One of the largest sewers in Melbourne, the South East Trunk Sewer is the backbone of the eastern system, connecting the Kew Pumping Station to the Eastern Treatment Plant. The South East Trunk Sewer carries an average flow of about 350 million litres per day, with capacity to reach a maximum of 1700 million litres a day.

The Trunk Sewer is 55,000 feet (16.8km) long, consisting of 33,000 feet (10km) of 8 ft 6 inch (2.6m) diameter, 11,000 feet (3.4km) of 10 ft (3.05m) diameter and 11,000 feet (3.4km) of 11 ft 6 inch (3.5m) diameter lined conduit. The tunnel grade varies from 1 in 1330 to 1 in 2244. There are 11 changes in direction along the tunnel line with 800 foot radius curves adjacent to the shafts. There are 12 major permanent shafts of 10 foot (3.05m) lined diameter which are generally distributed equally along the line of the tunnel which vary in depth from 60 to 220 feet(18.3 to  67m). The tunnel lining is unreinforced concrete which is rich in sulphate resisting cement.
Construction commenced in 1965 and was completed in 1974 at a total system authorized cost of $164,000,000.  The authorized cost of the rock tunnel section of 10.5 miles was $18,060,755.
The10 ½ miles (16.8km) of tunnel from Kew to Moorabbin lie within Silurian strata. Over the southernmost 2 miles (3.2km) of this length the Silurian bedrock is capped with water bearing Tertiary sandy sediments leaving only 20 to 50 feet (6 to 15.3m) of rock cover above the tunnel. The Silurian strata are intensively folded with extensive faulting and shearing, a deep level of weathering and frequent dykes. Moderate groundwater flows of varying salinity occur over most of the tunnel length.
Conventional tunnelling for these diameters at this time required 100% ground support with ribs and heavy timbering, and face boards and forepoles in sheared zones achieving only about 10 feet (3.05m) per shift. Following the success of the Tasmanian Hydro-electric Commission with a Robbins TBM at Poatina, it was decided to pursue a bored tunnel.
The proposal was for a single machine to excavate both the 8ft 6 inch (2.6m) and 10 ft (3.05m) diameter tunnels. A Robbins rock TBM suitable for excavating the Melbourne Silurian was selected with interchangeable cutters, a thrust system designed for broken and soft wall conditions, a muck disposal system capable of handling sticky material, a ground containment system which allowed ring beams and lagging to be erected within its shelter, provision for diameter changes from 11 ft (3.35m) to 12 ft 8 inch (3.8m) to 14 ft 5 inches (4.4m), and an advance rate of 6ft/hour (1.8m/hr).
Excavation commenced early in 1968. Unfortunately progress was poor with less than 100 feet (30.5m) per week and many cave- ins. It was considered that the original design had some shortcomings including an unsupported span of 3 ft (0.9m) between the support shield and central cutter, protruding cutters disturbing unstable ground ahead of the face, small side entry buckets which were blocked by oversized material, disc cutters required high machine thrust, the front steering shoe tended to push into soft ground, and the necessity to hand mine around the head in caved ground.
The speed of the machine was therefore reduced from 6 ½ revolutions per minute to 3 1/3, replacement of the hydraulic shield to a fixed flexible 360 degree shield, some of the cutters were changed to drag-bits to lessen the disruptive forces at the face and at the grippers, three short flexible shields were fitted with trailing fingers with a movable arch to support forepoles, and improved flow of material through the buckets.
The provision of the revised shield provided greater stability of the tunnel crown and face, and the provision of drag bits ahead of the disc cutters reduced the required thrust. The modifications were successful and improved all short comings in the original design. Cave- ins still occurred but less frequently, and with improved access the average time required to control caving ground was reduced from an average of 25 shifts to 8 shifts. Prior to the head modification the 12 ft 8 inch (3.8m) tunnel achieved an average production rate of 4.13 ft/shift (1.25m); after modification this was increased to 16.51 ft/shift (5m).  Later production at 14ft 5inch (4.4m) diameter was 19.41 ft/shift (5.9m).

The construction of the South Eastern Trunk Sewer project of the then MMBW was a landmark in TBM technology. After an inauspicious start and machine difficulties, the re-design of the head of the Robbins machine by Dave Sugden, Frank Watson, Allen Neyland and The Robbins Company to produce “The Melbourne Head”, thereby produced record breaking performance and the design being replicated on many machines worldwide.

The MMBW over a period in excess of 30 years were at the forefront of TBM tunnelling and as well as the South Eastern Trunk Sewer, constructed the Frankston tunnel (using the same Robbins machine) as part of the ocean outfall from the Carrum Treatment Plant (now called Eastern Treatment Plant), the Dandenong Valley Trunk Sewer (DVTS), the Western Trunk Sewer (WTS) and North Western Sewer (NWS).

