Boring - Trenchless International

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istt news April 2010 - Trenchless International South African award recognises HDD project A reticulation project in South Africa, using horizontal directional drilling to connect ten buildings in Johannesburg’s CBD, has received the 2009 SASTT Award for Excellence. The Joop van Wamelen SASTT Award was presented to Managing Member Sam Efrat and General Manager Marco Camarda of Trenchless Technologies cc at the SASTT Annual General Meeting by the outgoing SASTT President Johann Wessels. The award ceremony took place at the regional offices of Johannesburg Water in Midrand on 2 February 2010. Award ceremony L-R, Marco Camarda, Samuel Efrat and Johann Wessels. Fast facts • Contractor: Trenchless Technologies cc • Employer: ABSA Bank Limited • Project Managers: Mokala Collins/JM Henrey & Associates Joint Venture • Consultants: Taemane/SDE and Asak/LC. The project The works involved connecting ten of ABSA Bank’s buildings in Johannesburg’s CBD with 100 underground sleeves for electricity, gas, fibre optic, as well as low temperature hot water and chilled water. Drilling took place from building basement-to-basement beneath the busy CBD roadways, at depths of up to 16 metres, using horizontal directional drilling. Sleeve diameters ranged in size from 160, 225, 450, 500, 560 and 710 mm using PE 100 PN 8 HDPE pipe. The 160 mm and 225 mm sleeves were installed in bundles of three, four or six pipes. The ten month contract had a value of R13 million ($US1.7 million). The type of contract document used was the NEC3. Challenges and solutions The ABSA building’s basement floors were originally designed to support the weight of a typical sedan vehicle. Consequently the Terra-Jet 7520 automatic rod loading system was removed to decrease the machine weight and propping was undertaken from the floor below to support all areas over which the drill needed to travel into the required positions within basements. A floor to sprinkler height restriction required that all equipment be less than 2.1 metres in height. Consequently the Terra-Jet 7520 was further modified by removing the operator cabin, rebuilding the hydraulic oil tank at a lower position and lowering the encapsulating body work such that the remodelled drill resembled a tank with a height of only 1.8 metres. The majority of the installations took place in clay whilst the remaining 20 were in rock. The presence of the rock necessitated the use of percussive hammer and rock reamers to expand the holes to the required diameters. Lateral support ground anchors were encountered during drilling on 26 of the Terra-Rock Air Percussion Head OD 95. TCI Roller low torque rock reamer. crossings. The presence and position of these were unforeseen, and resulted in the entanglement of drilling equipment in several instances. Drilling tools were pulled, pushed and rotated until they became free or broke the ground anchoring cables. In two instances the entangled cable would not break and an acetylene oxygen cutter was modified and inserted within the bore to cut the cable and free the drilling tools. In order to gain access to the drill face, coring to remove concrete lateral walls from 300 – 500 mm thick was required. Containment of the large volumes of bentonite and spoil was a necessity as the basements are maintained in a pristine condition and in daily use. This was made possible using specially constructed tanks and brick burms. The removal of bentonite to the surface was one of the greatest challenges the project faced. Initially pumping, which is by far the preferred method of spoil removal did not look feasible. This was due to requiring extremely long pipe lengths – of up to 600 metres – to remove the bentonite from basement-to-basement up the vehicular ramps. However, at the planning stage the idea was put forward Ground anchor in rocky bore. Pilot drill and bentonite collection. to core holes through the slabs and enable vertical pumping along the shortest route to reduce pumping lengths to less than 200 metres. For the first six months of contract no drilling was allowed during the ‘freeze period’ from the 26th of the preceding month to the 5th of the following month. This was to prevent any potential damage to cables and infrastructure during the busy end of month banking period. This resulted in a very tight work schedule necessitating crews to work day and night shifts, seven days a week. The location of drilling equipment on either side of the walls was required through concrete, rock and at depths of up to 16 metres. Trenchless Technology cc made use of the radio detection i-track system and tracked the equipment horizontally from the basements on either side of each crossing. Confined access into basements via vehicular ramps required short six metre lengths of HDPE pipe to be individually transported down into basements where they were butt-welded into long continuous lengths for installation. Whilst in the museum the only access was by means of a lift and pipe lengths were limited to three metres. Here, and in other confined and storage areas and plant rooms, the bentonite was collected in tanks and removed in ‘wheelie’ bins. In two instances the HDPE pipe was hammered into the completed bore from the drill machine side in a pipe ramming operation, as there was no access to pull the piping in from the opposite side of the bore. The benefits of using Trenchless Technology for the