with the Atlantic at the top
Jacking the MTBM in the shaft, and a completed section of the tunnel
Head to head Tunnelling began in October 2013 and ended in April 2014. Excavation took place mainly in rocky conditions (siltstones and calcarenites), but with highly faulted zones connected to the upper sand fills. These zone crossings were challenging in relation to lubrication grouting or face interventions for the cutterhead maintenance. A mixed zone sand/siltstone was also excavated in the last 150m, with a low overburden of just 4m and a depth of 20m below sea level.
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The 12m internal-diameter and 13m-deep working shaft allowed for the jacking of two 2.5m-long pipes simultaneously, generating a daily production rate of 28m. The fractures and abrasive rock led the construction team to regularly access the excavation
chamber to carry out preventive disc-cutter inspection and changes in hyperbaric conditions, in areas previously identified as safe. Two main faults were encountered; the rock was particularly unstable around chainage 760
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Microtunnelling
and chainage 850, generating
“The increased friction along the machine tunnel and requiring the use of remained in three to four of the seven intermediate stations installed. the pit, as Extensive work had to be the weather carried out on the lubrication conditions grouting, which required the use three independent lines, each did not of with its own formulation of mud, allow the injection sequence and injection safe parameters (volumes/pressures). This challenging area was finally intervention crossed, once the faults stabiof marine lised, and progress could resume means with an average excavation rate necessary of about 15m/day. for its Waiting on calmer waters recovery” The microtunnelling machine was stopped at chainage 1,057, in the
receiving pit, pre-excavated in the bedrock and sand, in July 2013 by the JV partner in charge of marine works. The machine remained in the pit, as the weather conditions did not allow the safe intervention of marine means necessary for its recovery. In the last days of June, when the Atlantic was calmer, a barge and dredge evacuated the sand covering the microtunnelling machine. The divers disconnected the machine from the first pipe using specific expulsion hydraulic cylinders, then the barge, equipped with powerful winches, lifted the machine. It was hauled a few kilometres away to the port
of Casablanca and lifted out of the water by a powerful mobile crane. Meanwhile, the tunnel was closed by a gate, the temporary equipment (pipes, cables, etc.) was removed from the tunnel and the steel-cylinder concrete pipes were welded together to ensure the watertightness of the tunnel during the 6bar test. The remaining 1,350m-long HDPE pipe will be installed and connected to the tunnel in August and September 2014 for the commissioning of the works, scheduled for December 26, 2014, in the presence of Mohammed VI, King of Morocco, in accordance with contractual schedule.
Done with a Bang Microtunnelling records broken on a project in Thailand Working on the Terratec MTBM
The machine bored a 380m-long irrigation tunnel
C
ontractors have completed an irrigation tunnel at the Bang Pakong River in Thailand using a microtunnelling machine. On June 18, a Terratec microtunnel boring machine (MTBM) completed the 380m-long drive of the 1,800mm inner-diameter tunnel developed by a joint venture of Ch.Karnchang PCL and Krung Thon Engineers (KTE) for the Royal Irrigation Department of Thailand (RID). This pilot project enables RID to support the rapid development of the industrial estate in the Eastern Seaboard area. The geology consisted of a
combination of very stiff clay with high underground water level and sand spots. The project was completed smoothly maintaining a very low jacking force of less than half the installed capacity (5,000kN out of 11,000kN). This was achieved thanks to the high performance of the lubrication system and the two strategically placed intermediate jacking stations. This minimised the pipe friction, which is key to a successful pipe jacking long drive. The site worked around-theclock with the system in two 12-hour shifts to achieve a timely completion of the project. In total, 150 pipes of 2.5m each were installed in 23 calendar days.
Notable achievements This is RID’s first pipe-jacking project to be achieved by a MTBM. This is also a cornerstone for KTE, as it is the longest and quickest drive ever performed with MTBM by the company. KTE ordered a Terratec DN1800 microtunnelling system, which includes several compo-
nents: slurry-shield MTBM, guidance system, slurry-transport system, main jacking station, intermediate jacking stations and lubrication system. The MTBM was fully assembled and tested at the company’s plant in Thailand. Shortly after the factory acceptance test, the system was deployed and operational at the project site. Terratec also provided KTE with a comprehensive service package on site, which included the dispatch of key engineers and MTBM operators. These specialists were involved from the initial ground works to the final completion of the tunnel.
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Company profile
UK
microtunnelling
Iseki Microtunnelling Crossrail Recent location: Plumstead, London Main sector: microtunnelling Recent key project:
Company summary Iseki Poly-Tech Inc., founded in 1971, and Iseki Microtunnelling, founded in 1984, have been instrumental in developing small-diameter slurry microtunnelling systems to meet expanding infrastructure needs and, with nearly 2,500 units produced, they are probably the world’s most popular slurry machines.