 The tunnelling works are part of the plant’s outfall and intake pipeline construction. Marine excavation works began in November 2009 with the arrival of the 2,400 tonne jack up barge, the Santa Fe, off the coast of Port Stanvac.
The 11.5 kilometre pipeline delivers desalinated water from Port Stanvac to the Happy Valley water treatment storage area. The Adelaide Desalination Project delivers up to 100 billion litres of water annually, which is approximately half of Adelaide’s water supply.

The Victoria Park Viaduct is a major motorway viaduct carrying the Auckland Northern Motorway (State Highway 1) over the Victoria Park area in Auckland City, New Zealand. Due to the high traffic volumes passing through on their way to and from North Shore City, and because the viaduct is only four lanes wide in total (while adjacent motorway stretches are at least six lanes), the bridge over the park is considered "one of the country's worst traffic bottlenecks",with around 200,000 vehicles a day.
As of early 2010, preparatory work near the St Mary's Bay onramp has begun. NZTA provide a project website. NZTA have also announced that the Birdcage hotel (sitting over the site of the future tunnel portal) will now be shifted 40m away only temporarily - eventually returning to almost the same site as before, and to become integrated into a new plaza space

The Northern Diversion Sewer Project was comstructed by Melbourne Water as part of the Northern Suburbs Sewerage Strategy. This $300 million upgrade of the sewer system in Melbourne’s north to improve the health of the Yarra and other Melbourne waterways. The project will help protect the Merri and Moonee Ponds creeks from sewage overflows that can occur after heavy rain. The new sewers will increase the capacity of Melbourne's sewerage system to meet the rapidly growing demand for services in the northern suburbs.

The project involves the construction of 13 km of new sewer pipes ranging in diameter from 1.6 to 2.5 metres and five major access shafts of up to 65 metres in depth and 13 metres in diameter.

AquaSure financed, designed, built, operates and maintains Australia's largest desalination plant on the South Gippsland coast.
AquaSure bought together three companies, all leaders in their fields:
• Degrémont - a SUEZ ENVIRONNEMENT company and world leader in reverse-osmosis desalination technology
• Thiess - one of Australia's largest and most trusted construction and services companies, and
• Macquarie Capital - the world's strongest and most experienced infrastructure advisor.
Thiess Degrémont designed and constructed the reverse osmosis desalination process plant, marine tunnels and structures, 84km water transfer pipeline and 87km underground powerline to supply power to the plant.
The Victorian Desalination Project is a key part of the State Government's Water Plan to save, recycle, distribute and create water.
It is the largest desalination plant in Australia, capable of supplying up to 150 billion litres of water a year - a third of Melbourne's annual water needs - with capability to expand to 200 billion litres a year in the future.

In November 2006, the Minister for Planning gave approval for the desalination project at Kurnell and the seawater intake and outlet structures. Blue Water (the joint venture of John Holland and Veolia Water) has been contracted by Sydney Water to design, construct, operate and maintain the desalination plant, tunnels and intake and outlet risers.
The plant will use reverse osmosis technology to remove salts and other impurities from seawater to produce drinking water. Water from the desalination plant at Kurnell will be pumped into Sydney's water distribution system through a pipeline from Kurnell, across Botany Bay to Kyeemagh. Seawater will be pumped into the plant through a tunnel from the Tasman Sea. From Kyeemagh the water will be distributed to up to 1.5 million people south of Sydney Harbour, to supplement their water supply. The proposed pipeline route from Kyeemagh connects to the main City Water Tunnel at Erskineville.
The land portion of the pipeline will be laid using a number of methods, including open trench and trenchless construction. Microtunnelling will mainly be used in residential areas and to cross rivers,
railways and major roads.

A joint venture between Downer and Seli (an Italian specialist tunnelling contractor) undertook the construction of a cable tunnel in Auckland for client Mercury Energy (which later became Vector) between 1997 and 2000. The Engineer for the contract was Tonkin & Taylor who undertook the detailed design and contract supervision.
The contract consisted of approximately 9kms of 3.0m diameter tunnelling with 3 primary shafts and several minor shafts providing network access to the city for power supply cabling. The tunnel follows an alignment from the Hobson Street substation in the CBD and then under public streets until it meets with the State Highway 1 southern motorway where it continues to the Grid Exit Point at Penrose.
The tunnel is located up to 80m below ground in the East Coast Bays Formation (ECBF) of the Waitemata group which are low strength (5-10MPa) interbedded siltstones and sandstones. The southern section of the project was overlain with basalt lava flows to a depth of approx 30m and required the Penrose shaft to use drill and blast methods for its initial sinking.
The project had three primary construction sites Hobson, Newmarket and Penrose with minor work carried out from Liverpool Street and Gilies Avenue.
The primary means of tunnel excavation were roadheader and TBM with the roadheader tunnelling being mainly undertaken from Hobson St and the TBM tunnelling from the Penrose site in Gavin Street.

Extract from Brisbane ATS Newsletter March 2008

 

Tunnelling is proceeding with extreme care at the Boggo Road Busway tunnel in South Brisbane.  In early March the tunnel had advanced around 100m and was located directly beneath the heritage listed gaol built back in 1903.  Canopy tubes and lattice girders are being utilised to manage ground settlement with the tunnel cover to surface getting down to five metres (see photo).

