All necessary investigation work was carried out during the week to locate and identify existing underground assets before the bore path was plotted. Drilling operations began at 7 am on Saturday morning. The drill head was ‘out’ by 11:30 am after drilling through a variety of ground conditions from clay through to sand and some sandstone.

The conduit was attached via a special pipe trailer accommodating 250 m, saving any manual handling and a specialised vacuum truck was on hand to remove excess drilling fluids and clean up in the event of any ‘frac-out’ occurring.

A bentonite mixture to suit the ground conditions was made in the drilling mixing tanks and then the conduit installation operation began. Pull-back operations took about two hours, including site clean up and equipment pack up. Traffic control was used as a speed control measure and for general safety reasons.

Once again a very successful and timely HDD operation, no trenches, no costly reinstatement, and the project completed in one day without disturbance to anyone. Communication conduits at Docklands

BTB was used by Communications Connect Pty Ltd to install a large project for Optus in the new Docklands precinct and also to deliver communications to the new Bureau of Meteorology Building. HDD techniques were successfully used to install the communication conduits, thus preventing disturbance to large areas of new footpath and roadway infrastructure and minimising any impact on vehicle and pedestrian traffic.

Installation of a signalling conduit at Mentone Station

The drill involved boring from one side of the station, under the platform areas and railway tracks and entry into car park area on opposite side. The bore was completed successfully with no disruption to any rail traffic and pedestrian traffic at the station area. Installing new water mains for Scariff Constructions at Scotch College, Hawthorn

BTB was engaged to use HDD to install a large number of new water mains in the pristine grounds of Scotch College.

Pipe diameters ranged from 50 mm up to 250 mm and BTB demonstrated that HDD was an excellent technique to use on a project that needed care and skill to successfully install the new water mains in some very tough rock ground conditions in areas that included pristine gardens and many old buildings and paths that could not be disturbed.

All installations were completed on time and without disturbance, once again demonstrating the advantages of a professional HDD operation.

M41 Water Main

The replacement of the M41 Water Main for Melbourne Water was a critical project for Melbourne Water’s ongoing commitment to improve water supply infrastructure.

The project involved replacement of the arterial main which provides the primary north–south transfer of potable waters. The old main was first laid in the 1880s, although some sections were upgraded in 1926. The main had a history of leaks and it needed to be replaced.

Critical to the selection process was McConnell Dowell’s technical expertise in the area of microtunnelling. The selected route traversing Swan St, and beneath Victrack’s Main Eastern Line at Richmond Railway Station. Further, the alignment crossed through the sensitive Yarra Park and the MCG environs requiring management of over 200 mature Dutch Elm trees.

A second major pipe jack extended out of the MCG Park and under Wellington Parade South. The pipeline was laid through extensive existing infrastructure and required negotiatiory 220 kV HV service to the CBD.

The project team successfully inter-faced and engaged in a consultative process with in excess of 28 key stakeholder groups in order to protect all assets and environmentally significant Elm Trees and Eucalypts within Yarra Park.

Detailed Tree and Turf and Asset Management Plans were prepared for all key sporting events and traffic and pedestrian management was key to the successful outcome of the project. Testimony to the success of the project was the fact that no community concerns or complaints were raised during the course of the works.

Georges River Project Hoxton Park Pipe Jacking

The Georges River Project for Sydney Water was a major infrastructure project to improve the wastewater treatment programme at Hoxton Park in Sydney, New South Wales.

The contract involved the underground pipe jacking construction of sewerage transfer pipes of 1.4 m, 1.6 m and 1.8 m diameters with a total installed length of approximately 2,000 m. The sewerage transfer pipes connect into the Liverpool Sewerage Treatment Plant.

The works took place within the Liverpool CBD area and in residential areas, requiring the installation of significant noise attenuation measures to mitigate noise disturbance to local residents. This was achieved using sound barriers manufactured using a material called “Wavebar” which greatly reduced noise disturbance from the works.

