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Mt Eden stormwater diversion works Updates

mt eden STORMWATER works - UPDATES

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On this page you will find a brief introduction to the stormwater work in the Mt Eden area.

THE WORKS

City Rail Link's C6 contract involved diverting a section of the existing Mt Eden stormwater pipe. It created a new alignment between Water and Nikau Streets to enable CRL's redevelopment of the Mt Eden train station. The existing stormwater pipe was in the path of the new CRL tunnels that will be built there.

March Bessac Joint Venture (MBJV) was awarded the contract to undertake the works. MBJV is a partnership between NZ-based company March Construction and specialist French-based tunnelling company Bessac.

A micro-tunnel boring machine named Jeffie simultaneously tunnelled and laid a replacement 420-metre section of stormwater pipe. She was launched from a 16m-deep shaft at Water Street and arrived at her Nikau Street reception shaft in April.


THE NUMBERS

Water Street launch shaft: 16m deep secant pile construction, 8.5m internal diameter

Mt Eden Road access shaft: 18m deep, 2.5m internal diameter

Nikau Street reception shaft: 15m deep shaft, 9.4m internal diameter

Length of new stormwater line: 420 metres

Number of concrete pipe segments used: 215


In addition to the stormwater realignment, pollutant traps were installed at Boston and Normandy Roads as part of the stormwater network improvements for Auckland. They capture large and non-biodegradable waste such as litter and coarse sediment to prevent it reaching waterways.


THE MACHINE USED

Micro-tunnel boring machine

The tunneling was done by a German-built Herrenknecht AVN machine. You can read about how it works here.

The machine was named Jeffie following a hugely popular CRL social naming contest. The most popular name was Jeff but traditionally such machines adopt a female name so Jeffie - a popular girls name in the early 1900s - was chosen.

Naming digging equipment after women is said to be a tradition that dates to the 1500s when miners prayed to St. Barbara to keep them safe underground.

Saint Barbara is the patron saint of armourers, artillerymen, military engineers, miners and others who work with explosives because her legend associated her with lightning.

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PROJECT UPDATES


08 July 2019

Nikau Street

We have now completed the excavation chamber and exposed part of the pipe connection at Nikau St.

The ground conditions for mining the connection tunnel from the Nikau St shaft to the existing stormwater pipeline have been challenging. We have had to take extra care not to damage the concrete pipe while removing the hard material covering it.

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To give us room to be able to work and dig around the existing pipe, we have excavated out and stabilized a working chamber in the ground. Rock bolts have been drilled into the walls and roof to hold them in place.

Mt Eden Hole in ground 8 July 2019.jpg

Water Street

We have completed the lower level of the permanent access chamber at Water St. The level now includes the tunnel connection to the existing stormwater pipe.

Once the tunnel connection is complete and concreted we can break into the pipeline connecting it to the tunnel we have made. This is the last step required for completion of the storm water diversion project.

28 Mt Eden Rd

Access to the tunnel has been cut and we are placing the precast cylindrical concrete risers into the shaft to create the permanent access chamber.

Three of the seven risers are in place and the remaining four will be placed in the next few days. The lid can then be installed, after which we will start to clean up and demobilize.


19 June 2019

Jeffie leaves

From solving a stormwater issue in Auckland to helping the water supply in Ecuador.

She has just finished replacing the stormwater main around Mt Eden’s Water and Nikau Streets as it was in the path of the future CRL tunnels.

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She's shown heading to port for her sea voyage.

The micro tunnel boring machine is off to dig a 4km long tunnel in the second biggest city in Ecuador, Guayaquil. Guayaquil is on a river estuary and the tunnel will take water from the river to a new treatment station.

The machines are given female names as an acknowledgment of St Barbara, patron saint of miners and tunnellers, and Jeffie will be blessed with a new name in Ecuador.



FOR INFO ABOUT THE REDEVELOPMENT —