World Tunnelling & Trenchless World November 2014

North America

The importance of correct construction methods

TBMs

Lessons learned in EPB tunnelling

Ventilation

A lifeline on the deepest undersea tunnel

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November 2014

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CONTENTS

1

Man walks into a bar…

V

ia a tunnel that he built himself. It is something reminiscent of the world’s favourite film – The Shawshank Redemption. You know the … scene where Andy Dufresne acquires a rock hammer and scratches his way from his prison cell to freedom in a tunnel concealed behind the giant poster of actress Rita Hayworth and later Raquel Welch.

It took him 20 years.

Last month Omagh County Court in Northern Ireland heard how a man spent 15 years tunnelling from his bedroom to the local pub 800ft (244m) away. He was only caught when his activity caused the collapse of a sewage pipe from a neighbouring house.

The man, Patsy Kerr, explained his reason to the court: “The wife has a bad snore and after watching The Shawshank Redemption one night in 1994, I decided to do something about it. I waited until she was in a deep sleep and then set about digging a hole under the bed in the direction of the pub.”

“The landlord also wondered how I just appeared out of nowhere at the same time every night and disappeared from the women’s toilets”

News

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Features North America TBMs Ventilation Immersed tunnels Contacts

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Classified advertising

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Kerr was a man on a mission. “I used all manner of tools from spoons to a heavy-duty tunnel boring machine I managed to sneak down there when she was at the shops. It wasn’t until 2009 that I hit the jackpot and came up through the women’s toilet mop-andbucket room.”

Kerr had spent the last five years heading to the pub via his tunnel at 11pm before returning at 1am without his wife any the wiser.

Despite explaining the smell of alcohol as a ‘natural odour’, Kerr said it was his singing that almost got him caught.

“I was singing rebel songs coming back up the tunnel and it was only a matter of time before I was caught. The landlord [of the pub] also wondered how I just appeared out of nowhere at the same time every night and disappeared from the women’s toilets.”

The tunnel was discovered after the Department of the Environment performed a survey on a sewage issue, which was later identified to have been caused by a pipe Kerr had hit, causing sewage to leak into his tunnel for five years.

So if your husband goes missing in the middle of the night, look no further than under the bed.

LUKE BUXTON, EDITOR luke.buxton@aspermontmedia.com

Next month North America – focus on Canada Segments Grouting

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NEWS

COWI buys Donaldson Associates Engineering consultancy group COWI has acquired geotechnical design, tunnel and underground engineering firm Donaldson Associates.

“The acquisition is in line with our growth strategy,” Lars-Peter Søbye, CEO of COWI, said. “We have complementary market coverage, and together we will be one of the world’s leading engineering consultancies with a large, highly qualified pool of specialists who are able to bring significant strength and expert skills to our customers around the globe.”

Based in Denmark, COWI has a strong presence in the Scandinavian and international transport market. The acquisition strengthens underground engineering in COWI and widens the skill set to include caverns, hard rock, leading edge spray concrete lining and microtunnelling.

Donaldsons employs 143 staff in five UK offices and one in Hong Kong.

Continuing to operate as Donaldsons, the team will work with COWI centres in Denmark, Qatar, India and the US.

DriftShot promises better blasting Commercial explosives player Dyno Nobel and its joint-venture partner DetNet have released an electronic initiation system for underground development blasting.

DriftShot provides the underground blaster with electronic initiation while retaining the tie-in characteristics similar to the company’s NONEL initiation system.

DriftShot’s electronic accuracy can help deliver better advance rates and improved wall stability, the company said.

DriftShot has flexible timing options that assist in providing more consistent fragmentation and reduced overbreak as part of optimising underground

Speedy scanner

Renishaw has launched new 3-D laser scanning software to speed underground mapping and moddevelopment blasting. elling operations.

The DriftShot initiation Cavity Profiler allows system was designed with customers to progress easy-to-use timing temprojects faster, by enabling plates for the blaster, which quicker deployment, more can also be customised for efficient scanning and specific applications. rapid data visualisation, The Blast Control Unit editing and processing, allows for up to 200 the company said. detonators per channel to The software is available be fired. in two versions, to support DriftShot also offers either the Renishaw Void minimal components at the Scanner – a boom-deployface – the electronic able underground laser DriftShot detonator in the scanner – or the Renishaw borehole and a two-wire C-ALS – a slimline, busline. borehole-deployable laser The DriftShot Tagger is a scanner. The Cavity Profiler handheld device that software replaces earlier communicates with versions. detonators and collects The company is making data. both variants available to The Tagger identifies and all existing customers free mof mm $ l c jit #announced. ]cX^$Z[ tests each detonator charge, contained in the blast.

Fire-protection lining system makes escape route safer at Serralunga Morgan Advanced Materials has supplied a fire-protection system to the 1,300m Serralunga Tunnel in Italy.

The tunnel has two escape routes, which take the form of suspended paths. The challenge that faced the design team working on this project was lining those escape paths with a material that could withstand high

J^[ Z_Wc[j[h e\ Wdj[ddW[ e\ j^[ Yecced mWif ØL[ifkbW Lkb]Wh_iÈWdZ j^[ WYYkhWYo In the Serralunga Tunnel, temperatures, protecting both e\ KBIÉh 6Xi^kZ AVhZg IVg\Zi Jc^i# the tunnel’s structure the product has been and the people within from applied over a galvanised the ravages of fire and the wire mesh, allowing it to reach every part of the effects of smoke.

The team chose FireMas- tunnel surface.

“Installation of approxiter FireBarrier 135, supplied through specialist mately 6,500 square feet (600m²) of [36mm thick] installer Kapyfract. protection has been The product can be achieved in under 40 applied either in the form days,” Francesco Ferrari, of pre-cast sheets, or by specialist fire-protection spraying to a substrate consultant, commented. attached to the tunnel.

1 mm

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Your challenge.

Our specialty.

A massive grouting operation performed in the country’s busiest port requires a one-of-a-kind solution that is as innovative as it is flexible.

Nicholson is performing onshore and offshore grouting ahead of the TBM for the new twin-bored Port of Miami tunnels — working around an active cruise ship schedule and strict environmental restrictions.

Geotechnical challenges come in all shapes and sizes.

Fortunately, so do specialized solutions.

www.nicholsonconstruction.com

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North america

the strongest solutions What to consider when constructing tunnel launch pits or access shafts in challenging conditions Fig 1: view of the excavated OARS shaft

T

he list of construction methods to build vertically supported excavation in the ground is endless. A non-exclusive list of the techniques that could be used for that purpose would include, from most to least commonly used: soldier beam and lagging; sheet piles; shaft caissons; diaphragm wall; secant piles; vertical boring machine; jet grouting; and ground freezing.

Before discussing techniques, a detailed analysis of the site has to be done to understand the limitations. Three of the most important considerations are: hydrogeology and site environment (external project constraints); the shape, depth and use of the shaft (internal project constraints); and cost and schedule (both internal and external project constraints).

In shaft construction for a tunnel project, all these parameters are also linked to the tunnel construction itself. None of the techniques outlined above fits all circumstances, and there is no magic solution – usually more than one technique can be used.

This article will discuss two of the main techniques that are most common for access shafts or launch pits on tunnel projects when typical challenges have to be overcome, such as a high water table in an urban or semi-urban environment.

It will also discuss the main

Fig 2: building circular shafts from flat panels becomes harder as the diameter decreases

application of each technique on several recent or ongoing projects: construction shafts using different techniques – the Columbus OARS deep sewer tunnel (Ohio); circular access shaft using secant pile wall – the Norris Cut Tunnel in Miami (Florida); and low-headroom access shaft constraints – Central Subway in San Francisco (California).

circular access shafts When it comes to the shape of a shaft, the most structurally efficient type is the cylinder. The nature of the compression forces and hoop forces that develop when external radial pressure is applied make a circular-shaped shaft work in “pure” compression.

Provided that the compression strength is enough in the material, combined with the absence of tension forces, the circular

Fig 3: alternative shaft shape requiring less bracing

shaft will not require any bracing or tying to the ground. Also, the vertical bending moments will be less than in any other shaft shape.

This is what makes circular shafts so attractive, despite the fact that the use of space is generally not optimal given the footprint of a tunnelling machine. For this reason, circular shafts are mainly used for small-diameter tunnel access shafts and are more typical on combined sewer overflow projects.

Diaphragm-wall equipment cannot excavate a perfect cylindrical shaft. The equipment (mechanical or hydraulic clamshell Hydrofraise) leaves an oblong footprint in the ground for each panel. The smaller the shaft, the more difficult it is to include a circle with rectangular-shaped panels (see Figure 2).

Also, the deviation of the excavation has to be taken into consideration to account for the worst-case scenario, especially for deep shafts – although recent improvements make it possible to build a shaft with 0.3% vertical deviation or better.

Secant-pile walls can also be used to build a cylinder-shaped access shaft and are used in similar conditions, such as the diaphragm wall (high water table in non-cohesive soils). Secant-pile

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walls have technical limitations due to the type of equipment used, with the current limitation being around 120ft in depth and the multiple joint locations; however, in similar geology, secant-pile walls can be more effective since the equipment is more versatile.

columbus oars The three tunnel access shafts were respectively 58ft, 48ft and 54ft in internal diameter, 3ft thick and 108ft, 110ft and 103ft deep.

The Hydrofraise had to be used to anchor the wall 5ft into the limestone bedrock and to achieve the verticality requirements given the depth of each shaft.

In addition to the embedment into bedrock, three grouting phases were completed to ensure the complete watertightness of the shaft before excavation. The first phase of grouting was installed ahead of shaft construction; the second phase was performed through pipes installed in the wall to seal the contact zones.

