Mob/Demob.: 3 vibro replacement rigs

Vibro replacement works: 100,879 lm

The project includes the design, build and construction for the new NSWWTP, which will have a state-of-theart secondary treatment and energy recovery facilities. The new plant will be built to LEED standards on a very compact site. Much of it will be buried underground. Its design incorporates energy efficiency and recovery solutions, water conservation and reuse, on-site storm water management and measures to minimize waste generation.

The subsurface conditions on site typically consisted of:

– a 1 m to 3 m thick upper granular Fill

– underlain by a 5 m to 8 m thick generally compact Upper Gravel, Sand, and Cobbles layer

– underlain by 3 m to 5 m of interbedded Silt, Sand, and Clayey Silt, loose to compact and significantly compressible

– underlain by a lower Gravel, Sand, and Cobbles layer up to a depth of 14 m to 19 m

– underlain by Sand down to a depth of 30 m to 45 m approximately

Carry out ground improvement using vibro-replacement (stone columns) using wet top feed methods to 29 m depth below average existing site grade. The ground improvement is intended to mitigate seismically induced soil liquefaction potential and minimize post-seismic settlements and lateral movements of structures. Full depth pre-drilling of every column was required to allow penetration of the vibro probe.