Interceptor sewer and access tunnels, in total 20km of TBM drive using three Wirth machines of diameters 6.57m, 6.33m and 3.8m. Access tunnels driven by roadheader. Spoil from North Head excavations will be transferred to a loading wharf. Small TBM started October 1998 and large machines early-1999. Completion 2000. Dec 1998.
First breakthrough recorded at Little Manly Point by 3.8 m Wirth after 1.2 km drive in 10 weeks. Advances of 40 m per 10 h shift, and cutter life consistently more than 200 m. Machine upgraded for 7.5 km Lane Cove tunnel starting June, 1999. The second and third Wirth TBMs will commence their drives in July and august, 1999. Northside Storage Alliance comprises Transfield, Montgomery Watson, Connell Wagner and Sydney Water. June 1999.
Connell Wagner reports project will capture sewage from four major overflow points for transfer to North Head STW and discharge through ocean outfall. Ten shafts, 3 km of access tunnels and two underground pumping stations completed. Project now has a fourth TBM, a Robbins remanufactured by Terratec and increased in diameter from 5.5m to 6.5 m. This is a double shield with multiple modifications by Terratec to suit the Sydney sandstones. Due to the tight delivery requested, CTS of Kent, WA, USA assisted with design services.
The Wirth 3.8 m and 6.56 m TBMs are consistently achieving 250 m/week, and all three are now on 2 x 12 h/day operation. The 180 m-high, 650 t/h vertical shaft conveyor at North Head is the longest in the southern hemisphere, possibly in the world. Most of spoil removed by barge for reuse inland. December 1999.Contractor reports final breakthrough on Sunday, 16th July to complete 20 km of storage tunnel and all other tunnelling on the project within a two-year span. Total excavation 1.8 million t, or 720,000 cu m, of sandstone and shale, one-third by roadheader and two-thirds by TBM. Visit www.connellwagner.com and www.wirth-drilling.com July 2000.