The temporary outer wall (97ft id) at the ODS Shaft 1 was constructed using the cutter soil mixing (CSM) method and a mechanical grabber for the construction of a digester. Shafts 1 and 2 were first drilled and grouted in the outer area of the shaft walls before D-wall construction. On completion of the first drill and grouting, the CSM was installed in Shaft 1. Subsequently, the D-wall for both shafts was installed and the second phase of the drilling and grouting (through pre-installed PVC pipes into the rock formation) was completed.

Due to unforeseen subsoil conditions consisting of a heavy presence of large boulders and cobbles noted during the installation of the first panels, Nicholson Construction Company proposed the use of a mechanical grabber and chisels fitted to a crawler-type excavation crane while the bentonite/cement mix was supplied into the trench at

miami Norris cut

ground level. Installation of the soldier piles and trench size and depth was kept in accordance with the original design.

Sixty eight secant piles comprise the launch shaft for the Norris Cut Tunnel Project on Virginia Key, Miami, Florida. The overlapping piles are drilled to a depth of approximately 100ft below grade with the water table at 10ft below grade. The soil formation consists of 50ft of silty sand followed by 50ft of porous, vuggy limestone.

Drilling is performed with a

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Fig 4: aerial view of the Norris Cut site

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Fig 5: lowheadroom diaphragm-wall clamshell

Fig 6: aerial view of the launch shaft for Central Subway in San Francisco

rotary drill rig by advancing 1,000mm sectional double-wall casing to tip elevation. After the casing has reached tip elevation, an oscillator is used to extract the casing during the concrete pour.

6,000psi concrete is placed using traditional tremie concrete methods.

After the piles are completed, the interior of the shaft will be predrilled using a continuous flight auger to loosen up the material followed by excavation of the shaft in the wet by use of a crane and clamshell. Once the shaft is excavated, an underwater tremie slab will be poured and finally dewatered before TBM launch.

saN fraNcisco subway shaft On this project, alternative shapes have been used to limit the amount of bracing for shafts and to take advantage of the diagram of forces that develop in cylinders.

In many cases, though, the internal and external project constraints dictate the final shape of the shaft. The project environment also often imposes limitations on the type of equipment that can be used. Low-headroom diaphragm-wall equipment is sometimes the only option to overcome constructability issues such as low room overhead.

A working platform could not be lowered because of the high water table (5ft below the ground level) in San Francisco for the construction of the launch shaft for the two TBMs, so a low-headroom clamshell (Figure 5) was the only available option to build a 61ft-deep shaft in wet silty sands and the Old Bay deposits with 17ft of headroom.

Every step of the diaphragmwall construction takes more time (30% to 50% slower for the excavation on average) with these

methods than using standard equipment.Out of the three steps to building a diaphragm wall (excavation / reinforcement installation / concrete pouring), the most difficult under tight overhead conditions is the reinforcement placement.

Instead of installing standard steel rebar cages, it was decided that the wall would be reinforced with W30 wide-flange soldier beams instead to accelerate the whole process. This reinforcement limits the number of splices and lifting operations, so it is easier and safer.

This article was written by Boris Caro Vargas, director of business development, at Nicholson Construction Company

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7

New design for deep rock

After a concept change, construction on the Deep Rock Tunnel Connector project is at the halfway point. World Tunnelling reports

A

quarter of an inch (6.4mm) – that is the meagre measurement of rainfall it would take for sewers to reach capacity and overflow in many neighbourhoods in Indianapolis, Indiana, US. The Deep Rock Tunnel Connector (DRTC) is phase one of Citizens Water’s plan to eradicate this overflow of raw sewage into rivers and streams. The US$1.6 billion Long Term Control Plan must be completed by 2025.

The DRTC will address three of those Combined Sewer Overflow (CSO) locations: CSO 008 near Harding Street and the White River; CSO 117 near Southern Avenue and the White River; and CSO 118 near West Street and White River Parkway East Drive.

Construction on the $179.3 million DRTC began in December 2011, and it will be complete and in operation by late 2017.

GoiNG further dowN Under the DRTC “storage and transport concept”, sewage captured at CSOs 008, 117 and 118 will be stored in the tunnel and then transported to the wastewater treatment plant. When complete, the tunnel will have the capacity to store sewage during large storms, and overflows into Indianapolis waterways will be significantly reduced.

AECOM is the project’s design engineer and construction inspector. Shea-Kiewit (joint venture) is the construction

contractor. Other construction companies include Nicholson Construction Company and Black & Veatch (B&V), which is on the construction management team.

Robbins supplied the 20ft 2in-diameter, open-face mainbeam TBM. Tunnelling started on March 15, 2013, and the TBM holed through at the retrieval shaft on July 11 this year.

It was not plain boring. “The rock types are limestone and dolomite,” reports David Egger, senior vice president – heavy civil at B&V. “Groundwater inflow has been greater than anticipated. However, the contractor has effectively managed the additional inflows and all contractual matters have been resolved between CEG and the contractor.

“[As of the start of October] the TBM has been backed up through the main tunnel 11,000ft and is getting ready to mine another 9,000ft, a branch off to the west added onto the original tunnel contract. Following this, the tunnel will be concrete-lined.”

From the DRTC, additional storage tunnels will extend along White River, Fall Creek, Pleasant Run and Lower Pogues Run to create a collective, underground storage facility for sewage.

B&V is also the design engineer on the Fall Creek/White River Deep Storage Tunnel, construction of which is expected to begin in 2017. Groundbreaking on one other tunnel is slated for the same year with boring expected to begin on the last two about 2021.

“Groundwater inflow has been greater than anticipated.

However, the contractor has effectively managed the additional inflows”

“When complete, the tunnel will have the capacity to store sewage during large storms, and overflows into Indianapolis waterways will be significantly reduced”

Change of plan In the initial concept, the seven-mile (11.3km) DRTC would have been constructed in soft ground under high groundwater conditions at 35ft to 75ft (10.7m to 22.8m) below surface with an internal diameter of 12ft. Now, the DRTC will be constructed more than 250ft below ground in bedrock, with an internal diameter of 18ft.

The reason behind the change was lower risk and significant cost savings on the CSO programme, of the order of $100 million, Egger tells WT.

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TBMs

Adjusting the parameters From India to Mexico: lessons learned in EPB tunnelling Dual-mode EPB/ rock machines such as this Robbins design used at Australia’s Grosvenor Decline Tunnel may be the answer in complex mixedface rock conditions

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n recent years tunnelling with earth pressure balance (EPB) TBMs has exploded, taking the machines into new types of geology, from mixed ground conditions to sections of rock and high water pressure.

The versatile EPB machine can be adapted for many of these situations, but learning from past projects in difficult ground is key to keeping this machine type successful.

Shinichi Konda, chief EPB engineer at Robbins with over 30 years of experience in slurry and EPB tunnelling, advises planners to invest in a detailed and accurate geologic report. He also suggests trying newer technology such as dual-mode/hybrid-type machines.

Understanding the implications of these lessons requires looking at the projects that inspired them through both successes and struggles in difficult ground.

“Learning from past projects in difficult ground is key to keeping this machine ExTrEME gEology type “It may be time-consuming but successful” an accurate geological report

The Robbins EPB TBMs for Emisor Oriente needed man locks because of the high water pressure in the ground The machines at Lots 3 and 4 in Mexico City have encountered difficult conditions including a full face of abrasive basalt rock

ultimately saves time and money when designing the machine and during tunnelling,” reiterates Konda of his first key point.

Knowing the geology may be at its most crucial in projects such as Emisor Oriente, a vast 62kmlong wastewater tunnel being constructed in Mexico City, Mexico.

Six 8.93m-diameter EPB machines are currently at work deep below the capital, working towards an aggressive deadline of 2018. The machines are boring through a challenging combination of watery lake clays, boulders and abrasive basalt rock with water pressures up to 6bar.

Comissa, a consortium of Mexican heavy civil contractors – ICA, CARSO, Lombardo, Estrella and Cotrisa – is managing the construction, which is divided

into six lots. 24 shafts up to 150m deep support the TBM operations, which total about 10km for each.

The ground conditions of the pipeline are some of the most difficult in the world. Located in the Valley of Mexico, geology consists of a drained lake bed with clays interspersed with volcanic rock and boulders from long-dormant, buried volcanoes.

After five years of work, about 53% of the entire project has been completed including the shafts, and the owner of the project, CONAGUA, is rethinking its strategy based on the difficult and unforeseen ground condi-

tions encountered. The conditions require frequent hyperbaric interventions and multiple modifications to the existing machines.

During shaft excavation at Lots 3 to 5, it was discovered that the ground was significantly more complex than previously thought.

Multiple borehole tests confirmed the results, and it was decided to redesign the machines before launch in order to cope with the severe conditions.

The machines were designed with robust, high-pressure screw conveyors and ribbon-type screws to deal with large boulders, as well as abrasion-resistant wear plating on the cutterheads to excavate rock. High-pressure man locks and sturdy scraper designs rounded out the improvements.

Even with those modifications, the machines have thus far encountered very challenging conditions, including full-face abrasive basalt rock. At Lots 3 and 4, impact loading and wear on the cutterhead has been beyond what was expected.

Large amounts of fines are also being encountered, requiring significant quantities of foam to be used.

Because of these issues, when the machines break into interme-

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TBMs

The Emisor Oriente EPBs were redesigned for challenging conditions

diate shaft sites, they will be further modified. “The rock face encountered required them to bore in open mode with the EPB, resulting in high wear to the screw conveyor,” Konda explains.

To remedy the situation, Robbins developed a new, more w robust version able to take on rock that will be installed in the intermediate shaft. “The screw has been designed with multiple replaceable flights. Access windows every few metres allow for easier replacement,” says Konda.