On the right track Unclemole TCC-R makes its debut on Crossrail Crossrail is the largest civil engineering project in Europe. It is creating an east-west rail link across one of the world’s largest and busiest cities – London. It is a phenomenally complex project, years in the planning, and involves many kilometres of new tunnels, and many new or upgraded stations. In the 19th century, London was already the largest city in the world when railways and modern sewerage and water supply systems were installed below ground. Subsequently, electricity, gas and communication networks joined them under the streets of the English capital, and Crossrail has to share the ground with all of them. In such a congested environment, it was inevitable that the Crossrail route would intersect with existing utilities, requiring diversions to be constructed. One such re-routing was near to London City Airport, on the south bank of the Thames at Plumstead, where an existing sewer line had to be diverted. Consequently, a new deeper sewer needed to be installed. This sewer called for installation of two 1,200mm id drives from a common shaft, the first drive of 28m and the second 127m long. The longer drive crossed Crossrail’s Plumstead Portal, formed within two walls of secant piles. The Portal forms the transition for Crossrail to the ‘Woolwich Box’, the new underground station at Woolwich. Iseki Microtunnelling hired its Unclemole TCC-R 1,450mm od system to Johnston Trenchless Solutions, which was subcontracted to construct the shafts and install the tunnels. The soil conditions were a mix of soft clay, peat and fine sand – ideal for the Unclemole, widely recognised as the complete slurry machine for all soft ground conditions. However, the shield also had to cut through structural concrete of 50MPa compressive strength in five different locations. Iseki’s solution was to install its bolt-on mediumstrength rock-cutting head (shown above), a recent development successfully deployed on projects in Europe. Iseki mobilised to site mid-October 2013 and by the end of the month the shield had reached the first reception shaft. En route, the shield cut through the 50MPa concrete segments of the working shaft, excavated the grout plug around the shaft then cut into and through similar strength concrete segments at the reception shaft. The cutters exhibited
minimal wear so there was no need to replace them with spare cutters that had been provided. On the second drive the shield again cut through the shaft concrete segments and grouted soil, then tunnelled to the first line of 900mm-diameter 50MPa concrete secant piles of the Portal. Once through these piles, the shield crossed the Portal and cut through the second row of piles. While the Unclemole had been travelling at over 100mm/min through the natural ground, it had to slow to 5mm/min cutting the piles. This created the potential for over-excavating the surrounding soft ground but the operators adjusted the slurry flow and pressure and thickened the slurry to support the ground. The client had been monitoring the surface level along the drive before the shield passed under the live North Kent rail line, in case of settlement problems, and were happy to approve the continuation of the drive. Having successfully negotiated two rows of concrete piles the shield then excavated through a cocktail of sand, gravel, clay, peat and wood to reach the second reception shaft in the third week of November. There was no room on site for a crane big enough to lift the whole shield so the shield was split in-situ and recovered in two pieces. On the drives, the TCC-R’s operators achieved production of over five pipes in a shift and, despite the widely varying ground conditions (from soft clay to structural concrete), installed the tunnel without surface-level disruption. The effectiveness of the TCC-R head has been further demonstrated at Plumstead and Iseki Microtunnelling is able to offer this development as a new supply or as a modification to a customer’s existing shield.
Contact
Iseki Microtunnelling Airfield Road, Hinwick, Wellingborough, NN29 7JQ, UK Tel: +44 (0)1234 781166 Fax: +44(0)1234 781992 E-mail: info@isekimicro.com
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Pipe bursting
In full flow
Innovative and cost-effective approaches to potable-water pipe replacement in the city of Sanford
Pipe bursting under way in Sanford
U
nderstanding the costs involved in delivering safe water to the customers’ tap, such as the costs of pipe upgrades, operations and quality compliance, is very complex. The April 2011 American Water Works Association (AWWA) Inside Insight estimates that the cost in the US for replacing aged infrastructure ranges from hundreds of billions to more than US$2 trillion. For many years, the City of Sanford Utility Department in Florida, US, tried to keep its water-services cost low by performing minor repairs and addressing pipe rehabilitation as needed. However, the water quality, water loss and operational limitations elevated the need to address the water-system infrastructure to ensure that natural resources are maximised and public health is protected.
“The city concluded that innovative pipebursting construction would be the best approach given the financial and implementation Undertaking the assessment benefits” Serving 57,000 customers, the city
Figure 1: comparison between actual measured flows and those predicted by modelling
owns and operates two watertreatment plants (WTPs) producing approximately 7 million gallons per day (26.6 million litres). The main WTP provides 73% of the city’s supply of potable water, whereas the auxiliary WTP provides the other 27% over 300 miles (482km) of piping. City staff, with the assistance of Reiss Engineering, performed a condition assessment of potablewater infrastructure using the
the model data to demonstrate that the model consistently simulates hydraulic and water quality parameters over a 24-hour period using an extended-period simulation (EPS) scenario. The ability to forecast the impact of the pipe-bursting project on the water quality of the distribution system gave the city a decision-making tool that assisted in selecting rehabilitation projects and planning for additional treatment regimes.
