Opua Boat Yard, Contaminated Site Remediation

Client:                      Doug’s Opua Boat Yard
Location:                Opua, Far North
Project Value:       Undisclosed
Sector:                    Commercial/Industrial, Environmental
Completion:          April 2021


GWE was engaged to undertake in-situ and ex-situ ground contamination remediation and geotechnical design for specifically engineered retaining walls.

Typical of the land-use history, the site was identified to contain significantly elevated concentrations of select heavy metals and hydrocarbons.  Remediation was proposed as part of the Consent renewal process and to enable site redevelopment.

The GWE remediation involved lime stabilisation of significantly contaminated materials, removal to landfill and re-use of suitable materials in the redevelopment design.

To enable re-use of suitable materials on site, GWE undertook specific geotechnical design of cantilever retaining walls.  Adopting steel Universal Columns instead of timber poles to maximise useable space on the site with vertical walls.  The retaining walls were terraced into a slope in places and designed to restrict deflection movement on critical infrastructure.

GWE was retained to provide construction monitoring and validation of remediation works and retaining wall construction.


  • Contaminated and remediation
  • Professional witness services
  • Geotechnical investigation and design
  • Detailed engineering 3D modelling and drawings
  • Construction observation and compliance