The bolt-on flights are additionally coated with an abrasion resistant, casted material and the inside of the screw conveyor casing has been reinforced with Trimay wear plating.

Despite the hardships, many lessons have been learned at Emisor Oriente. “If we could provide these machines knowing what we know now about the geology, a dual mode EPB/rock type TBM may have been the better choice,” reflects Konda.

Challenges in Chennai In India, Chennai’s Metro construction is another case of excavation in largely unknown ground conditions. A 6.65m-diameter Robbins EPB was designed to excavate granite, sand, silt and clay with boulders up to 300mm in diameter.

The 1,063m drive for contractor Afcons Infrastructure is part of Lot UAA-01 on Line 1 of the city’s metro, consisting of two parallel

1km tunnels running from the Washermanpet area towards Chennai International Airport.

The specialised design utilises a combination of 17in-diameter disc cutters as well as soft-ground tools. Small grippers located around the circumference of the machine’s shield allow for cutterhead stabilisation in harder ground, and additionally react against the forces needed to pull the cutterhead back from the face in difficult conditions.

Launch of the machine took place in January 2012 from a 28m-deep starting pit, with the machine encountering obstacles from the outset.

“The TBM bored mixed-face conditions consisting of varying strengths of granite ranging from completely weathered and highly fractured through to hard granite with strengths estimated at 150MPa. This resulted in high cutter consumption due to impact damage as the cutter

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TBMs

discs rotated through relatively soft rock and encountered the much harder rock,” Jim Clark, Robbins projects manager – India, says.

“Robbins India provided a geologist who carried out face mapping for the whole of the first drive, in both hyperbaric and open-mode conditions on a daily basis.”

The data assisted the crew in operating the TBM, and provided a comprehensive geological record for the second drive. With the data gleaned from the geological investigation, Robbins was able to advise Afcons on the optimal operating parameters to get through the difficult conditions, including cutterhead RPM, thrust pressure, penetration rate and cutterhead torque.

The cutterhead RPM was reduced from 2.0 in soil to approximately 0.75 in mixed-face

conditions. Rate of penetration was also reduced to prevent impact damage to cutter discs. In a full face of rock the rate of penetration and RPM were increased. Ultimately, the bore was a success, with the TBM achieving rates of up to 44.8m per week.

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Operational parameters including RPM and rate of penetration were altered on the Chennai TBM to aid in excavation of challenging rock

The next wave of TBM technology As a result of lessons learned on projects such as Emisor Oriente, more mixedground projects are being proposed as dual-mode EPB/rock tunnel projects.

Mexico City’s Tunel Emisor Poniente (TEP) II Project is such an example – a complex wastewater conduit that promises some challenging ground conditions during excavation. The 5.9km-long tunnel is expected to be more than 90% rock, but with some significant sections of softer ground.

Robbins is providing an 8m-diameter

hybrid EPB/single-shield TBM, optimised toward rock excavation, for the Aldesa/ Proacon/Recsa joint venture. A canopy drill will be installed, providing another ring for probe drilling close to the cutterhead, or for forepoling if needed.

Overall, the lessons learned from mixed-ground tunnelling are constantly evolving. “We are always in the process – we are currently modifying our cutters for mixed ground conditions to make them even more efficient,” Konda concludes.

This article was written by Desiree Willis, technical writer, The Robbins Company

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FEATURE NAME TBMs NASTT’S TRENCHLESS TODAY | SUMMER 2014

NASTT.ORG

on the edge of the lake

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Sulariumus porum mente forMaremulium factus confirmihi, nos at, cae egit dicultuidet que nihilic discounted traditional large role in creating the historiactam publinirid prorus.

Quid rectoraet, nos, cone paticas est project ingulic butonvoculiciis cutus ex nos et dem ia terra in tuus audam Romne quita, non-trenchless given calnonvere, and social of the nation. venderehemus pultus, nos fabric ca in tescem pora quam.

Soli quiummethods ur. Epopora, clutthe vivit, nonere, vehebunum quo etil huconfere environmentally sensitive nature provides permanent pore conscerfir qui sesKingston consis, quod serferc endaci tam nequide num sessultis aus fortum ia remus Cateret; Catiquam us co te non the parkEtrum and the potential iam tem conte manum. eris. and migratory homes for a et; wide ffrehem sulistissis aucissu piorum aperum inatquos num et; of et que aut foratuusquod traffic congestion issues. rangenium of flora and fauna.

Project dicidin vistra? Ita, consum locaeque terei pra dum iam ocatuis Hen antra ne opoptil us ocurbi egernum in viris, opublia pos, owners and are opulto Catiferis. derioraelus et? Nos consignos, C.contractors Us tatam Patuis Catrorum consu stis oma, ut venatero vidines modient ifecta cler in apply strict rules and Solis viviri pulego vis, careful Patabes!toErbit; hum ommo publiisqua dii TrouBlesoMe si patil actanteground moraet; horterions id ad nos co mo vivilieniu quem incum, processes toobsenat ensure that the city’s shorter 140ft drive was underserbem the The tunnelling portion of the tua nonte is. Sena, nos se patiem inpraci tum publingulem vermilica nox no.

Ublicae toruro hici sede mentebem in inum iumus hae inam movessensus pracipio conferi, cotastrora miusproject acrei called wildlife and sensitive ecosystems regional highway. two rem separate esiliufor quem quost L. Catus, C. Entem esillartes caveres? Med sen neri, obus non seare conloct aribus con patquit re cure, demurbertiam unum essilicae rei stodiu comnihi licissici consupe protected when surface or que noximpr From a tunnelling perspective, tunnels 74in (1.88m) diameter to idessus? int vese abem, teredeffre publiis peceps, sissign oximum in hi, pero ego sultora subsurface work planned.ses bonessultus, the viricauciam, scope of work wasmoverum straight-sent. install 530ft and 140ft of foreno. Cupio pertili civit. Sp. Ad renis ponsultior ubliissum intem Muliuris.

Vive, quitus senam consuntesi prathe inat, unul urewas poendam General contractor Taggart forward but geology not. mainsaand trunk water-main pipe egilina riurit? Ubit? Nostempl.

Viviurniam etreo ensum inequis intus ad in Etre fit.of 620ft Kingston’s geology is often Construction and iaciem tunnelling in rock. The longest drive pules? Untis et cutemquam sendeferidet actum nihilis, fit aceriswas Mae, etia rei senatus intractore, simanulius contractor Marathon Drilling variable and eorunt. unpredictable. Even under anPio environmentally publincus sedo, quam la dit? Andessul perumPump esit; C. Arisulint.

Decienique noc,the cepon sid maximan dacchum rem neme tur, executed the RivervitStreet with extensive geotechnical sensitive parkland area and nocum prae, Ti. etravocupio, investigations et vil hus essente autes egit. at conferum the design Vere con is ad faciis notiquonsu estande nericon can clernum stage, the ground ofteneore que nos, ment in redo, que consisu ltorununtem et; when nosta, itcla iustam prove problematic comes lisses! Sere, aucomne queridtoconsule Catum simorente, SPECIALIZING IN ALL choice gerfit of TBMs andetis cutters. facerdiem. Us. Onsus, nostemThe progeotechnical coenimis, conosti linamenat, information UNDERGROUND ponsciem potiend uconosu lvidiculi perente dientea in haet, ere provided showed a competent “From a tunnelling novenatu manum nius fit Cuperitister in tainmenem.

EQUIPMENT AND limestone an anticline fold perspective, the hocrum diis catuit is lossa novir peri, Aper quitabit patam inatil along the projected path. Given ANCILLARIES scope ofcowork was conlocuperis quem pere mis nihicau mius; adhuius diero mo this geology, thenit, contractors TBM, EPB, MTBM, GBM, atilineque ninatus, side audefex nihicum sim tiema dem Cupions straightforward chose to deploy 72in intis, doublePilot Tube, Road Headers, upiocuppl. Dit. Saticior ad shield morumRobbins ubliisse rock poreTBM. estrarisul hem As the but the geology Auger Boring,Pipe Jacking, untesse ndacta, vent. Imor adhui co Cat, conerfessua perra, niam project started, the excavated was not” Segment Forms fur, nox num publibus publis;entrance et viverebshafts aturbis.

Gered nonsumena, showed excellent sena, se nonsulego hosus; hostuiu quam, que coterit Na, vituam rock competency and vis? cover. interei sernihil hi, vius.

Udacibuntem ves obse etio, num ina, nosulego LET US HELP YOU….

From the start, the drilling es et; num revivis vir ipiocris, sesta re, occiam orte mus, no.

• Market your progressed well with the TBM,Quitis et; Caticas Muliumust? Quitanum omnon vit; iam, sulabena maximus the contractor reports. It proved unneeded equipment pesse oc, visulibus clabes bon prarbis aribus vocciemorei pat, Spoil removal in action to be robust and powerful. The to buyers worldwide esidem oponsim ilique pes C. M. It. • Source quality Quod pecum nihi, atuam tractus; egeroren sede rei sedit. Verbi pro used equipment at trit, con resterei propulies fatus in tame nonferum test vit; nosterbis. substantial savings Sp. Foreis.

EXTENSIVE GLOBAL Ximihicaede caet prae omnerfit venit. Niam la senducerit, utem, over new noratan detebatu vivit; nonvenisquam ta L. Habuntra? Udacieni MARKETING REACH consuss imissed nest rem intrideo manum postam ini senatus NO UPFRONT FEES! AND CONTACT BASE tanterissa L. Do, omnimil icepos nemorit. O teraeste nonsilicest Catumur. Verit; nostra sus? Quis culoctum, cre co verunih ilibultu meremquitiam orio por pra vidit.