 

When completed, the 430m long tunnel will connect the South East busway to the recently opened Eleanor Schonell Bridge. 

 

Tunnelling commenced in September 2007 using a Voest Alpine AM105 roadheader.  The work is being undertaken in an alliance which includes Queensland Transport, Thiess, SKM and United Group. 

                                                         

 Photo:  Voest Alpine AM105 Roadheader at Boggo Road

 

                                                

The underground car park for Sydney Opera House with a capacity of 1,100 cars was officially opened by NSW Premier and Treasurer John Fahey on 17th March 1993, at a cost exceeding $40 million.
The Sydney Opera House car park, known as the Bennelong Point Parking Station, is unique in shape and size and has established a number of firsts during its construction.
It is the first helical underground parking station tunnels with a huge doughnut-shaped cavern, with a span of up to 19 m and an outer radius of 75 m, contains a 12 story free-standing double-helix concrete structure which, while providing 1100 parking spaces It is possibly the widest shallow-cover rock cavern in the world. The roof spans between 17.5 m and 19 m and comprises between 7 m and 8 m of variably weathered Hawkesbury sandstone, a rock which ranges in strength from 15MPa to about 40 MPa.
The roof is the key feature of the cavern. It is not supported with a formed concrete arch but rather, internal reinforcement comprising tensioned Macalloy bar anchors up to 7.5 m long and untensioned galvanised dowels up to 4.5 m long. There are about 2000 anchors and dowels in the roof. Design of the reinforcement system involved the development of a new design method which is described in a paper presented at the 7th ISRM Congress, Aachen, 1991.
 The impor¬tant design features of the roof are:
• the roof is almost flat, as this is found from both analytical studies and experience to be appropriate in horizontally bedded strata with a relatively high horizontal stress field
• the capacities and distribution of the rein¬forcing elements were designed so as to tie together the horizontal beds of sandstone (ranging in thickness from 1 m to 3 m) to act as a single pseudo-elastic no-tension linear arch.
• the roof surface is covered with a 150 mm skin of reinforced shotcrete and fibrecrete which acts as a membrane between the reinforcing elements.

Other special challenges in this project were
• portions of the underground excavations are beneath outbuildings of Government House.
• the cavern is within 60 m of Sydney Harbour and extends 28 m below sea level.
• all work had to be done without disrupting the surface other than for the two 9 m wide access which have to pass over the Sydney Harbour Tunnel and have, in places, rock cover as low as 2.5m.

In addition to the main cavern, 16 tunnels had to be excavated ranging in span from 2 m to 12 m.

Excavation of the access tunnels and the crown section of the main cavern was achieved primarily by a Mitsui S200 roadheader. This machine proved to be the first roadheader which could cut the high silica content Hawkesbury Sandstone (75% to 85% silt and sand size quartz) with both reasonable productivity and pick-wear rate. Attempts were made to use an AM65 in parallel with the Mitsui but, as in previous Sydney tunnelling projects, pick-wear rates were unacceptably high. A second S200 machine was brought onto the site and a small S65 machine was also used for a 1.6 m wide tunnel required for diversion of an old stormwater tunnel.
The crown section of the main cav¬ern was excavated by successive widen¬ing from an initial outer 6 m wide heading. Support was installed as the heading was widened from 6 m to 10 m to 15 m to 18 m. Careful monitoring of roof deflections, rock anchor loads and roof delamination was undertaken as the span increased, as a check against design assumptions. Once the crown was fully excavated and sup-ported, a D10 bulldozer fitted with an impact ripper was used for bulk excava¬tion, this was probably the first underground use of a Caterpillar D10 with an impact ripper. The cavern walls were trimmed by two Kato HD 1250 30 tonne excavators and one Kato HD900 fitted with Montabert hydraulic impact breakers. These were also used to cut slots up the cavern walls for ventilation risers and for excavation of the lift shaft

Instrumentation of the cavern included:
• multipoint extensometers installed from the ground surface prior to cavern excavation
• inclinometers installed around the perimeter and in the core prior to excavation
• sag measurement points on the cavern roof
• a subsidence grid on the ground above the cavern
• a piezometer network

Main cavern design calculations predicted roof sag of about 15mm at full span and also settle¬ment above the core of about 8mm. Monitoring showed that the roof rock deflected as a unit, with surface settlements being only a few millimetres less than internally measured roof sag.

Excavation of the cavern and associated tunnels, involving some 130,000 m3 of sandstone, started in late 1990 and was completed in April 1992. The twelve story concrete helix was com¬pleted in September 1992 and the parking station is expected to open March 17, 1993, six months ahead of schedule

The Northern Gateway Alliance is constructing New Zealands largest tunnel project

The 90-year-old sewer, which cuts across Hobson bay, will be demolished as part of the $118.6 million project let by Watercare Services.