Rehab projects selection
city’s updated hydraulic and water-quality model that would maximise the benefit from pipe rehabilitation with respect to water loss and quality improvement within the ageing distribution system. To achieve the objectives, a methodology was developed to identify projects that would improve water loss and water quality utilising the city’s model. Using the simulated hydraulic conditions and water-quality improvements, the city justified the need for grant and low-rate loan funding. In addition, the city concluded that innovative pipe-bursting construction would be the best approach given the financial and implementation benefits.
Pipe-bursting impacts The model was developed and calibrated for flow, pressures and water quality to simulate how potable water is used throughout the day with predictive accuracies of over 90%. Figure 1 shows an example of field data collected using data loggers and the city’s SCADA communications system versus model simulated data for the calibration period. Error bars representing 10% are included in
Using the modelling, the city identified 38 projects to replace iron-based water pipes with high-density polyethylene (HDPE) piping throughout the distribution system. In addition, nine looping projects and other replacement projects were identified that enhanced the movement of water and significantly improved water quality. To secure funds, the city used the modelling to show how the projects would improve water quality. The first phase of pipebursting and looping projects was completed in April 2011 and the second phase will be completed in 2015.
Evaluation of projects Reiss Engineering conducted an evaluation to determine which pipe-replacement and looping projects would be technically and financially feasible, prioritise the projects and provide recommendations for implementation. The phase 1 projects were selected based on pipe material, condition (i.e. number of repeated main breaks), age/improvement potential (aesthetic and regulatory compliance), treatment facility upgrades, customer complaints and estimated cost. For the selection of the phase 2 pipe-replacement projects, the evaluation was expanded to include location and model trihalomethane and chlorine residual results. Based on this evaluation, eight pipe-replacement projects and six looping
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projects were selected for construction as shown in Figure 2.
Figure 2: map of pipe-replacement and looping projects in phase 2 of the Sanford infrastructure programme
Project funding The city received funding from the State Drinking Water State Revolving Funds and grants from funds such as the American Recovery and Reinvestment Act, totalling $22 million for distribution-system infrastructure and treatment upgrades during 2009 to 2015. Pipe-replacement and looping funds of approximately $7.5 million were used to complete 120,000 linear feet of piping improvements that were ready to be executed. A portion of the grant, approximately $1.6 million, was used to replace water meters for homes, schools and businesses in locations throughout the city. The replacement programme has assisted in reducing water loss from 22% to 11%. Given the potential for water conservation, this is considered a ‘green project’by the Florida Department
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of Environmental Protection , which allowed Sanford to be considered a priority and listed in the top four water providers’ funding list. Other projects funded include source-water quality management, replacement of two ground-water wells, and treatment-facility modifications.
Defining roles Pipe bursting was determined to be the most viable method of construction for the pipe replacements. This method is well-established for installing new HDPE pipe. In addition, moulded couplings, centurion fire hydrants and ball valves can then be installed without significant
Driven for our customer’s success. For over forty years, Akkerman has developed, manufactured and supported quality pipe jacking and tunneling equipment that accurately installs a variety of underground infrastructure. We help contractors explore project solutions for an extensive range of diameters and geology. Trust Akkerman to be your partner, every step of the way.
+1 (800) 533.0386 | akkerman.com
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Pipe bursting
New HDPE pipe with cap
“The replacement programme has assisted in reducing water loss from 22% to 11%”
customer disruptions, as would occur with open trenching, which would translate to significant cost savings to the city. Pipes were replaced to match the existing sizes or have a maximum increase of two pipe diameters to avoid design and permitting costs. An added benefit from water-pipe replacements is the ability to increase fire protection for older areas of the city. A key step in project co-ordination is to identify construction team members and key personnel and to define specific individual roles to avoid unnecessary delays during the construction process. As part of the co-ordination effort, the city developed project schedule goals and requirements.
Lessons learned Planned quarterly meetings with the key project entities identified salient points and key tips to a successful pipe-replacement project. The first is to conduct field verification before construction – locate and confirm pipe layout and sizes, and the number of required accessories such as valves and hydrants. Representatives should confirm the pipe-replacement method by determining locations where pre-chlorinated pipe bursting is not feasible and selecting a
replacement method that is cost-effective for the location. The site needs to be documented before and after construction. Using documentation such as pictures and videos ensures the site remains in an acceptable appearance after construction is complete. This includes data-collection management with the determination of feasible timing to collect global positioning system (GPS) mapping data of key items. Communication with the public is key and companies involved should develop a low-cost yet effective way to inform the public of the project status. Project leaders need to implement timely meetings between city department leaders and key project personnel to discuss construction tasks. The distribution-system hydraulic model may also need to be updated to incorporate new pipe layouts and collected field information.