Aximmo teritreo, contimus. Ignosum publicam vicia ma, Catatum pos, cen sente nihicus dempra corem in pro complis? Sa terfenicaet Catiaederura rei perfene vivid nos forudeor porum cultod porsules ius co eorunte mplicastre tem nox menatilicon vic vis? Tus hocriss imante nos es horunimprae et vo, utum sinverfirtem iame cori se effre immo Sales@Rhinotraders.com +1 (520)404-7535 vit. Patum nonerem dem int, ver ut novenes tiam culvid cae et grari publium tusque erferfeNovember rficonsul cupientemque aciptilia Sat iderum 2014

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TBMs

steering controls and guidance system is well developed and enabled the crews to drill to the projected advancement rate of 30 to 40 feet per shift.

The gripper system worked well until approximately 530ft into the 620ft drive under the parkland. Without any warning the TBM just stopped advancing.

The contractors went through the standard mechanical checks and then pulled back to investigate what was happening at the face and head.

From examining the head, the team realised it had encountered a significant change in ground conditions. However, one can never tell the full extent of the change without pursuing a proper investigation of both equipment and ground conditions.

The TBM itself was found to be in perfect working order and its cutters showed little wear. The investigations shifted to focus on potential geotechnical anomalies in front of the TBM. A focused geotechnical drilling programme was conducted and it was found that the rock had indeed sloped down and the TBM was now straddling a softer trench of mixed ground condition.

The exact nature and cause of the trench is still under investigation. Regardless of its origin, it was too soft for the TBM grippers to anchor into to pull the TBM forward.

project stakeholders, the contractors came up with several options to complete the last 90ft of tunnel.

If it was a short anomaly, one proposed solution was to install a liner plate system in conjunction with some hydraulic jacking stations to advance the TBM to a ‘potential’ rock zone.

Hand-mining would be too time-consuming and mobilising a new TBM system for 90ft was not going to be a cost-effective solution.

On the back of new geotechnical information, the contractors did a time/cost /environmental impact analysis and it was decided that since the remaining 90ft feet of the tunnel would have no significant impact on any parkland and environmentally sensitive areas, the best solution was to open-cut the remainder and intersect the tunnel.

The team backed the TBM out of the tunnel and readied it for the second shorter drive across the highway.

13

The cutter of the Robbins TBM at work

“The gripper system worked well until 530ft into the 620ft drive under the parkland.

Without any warning the TBM just stopped advancing”

Laser guidance in the tunnel

assessing The opTions With the TBM stuck and unable to advance, choices had to be made. In discussions with all the

Andrew McPhedran is VP of business development for Marathon Drilling

The specialist for tunnelling equipment and logistic systems

Maschinen Stahlbau and

Dresden

Branch of Herrenknecht AG

www.msd-dresden.de | info@msd-dresden.de

• High-performance rolling stock • Jobsite logistics • Customized back-up systems • Shaft installations MSD_09_2014 WT.indd 1 08-13 TBM_WT1411.indd 13

12.05.2014 14:19:09 17/10/2014 09:34

14

ventilation

From left: tunnel portals on the European side; aerial view of Bosphorus showing Uskudar station site; digging at Sirkica uncovered a 6,000-year-old historical site All photos: TGN

Connecting east and West

Mohammed Tabarra, associate director of Arup, talks to World Tunnelling about uniting the future with the past on the Marmaray Tunnel project in Turkey

C

“The ventilation fans need to be much larger than for most tunnels”

Anemometry rig measuring airflows in tunnel Render of transporting immersed tube segments by sea Tunnel crossover caverns between Sirkeci and Yanikapi Stations

onnecting Asia to Europe across the Bosphorus Strait has been an ambition dating back to the Ottoman Empire in 1860. Shifting tectonic plates and construction across one of the busiest shipping lanes in the world has meant that until recently this dream could not become a reality.

On October 29, 2013, the Marmaray Tunnel officially opened, the deepest undersea tunnel and one of the largest transport projects in the world.

The opening coincided with the 90th anniversary of the modern Turkish republic and is part of a national infrastructure plan that includes a third bridge across the Bosphorus and the creation of the largest airport in the world.

Once fully operational, the tracks underneath the Bosphorus are expected to connect more than 1.5 million people each day between Asia and Europe within approximately four minutes. The link will place Istanbul at the hub of travel between East and West, offering huge economic benefits, as well as forming the first tunnel connecting two continents.

The tunnel is 13.6km long and includes 1.5km of immersed tube on the ocean floor, accessed by twin-bore tunnels from Kazlıçes˛me on the European side and Ayrılıkçes˛me on the Asian side.

The route of the tunnel, incorporating three underground stations, Uskudar, Sirkeci and Yenikapi, passes under Istanbul’s old city centre, so careful planning was needed to protect ancient foundations.

Working in harmony This combination of cultural and engineering challenges meant that experience across multiple disciplines was essential.

Arup’s experience in other complex geotechnical and tunnelling projects, including High Speed 1 in the UK and the Hong Kong-Zhuhai-Macau bridge, enabled the company to provide a full peer review of all tunnel-ventilation and smoke-control system design reports, drawings, specifications, risk-analysis management system and test procedures, from preliminary design to installation, commissioning and handover.

A key challenge was providing the necessary ventilation for the tunnel while taking into consideration the precious artefacts and archaeological sites on the route.

The Marmaray Tunnel will provide seamless transport from Turkey to China for a large volume of freight. Freight trains typically have a much larger fire load (around 100MW) than passenger

trains (which might be closer to 20MW). This means that the ventilation fans must be much larger than for most tunnels.

a test of time Soon after work began at the middle station, Sirkica, a 6,000-year-old archaeological site was uncovered 5m below ground.

This revealed thousands of artefacts, and it was essential to excavate these, which delayed the build at Sirkeci for two years.

As a result, the fan plants at Sirkeci Station would be unable to operate on time, and engineers had to revise the tunnel-ventilation strategy to deliver a safe service during the initial operating phase, so that the building process could still progress.

A full analysis including station smoke-test procedures resulted in ventilation zones becoming longer and there was a restriction on the number of trains that could be in the tunnel at one time. This approach has meant that the project was not delayed further, and safety was not compromised.

Collaboration between Japanese and Turkish contractors, designers from Singapore, specialists from the US, rail-safety officers from Germany and designverification engineers from UK makes the Marmaray crossing a truly international effort.

However, it was the flexibility and readjustment of ventilation plans that enabled such a successful and futuristic project to continue while protecting Turkey’s ancient heritage.

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ventilation

a good wind blowing New tunnel-ventilation technology in Norway has called for three-dimensional thinking. Dr Fathi Tarada, managing director of Mosen, reports

T

he ambitious tunnels through the mountains rising high above the Norwegian fjords have always been a challenge to ventilate, partly because of their length (up to the 24.5km-long Lærdal Tunnel), the presence of bidirectional traffic and portal pressure differences.

Some of these tunnels, however, have just benefited from an innovation shown to reduce the number of fans required and to improve power consumption.

too muCh poWer When I wrote the original MoJet patent in 2008, my idea was to use convergent nozzles to accelerate the air through a jetfan, and to turn it away from the tunnel surfaces.

Turning the air minimises the Coanda Effect, where a reduction in static pressure – due to the high jet velocity – deflects the jet towards any solid surface, causing friction and loss of thrust.

The idea of turning the jet away from the tunnel walls had previously been patented by Woods of Colchester in 1995 and by Witt & Sohn in 1999. However, the attraction of the MoJet is its compact size – the lower edge of the MoJet is parallel to the tunnel axis, and the nozzles do not protrude into the traffic space as was the case with the previous patented designs.

The MoJet fan diameter can therefore be maximised to fill the available equipment space, and this reduces the power consumption for a given required thrust.

Systemair, one of the largest manufacturers of tunnel-ventilation equipment in the world, is a licensee of the MoJet. In September 2012, Systemair carried out tests in the Galleria Buttoli tunnel near Florence (Italy), the results of which were reported at the

International Symposium on Aerodynamics, Ventilation and Fire in Tunnels in September 2013.

The tests confirmed a significant enhancement in aerodynamic thrust, but also indicated an increase in power consumption.

The pressure drop, particularly at the inlet side of the fan, had been increased by the presence of a convergent nozzle.

Although the fan was more efficient due to operating at a higher pressure drop, that was not sufficient to compensate for the increased aerodynamic resistance.

The MoJet needed to go back to the drawing board.

moJet on the menu How can we turn the airflow away from the tunnel surfaces without increasing the overall height of the jetfan, and without using converging nozzles?

I remember sketching the answer on a paper napkin at a cheap pizza restaurant after the tests in Galleria Buttoli; a fellow diner found the napkin and handed it back to me as I was walking out of the restaurant. The concept has just been published as a patent application by the Intellectual Property Office, and has formed the basis of Systemair’s supply for a number of tunnels in Norway.

The solution was to think in three dimensions. While the top edge of the discharge nozzle should point ‘down’, there was no reason why the outlet edge should not be inclined, in order to

increase the discharge flow area.

The overall effect is to have an undercut suction side. To reduce the inlet pressure drop further, the inlet edge has a circular shape, in order to use spun bellmouths.

The nozzle’s developed sheet-metal profile becomes a complex shape, but that is well within the capabilities of modern cutting and bending machinery.

The new MoJets have been installed in the Grimstad Port Tunnel in Norway. The fans will ventilate the tunnel to dilute CO and NO2 emissions, as well as to control smoke in case of fire.

Some of the existing jetfans had been damaged by vehicle strikes; the new MoJets will provide additional clearance. Tests on the MoJets have indicated a reduced sound pressure level as well as increased aerodynamic thrust.

While ‘horseshoe’-section tunnels benefit significantly from MoJets, it is in tunnels with rectangular sections and in short tunnels of 1km or less that the systems’ advantages are apparent.

