Wellington Regional Stadium site assessment

The Wellington Regional Stadium is one of a number of projects planned or under construction along Wellington’s reclaimed waterfront. Each of these projects has had to consider ground stability with respect of liquefaction and lateral spreading, taking into account Wellington’s relatively high seismic activity and the weak and variable nature of the reclaimed land.

The proposed stadium site straddles two distinct areas of reclamation; one of hydraulic fill and the other of end tipped gravel fill. The potential for liquefaction and lateral spreading of the site has been assessed. A relatively high potential for liquefaction of the hydraulic fill sands has been concluded. On the basis of an approach proposed by Newmark [4] a potential for up to 1 m of lateral movement of the site has been predicted under the design earthquake (600 to 800 year return period). Ground improvement options have been considered to mitigate these predicted movements. The formation of gravel columns by vibro-replacement has been concluded to be an appropriate form of ground improvement.