Dudley Creek Flood Remediation Bypass Outlet



  • Installation of 20 no. 7.9m wide culverts
  • Installation of two in situ wingwalls and soffit structure
  • Dewatering using a combination of spears and well points
  • 104 metres of sheet piling including a cofferdam in the river
  • 0.5m high retaining wall of 5.8m length
  • Construction of 22 no. 1m x 1m x 1m gabion baskets
  • Significant steel works for the viewing platform
  • Bespoke purple heart timber decking
  • Stormwater drainage
  • Pavement and footpath works

Project Description:

Seipp Construction was awarded this Christchurch City Council project based alongside the Avon River, which was badly affected by the 2011 Canterbury earthquake. The works involved installation of 30m of culverts and an outlet structure to complete an 800m long culvert run taking flood waters out of Dudley Creek to the Avon River. The works will bring flooding levels to below pre-earthquake levels and reduce flooding of about 600 houses.
Project highlights included the feat of placing 20 culverts within one day using a 110T Crane, the high quality finish of the outlet structure and associated viewing platform and the aesthetically pleasing, hand stacked, angular basalt rock which made up the 22 gabion baskets.

Seipp Construction are dewatering experts. Our experience includes wellpoint systems, large and small diameter wells and surface dewatering. We have comprehensive controls in place, including 24-hour rem ote monitoring of all pumps, live web access to the data of turbidity metres installed at the point of discharge and pH sensors. This system is a New Zealand first and enables immediate action in the face of any issues. We also have an extensive range of sediment and decanting binds, including oil separators.

Client: Christchurch City Council
Main Contractor: Downer NZ Ltd
Start Date: December 2016
Completion Date: July 2017