The project included a 670 m long pipe jack, the longest in Australia for a 1.8 m diameter pipeline. This was achieved through continually varying ground conditions. To achieve these long distance pipe jacks McConnell Dowell were required to adopt latest developments in pipe jacking techniques, including several interjacking stations, automated lubrication systems and the use specialised polymers to assist with reduced jacking loads. Purpose designed jacking pipes used for this project were imported from Germany. These pipes are manufactured using aggregate and resin only without steel reinforcing and are therefore not susceptible to corrosion.

Bankstown Cable Tunnel

The Bankstown Cable Tunnel Project involved the construction of three cable tunnels all located in the Bankstown/Punchbowl area of Sydney.

The three cable tunnels had a total length of 245 metres consisting of 69 m under a suburban railway corridor, 98 m under a primary arterial road and 78 m under a major waterway. The purpose of the tunnels was to allow the laying of 132 kV cables to transfer power from Sefton/Greenacre Park to Bankstown Substations. The works formed part of the 132 kV supply upgrade at Energy Australia substations within the inner Sydney suburbs.

The cable tunnels were constructed from reinforced concrete jacking pipes with an internal diameter of 1500 mm. Each jacking pipe was 3 metres long and manufactured by a vertical cast method in Newcastle. The pipes were then transported by road to Sydney.

This was a fast-tracked project completed in a 16-week period including TBM and pipe procurement. The design team included both URS and McConnell Dowell personnel.

The tunnel alignments were designed to be entirely within bedrock consisting of Ashfield Shales, Bringelly Shales (UCS range 6-24 MPa) and sandstone (UCS 168 MPa).

The ground conditions dictated the use of a mixed face cutter head and the discharge of excavated materials by slurry pumping.

The overburden soils at all jacking and receiving pits were supported with timber and steel sets and the lower exposed rock used friction bolts and mesh for support.

Access to each tunnel was provided by the construction of entry/exit pits and inclined structures using a combination of precast concrete pipes of 1800 mm internal diameter and in-situ cast concrete bends. Design constraints for these structures included a minimum bend radius for the 132 kV cables and the provision of access walkways into the tunnel.

JOCASP, Manila Ninoy Aquino International Airport, Philippines

McConnell Dowell Philippines Inc were awarded an Engineering Procurement and Construction (EPC) Aviation Fuel Project by Pilipinas Shell Petroleum Corporation, at Manila’s Ninoy Aquino International Airport.

The contract involved the relocation of the Joint Oil Companies Aviation Fuel Storage Plant (JOCASP), from a congested site between Passenger Terminal I and II, to a new greenfields location on the southeastern fringe of the Airport.

The Scope of Work called for the construction of Bridger Area for fuel importation by road tankers, a new Tank Farm which included 6 x 5,000 cubic metres of Jet A1 Fuel Storage Tanks and an Into Plane Area. Fire Water Storage, Fire Fighting Systems, Administration and Control Buildings/Systems and Aviation Fuel Pipelines were also included.

The Aviation Fuel Pipelines consisted of 5,500 linear metres x 450 mm diameter, internally lined, HPDE Coated Pipe, connecting the new Tank Farm to the existing fuel lines at Terminals I and II. Another branch line now takes fuel to the new International Terminal III.

Included in the pipeline are special high point air vents and low point drains. Two runway crossings were required for the pipelines, resulting in microtunnelling techniques being employed. Two drives using Herrenknecht AVN 1500 microtunnelling equipment totalling 555 linear metres were undertaken.

The tunnels were driven under live runways and taxiways within the airport to provide a duct to run aviation fuel lines to a new terminal building being constructed. This option was adopted to avoid the disruption that open cut pipeline trenching would have caused to the operation of the airport.

Working ‘airside’ within an international airport presented its own set of unique challenges to overcome including cranage restrictions due to the proximity of live runways and full time two-way radio communication between site and air traffic control.

The tunnels were in the order of 8 metres below ground level and driven through ground conditions that varied between stiff to very stiff clay and volcanic tuff.