ABSA project The installations were exceptionally deep, precluding conventional excavation methodology. There was no damage to roadways and existing buried infrastructure, nor was there any disruption to pedestrian and vehicular traffic in the busy CBD area. Cost savings were also significant when compared to other possible methodologies. Why HDD? HDD allowed the insertion of the preferred HDPE sleeves without requiring the installation of a temporary pipe or permanent rigid pipe, followed by the HDPE pipe installation. HDD required no thrust abutment wall, and also allowed for adequate steering accuracy. The equipment is selfpropelled and capable of drilling in a wide range of soil conditions including clay and rock. It is also sufficiently compact and manoeuvrable to be able to operate in the confined basement spaces. Six metre lengths of HDPE piping. Trenchless Technologies cc was established in 1991 and to date have completed over 220,000 metres of trenchless pipeline rehabilitation and new installation works. They have been the Southern African agent for Terra AG since 1993. Previous awards include the SAICE Pretoria Branch Award for Technical Maxi-Rig Directional Drills Auger Boring Machines Product Tooling & Accessories Mud Pump & Cleaning Systems Oil & Gas Drill Rigs Mid-Size Directional Drills Completed installation with basement returned to their pristine condition. Excellence in 2000, along with the City of Tshwane and consultants Bigen Africa, for the rehabilitation of sewers in Mamelodi. The SASTT Award of Excellence in 2007, along with Johannesburg Water and Consultants Vela VKE for the rehabilitation of sewers pipes in Klipspruit Basin. Exceptional Force … Reliable Results. For 40 years, customers worldwide have come to know American Augers as a dedicated manufacturer of underground technology equipment, which includes state-of-the-art horizontal directional drills, earth boring machines, mud pump and cleaning systems, oil and gas drill rigs, and various product tooling or accessory items. Each of the product categories produce equipment that maintains rugged, unsurpassed power, and industry leading designs. istt news April 2010 - Trenchless International 18 AA Company island Ad TI.indd 1 12/14/09 4:57 PM 19
Outstanding support for No-Dig 2010 istt news April 2010 - Trenchless International 20 The international Trenchless Technology community is lining up in force to support the ISTT’s 28th Annual International No-Dig Conference and Exhibition, to be held in Singapore 8–10 November 2010. The Right Tool Manhole Renewal Tool Box Permacast® Liners Cor+Gard® Coatings Permaform ® Con MIC Shield® Calcium Aluminate Cements Water Plug & Patch COR+ROC Structual Polymer I & I Barrier® Top Seal TM CIPPChimney Liners Spray Equipment Applicators Worldwide in Denmark, Ireland, UK, Singapore, Israel, Norway, Sweden and USA. For Every Problem! AP/M PERMAFORM ® Fax: +515.276.1274 • www.permaform.net Headline sponsorship packages have been taken up by Vermeer and Pure International and key manufacturers from around the globe have already booked some 80 per cent of the available exhibition space. In addition to National Pavilions from Germany and Singapore, China is participating with a significant presence alongside individual representation from UK, North America, Denmark, Italy, Australia, Japan, UAE and Malaysia. The Conference call for papers has drawn more than 50 offers from potential presenters and Professor Sam Ariaratnam, Vice- Chairman of ISTT and head of the Program Committee said “We are delighted with the range of presentations that have been offered for the Singapore conference. This is the first time that ISTT has presented a conference in this location and I am confident that the program will have a wide appeal, not only to delegates from the Asia Pacific region, but also from ISTT affiliated members around the world – many of whom are already anticipating group delegations.” The closing date for papers is 15 March and the full Conference program is scheduled for publication in July. International No-Dig 2010 is organised by ISTT, who have engaged the official support of several influential organisations, including Singapore’s National Water Agency, PUB. They are also joined by the Institution of Engineers Singapore, Institution of Civil Engineers, Tunnelling & Underground Construction Society (Singapore) and the Malaysian Water Association. Singapore is a regional centre of excellence for Trenchless Technology, established through many major microtunnelling projects undertaken by PUB. The ongoing sewer rehabilitation program continues today, as PUB maintains some 3,400 kilometres of public sewers and the current phase (2009–2014) will see the refurbishment of more than 1,000 kilometres of this network. For more information on exhibition space availability, sponsorship opportunities and the conference, contact Westrade Group Ltd Tel: +44 (0) 845 0948066 Email: trenchless@westrade.co.uk Full details of International No-Dig 2010 are also to be found on the show website www.nodigsingapore.com The fastest way to bore through hard rock is with a Robbins SBU-A. Extreme conditions? The machine can bore up to 150 MPa UCS. Mixed ground? Just change the cutterhead. Talk with Robbins about leasing or buying the most cost-effective solution for your next project. Crack hard rock with confidence. therobbinscompany.com sbusales@robbinstbm.com +1 440.248.3303
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