Karepiro Drive

Whangaparaoa, Auckland

Background

This project involves the formation of 127 industrial and residential lots. Extensive earthworks are required to form the lots, including the remediation of existing large scale land instability.

The site falls steeply towards the north with a stream at the base. Historic landslides and faulting of the bedrock are present throughout the site. Earthworks operations to form the subdivision will take place over a four year period.

CMW staff have been involved since the inception of the project in 2008.

Scope

• Site investigation including hand augers, machine borehole and test pits;
• Ground modelling;
• Stability analyses;
• Remediation design including palisade walls, retaining walls, shear keys, pavements and reinforced earth slopes;
• Construction supervision and support;
• Geotechnical Completion Certification.

Findings/Challenges

Challenges on the site include poor ground conditions, temporary stability during construction works, control of high localized groundwater flows and complex construction sequencing.

Shear zones are present throughout the soil profile correlating with the geomorphic evidence of historic movement. Constructing the remedial works without causing further instability meant careful liaison with the contractor was required along with extensive onsite supervision.