Reaping the benefits The benefits of pipe replacement include minimising water loss, improving water quality and maintaining safe drinking water for the citizens of Sanford. The city utilised hydraulic and water-quality modelling to select pipe-replacement projects and forecast water quality after system improvements that would benefit the city. This forecast information was used to justify grant and low-rate loan funding of approximately $22 million to cost-effectively improve the distribution system. With the funding in place, the city implemented a cost-effective pipe replacement method – pipe bursting – which saved significant design and permitting fees. The lessons learned during this project will help utilities successfully plan, manage and implement similar construction projects.
This article was written by Kelcia Mazana from Reiss Engineering and the City of Sanford’s Migdalia Hernandez. It is an updated version of the paper given at the NASTT No-Dig 2014 show
Success in zero visibility Two teams tackled a Canadian sewer-replacement job in tricky circumstances
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he city of Dawson Creek in British Columbia, Canada, had an old, badly corroded 300mm steel pipe that needed to be replaced. The outfall pipe, 130m long, went to the centre of the last sewage lagoon at the city’s sewage treatment plant. The pipe was approximately 2.5m under water and had a 90º diffuser welded on. There was also an extreme elevation change of 15m over the first 80m of the pipe. 3D Pipe Bursting of Millet, Alberta, and Fraser Burrard Diving of Delta, British Columbia, combined their expertise in their respective fields to tackle this challenging project.
Pitch black The first challenge on this project was that the diffuser needed to be cut off the old pipe. This is simple in normal conditions but challenging when you are 2.5m under water and there is zero visibility. The Fraser Burrard team used specialised tools to cut off the old diffuser and then grind smooth the pipe to make sure that there was no sharp edges that could damage the new HDPE pipe during the pipe-bursting process. Secondly, 3D Pipe Bursting had the challenge of feeding its steel rods through the existing pipe. Because of the badly deteriorated pipe, there was a chance of the rods going through the side wall of the pipe at the bends. 3D Pipe Bursting therefore made a special head that eliminated this risk. When the rods reached the end of the pipe, a co-ordinated effort was needed to
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PIPE BURSTING
Top: divers assisting pipe bursting in the lagoon; above: inspecting damaged pipe
attach the tool string to the rod string. The tool string (flex joint, expander and steel slitter) was attached to the new 300mm DR17 HDPE pipe on land. A concrete block and pipe roller was placed at the bottom of the lagoon so that the HDPE pipe would feed properly into the old pipe during pipe-bursting.
Taking precautions Safety was the utmost priority while hooking up the tool string to the rod. The two teams made sure that they had good radio communications with the diver and with the operator of the
pipe-bursting unit. The tool string weighs approximately 700kg and the bursting unit has 800ft/lb of rotational torque with 250,000lb of pulling force, so there is a lot potential for injury, especially when operatives are under water and performing all tasks by feel. 3D Pipe Bursting has an operator with thousands of metres of static pipe-bursting experience. An excavator lifted the tool string and pipe into the water and with the assistance of one of Fraser Burrard’s divers it was fed through the pipe roller at the lagoon bottom. The tool string was then laid on the bottom in line with the old pipe. Because of the weight of tooling and the limited reach of the excavator, a combination of cables and ropes were used to get the tooling threads and rod threads in line so that they could be threaded together. This takes about 20-30 minutes on dry ground, but when you are in these conditions and safety is the number one concern, it takes many hours. Once everything was connected and aligned, pull-back started. A diver stayed in the water for the entire pull-back. For the first 15m the pipe was checked each metre to make sure there was no scarring of the HDPE from the old steel pipe. The pull-back took two hours to complete. A flange was pre-fused onto the end of the HDPE pipe, then a diffuser was bolted on by one of the divers.
This article was provided by Darren Norton, president of 3D Pipe Bursting 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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Supplies & Services USED EQUIPMENT
WANTED The following USED equipment: • CIPP Mobile Boiler / Steam / UV Curing Equipment Air Inversion Unit Wet Out / Impregnation Unit Robotic Cutters CCTV Equipment 150mm Ø Silent Pumps • PIPEBURSTING Grundo Burst 400/800/1250 G Pipe Coil Trailers Electro / Butt Fusion Equipment De Beaders • SUCTION EXCAVATORS • ZERO SWING MINI EXCAVATORS / RUBBER-TYRED EXCAVATORS • TEREX PS 6000 DUMPERS E-mail: jorourke@mmainline.ie or tiernan@mainlinesa.co.za
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