This is because of spatial awareness in the design: the MoJets can be installed much closer together than conventional jetfans, because upstream jets can be arranged not to interfere with downstream MoJets.

With power consumption in a tunnel typically absorbing a few megawatts of power, the MoJet can provide a significant reduction in the operational cost, which can pay for the installation many times over within a few years.

But it is not all about costs: the reduction in carbon emissions should improve the environment and ensure that we can enjoy our journeys through tunnels with minimum carbon footprint.

15

It is a challenge to ventilate the tunnels through the mountains above the Norwegian fjords

“The MoJet can provide a significant reduction in the operational cost, which can pay for the installation many times over within a few years”

A MoJet with its inclined air outlet

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16

immersed tunnels

no longer in third place From Doha to Denmark, the reputation of so-called ‘sunken tunnels’ is rising

I

n the pre-design phase there is commonly a choice to make between a bridge, bored tunnel or immersed tunnel.

Immersed tube tunnels are formed by connecting together prefabricated box segments in trenches excavated in waterways.

Floating tunnel elements are towed into position before being

Planned immersed tunnels Name and location

Immersed length

Expected opening

Fehmarnbelt Fixed Link, Denmark to Germany

18km

2021

Sharq Crossing, Doha, Qatar

6km

2020

Santos -Guarujá Link, Brazil

500m+

2018

lowered to the seabed for assembly. The tolerances involved in the complex process are tiny – each element must line up exactly for the watertight gaskets to seal properly, Mott MacDonald senior civil engineer Jonathan Baber says.

There are only around 200 immersed tunnels in the world, used mainly for transport and utilities. It is typically an option for shallow water over short lengths, but new designs are varying from the book.

The main advantages of an immersed tunnel are the economic use of shape (cross-section), economic length, vertical clearance and ground condition and seismic conditions, consulting engineering group Ramboll states.

The cross-section of an immersed tunnel does not have to be circular as it does for a bored tunnel.

A wide variety of cross-section demands can be accommodated, making immersed tunnels attractive for housing wide highways and combined road/rail tunnels.

Immersed tunnels can be placed on the bed of a waterway or just below it, while a bored tunnel must normally be placed at least one diameter below the bed of the waterway. This allows immersed-tunnel approaches to be shorter and/or approach gradients to be flatter. This is of benefit to rail tunnels where gradients are low.

The immersed option eradicates the limited clearance that

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immersed tunnels

bridges offer ships on a body of water.

They can be laid in poor ground conditions such as soft alluvial deposits that are found in large river estuaries that would cause major risks to building bridge foundations or driving through a tunnel boring machine. They can also be designed to withstand seismic activity.

Ramboll is involved in the planned Fehmarnbelt Fixed Link, and has worked on the Øresund Link, a 3.7kmlong immersed road and railway tunnel, opened in 2000.

On the US$1.6bn (3.2km) BusanGeoje fixed-link project in South Korea, the contractor – a consortium of Korean companies led by Daewoo Engineering & Construction – used the innovative ‘external positioning system’ solution from Dutch specialist Strukton Immersion Projects, Mott MacDonald’s Baber adds. The tunnel opened in 2010.

two regional firsts Design works on the first Middle East immersed tunnel, part of the Sharq Crossing in Doha, are under way. TEC, the permanent joint venture between Royal HaskoningDHV and Witteveen+Bos, is designing two immersed tunnels and three cut-andcover tunnels that will connect the bridges to the mainland.

In April last year TEC won a €5 million (US$6.4 million) contract to lead the design process for the first immersed tube tunnel in Brazil, at the country’s

largest seaport, Santos. The 500m-long tunnel will directly link the cities of Santos and Guarujá.

In March 2014, 18 companies prequalified to construct the $800 million tunnel, which will run for 1.7km.

500m will be constructed by sinking six precast concrete elements to a depth of 21m below the water surface.

17

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the long wait In early September this year the Fehmarnbelt tunnel’s management body, Femern, pre-qualified the tunnel’s electrical and mechanical installations, as well as the establishment of the sub-station, which will supply the tunnel and electric trains with power.

The contract concerns the ventilation of the tunnel and buildings, emergency doors, fire-suppression systems, drainage, cabling and pipework, elevators, transformers, lighting, monitoring and control systems as well as communication systems in the tunnel.

The pre-qualified companies from Austria, Denmark, France, Germany, Italy, Poland, Spain, Sweden and the UK will now prepare their technical bids for the contracts in line with the same tender model as for the four major tunnel contracts.

Femern expects to receive the final bids at the end of 2015. The company anticipates signing in 2016. The tunnel is slated for completion in 2021.

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CONTENTS

1

Plenty of fish in the sea?

R

eviewing the recent headlines from the UK construction market is like sampling pieces from a Smörgåsbord, that Scandinavian buffet of hot and cold food.

Opportunities and challenges seem to run at a temperamental rate of flow. The skills shortage is the tempest of our time, but then you hear the one about the five employer-led project groups coming together to invent the hole-free net to attract the latest school of talent.

The quintet will receive a total of over £630,000 (US$1 million) in investment from the UK Commission for Employment and Skills. They will improve collaboration and provide better training opportunities for both new and existing workers. Companies involved include Skanska, Laing O’Rourke and Steel Construction Institute.

In related news, 10 graduates, picked from 1,400 applications, are starting Wolseley UK’s management training programme within the group’s Plumb and Parts Center, Pipe Center, Drain Center, Integrated Services, Burdens and William Wilson businesses.

And market reports come in that planners and project managers’ salaries are breaching “While people in the UK that £100,000 bubble. But set that against are looking to reel in news that only one in 10 subcontractors is being paid within 30 days. work, fish in one city in There is also a stirring current of resentment Canada might be among British workers that the number of homeless due to an augerengineers coming to the UK from outside the boring job gone wrong” European Union has risen by more than a third this year.

Worse still perhaps, on a larger scale, is the Office for National Statistics’ Construction Output figures for August 2014. UK figures fell 3.9% for the month compared with July.

“Infrastructure and Commercial [are] continuing to record declines in growth. It is vital for the industry that all of these sectors grow to ensure pre-recession levels of activity are achieved sooner,” Michael Dall, lead economist at construction intelligence specialist Barbour ABI, commented.

Speaking of fish… While people in the UK are looking to reel in work, fish in one city in Canada might be looking for a home due to an auger-boring job gone wrong. A subcontractor on the C$33.5 million (US$29.7 million) East Langley water-line project in British Columbia was using an auger-boring machine to push pipe under Michael’s Brook, upstream from the Nicomekl Enhancement Society fish hatchery, when parts of the ground in the area collapsed.

The collapse muddied the waters before the salmon run had started – a fitting analogy of the new entrants and opportunities in the UK construction market? Let’s hope not.

LUKE BUXTON luke.buxton@aspermontmedia.com

News Features North America HDD Suction excavation Contacts

2 3 12 20 23

Next month Asia Microtunnelling Drilling Fluids

COVER No-Dig United offers turnkey solutions for largescale pipe replacement. The ability to supply hardware, software and consulting services, combined with the actual execution of the project, is the key to great success for the company powered by Scandinavian No-Dig Centre. Using pipe-bursting equipment with 400 tonnes of pulling power, all existing pipes with an internal diameter of up to 1,500mm can be replaced with new product pipes of the same or larger ID. info@nodigunited.com

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2

NEWS

UIS hopes new products will click with users UK-based UIS has launched two new products aimed at the trenchless market.

The company has developed a solution to the replacement of breaking out cast mains with a podger bar.

The Click Stick is designed to be used with two options: a hydraulic pump (foot or hand); and a battery-powered pack system.

The battery-powered option offers operatives a safer and more controlled alternative to that of vertically mounted 14lb (6.4kg) hammers, which are used manually to strike metallic pipe.

UIS has also released the UIS Transmatic, which the company said is the first coil trailer to fully incorporate pipe-pushing technology.

It is designed to ensure a compliant and controlled dispensing operation of coiled PE pipes.

The Transmatic can transport coils up to 500m in length.

UIS Click Stick with battery power pack (right)

Safer pipe trailer makes its debut UK-based Pipe Trailers debuted its HyPower 500 at No-Dig Live 2014 in the UK during September.

The coil-pipe trailer’s design transports and dispenses up to 500m of 90mm pipe. It also accommodates pipe in other sizes and wall thicknesses up to 125mm. Pipe Trailers claimed the HyPower 500 has enhanced versatility, flexibility and safety features.

Remote-controlled, powered hydraulics keep the operator at a safe distance from the trailer during the setting up and dispensing of the pipe.

The HyPower 500 was shown at No-Dig Live 2014

The hydraulic arm lifts and encloses the coil in one operation, eliminating the risk of the coil springing outside the confines of the trailer.

The incorporated electric winch safely releases the end of the pipe, eradicating

Visitors get hands-on trenchless experience Tracto-Technik (TT) marked its 10th ‘Hands-on Days’ event at its headquarters in Lennestadt, Germany, from September 16 to 26.

The no-dig systems manufacturer demonstrated its machines to over 600 visitors from Africa, Asia, Australia and Europe, especially eastern Europe where there is a strong demand for underground pipe infrastructure.

The multi-lingual programme also included a factory tour, a choice of 30 lectures by speakers from TT and exhibiting partner companies Bagela, Bohrtec, Föckerperger, Hauff-Technik, Prime Drilling and RSP suction excavators.

In co-operation with Prime Drilling from Wenden, Germany, engineers operated the complete range of HDD technology from

mini-bore rigs to large drilling rigs.

TT is finding more demand for its Grundomat soil-displacement hammer due to the growing number of fibre-to-the-home installations. One solution is the 45mm- or 55mm-diameter model, which bores out of the building while pulling in a 32mm-diameter PE protection pipe.

The bore through the brick wall is sealed to make it gas- and water-proof using a wall duct manufactured by TT’s partner company Hauff-Technik. All works can be carried out without trenches except for the connection to the main pipeline in the street.

The Grundopit Power mini-bore rig can handle longer service connections along varying elevation or curved bore paths.

the need for operators to place hands inside the trailer to perform a manual release.

The HyPower 500 has been developed so as to ‘design out’ the risks and build safety into the coil-pipe handling operation.

The HyPower 500’s lifting mechanism means no pipe snagging and pipe jamming, unlike traditional trailers, which use pipe end clamps and ratchet straps, the company said.

Additionally, the autoadjusting side rollers prevent pipe from straying from the coil, even when too many bands have been cut, which not only prevents kinking and damage to the pipe but also the need to rotate the pipe by hand, saving both time and money, the company added.

Tracerco opens research and testing facility Technology company Tracerco has unveiled a £9 million (US$14.36 million) custom-built research, development and engineering test centre for oil, gas and petrochemical measurement technology.

The new building includes a 30,000L underwater testing pool, designed specially for the company’s latest invention – the Discovery CT scanner, which allows operators to inspect subsea pipelines from the outside without having to remove protective coatings.

The company claimed that it is the world’s first CT scanner designed for pipeline inspection.

Fifty new jobs will be created at the site in Billingham in Teesside, UK, where Tracerco’s origins date back to 1958.

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considerate construction Pipe bursting at the historic Arlington National Cemetery called for a sensitive approach

The cemetery was founded 150 years ago

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rlington National Cemetery in Virginia, the most famous cemetery in the US, is the final resting place for many of the nation’s greatest veterans of every American conflict, from the Revolutionary War to Iraq and Afghanistan.

The Arlington National Cemetery was founded 150 years ago in 1864. It has provided a solemn place to reflect on the sacrifices made by the men and women of the United States Armed Forces.

Today the cemetery covers over 600 acres (2,428,000m2) and contains the remains of more than 300,000 veterans in 70 burial sections, and 38,500 remains in the eight columbariums.

Cemetery facts 300,000 veterans in 70 burial sections 4 million visitors a year 60 years ago – water mains installed The curvilinear pathways of the cemetery conform to the natural topography of the site, and much of the site is naturally landscaped, with immaculate pathways lined

with stately flower gardens and trees.

Throughout the hallowed grounds, monuments are placed atop prominent hills, many

Final resting place of John F. Kennedy

Centre of excellence...

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system was constructed to support the needs of the cemetery. More than 60 years ago, a series of cast-iron water mains was installed for fire suppression and potable-water uses on the site. Today, most of the cast-iron water mains are in need for replacement.

Low-impAct soLutioN HDPE pipe sections buttfused together in staging area

providing visual and symbolic links to Washington, DC, located across the Potomac River.

Almost 4 million people a year visit the national cemetery. A constant vigil is maintained at the Tomb of the Unknowns, where the changing of a military guard occurs around the clock. On average, 28 burials occur each weekday, for a total of nearly 6,900 each year.

Naturally, as the cemetery and national park grew more sophisticated, an underground utility

The US Army Corp of Engineers Norfolk District was tasked with the challenge to find a construction method that would not interfere with the 11,000 daily visitors, 28 daily burials, the changing of the guard at the Tomb of the Unknowns and other ceremonies that take place.

In addition, the water-main replacement method needed to reduce the environmental impact on the landscaping and trees.

Pre-chlorinated pipe bursting was ultimately selected as the most advantageous technology that would reduce the impact of

construction on the surroundings and cemetery activity.

In total, five construction phases progressed replacing over 38,500ft of existing 6in cast-iron water main with new 6in highdensity polyethylene (HDPE).

Murphy Pipeline Contractors was awarded the phases through Patriot Construction, 8(A), SDVOSB, a full-services general contractor, headquartered in Maryland, US. Murphy Pipeline Contractors is a North American trenchless contractor focused on the replacement of pressure pipeline systems. Established to bring the trenchless technologies of Europe to the US, its speciality is static pipe bursting and swagelining (HDPE pipe lining). The team is led by president Andy Mayer, who is a native of the UK and worked for British Gas at a time when it was first developing pipe-bursting and swagelining technologies.

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Pre-chloriNAtioN

can have a lifespan of over 100 years.

Murphy Pipelines has a large fleet of McElroy fusion machines, and for good reason. “Quality is most important, as any breakdowns require an extensive amount of lost production time and expense,” Andy Mayer, president of Murphy Pipeline Contractors, says.

To protect its fusion machine

The method of pre-chlorinated pipe bursting has a history that extends many decades, as the process was first adapted by water companies in the UK. The method utilises HDPE pipe and entails the pre-assembly and testing of approximately 300ft to 600ft lengths of pipe above grade at a nearby staging location.

This work is completed in advance of pipe-bursting operations. Once the pipe string is proven to be sound by the testing and disinfection procedures, bursting operations can begin. In the area of water main being replaced, a series of small excavations are made and the new pipe is pulled into place by pipe bursting the existing main.

A post-chlorination and flushing of the main is then performed and the new line is connected into the distribution system. Ultimately, all services are connected into the new main and the surface area is backfilled to preconstruction grade. The entire process is completed within a single day, taking seven to 10 hours, thereby minimising the disruption to residents and businesses – and in the case of this project to park visitors and funeral processions.

The process starts in an isolated staging area located away from burst locations to minimise site impact. Forty-foot lengths of pipe are fused together using butt fusion. At Arlington National Cemetery, workers from Murphy Pipelines used a McElroy Rolling 28 fusion machine to fuse the 6in DIPS DR 11 Driscoplex HDPE pipe. The Rolling 28 is capable of fusing thermoplastic pipe from 2in IPS to 8in DIPS. HDPE has become the preferred pipe material to install with static pipe bursting as the material is lightweight and flexible, combining a high impact strength with ductility and toughness. Third-party research indicates that HDPE pipelines

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Above: team meetings were vital to ensure co-ordination of construction activity in the high-profile areas Above right: Murphy Pipelines crews installing 520ft of HDPE by static pipe bursting

Connections utilised ductile iron fittings, mega lugs and stainless steel inserts

fleet, Murphy Pipelines uses McElroy Pipe Stands. The Pipe Stands are set up on either side of the fusion machine, and help to bring the pipe into the fusion machine at a consistent level for a more efficient fusion process. Not using pipe stands can cause undue stresses on the pipe rollers and the machine itself.

Once the 300ft to 600ft lengths of pipeline were fused together, Murphy Pipelines personnel capped the pipe ends.

Each pipe section is then bacteriologically disinfected and pressure tested in the staging area prior to installation.

Two consecutive days of samples are taken, 24 hours apart, and checked for bacteriological clearance. This step is critical, as it eliminates the alternative of temporary water services to be set up, which can slow production and cause an inconvenience due to the above-ground lines.

Because the pipe has been

the surrounding soil. The new HDPE pipe was then pulled through the space created by the expander.

On the days spent pipe bursting, crews could often be found making connections in the early afternoon. All tools, connections and fittings were sprayed with a hypochlorite solution. After all connections were made, the main was then super-chlorinated with 300ppm chlorine, flushed and put back into service.

Site chAlleNgeS properly pre-chlorinated, it is ready to be put into service immediately after installation.

The final component of the staging process is the addition of a manifest attached to each pipe section that identifies the testing results and that the steps have been taken. Records of testing are given to inspectors, project managers and project owners.

StAtic pipe burStiNg To install the replacement piping, workers excavated small entry and exit pits in the cemetery. The original cast-iron main was decommissioned and readied for the pipe-bursting process as equipment was installed in the pits.

Metal rods travelled through the existing main to the launch pit, where a blade set, expander, tracing wire and HDPE piping were attached to the rods. By mid-morning, the pull back process began. In most cases, the new HDPE pipe was pulled back and burst through the old pipe by the early afternoon.

The static bursting process can also be used to replace existing mains made of AC, PVC, ductile iron and steel.

During the pull, the expander forced the existing cast iron mains to fracture and the pieces of the old pipes were pushed into

Murphy Pipelines personnel were challenged with working in an operational national landmark that would not be closing to tourists and visitors. Arlington National Cemetery holds, on average, about 25 to 30 funerals each day.

Inevitably, funeral processions and funerals would occur near and through construction areas.

Out of respect to the deceased and the services, workers stopped work and shut down equipment.

Many of the burst locations also occurred at high-profile areas including the Welcome Center by the park’s entrance, former president John F Kennedy’s grave, the Memorial Amphitheater and the Tomb of the Unknowns with the changing of the guard occurring every hour.

“The project progressed without incident and it is a true testimony to the pre-chlorinated pipe-bursting technology and the team atmosphere to replace the extensive water-main system with little to no impact on the cemetery and its daily activity,” Mayer says.

“Team work was vital to ensure a successful project. The Norfolk District US Army Corp of Engineers and Arlington National Cemetery personnel showed great resolve in working with our crews to properly plan, adapt and execute the project.”

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FEATUREAmericA North NAME

investigating the line Pipe-inspection and leak-detection system reveals need for rehab in Vancouver A view of the software used to control the sensor head and view both video and acoustic results from live surveys

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s part of a pilot project with the City of Vancouver, Canada, a location between 34th and 36th Street close to Prince Edward Street was selected in order to perform an internal pressurised inspection using the JD7 Investigator unit from UK-based JD7.

For the purpose of this project, nine access points were selected in the Vancouver area. The launch system utilised with the equipment was adapted in order to provide access into a vast majority of fire-hydrant models from the major manufacturing companies, including both slide-gate and compression-style hydrants.

Unlike the UK, in North America there are many different types of hydrant, and inspection

inspection of assets ranging from 100 to 300mm in diameter while maintaining the lines in full service. Minimal preparation is required for an intervention as it utilises various existing entry points, such as fire hydrants and pressure fittings.

FiNdiNg the right solutioNs companies need to make modifications to their launch apparatus to accommodate the variances in design.

The JD7 Investigator watermain condition-assessment tool is used for in-service distribution systems. It has a high-definition camera system with hydrophone technology, as well as a highpowered sonde.

The Investigator allows for the

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   



In Canada slide-gate hydrants are considered to be antiquated in the water-distribution systems.

It was therefore a surprise to see so many in good working order.

It was concluded that, in order for the Investigator to work

Inspecting the water mains in Vancouver

Focus on the equipment The pressurised pipeinspection and leak-detection system is used for 3in-diameter pipework and larger with pressure up to 16 bar. The system is mounted onto pipework through a selection of fittings and/or ‘hot tappings’.

Monitoring the real-time data captured by the camera and hydrophone sensor head allows the operator to understand internal pipework conditions and leakage points.

The maximum distance for each insertion is 100m due to the length of the cable supplied with the system. During insertion, the maximum distance

achievable will be influenced by the pipe diameter, internal condition and number of bends present.

The JD7 software is specific for the Investigator technology and is used to control the sensor head and view both video and acoustic results from live surveys. The software displays video in a resizable window and also acoustic results in order of amplitude and frequency.

The software also operates the sonde, which is built into the camera sensor head. The system is compatible with JD7LiveFeed software for maximum performance.

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properly, JD7 would have to devise a way to simultaneously seal the single drain plug in the shoe as well as isolate the barrel, essentially transforming the barrel into that of a wet-barrel hydrant.

The team quickly developed a solution with the modifications completed on the launching device. Following this, only a rapid adjustment was required between hydrant mobilisations to accommodate the varying burial depths.

Throughout the inspection process of the various water mains, JD7 was able to identify sectors that had been rehabilitated with cement mortar lining, as well as others that had not been examined yet.

The cast-iron lines, which had been lined, showed no signs of tuberculation throughout the

9

JD7 equipment being used on an inspection project in the US The Investigator unit on site

pipe other than at the tees and various bends or valves. The cast-iron lines, which were approximately of the same period, without having undergone rehabilitation, were now showing signs of anywhere between 5% and 20% reduction due to tuberculation.

Despite encountering some areas with heavy tuberculation, no acoustic points of reference or anything that may have been perceived as a leak were

detected. The nine access points, which were utilised, allowed JD7 to cover over 300m of water main in the area.

Having identified zones where tuberculation was becoming an issue, the city now possessed the documentation validating the actual condition of the water mains in that area. As a result of the work performed, the unlined mains have been identified as rehabilitation candidates in the near future.

This article was written by Stuart Hamilton, managing director, JD7 and David Gosselin, project engineer, GAME Trenchless Consultants (JD7’s preferred partner for delivering projects in Canada)

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HDD

A case for the coolheaded A relatively new technique in North America, thermal grouting of long and short electric utility underground bores, should be seen as a key step in the engineering plan Cable bundle in downtown Vancouver on the VCCT project. The line has come from across False Creek and Fairview Slopes, visible in the background

“Thermal grouts need to be pumpable, flowable and stable”

T

hermal grouting, in basic terms, is the process of injecting grout between conduits and casings (or the ground in uncased bores) to reduce the heat generated by large amounts of electricity passing through the cables.

In the US, long-bore thermal grouting became a reality in spring 2007, when the first two long horizontally directional drilled (HDD) casings were successfully thermally grouted.

This project was in Austin/ Davenport (Texas) and has been written about in several technical and magazine articles. Two 2,000ft 30in-diameter conduitsin-casing bores were successfully grouted by Mears Group and Constellation Group.

Many shorter jack-and-bore casings have been installed and grouted for many years with varying degrees of success. Often the contractor is successful, but in the US only the disasters become well known. Crushed or melted conduits can ruin a contractor’s, and a utility company’s, day.

This article will highlight several long HDD projects successfully completed in the US, the longest being 1,869m (6,131ft) under Wolf Bay, Alabama.

Other projects discussed include electric utility BC Hydro

Canada’s Vancouver City Center Transmission (VCCT); energy-project developer Woodbridge Competitive Power Ventures’ (CPV) six bores totalling nearly 3,353m (11,000ft); the Public Service Electric and Gas Company (PSE&G) New Jersey project, which is still under construction, with several shorter bores completed; and Platte River Power Authority’s (PRPA) jack-and-bore grouting operations at Longmont, Colorado.

Step by Step Thermal grouting is a process and needs to be considered during the engineering phase. Often, in the US, this is not the case, or is minimised. It is not uncommon to see ‘Fill the casing with thermal grout’ on the Plans and Specifications page. Grouting needs to be engineered, planned and executed as part of the construction process, much like HDD

drilling or microtunnelling or jack and bore.

The engineering team needs to determine the thermal characteristics of all the components of the system (such as cable design, ampacity, conduit material, casing material, electric load and ground properties).

The thermal grout should be designed and tested before installation to ensure that it meets/exceeds the electrical engineer’s requirements.

The casing and bundle (conduits and spacers) need to be designed to accommodate the grouting. Often this step is missed. Other steps missed are grout-pipe installation points and flow paths or holes for the grout.

Thermal grouts have to have two primary characteristics – meet the thermal requirements of the project and be constructible.

This sounds almost too easy, you say. Now consider that this grout

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Grout being poured for a short-bore project

Example of cables badly grouted by another contractor

needs to be pumped 400m and then flow through spacers (think baffles) spaced every 1.6m for several hundred metres.

This is not so simple. Thermal grouts need to be pumpable,

flowable and stable. The use of chemical admixtures such as superplasticiser and stabilisers can be of immense value. On most projects, retarders are utilised as well.

first long-Distance project The Austin Energy project in Texas consisted of two 610m (2,000ft)-long, 813mm (32in)diameter casings with two 12in and six 3in HDPE conduits. The

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HDD

larger conduits were for forcemain sewers and the smaller conduits were used for distribution-voltage (13.5KV) cables.

Grouting consisted of using a slightly modified grout originally designed by Geotherm.

The bores were drilled by Mears Group of Houston. The bores went under Lake Austin and the Austin Country Club.

Grouting was performed in planned stages, primarily due to limitations in on-site grout mixing. Grout was first pumped into the lowest segments of each bore and allowed to harden.

Subsequent upper sections were grouted.

Ready-mix set-up for Vancouver’s VCCT project

Grouting at David Lamb Park in downtown Vancouver

first long uncaseD bore BC Hydro’s Vancouver City Center Transmission job in British Columbia, Canada, is a major project undertaken in downtown Vancouver – from David Lamb Park, under False Creek to the suburb of Fairview Slopes.

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HDD

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Grout being prepared for the VCCT job, and a bundle of cables going into the pipe

The HDD bore (1,100mm in diameter) was roughly 850m (2,800ft) long with drilling performed by Michels, Canada.

Planned cabling was 1250A, 230kV XLPE. This was the first and longest uncased bore to be successfully

thermally grouted in North America. Over 730m of bore went through sandstone, with conductor casing at either side.

Grouting was performed in planned stages by Michels’ personnel. Pressure and temperature transducers were installed

during bundle installation to monitor grouting conditions in real time and temperatures during grout hydration.

This project, which was constructed in residential and urban environments, has been energised.

“This bore is 1,869m (6,131ft) and is the unofficial distance record for a thermal grouted casing”

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HDD

Above: route of the Wolf Bay bore Top right: bundle of cables on north side of Wolf Bay Right: water discharge from grouting on south side at Wolf Bay

Pumping grout on the Platte River Power Authority project

THe longesT bore Another major project conducted in the US was under Wolf Bay, Alabama, for PowerSouth Energy Cooperative. This bore is 1,869m (6,131ft) long and holds the unofficial distance record for a thermal grouted casing. Southeast Directional Drilling (SEDD) executed this project on completing grouting in two working days.

Nearly 700 cubic yards of highly fluid thermal grout was injected. This project has been energised at 115kV, XLPE cable.

FresH From THe FielD The HDD portion of the Woodbridge CPV Energy project in Edison, New Jersey, US, has just

been completed. Over 3,350m (11,000ft) of 32in fusible PVC were installed by Carson Corporation in three pairs of bores.

Overhead transmission lines from a planned gas-powered generating station enter the ground near the Raritan River, New Jersey, and travel underground through both trenchless and trenched conduits to the distribution station. The trenchless portion is below environmentally sensitive wetlands. Planned cabling (already on site) is suitable for 230kV.

A mulTiTuDe oF sHorT bores There have been numerous shorter bores completed in the US. Current federal regulations now prohibit new overhead lines above the Interstate Highway system. Individual states have

similar requirements when working in wetland areas and require trenchless installations.

Thermal grouting in the US is becoming more commonplace, but is often left up to the contractor with little engineering performed in advance of construction. Grouting should be part of the overall construction plan.

In all of the major projects listed above, Constellation Group provided technical grouting services to allow each contractor to perform the necessary task itself.

The company has also worked with Golder Associates and Haley & Aldrich on the engineering aspects of their projects; as well as working on thermal-grouting national guidelines for the utility industry.

This article was written by Guy Dickes, president of Constellation Group. Constellation Group, of Baltimore, Maryland, US, has no relationship with Constellation Energy, Baltimore Gas and Electric or any other utility or construction company November 2014 12-18 HDD_Trench1411.indd 16

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HDD

Direct results by doubling up Combining different trenchless technologies can provide the best of both worlds Direct-pipe drilling technology on site at the Hauts de France II project

The trenchless drive exceeded 1,000m

T

ogether with its clients, A. Hak Drillcon is on a mission.

The Netherlands-based fullw service provider for pipelines, cables and industrial services wants to make a significant contribution to a sustainable society.

The company’s direct-pipe drilling technique, which has significantly less impact on the environment, exemplifies this.

Compared with other drilling methods, the direct-pipe method is characterised by minimal risk when it comes to difficult soil conditions and an unstable borehole.

Direct-pipe drilling technology combines microtunnelling with horizontal directional drilling (HDD). One advantage of this method is that a work area is only required on the entry side.

25% to 30% of the maximum thrust force is needed.

Twice THe THrusT force

The direct-pipe technique is a newly developed drilling method, where the product pipe is pushed directly behind the tunnelling machine in front.

This pipe-mounted TBM is pushed forward by one or two pipe-thrusters, which grip the pipe and deliver a thrust force of more than 500t. However, in A. Hak Drillcon’s experience only

A.Hak Drillcon claims to be the first company in the world to show that the direct-pipe method allows drills in excess of 1,400m. However, under the right circumstances, it is possible to drill even longer distances, the company states.

In the case of long drilling distances, two pipe thrusters can be deployed in order to double the thrust force.

As with HDD, the first part of direct-pipe drilling is implemented at a downward angle.

When reaching the desired depth, the TBM is adjusted to horizontal drilling. When approaching the target site, the

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HDD

TBM is adjusted upwards until it breaks out of the soil.

During the drilling process, the drilling line is continuously monitored and, where necessary, adjusted by the company’s gyroscope measurement system.

Similar to HDD, the entire pipe string can be laid out beforehand, and with continuous and uninterrupted insertion. However, when necessary (for instance when the stringing space is restricted), the direct-pipe technique also allows insertion of the pipe section by section. Only the activities at the entry side require a large work area. This drilling technique renders route tracking (surveying) unnecessary and also minimises the need for site access permits.

Hauts De France II project From August to October 2013 A. Hak Drillcon worked with main contractor Max Streicher France

on GRT Gaz’s Hauts de France II project in Corbie, France.

The new pipeline is part of the parallel expansion of GRT Gaz’s existing pipeline. The total pipeline connects Pitgam (Nord) to Cuvilly (Oise) with a length of approximately 174km, divided into several lots. The lot awarded to Max Streicher France comprised the trenchless crossing, which was subcontracted to A. Hak Drillcon.

The soil conditions along the route and in the crossing section vary from clay to gravel, chalk, marl and flint. For this reason the direct-pipe technology was the ideal solution.

The trenchless drive totalled 1,072m of 48in carbon steel pipe.

The wall thickness was 28.2 mm and the coating was dual-layer PP (14mm). The maximum push force was 270t. A.Hak Drillcon used a Herrenknecht AVN 1000 micro-

tunnelling machine, in combination with an HK 500 PT PipeThruster. After mobilisation on the jobsite, the drilling process took only a few weeks, including two days’ standby for welding the second 48in pipe section.

A.Hak Drillcon carries out trenchless crossings of pipelines for oil and gas, district heating and cooling, potable water and waste water, medium- and high-voltage cables and telecommunication connections.

The company has a large fleet of HDD rigs with capacities ranging from 3t to 500t using seven maxi/mega rigs ranging from 150t to 500t. It also has pipe thrusters with capacities up to 750t, which, as a redundancy, can be deployed in support of pulling in or reversing the pipe if necessary.

The company also performs auger boring and pipe ramming.

19

Varied geology on the Hauts de France II project included clay, gravel, chalk, marl and flint

This article was written by Richard van Santen and Karin Vijverberg from A.Hak Drillcon

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20

SUCTION exCavaTION

The mission under the maze When numerous utility pipes and cables crisscross their way under our city’s streets, conventional sewer-repair techniques can be too risky. Step in suction excavation…

On the King’s Lynn job, a mass of services were found under the surface. All were secured to prevent any movement or damage during suction excavation

A

large strategic partnership working for a national utility supplier was tasked to expose and repair a collapsed sewer in an old cobbled street of King’s Lynn, UK. The sewer was estimated to be 4m below ground level. When the client manually excavated down to 800mm, it quickly discovered a myriad of existing utilities.

At this point the client insisted on the use of non-invasive suction-excavator technology to eliminate the risk of service strikes and damages to the existing infrastructure.

UK-based Suction Excavator Solutions (SES) provides an alternative safe digging method to mechanical and manual excavation techniques. This method has been proven to help save millions of pounds across the UK.

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SUCTION exCavaTION

SES provided a full consultation service and site survey before the work was carried out. This ensured the best possible solution to the task providing maximum safety and minimum disruption to the general public.

This was imperative as the section of sewer that needed to be exposed was directly outside the Civic Hall and cathedral where weddings and council meetings were taking place.

SES suction excavators use the latest RSP DV fan technology, which exhibits optimal performance characteristics, excellent running capacities and incorporates many health-and-safety benefits. The fan assembly has an air-outlet silencer, which is designed to lower the working frequencies to ensure minimal noise and effect on the environment.

Once the start date was confirmed, SES dispatched a suction excavator and operating

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were completed and agreed with the client before the works started.

ON-SITe SOlUTIONS

team to carry out the work. All the SES team of operators hold EUSR/CSCS cards, and SHEA Gas and Water Hygiene accreditations as a minimum. The members also attend the manufacturer’s specialist suction-excavator training courses that are held periodically.

All work permits, risk assessments and method statements

SES mobilised one of its ESE 26/8 suction excavators fully equipped with non-conductive air tooling, accessories and extension pipes to cope with the estimated 4m depth of the sewer.

Once on site, the suction excavator moved into position to allow traffic to flow continuously.

All traffic management, lighting and guarding was supplied and put in place.

The suction-excavation team used compressed-air tooling to loosen the ground and rapidly remove all the material around the existing utilities such as gas, water, electric, British Telecom, fibre optic and cable TV. Many unknown services that were not present on any drawings or plans were also found and relocated safely. The company did not

21

Suction excavation under way at King’s Lynn

“SES managed the project safely, on time and within budget, much to the client’s satisfaction”

17/10/2014 09:45

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SUCTION exCavaTION

23

Focus on the company

cause any damage to the utilities or services while employing the suction-excavation technique.

Suction excavators are designed and manufactured using special suction fans that create the negative pressure and air flow to transport material.

The suction fans are driven via an engine-driven power take off (PTO).

The fans are capable of creating an airflow of up to 44,000m³/h, maximum vacuum of 55,000Pa. This air flow enables the operator to suck all kinds of materials, liquid or solid up to 250mm in diameter, through the air-intake suction nozzle.

The excavation was reduced and shuttering was put into place to maintain a safe working environment at all times.

The team continued to excavate down to 3.2m, where it exposed the collapsed clay-lined sewer. It was then apparent how fragile the sewer was, as even hand-digging could have caused further damage. All connection pieces were exposed for inspection and repair.

All the material removed from the excavation travelled in the airflow through the extension pipes into the 8m3 container/ tipping body. Once full, the container was tipped directly into

Suction Excavator Solutions (SES) provides safe, effective and trenchless techniques for all kinds of projects across many different sectors. Since the company’s formation, it has grown to be a successful nationwide provider for both largeand small-scale utilities, construction and specialist applications.

Gone are the days when suction excavators were used solely for utility works. The technology is evolving and rapidly growing. SES is continually shifting and adapting to its clients’ needs. The company often provides on-site consultation and problem-solving solutions.

SES has recruited and retained highly skilled and experienced operators who play a supportive team role and provide tailored solutions and the highest level of customer satisfaction.

The company has a rapidly evolving fleet to meet the elevated demand for trenchless suction excavation. low-level skips ready for disposal and removal from site.

This allowed the suction excavator to remain on site at all times, ensuring continuous working and maintaining excellent productivity.

SES managed the project safely, on time and within budget, much to the client’s satisfaction.

SES has since returned to carry out similar tasks for the same client and continues to receive positive feedback.

Far left: rear view of suction excavator showing extension arm and pipework on a different job Above left: another sewer being exposed by suction for repair and cleaning

For more information: www.suctionexcavatorsolutions.co.uk 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

Annual subscription – UK and Europe £95.00 (160.00 euros) Rest of the world US$170.00. Additional current copies are available to subscribers at £12 (US$21; €18) each Trenchless World (ISSN 1756-4107) USPS No: 023-551 is published monthly (except January & July) by Aspermont Media, 120 Old Broad Street, London EC2N 1AR, UK. Printed by Stephens & George Magazines, Merthyr Tydfil, UK The 2014 US annual subscription price is US$170. Airfreight and mailing in the US by Agent named Air Business, c/o WorldNet Shipping USA Inc, 155-11 146th Avenue, Jamaica, New York, NY11434. Periodicals postage paid at Jamaica NY 11431

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US Postmaster: send address changes to Trenchless World, Air Business Ltd, c/o WorldNet Shipping USA Inc, 155-11 146th Avenue, Jamaica, New York, NY11434 Subscription records are maintained at Aspermont Media Ltd, Chancery Exchange, 10 Furnival Street, London EC4A 1YH, UK Aspermont Media, publisher and owner of Trenchless World (‘the publisher’) and each of its directors, officers, employees, advisers and agents and related entities do not make any warranty whatsoever as to the accuracy or reliability of any information, estimates, opinions, conclusions or recommendations contained in this publication and, to the maximum extent permitted by law, the publisher disclaims all liability and responsibility for any direct or indirect loss or damage which may be suffered by any person or entity through relying on anything contained in, or omitted from, this publication whether as a result of negligence on the part of the publisher or not. Reliance should not be placed on the contents of this magazine in making a commercial or other decision and all persons are advised to seek independent professional advice in this regard.

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